package nomad

import (
	"context"
	"errors"
	"fmt"
	"io/ioutil"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/armon/go-metrics"
	capOIDC "github.com/hashicorp/cap/oidc"
	"github.com/hashicorp/go-hclog"
	"github.com/hashicorp/go-memdb"
	"github.com/hashicorp/go-set"

	policy "github.com/hashicorp/nomad/acl"
	"github.com/hashicorp/nomad/helper"
	"github.com/hashicorp/nomad/helper/uuid"
	"github.com/hashicorp/nomad/lib/auth/oidc"
	"github.com/hashicorp/nomad/nomad/state"
	"github.com/hashicorp/nomad/nomad/state/paginator"
	"github.com/hashicorp/nomad/nomad/structs"
)

var (
	// aclDisabled is returned when an ACL endpoint is hit but ACLs are not enabled
	aclDisabled = structs.NewErrRPCCoded(400, "ACL support disabled")
)

const (
	// aclBootstrapReset is the file name to create in the data dir. It's only contents
	// should be the reset index
	aclBootstrapReset = "acl-bootstrap-reset"

	// aclOIDCAuthURLRequestExpiryTime is the deadline used when generating an
	// OIDC provider authentication URL. This is used for HTTP requests to
	// external APIs.
	aclOIDCAuthURLRequestExpiryTime = 60 * time.Second

	// aclOIDCCallbackRequestExpiryTime is the deadline used when obtaining an
	// OIDC provider token. This is used for HTTP requests to external APIs.
	aclOIDCCallbackRequestExpiryTime = 60 * time.Second
)

// ACL endpoint is used for manipulating ACL tokens and policies
type ACL struct {
	srv    *Server
	ctx    *RPCContext
	logger hclog.Logger

	// oidcProviderCache is a cache of OIDC providers as defined by the
	// hashicorp/cap library. When performing an OIDC login flow, this cache
	// should be used to obtain a provider from an auth-method.
	oidcProviderCache *oidc.ProviderCache
}

func NewACLEndpoint(srv *Server, ctx *RPCContext) *ACL {
	return &ACL{
		srv:               srv,
		ctx:               ctx,
		logger:            srv.logger.Named("acl"),
		oidcProviderCache: srv.oidcProviderCache,
	}
}

// UpsertPolicies is used to create or update a set of policies
func (a *ACL) UpsertPolicies(args *structs.ACLPolicyUpsertRequest, reply *structs.GenericResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	args.Region = a.srv.config.AuthoritativeRegion

	if done, err := a.srv.forward("ACL.UpsertPolicies", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "upsert_policies"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of policies
	if len(args.Policies) == 0 {
		return structs.NewErrRPCCoded(400, "must specify as least one policy")
	}

	// Validate each policy, compute hash
	for idx, policy := range args.Policies {
		if err := policy.Validate(); err != nil {
			return structs.NewErrRPCCodedf(404, "policy %d invalid: %v", idx, err)
		}
		policy.SetHash()
	}

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.ACLPolicyUpsertRequestType, args)
	if err != nil {
		return err
	}

	// Update the index
	reply.Index = index
	return nil
}

// DeletePolicies is used to delete policies
func (a *ACL) DeletePolicies(args *structs.ACLPolicyDeleteRequest, reply *structs.GenericResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	args.Region = a.srv.config.AuthoritativeRegion

	if done, err := a.srv.forward("ACL.DeletePolicies", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "delete_policies"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of policies
	if len(args.Names) == 0 {
		return structs.NewErrRPCCoded(400, "must specify as least one policy")
	}

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.ACLPolicyDeleteRequestType, args)
	if err != nil {
		return err
	}

	// Update the index
	reply.Index = index
	return nil
}

// ListPolicies is used to list the policies
func (a *ACL) ListPolicies(args *structs.ACLPolicyListRequest, reply *structs.ACLPolicyListResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.ListPolicies", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "list_policies"}, time.Now())

	// Check management level permissions
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil {
		return structs.ErrPermissionDenied
	}

	// If it is not a management token determine the policies that may be listed
	mgt := acl.IsManagement()
	tokenPolicyNames := set.New[string](0)
	if !mgt {
		token, err := a.requestACLToken(args.AuthToken)
		if err != nil {
			return err
		}
		if token == nil {
			return structs.ErrTokenNotFound
		}

		// Generate a set of policy names. This is initially generated from the
		// ACL role links.
		tokenPolicyNames, err = a.policyNamesFromRoleLinks(token.Roles)
		if err != nil {
			return err
		}

		// Add the token policies which are directly referenced into the set.
		tokenPolicyNames.InsertAll(token.Policies)
	}

	// Setup the blocking query
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Iterate over all the policies
			var err error
			var iter memdb.ResultIterator
			if prefix := args.QueryOptions.Prefix; prefix != "" {
				iter, err = state.ACLPolicyByNamePrefix(ws, prefix)
			} else {
				iter, err = state.ACLPolicies(ws)
			}
			if err != nil {
				return err
			}

			// Convert all the policies to a list stub
			reply.Policies = nil
			for {
				raw := iter.Next()
				if raw == nil {
					break
				}
				realPolicy := raw.(*structs.ACLPolicy)
				if mgt || tokenPolicyNames.Contains(realPolicy.Name) {
					reply.Policies = append(reply.Policies, realPolicy.Stub())
				}
			}

			// Use the last index that affected the policy table
			index, err := state.Index("acl_policy")
			if err != nil {
				return err
			}

			// Ensure we never set the index to zero, otherwise a blocking query cannot be used.
			// We floor the index at one, since realistically the first write must have a higher index.
			if index == 0 {
				index = 1
			}
			reply.Index = index
			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

// GetPolicy is used to get a specific policy
func (a *ACL) GetPolicy(args *structs.ACLPolicySpecificRequest, reply *structs.SingleACLPolicyResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.GetPolicy", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_policy"}, time.Now())

	// Check management level permissions
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil {
		return structs.ErrPermissionDenied
	}

	// If the policy is the anonymous one, anyone can get it
	// If it is not a management token determine if it can get this policy
	mgt := acl.IsManagement()
	if !mgt && args.Name != "anonymous" {
		token, err := a.requestACLToken(args.AuthToken)
		if err != nil {
			return err
		}
		if token == nil {
			return structs.ErrTokenNotFound
		}

		// Generate a set of policy names. This is initially generated from the
		// ACL role links.
		tokenPolicyNames, err := a.policyNamesFromRoleLinks(token.Roles)
		if err != nil {
			return err
		}

		// Add the token policies which are directly referenced into the set.
		tokenPolicyNames.InsertAll(token.Policies)

		if !tokenPolicyNames.Contains(args.Name) {
			return structs.ErrPermissionDenied
		}
	}

	// Setup the blocking query
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Look for the policy
			out, err := state.ACLPolicyByName(ws, args.Name)
			if err != nil {
				return err
			}

			// Setup the output
			reply.Policy = out
			if out != nil {
				reply.Index = out.ModifyIndex
				rules, err := policy.Parse(out.Rules)

				if err != nil {
					return err
				}
				reply.Policy.RulesJSON = rules
			} else {
				// Use the last index that affected the policy table
				index, err := state.Index("acl_policy")
				if err != nil {
					return err
				}
				reply.Index = index
			}
			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

func (a *ACL) requestACLToken(secretID string) (*structs.ACLToken, error) {
	if secretID == "" {
		return structs.AnonymousACLToken, nil
	}

	snap, err := a.srv.fsm.State().Snapshot()
	if err != nil {
		return nil, err
	}

	return snap.ACLTokenBySecretID(nil, secretID)
}

// GetPolicies is used to get a set of policies
func (a *ACL) GetPolicies(args *structs.ACLPolicySetRequest, reply *structs.ACLPolicySetResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	if done, err := a.srv.forward("ACL.GetPolicies", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_policies"}, time.Now())

	// For client typed tokens, allow them to query any policies associated with that token.
	// This is used by clients which are resolving the policies to enforce. Any associated
	// policies need to be fetched so that the client can determine what to allow.
	token, err := a.requestACLToken(args.AuthToken)
	if err != nil {
		return err
	}
	if token == nil {
		return structs.ErrTokenNotFound
	}

	// Generate a set of policy names. This is initially generated from the
	// ACL role links.
	tokenPolicyNames, err := a.policyNamesFromRoleLinks(token.Roles)
	if err != nil {
		return err
	}

	// Add the token policies which are directly referenced into the set.
	tokenPolicyNames.InsertAll(token.Policies)

	// Ensure the token has enough permissions to query the named policies.
	if token.Type != structs.ACLManagementToken && !tokenPolicyNames.ContainsAll(args.Names) {
		return structs.ErrPermissionDenied
	}

	// Setup the blocking query
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Setup the output
			reply.Policies = make(map[string]*structs.ACLPolicy, len(args.Names))

			// Look for the policy
			for _, policyName := range args.Names {
				out, err := state.ACLPolicyByName(ws, policyName)
				if err != nil {
					return err
				}
				if out != nil {
					reply.Policies[policyName] = out
				}
			}

			// Use the last index that affected the policy table
			index, err := state.Index("acl_policy")
			if err != nil {
				return err
			}
			reply.Index = index
			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

// Bootstrap is used to bootstrap the initial token
func (a *ACL) Bootstrap(args *structs.ACLTokenBootstrapRequest, reply *structs.ACLTokenUpsertResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	args.Region = a.srv.config.AuthoritativeRegion
	providedTokenID := args.BootstrapSecret

	if done, err := a.srv.forward("ACL.Bootstrap", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "bootstrap"}, time.Now())

	// Always ignore the reset index from the arguments
	args.ResetIndex = 0

	// Snapshot the state
	state, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Verify bootstrap is possible. The state store method re-verifies this,
	// but we do an early check to avoid raft transactions when possible.
	ok, resetIdx, err := state.CanBootstrapACLToken()
	if err != nil {
		return err
	}
	if !ok {
		// Check if there is a reset index specified
		specifiedIndex := a.fileBootstrapResetIndex()
		if specifiedIndex == 0 {
			return structs.NewErrRPCCodedf(400, "ACL bootstrap already done (reset index: %d)", resetIdx)
		} else if specifiedIndex != resetIdx {
			return structs.NewErrRPCCodedf(400, "Invalid bootstrap reset index (specified %d, reset index: %d)", specifiedIndex, resetIdx)
		}

		// Setup the reset index to allow bootstrapping again
		args.ResetIndex = resetIdx
	}

	// Create a new global management token, override any parameter
	args.Token = &structs.ACLToken{
		AccessorID: uuid.Generate(),
		SecretID:   uuid.Generate(),
		Name:       "Bootstrap Token",
		Type:       structs.ACLManagementToken,
		Global:     true,
		CreateTime: time.Now().UTC(),
	}

	// if a token has been passed in from the API overwrite the generated one.
	if providedTokenID != "" {
		if helper.IsUUID(providedTokenID) {
			args.Token.SecretID = providedTokenID
		} else {
			return structs.NewErrRPCCodedf(400, "invalid acl token")
		}
	}

	args.Token.SetHash()

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.ACLTokenBootstrapRequestType, args)
	if err != nil {
		return err
	}

	// Populate the response. We do a lookup against the state to
	// pickup the proper create / modify times.
	state, err = a.srv.State().Snapshot()
	if err != nil {
		return err
	}
	out, err := state.ACLTokenByAccessorID(nil, args.Token.AccessorID)
	if err != nil {
		return structs.NewErrRPCCodedf(400, "token lookup failed: %v", err)
	}
	reply.Tokens = append(reply.Tokens, out)

	// Update the index
	reply.Index = index
	return nil
}

// fileBootstrapResetIndex is used to read the reset file from <data-dir>/acl-bootstrap-reset
func (a *ACL) fileBootstrapResetIndex() uint64 {
	// Determine the file path to check
	path := filepath.Join(a.srv.config.DataDir, aclBootstrapReset)

	// Read the file
	raw, err := ioutil.ReadFile(path)
	if err != nil {
		if !os.IsNotExist(err) {
			a.logger.Error("failed to read bootstrap file", "path", path, "error", err)
		}
		return 0
	}

	// Attempt to parse the file
	var resetIdx uint64
	if _, err := fmt.Sscanf(string(raw), "%d", &resetIdx); err != nil {
		a.logger.Error("failed to parse bootstrap file", "path", path, "error", err)
		return 0
	}

	// Return the reset index
	a.logger.Warn("bootstrap file parsed", "path", path, "reset_index", resetIdx)
	return resetIdx
}

// UpsertTokens is used to create or update a set of tokens
func (a *ACL) UpsertTokens(args *structs.ACLTokenUpsertRequest, reply *structs.ACLTokenUpsertResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	// Validate non-zero set of tokens
	if len(args.Tokens) == 0 {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "must specify as least one token")
	}

	// Force the request to the authoritative region if we are creating global tokens
	hasGlobal := false
	allGlobal := true
	for _, token := range args.Tokens {
		if token.Global {
			hasGlobal = true
		} else {
			allGlobal = false
		}
	}

	// Disallow mixed requests with global and non-global tokens since we forward
	// the entire request as a single batch.
	if hasGlobal {
		if !allGlobal {
			return structs.NewErrRPCCoded(http.StatusBadRequest,
				"cannot upsert mixed global and non-global tokens")
		}

		// Force the request to the authoritative region if it has global
		args.Region = a.srv.config.AuthoritativeRegion
	}

	if done, err := a.srv.forward(structs.ACLUpsertTokensRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "upsert_tokens"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Snapshot the state so we can perform lookups against the accessor ID if
	// needed. Do it here, so we only need to do this once no matter how many
	// tokens we are upserting.
	stateSnapshot, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Validate each token
	for idx, token := range args.Tokens {

		// Store any existing token found, so we can perform the correct update
		// validation.
		var existingToken *structs.ACLToken

		// If the token is being updated, perform a lookup so can can validate
		// the new changes against the old.
		if token.AccessorID != "" {
			out, err := stateSnapshot.ACLTokenByAccessorID(nil, token.AccessorID)
			if err != nil {
				return structs.NewErrRPCCodedf(http.StatusInternalServerError, "token lookup failed: %v", err)
			}
			if out == nil {
				return structs.NewErrRPCCodedf(http.StatusBadRequest, "cannot find token %s", token.AccessorID)
			}
			existingToken = out
		}

		// Canonicalize sets information needed by the validation function, so
		// this order must be maintained.
		token.Canonicalize()

		if err := token.Validate(a.srv.config.ACLTokenMinExpirationTTL,
			a.srv.config.ACLTokenMaxExpirationTTL, existingToken); err != nil {
			return structs.NewErrRPCCodedf(http.StatusBadRequest, "token %d invalid: %v", idx, err)
		}

		var normalizedRoleLinks []*structs.ACLTokenRoleLink
		uniqueRoleIDs := make(map[string]struct{})

		// Iterate, check, and normalize the ACL role links that the token has.
		for _, roleLink := range token.Roles {

			var (
				existing       *structs.ACLRole
				roleIdentifier string
				lookupErr      error
			)

			// In the event the caller specified the role name, we need to
			// identify the immutable ID. In either case, we need to ensure the
			// role exists.
			switch roleLink.ID {
			case "":
				roleIdentifier = roleLink.Name
				existing, lookupErr = stateSnapshot.GetACLRoleByName(nil, roleIdentifier)
			default:
				roleIdentifier = roleLink.ID
				existing, lookupErr = stateSnapshot.GetACLRoleByID(nil, roleIdentifier)
			}

			// Handle any state lookup error or inability to locate the role
			// within state.
			if lookupErr != nil {
				return structs.NewErrRPCCodedf(http.StatusInternalServerError, "role lookup failed: %v", lookupErr)
			}
			if existing == nil {
				return structs.NewErrRPCCodedf(http.StatusBadRequest, "cannot find role %s", roleIdentifier)
			}

			// Ensure the role ID is written to the object and that the name is
			// emptied as it is possible the role name is updated in the future.
			roleLink.ID = existing.ID
			roleLink.Name = ""

			// Deduplicate role links by their ID.
			if _, ok := uniqueRoleIDs[roleLink.ID]; !ok {
				normalizedRoleLinks = append(normalizedRoleLinks, roleLink)
				uniqueRoleIDs[roleLink.ID] = struct{}{}
			}
		}

		// Write the normalized array of ACL role links back to the token.
		token.Roles = normalizedRoleLinks

		// Compute the token hash
		token.SetHash()
	}

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.ACLTokenUpsertRequestType, args)
	if err != nil {
		return err
	}

	// Populate the response. We do a lookup against the state to pick up the
	// proper create / modify times.
	stateSnapshot, err = a.srv.State().Snapshot()
	if err != nil {
		return err
	}
	for _, token := range args.Tokens {
		out, err := stateSnapshot.ACLTokenByAccessorID(nil, token.AccessorID)
		if err != nil {
			return structs.NewErrRPCCodedf(400, "token lookup failed: %v", err)
		}
		reply.Tokens = append(reply.Tokens, out)
	}

	// Update the index
	reply.Index = index
	return nil
}

// DeleteTokens is used to delete tokens
func (a *ACL) DeleteTokens(args *structs.ACLTokenDeleteRequest, reply *structs.GenericResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	// Validate non-zero set of tokens
	if len(args.AccessorIDs) == 0 {
		return structs.NewErrRPCCoded(400, "must specify as least one token")
	}

	if done, err := a.srv.forward("ACL.DeleteTokens", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "delete_tokens"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Snapshot the state
	state, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Determine if we are deleting local or global tokens
	hasGlobal := false
	allGlobal := true
	nonexistentTokens := make([]string, 0)
	for _, accessor := range args.AccessorIDs {
		token, err := state.ACLTokenByAccessorID(nil, accessor)
		if err != nil {
			return structs.NewErrRPCCodedf(400, "token lookup failed: %v", err)
		}
		if token == nil {
			nonexistentTokens = append(nonexistentTokens, accessor)
			continue
		}
		if token.Global {
			hasGlobal = true
		} else {
			allGlobal = false
		}
	}

	if len(nonexistentTokens) != 0 {
		return structs.NewErrRPCCodedf(400, "Cannot delete nonexistent tokens: %v", strings.Join(nonexistentTokens, ", "))
	}

	// Disallow mixed requests with global and non-global tokens since we forward
	// the entire request as a single batch.
	if hasGlobal {
		if !allGlobal {
			return structs.NewErrRPCCoded(400, "cannot delete mixed global and non-global tokens")
		}

		// Force the request to the authoritative region if it has global
		if a.srv.config.Region != a.srv.config.AuthoritativeRegion {
			args.Region = a.srv.config.AuthoritativeRegion
			_, err := a.srv.forward("ACL.DeleteTokens", args, args, reply)
			return err
		}
	}

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.ACLTokenDeleteRequestType, args)
	if err != nil {
		return err
	}

	// Update the index
	reply.Index = index
	return nil
}

// ListTokens is used to list the tokens
func (a *ACL) ListTokens(args *structs.ACLTokenListRequest, reply *structs.ACLTokenListResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.ListTokens", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "list_tokens"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Setup the blocking query
	sort := state.SortOption(args.Reverse)
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Iterate over all the tokens
			var err error
			var iter memdb.ResultIterator
			var opts paginator.StructsTokenizerOptions

			if prefix := args.QueryOptions.Prefix; prefix != "" {
				iter, err = state.ACLTokenByAccessorIDPrefix(ws, prefix, sort)
				opts = paginator.StructsTokenizerOptions{
					WithID: true,
				}
			} else if args.GlobalOnly {
				iter, err = state.ACLTokensByGlobal(ws, true, sort)
				opts = paginator.StructsTokenizerOptions{
					WithID: true,
				}
			} else {
				iter, err = state.ACLTokens(ws, sort)
				opts = paginator.StructsTokenizerOptions{
					WithCreateIndex: true,
					WithID:          true,
				}
			}
			if err != nil {
				return err
			}

			tokenizer := paginator.NewStructsTokenizer(iter, opts)

			var tokens []*structs.ACLTokenListStub
			paginator, err := paginator.NewPaginator(iter, tokenizer, nil, args.QueryOptions,
				func(raw interface{}) error {
					token := raw.(*structs.ACLToken)
					tokens = append(tokens, token.Stub())
					return nil
				})
			if err != nil {
				return structs.NewErrRPCCodedf(
					http.StatusBadRequest, "failed to create result paginator: %v", err)
			}

			nextToken, err := paginator.Page()
			if err != nil {
				return structs.NewErrRPCCodedf(
					http.StatusBadRequest, "failed to read result page: %v", err)
			}

			reply.QueryMeta.NextToken = nextToken
			reply.Tokens = tokens

			// Use the last index that affected the token table
			index, err := state.Index("acl_token")
			if err != nil {
				return err
			}
			reply.Index = index

			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

// GetToken is used to get a specific token
func (a *ACL) GetToken(args *structs.ACLTokenSpecificRequest, reply *structs.SingleACLTokenResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.GetToken", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return authErr
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_token"}, time.Now())

	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	}

	// Ensure ACLs are enabled and this call is made with one
	if acl == nil {
		return structs.ErrPermissionDenied
	}

	// Setup the blocking query
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Look for the token
			out, err := state.ACLTokenByAccessorID(ws, args.AccessorID)
			if err != nil {
				return err
			}

			if out == nil {
				// If the token doesn't resolve, only allow management tokens to
				// block.
				if !acl.IsManagement() {
					return structs.ErrPermissionDenied
				}

				// Check management level permissions or that the secret ID matches the
				// accessor ID
			} else if !acl.IsManagement() && out.SecretID != args.AuthToken {
				return structs.ErrPermissionDenied
			}

			// Setup the output
			reply.Token = out
			if out != nil {
				reply.Index = out.ModifyIndex
			} else {
				// Use the last index that affected the token table
				index, err := state.Index("acl_token")
				if err != nil {
					return err
				}
				reply.Index = index
			}
			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

// GetTokens is used to get a set of token
func (a *ACL) GetTokens(args *structs.ACLTokenSetRequest, reply *structs.ACLTokenSetResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.GetTokens", args, args, reply); done {
		return err
	}
	if authErr != nil {
		return authErr
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_tokens"}, time.Now())

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Setup the blocking query
	opts := blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, state *state.StateStore) error {
			// Setup the output
			reply.Tokens = make(map[string]*structs.ACLToken, len(args.AccessorIDS))

			// Look for the token
			for _, accessor := range args.AccessorIDS {
				out, err := state.ACLTokenByAccessorID(ws, accessor)
				if err != nil {
					return err
				}
				if out != nil {
					reply.Tokens[out.AccessorID] = out
				}
			}

			// Use the last index that affected the token table
			index, err := state.Index("acl_token")
			if err != nil {
				return err
			}
			reply.Index = index
			return nil
		}}
	return a.srv.blockingRPC(&opts)
}

// ResolveToken is used to lookup a specific token by a secret ID. This is used for enforcing ACLs by clients.
func (a *ACL) ResolveToken(args *structs.ResolveACLTokenRequest, reply *structs.ResolveACLTokenResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	if done, err := a.srv.forward("ACL.ResolveToken", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "resolve_token"}, time.Now())

	// Setup the query meta
	a.srv.setQueryMeta(&reply.QueryMeta)

	// Snapshot the state
	state, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Look for the token
	out, err := state.ACLTokenBySecretID(nil, args.SecretID)
	if err != nil {
		return err
	}

	// Setup the output
	reply.Token = out
	if out != nil {
		reply.Index = out.ModifyIndex
	} else {
		// Use the last index that affected the token table
		index, err := state.Index("acl_token")
		if err != nil {
			return err
		}
		reply.Index = index
	}
	return nil
}

func (a *ACL) UpsertOneTimeToken(args *structs.OneTimeTokenUpsertRequest, reply *structs.OneTimeTokenUpsertResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	if done, err := a.srv.forward(
		"ACL.UpsertOneTimeToken", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince(
		[]string{"nomad", "acl", "upsert_one_time_token"}, time.Now())

	if !ServersMeetMinimumVersion(a.srv.Members(), a.srv.Region(), minOneTimeAuthenticationTokenVersion, false) {
		return fmt.Errorf("All servers should be running version %v or later to use one-time authentication tokens", minOneTimeAuthenticationTokenVersion)
	}

	// Snapshot the state
	state, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Look up the token; there's no capability check as you can only
	// request a OTT for your own ACL token
	aclToken, err := state.ACLTokenBySecretID(nil, args.AuthToken)
	if err != nil {
		return err
	}
	if aclToken == nil {
		return structs.ErrPermissionDenied
	}

	ott := &structs.OneTimeToken{
		OneTimeSecretID: uuid.Generate(),
		AccessorID:      aclToken.AccessorID,
		ExpiresAt:       time.Now().Add(10 * time.Minute),
	}

	// Update via Raft
	_, index, err := a.srv.raftApply(structs.OneTimeTokenUpsertRequestType, ott)
	if err != nil {
		return err
	}

	ott.ModifyIndex = index
	ott.CreateIndex = index
	reply.OneTimeToken = ott
	reply.Index = index
	return nil
}

// ExchangeOneTimeToken provides a one-time token's secret ID to exchange it
// for the ACL token that created that one-time token
func (a *ACL) ExchangeOneTimeToken(args *structs.OneTimeTokenExchangeRequest, reply *structs.OneTimeTokenExchangeResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	if done, err := a.srv.forward(
		"ACL.ExchangeOneTimeToken", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince(
		[]string{"nomad", "acl", "exchange_one_time_token"}, time.Now())

	if !ServersMeetMinimumVersion(a.srv.Members(), a.srv.Region(), minOneTimeAuthenticationTokenVersion, false) {
		return fmt.Errorf("All servers should be running version %v or later to use one-time authentication tokens", minOneTimeAuthenticationTokenVersion)
	}

	// Snapshot the state
	state, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	ott, err := state.OneTimeTokenBySecret(nil, args.OneTimeSecretID)
	if err != nil {
		return err
	}
	if ott == nil {
		return structs.ErrPermissionDenied
	}
	if ott.ExpiresAt.Before(time.Now()) {
		// we return early and leave cleaning up the expired token for GC
		return structs.ErrPermissionDenied
	}

	// Look for the token; it may have been deleted, in which case, 403
	aclToken, err := state.ACLTokenByAccessorID(nil, ott.AccessorID)
	if err != nil {
		return err
	}
	if aclToken == nil {
		return structs.ErrPermissionDenied
	}

	// Expire token via raft; because this is the only write in the RPC the
	// caller can safely retry with the same token if the raft write fails
	_, index, err := a.srv.raftApply(structs.OneTimeTokenDeleteRequestType,
		&structs.OneTimeTokenDeleteRequest{
			AccessorIDs: []string{ott.AccessorID},
		})
	if err != nil {
		return err
	}

	reply.Token = aclToken
	reply.Index = index
	return nil
}

// ExpireOneTimeTokens removes all expired tokens from the state store. It is
// called only by garbage collection
func (a *ACL) ExpireOneTimeTokens(args *structs.OneTimeTokenExpireRequest, reply *structs.GenericResponse) error {

	if done, err := a.srv.forward(
		"ACL.ExpireOneTimeTokens", args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince(
		[]string{"nomad", "acl", "expire_one_time_tokens"}, time.Now())

	if !ServersMeetMinimumVersion(a.srv.Members(), a.srv.Region(), minOneTimeAuthenticationTokenVersion, false) {
		return fmt.Errorf("All servers should be running version %v or later to use one-time authentication tokens", minOneTimeAuthenticationTokenVersion)
	}

	// Check management level permissions
	if a.srv.config.ACLEnabled {
		if acl, err := a.srv.ResolveToken(args.AuthToken); err != nil {
			return err
		} else if acl == nil || !acl.IsManagement() {
			return structs.ErrPermissionDenied
		}
	}

	args.Timestamp = time.Now() // use the leader's timestamp

	// Expire token via raft; because this is the only write in the RPC the
	// caller can safely retry with the same token if the raft write fails
	_, index, err := a.srv.raftApply(structs.OneTimeTokenExpireRequestType, args)
	if err != nil {
		return err
	}
	reply.Index = index
	return nil
}

// UpsertRoles creates or updates ACL roles held within Nomad.
func (a *ACL) UpsertRoles(
	args *structs.ACLRolesUpsertRequest,
	reply *structs.ACLRolesUpsertResponse) error {

	// Only allow operators to upsert ACL roles when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	// This endpoint always forwards to the authoritative region as ACL roles
	// are global.
	args.Region = a.srv.config.AuthoritativeRegion

	if done, err := a.srv.forward(structs.ACLUpsertRolesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "upsert_roles"}, time.Now())

	// ACL roles can only be used once all servers, in all federated regions
	// have been upgraded to 1.4.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLRoleVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL roles",
			minACLRoleVersion)
	}

	// Only management level permissions can create ACL roles.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Snapshot the state so we can perform lookups against the ID and policy
	// links if needed. Do it here, so we only need to do this once no matter
	// how many roles we are upserting.
	stateSnapshot, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Validate each role.
	for idx, role := range args.ACLRoles {

		// Perform all the static validation of the ACL role object. Use the
		// array index as we cannot be sure the error was caused by a missing
		// name.
		if err := role.Validate(); err != nil {
			return structs.NewErrRPCCodedf(http.StatusBadRequest, "role %d invalid: %v", idx, err)
		}

		// If the caller has passed a role ID, this call is considered an
		// update to an existing role. We should therefore ensure it is found
		// within state. Otherwise, the call is considered a new creation, and
		// we must ensure a role of the same name does not exist.
		if role.ID == "" {
			existingRole, err := stateSnapshot.GetACLRoleByName(nil, role.Name)
			if err != nil {
				return structs.NewErrRPCCodedf(http.StatusInternalServerError, "role lookup failed: %v", err)
			}
			if existingRole != nil {
				return structs.NewErrRPCCodedf(http.StatusBadRequest, "role with name %s already exists", role.Name)
			}
		} else {
			existingRole, err := stateSnapshot.GetACLRoleByID(nil, role.ID)
			if err != nil {
				return structs.NewErrRPCCodedf(http.StatusInternalServerError, "role lookup failed: %v", err)
			}
			if existingRole == nil {
				return structs.NewErrRPCCodedf(http.StatusBadRequest, "cannot find role %s", role.ID)
			}
		}

		policyNames := make(map[string]struct{})
		var policiesLinks []*structs.ACLRolePolicyLink

		// We need to deduplicate the ACL policy links within this role as well
		// as ensure the policies exist within state.
		for _, policyLink := range role.Policies {

			// If the RPC does not allow for missing policies, perform a state
			// look up for the policy. An error or not being able to find the
			// policy is terminal. We can include the name in the error message
			// as it has previously been validated.
			if !args.AllowMissingPolicies {
				existing, err := stateSnapshot.ACLPolicyByName(nil, policyLink.Name)
				if err != nil {
					return structs.NewErrRPCCodedf(http.StatusInternalServerError, "policy lookup failed: %v", err)
				}
				if existing == nil {
					return structs.NewErrRPCCodedf(http.StatusBadRequest, "cannot find policy %s", policyLink.Name)
				}
			}

			// If the policy name is not found within our map, this means we
			// have not seen it previously. We need to add this to our
			// deduplicated array and also mark the policy name as seen, so we
			// skip any future policies of the same name.
			if _, ok := policyNames[policyLink.Name]; !ok {
				policiesLinks = append(policiesLinks, policyLink)
				policyNames[policyLink.Name] = struct{}{}
			}
		}

		// Stored the potentially updated policy links within our role.
		role.Policies = policiesLinks

		role.Canonicalize()
		role.SetHash()
	}

	// Update via Raft.
	out, index, err := a.srv.raftApply(structs.ACLRolesUpsertRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Populate the response. We do a lookup against the state to pick up the
	// proper create / modify times.
	stateSnapshot, err = a.srv.State().Snapshot()
	if err != nil {
		return err
	}
	for _, role := range args.ACLRoles {
		lookupACLRole, err := stateSnapshot.GetACLRoleByName(nil, role.Name)
		if err != nil {
			return structs.NewErrRPCCodedf(400, "ACL role lookup failed: %v", err)
		}
		reply.ACLRoles = append(reply.ACLRoles, lookupACLRole)
	}

	// Update the index. There is no need to floor this as we are writing to
	// state and therefore will get a non-zero index response.
	reply.Index = index
	return nil
}

// DeleteRolesByID is used to batch delete ACL roles using the ID as the
// deletion key.
func (a *ACL) DeleteRolesByID(
	args *structs.ACLRolesDeleteByIDRequest,
	reply *structs.ACLRolesDeleteByIDResponse) error {

	// Only allow operators to delete ACL roles when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)

	// This endpoint always forwards to the authoritative region as ACL roles
	// are global.
	args.Region = a.srv.config.AuthoritativeRegion

	if done, err := a.srv.forward(structs.ACLDeleteRolesByIDRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "delete_roles"}, time.Now())

	// ACL roles can only be used once all servers, in all federated regions
	// have been upgraded to 1.4.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLRoleVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL roles",
			minACLRoleVersion)
	}

	// Only management level permissions can create ACL roles.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Update via Raft.
	out, index, err := a.srv.raftApply(structs.ACLRolesDeleteByIDRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Update the index. There is no need to floor this as we are writing to
	// state and therefore will get a non-zero index response.
	reply.Index = index
	return nil
}

// ListRoles is used to list ACL roles within state. If not prefix is supplied,
// all ACL roles are listed, otherwise a prefix search is performed on the ACL
// role name.
func (a *ACL) ListRoles(
	args *structs.ACLRolesListRequest,
	reply *structs.ACLRolesListResponse) error {

	// Only allow operators to list ACL roles when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLListRolesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "list_roles"}, time.Now())

	// Resolve the token and ensure it has some form of permissions.
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil {
		return structs.ErrPermissionDenied
	}

	// If the token is a management token, they can list all tokens. If not,
	// the role set tracks which role links the token has and therefore which
	// ones the caller can list.
	isManagement := acl.IsManagement()
	roleSet := &set.Set[string]{}

	// If the token is not a management token, we determine which roles are
	// linked to the token and therefore can be listed by the caller.
	if !isManagement {
		token, err := a.requestACLToken(args.AuthToken)
		if err != nil {
			return err
		}
		if token == nil {
			return structs.ErrTokenNotFound
		}

		// Generate a set of Role IDs from the token role links.
		roleSet = set.FromFunc(token.Roles, func(roleLink *structs.ACLTokenRoleLink) string { return roleLink.ID })
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// The iteration below appends directly to the reply object, so in
			// order for blocking queries to work properly we must ensure the
			// ACLRoles are reset. This allows the blocking query run function
			// to work as expected.
			reply.ACLRoles = nil

			var (
				err  error
				iter memdb.ResultIterator
			)

			// If the operator supplied a prefix, perform a prefix search.
			// Otherwise, list all ACL roles in state.
			switch args.QueryOptions.Prefix {
			case "":
				iter, err = stateStore.GetACLRoles(ws)
			default:
				iter, err = stateStore.GetACLRoleByIDPrefix(ws, args.QueryOptions.Prefix)
			}
			if err != nil {
				return err
			}

			// Iterate all the results and add these to our reply object. Check
			// before appending to the reply that the caller is allowed to view
			// the role.
			for raw := iter.Next(); raw != nil; raw = iter.Next() {

				role := raw.(*structs.ACLRole)

				if roleSet.Contains(role.ID) || isManagement {
					reply.ACLRoles = append(reply.ACLRoles, role.Stub())
				}
			}

			// Use the index table to populate the query meta as we have no way
			// of tracking the max index on deletes.
			return a.srv.setReplyQueryMeta(stateStore, state.TableACLRoles, &reply.QueryMeta)
		},
	})
}

// GetRolesByID is used to get a set of ACL Roles as defined by their ID. This
// endpoint is used by the replication process and Nomad agent client token
// resolution.
func (a *ACL) GetRolesByID(args *structs.ACLRolesByIDRequest, reply *structs.ACLRolesByIDResponse) error {

	// This endpoint is only used by the replication process which is only
	// running on ACL enabled clusters, so this check should never be
	// triggered.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	if done, err := a.srv.forward(structs.ACLGetRolesByIDRPCMethod, args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_roles_id"}, time.Now())

	// For client typed tokens, allow them to query any roles associated with
	// that token. This is used by Nomad agents in client mode which are
	// resolving the roles to enforce.
	token, err := a.requestACLToken(args.AuthToken)
	if err != nil {
		return err
	}
	if token == nil {
		return structs.ErrTokenNotFound
	}
	if token.Type != structs.ACLManagementToken && !token.HasRoles(args.ACLRoleIDs) {
		return structs.ErrPermissionDenied
	}

	// Set up and return the blocking query
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Instantiate the output map to the correct maximum length.
			reply.ACLRoles = make(map[string]*structs.ACLRole, len(args.ACLRoleIDs))

			// Look for the ACL role and add this to our mapping if we have
			// found it.
			for _, roleID := range args.ACLRoleIDs {
				out, err := stateStore.GetACLRoleByID(ws, roleID)
				if err != nil {
					return err
				}
				if out != nil {
					reply.ACLRoles[out.ID] = out
				}
			}

			// Use the index table to populate the query meta as we have no way
			// of tracking the max index on deletes.
			return a.srv.setReplyQueryMeta(stateStore, state.TableACLRoles, &reply.QueryMeta)
		},
	})
}

// GetRoleByID is used to look up an individual ACL role using its ID.
func (a *ACL) GetRoleByID(
	args *structs.ACLRoleByIDRequest,
	reply *structs.ACLRoleByIDResponse) error {

	// Only allow operators to read an ACL role when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLGetRoleByIDRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_role_id"}, time.Now())

	// Resolve the token and ensure it has some form of permissions.
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil {
		return structs.ErrPermissionDenied
	}

	// If the token is a management token, they can detail any token they so
	// desire.
	isManagement := acl.IsManagement()

	// If the token is not a management token, we determine if the caller wants
	// to detail a role linked to their token.
	if !isManagement {
		aclToken, err := a.requestACLToken(args.AuthToken)
		if err != nil {
			return err
		}
		if aclToken == nil {
			return structs.ErrTokenNotFound
		}

		found := false

		for _, roleLink := range aclToken.Roles {
			if roleLink.ID == args.RoleID {
				found = true
				break
			}
		}

		if !found {
			return structs.ErrPermissionDenied
		}
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Perform a lookup for the ACL role.
			out, err := stateStore.GetACLRoleByID(ws, args.RoleID)
			if err != nil {
				return err
			}

			// Set the index correctly depending on whether the ACL role was
			// found.
			switch out {
			case nil:
				index, err := stateStore.Index(state.TableACLRoles)
				if err != nil {
					return err
				}
				reply.Index = index
			default:
				reply.Index = out.ModifyIndex
			}

			// We didn't encounter an error looking up the index; set the ACL
			// role on the reply and exit successfully.
			reply.ACLRole = out
			return nil
		},
	})
}

// GetRoleByName is used to look up an individual ACL role using its name.
func (a *ACL) GetRoleByName(
	args *structs.ACLRoleByNameRequest,
	reply *structs.ACLRoleByNameResponse) error {

	// Only allow operators to read an ACL role when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLGetRoleByNameRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_role_name"}, time.Now())

	// Resolve the token and ensure it has some form of permissions.
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil {
		return structs.ErrPermissionDenied
	}

	// If the token is a management token, they can detail any token they so
	// desire.
	isManagement := acl.IsManagement()

	// If the token is not a management token, we determine if the caller wants
	// to detail a role linked to their token.
	if !isManagement {
		aclToken, err := a.requestACLToken(args.AuthToken)
		if err != nil {
			return err
		}
		if aclToken == nil {
			return structs.ErrTokenNotFound
		}

		found := false

		for _, roleLink := range aclToken.Roles {
			if roleLink.Name == args.RoleName {
				found = true
				break
			}
		}

		if !found {
			return structs.ErrPermissionDenied
		}
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Perform a lookup for the ACL role.
			out, err := stateStore.GetACLRoleByName(ws, args.RoleName)
			if err != nil {
				return err
			}

			// Set the index correctly depending on whether the ACL role was
			// found.
			switch out {
			case nil:
				index, err := stateStore.Index(state.TableACLRoles)
				if err != nil {
					return err
				}
				reply.Index = index
			default:
				reply.Index = out.ModifyIndex
			}

			// We didn't encounter an error looking up the index; set the ACL
			// role on the reply and exit successfully.
			reply.ACLRole = out
			return nil
		},
	})
}

// policyNamesFromRoleLinks resolves the policy names which are linked via the
// passed role links. This is useful when you need to understand what polices
// an ACL token has access to and need to include role links. The function will
// not return a nil set object, so callers can use this without having to check
// this.
func (a *ACL) policyNamesFromRoleLinks(roleLinks []*structs.ACLTokenRoleLink) (*set.Set[string], error) {

	numRoles := len(roleLinks)
	policyNameSet := set.New[string](numRoles)

	if numRoles < 1 {
		return policyNameSet, nil
	}

	stateSnapshot, err := a.srv.State().Snapshot()
	if err != nil {
		return policyNameSet, err
	}

	// Iterate all the token role links, so we can unpack these and identify
	// the ACL policies.
	for _, roleLink := range roleLinks {

		// Any error reading the role means we cannot move forward. We just
		// ignore any roles that have been detailed but are not within our
		// state.
		role, err := stateSnapshot.GetACLRoleByID(nil, roleLink.ID)
		if err != nil {
			return policyNameSet, err
		}
		if role == nil {
			continue
		}

		// Unpack the policies held within the ACL role to form a single list
		// of ACL policies that this token has available.
		for _, policyLink := range role.Policies {
			policyByName, err := stateSnapshot.ACLPolicyByName(nil, policyLink.Name)
			if err != nil {
				return policyNameSet, err
			}

			// Ignore policies that don't exist, since they don't grant any
			// more privilege.
			if policyByName == nil {
				continue
			}

			// Add the policy to the tracking array.
			policyNameSet.Insert(policyByName.Name)
		}
	}

	return policyNameSet, nil
}

// UpsertAuthMethods is used to create or update a set of auth methods
func (a *ACL) UpsertAuthMethods(
	args *structs.ACLAuthMethodUpsertRequest,
	reply *structs.ACLAuthMethodUpsertResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the
	// authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	authErr := a.srv.Authenticate(a.ctx, args)
	args.Region = a.srv.config.AuthoritativeRegion

	if done, err := a.srv.forward(structs.ACLUpsertAuthMethodsRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "upsert_auth_methods"}, time.Now())

	// ACL auth methods can only be used once all servers in all federated
	// regions have been upgraded to 1.5.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLAuthMethodVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL auth methods",
			minACLAuthMethodVersion)
	}

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of auth methods
	if len(args.AuthMethods) == 0 {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "must specify as least one auth method")
	}

	// Snapshot the state so we can make lookups to verify default method
	stateSnapshot, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Validate each auth method, canonicalize, and compute hash
	// merge methods in case we're doing an update
	for idx, authMethod := range args.AuthMethods {
		// if there's an existing method with the same name, we treat this as
		// an update
		existingMethod, _ := stateSnapshot.GetACLAuthMethodByName(nil, authMethod.Name)
		authMethod.Merge(existingMethod)

		if err := authMethod.Validate(
			a.srv.config.ACLTokenMinExpirationTTL,
			a.srv.config.ACLTokenMaxExpirationTTL); err != nil {
			return structs.NewErrRPCCodedf(http.StatusBadRequest, "auth method %d invalid: %v", idx, err)
		}

		// Are we trying to upsert a default auth method? Check if there isn't
		// a default one for that very type already.
		if authMethod.Default {
			existingMethodsDefaultmethod, _ := stateSnapshot.GetDefaultACLAuthMethodByType(nil, authMethod.Type)
			if existingMethodsDefaultmethod != nil && existingMethodsDefaultmethod.Name != authMethod.Name {
				return structs.NewErrRPCCodedf(
					http.StatusBadRequest,
					"default method for type %s already exists: %v", authMethod.Type, existingMethodsDefaultmethod.Name,
				)
			}
		}
		authMethod.Canonicalize()
		authMethod.SetHash()
	}

	// Update via Raft
	out, index, err := a.srv.raftApply(structs.ACLAuthMethodsUpsertRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Populate the response. We do a lookup against the state to pick up the
	// proper create / modify times.
	stateSnapshot, err = a.srv.State().Snapshot()
	if err != nil {
		return err
	}
	for _, method := range args.AuthMethods {
		lookupAuthMethod, err := stateSnapshot.GetACLAuthMethodByName(nil, method.Name)
		if err != nil {
			return structs.NewErrRPCCodedf(400, "ACL auth method lookup failed: %v", err)
		}
		if lookupAuthMethod != nil {
			reply.AuthMethods = append(reply.AuthMethods, lookupAuthMethod)
		}
	}

	// Update the index
	reply.Index = index
	return nil
}

// DeleteAuthMethods is used to delete auth methods
func (a *ACL) DeleteAuthMethods(
	args *structs.ACLAuthMethodDeleteRequest,
	reply *structs.ACLAuthMethodDeleteResponse) error {
	// Ensure ACLs are enabled, and always flow modification requests to the
	// authoritative region
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	args.Region = a.srv.config.AuthoritativeRegion

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(
		structs.ACLDeleteAuthMethodsRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "delete_auth_methods_by_name"}, time.Now())

	// ACL auth methods can only be used once all servers in all federated
	// regions have been upgraded to 1.5.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLRoleVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL auth methods",
			minACLAuthMethodVersion)
	}

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of auth methods
	if len(args.Names) == 0 {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "must specify as least one auth method")
	}

	// Update via Raft
	out, index, err := a.srv.raftApply(structs.ACLAuthMethodsDeleteRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Update the index
	reply.Index = index
	return nil
}

// ListAuthMethods returns a list of ACL auth methods
func (a *ACL) ListAuthMethods(
	args *structs.ACLAuthMethodListRequest,
	reply *structs.ACLAuthMethodListResponse) error {
	// Only allow operators to list auth methods when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	if done, err := a.srv.forward(
		structs.ACLListAuthMethodsRPCMethod, args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "list_auth_methods"}, time.Now())

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// The iteration below appends directly to the reply object, so in
			// order for blocking queries to work properly we must ensure the
			// auth methods are reset. This allows the blocking query run
			// function to work as expected.
			reply.AuthMethods = nil

			iter, err := stateStore.GetACLAuthMethods(ws)
			if err != nil {
				return err
			}

			// Iterate all the results and add these to our reply object.
			for raw := iter.Next(); raw != nil; raw = iter.Next() {
				method := raw.(*structs.ACLAuthMethod)
				reply.AuthMethods = append(reply.AuthMethods, method.Stub())
			}

			// Use the index table to populate the query meta
			return a.srv.setReplyQueryMeta(
				stateStore, state.TableACLAuthMethods, &reply.QueryMeta,
			)
		},
	})
}

func (a *ACL) GetAuthMethod(
	args *structs.ACLAuthMethodGetRequest,
	reply *structs.ACLAuthMethodGetResponse) error {

	// Only allow operators to read an auth method when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(
		structs.ACLGetAuthMethodRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_auth_method_name"}, time.Now())

	// Resolve the token and ensure it has some form of permissions.
	acl, err := a.srv.ResolveACL(args)
	if err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Perform a lookup
			out, err := stateStore.GetACLAuthMethodByName(ws, args.MethodName)
			if err != nil {
				return err
			}

			// Set the index correctly depending on whether the auth method was
			// found.
			switch out {
			case nil:
				index, err := stateStore.Index(state.TableACLAuthMethods)
				if err != nil {
					return err
				}
				reply.Index = index
			default:
				reply.Index = out.ModifyIndex
			}

			// We didn't encounter an error looking up the index; set the auth
			// method on the reply and exit successfully.
			reply.AuthMethod = out
			return nil
		},
	})
}

// GetAuthMethods is used to get a set of auth methods
func (a *ACL) GetAuthMethods(
	args *structs.ACLAuthMethodsGetRequest,
	reply *structs.ACLAuthMethodsGetResponse) error {
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	if done, err := a.srv.forward(
		structs.ACLGetAuthMethodsRPCMethod, args, args, reply); done {
		return err
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_auth_methods"}, time.Now())

	// allow only management token holders to query this endpoint
	token, err := a.requestACLToken(args.AuthToken)
	if err != nil {
		return err
	}
	if token == nil {
		return structs.ErrTokenNotFound
	}
	if token.Type != structs.ACLManagementToken {
		return structs.ErrPermissionDenied
	}

	// Setup the blocking query
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, statestore *state.StateStore) error {
			// Setup the output
			reply.AuthMethods = make(map[string]*structs.ACLAuthMethod, len(args.Names))

			// Look for the auth method
			for _, methodName := range args.Names {
				out, err := statestore.GetACLAuthMethodByName(ws, methodName)
				if err != nil {
					return err
				}
				if out != nil {
					reply.AuthMethods[methodName] = out
				}
			}

			// Use the index table to populate the query meta
			return a.srv.setReplyQueryMeta(
				statestore, state.TableACLAuthMethods, &reply.QueryMeta,
			)
		}},
	)
}

// WhoAmI is a RPC for debugging authentication. This endpoint returns the same
// AuthenticatedIdentity that will be used by RPC handlers.
//
// TODO: At some point we might want to give this an equivalent HTTP endpoint
// once other Workload Identity work is solidified
func (a *ACL) WhoAmI(args *structs.GenericRequest, reply *structs.ACLWhoAmIResponse) error {
	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward("ACL.WhoAmI", args, args, reply); done {
		return err
	}
	a.srv.MeasureRPCRate("acl", structs.RateMetricRead, args)
	if authErr != nil {
		return authErr
	}

	defer metrics.MeasureSince([]string{"nomad", "acl", "whoami"}, time.Now())

	reply.Identity = args.GetIdentity()
	return nil
}

// UpsertBindingRules creates or updates ACL binding rules held within Nomad.
func (a *ACL) UpsertBindingRules(
	args *structs.ACLBindingRulesUpsertRequest, reply *structs.ACLBindingRulesUpsertResponse) error {

	// Ensure ACLs are enabled, and always flow modification requests to the
	// authoritative region.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	args.Region = a.srv.config.AuthoritativeRegion

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLUpsertBindingRulesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "upsert_binding_rules"}, time.Now())

	// ACL binding rules can only be used once all servers in all federated
	// regions have been upgraded to 1.5.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLBindingRuleVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL binding rules",
			minACLBindingRuleVersion)
	}

	// Check management level permissions
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of binding rules. This must be done outside the
	// validate function as that uses a loop, which will be skipped if the
	// length is zero.
	if len(args.ACLBindingRules) == 0 {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "must specify as least one binding rule")
	}

	stateSnapshot, err := a.srv.State().Snapshot()
	if err != nil {
		return err
	}

	// Validate each binding rules and compute the hash.
	for idx, bindingRule := range args.ACLBindingRules {

		// If the caller has passed a rule ID, this call is considered an
		// update to an existing rule. We should therefore ensure it is found
		// within state.
		if bindingRule.ID != "" {
			existingBindingRule, err := stateSnapshot.GetACLBindingRule(nil, bindingRule.ID)
			if err != nil {
				return structs.NewErrRPCCodedf(
					http.StatusInternalServerError, "binding rule lookup failed: %v", err)
			}
			if existingBindingRule == nil {
				return structs.NewErrRPCCodedf(
					http.StatusBadRequest, "cannot find binding rule %s", bindingRule.ID)
			}

			// merge
			bindingRule.Merge(existingBindingRule)

			// Auth methods cannot be changed
			if bindingRule.AuthMethod != existingBindingRule.AuthMethod {
				return structs.NewErrRPCCoded(
					http.StatusBadRequest, "cannot update auth method for binding rule, create a new rule instead",
				)
			}
			bindingRule.AuthMethod = existingBindingRule.AuthMethod
		}

		// Validate only if it's not an update
		if err := bindingRule.Validate(); err != nil {
			return structs.NewErrRPCCodedf(http.StatusBadRequest, "binding rule %d invalid: %v", idx, err)
		}

		// Ensure the auth method linked to exists within state.
		method, err := stateSnapshot.GetACLAuthMethodByName(nil, bindingRule.AuthMethod)
		if err != nil {
			return err
		}
		if method == nil {
			return structs.NewErrRPCCodedf(
				http.StatusBadRequest, "ACL auth method %s not found", bindingRule.AuthMethod)
		}

		// All the validation has passed, we can now canonicalize the object
		// with the final internal data and set the hash.
		bindingRule.Canonicalize()
		bindingRule.SetHash()
	}

	// Update via Raft.
	out, index, err := a.srv.raftApply(structs.ACLBindingRulesUpsertRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Populate the response. We do a lookup against the state to pick up the
	// proper create / modify indexes.
	stateSnapshot, err = a.srv.State().Snapshot()
	if err != nil {
		return err
	}
	for _, bindingRule := range args.ACLBindingRules {
		lookupBindingRule, err := stateSnapshot.GetACLBindingRule(nil, bindingRule.ID)
		if err != nil {
			return structs.NewErrRPCCodedf(http.StatusInternalServerError,
				"ACL binding rule lookup failed: %v", err)
		}
		if lookupBindingRule == nil {
			return structs.NewErrRPCCoded(http.StatusInternalServerError,
				"ACL binding rule lookup failed: no entry found")
		}
		reply.ACLBindingRules = append(reply.ACLBindingRules, lookupBindingRule)
	}

	// Update the index
	reply.Index = index
	return nil
}

// DeleteBindingRules batch deletes ACL binding rules from Nomad state.
func (a *ACL) DeleteBindingRules(
	args *structs.ACLBindingRulesDeleteRequest, reply *structs.ACLBindingRulesDeleteResponse) error {

	// Ensure ACLs are enabled, and always flow modification requests to the
	// authoritative region.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}
	args.Region = a.srv.config.AuthoritativeRegion

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLDeleteBindingRulesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "delete_binding_rules"}, time.Now())

	// ACL binding rules can only be used once all servers in all federated
	// regions have been upgraded to 1.5.0 or greater.
	if !ServersMeetMinimumVersion(a.srv.Members(), AllRegions, minACLBindingRuleVersion, false) {
		return fmt.Errorf("all servers should be running version %v or later to use ACL binding rules",
			minACLBindingRuleVersion)
	}

	// Check management level permissions.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Validate non-zero set of binding rule IDs.
	if len(args.ACLBindingRuleIDs) == 0 {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "must specify as least one binding rule")
	}

	// Update via Raft.
	out, index, err := a.srv.raftApply(structs.ACLBindingRulesDeleteRequestType, args)
	if err != nil {
		return err
	}

	// Check if the FSM response, which is an interface, contains an error.
	if err, ok := out.(error); ok && err != nil {
		return err
	}

	// Update the index
	reply.Index = index
	return nil
}

// ListBindingRules returns a stub list of ACL binding rules.
func (a *ACL) ListBindingRules(
	args *structs.ACLBindingRulesListRequest, reply *structs.ACLBindingRulesListResponse) error {

	// Only allow operators to list ACL binding rules when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLListBindingRulesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "list_binding_rules"}, time.Now())

	// Check management level permissions.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// The iteration below appends directly to the reply object, so in
			// order for blocking queries to work properly we must ensure the
			// ACLBindingRules are reset. This allows the blocking query run
			// function to work as expected.
			reply.ACLBindingRules = nil

			iter, err := stateStore.GetACLBindingRules(ws)
			if err != nil {
				return err
			}

			// Iterate all the results and add these to our reply object.
			for raw := iter.Next(); raw != nil; raw = iter.Next() {
				reply.ACLBindingRules = append(reply.ACLBindingRules, raw.(*structs.ACLBindingRule).Stub())
			}

			// Use the index table to populate the query meta as we have no way
			// of tracking the max index on deletes.
			return a.srv.setReplyQueryMeta(stateStore, state.TableACLBindingRules, &reply.QueryMeta)
		},
	})
}

// GetBindingRules is used to query for a set of ACL binding rules. This
// endpoint is used for replication purposes and is not exposed via the HTTP
// API.
func (a *ACL) GetBindingRules(
	args *structs.ACLBindingRulesRequest, reply *structs.ACLBindingRulesResponse) error {

	// This endpoint is only used by the replication process which is only
	// running on ACL enabled clusters, so this check should never be
	// triggered.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLGetBindingRulesRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_rules"}, time.Now())

	// Check management level permissions.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Set up and return the blocking query
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Instantiate the output map to the correct maximum length.
			reply.ACLBindingRules = make(map[string]*structs.ACLBindingRule, len(args.ACLBindingRuleIDs))

			// Look for the ACL role and add this to our mapping if we have
			// found it.
			for _, bindingRuleID := range args.ACLBindingRuleIDs {
				out, err := stateStore.GetACLBindingRule(ws, bindingRuleID)
				if err != nil {
					return err
				}
				if out != nil {
					reply.ACLBindingRules[out.ID] = out
				}
			}

			// Use the index table to populate the query meta as we have no way
			// of tracking the max index on deletes.
			return a.srv.setReplyQueryMeta(stateStore, state.TableACLBindingRules, &reply.QueryMeta)
		},
	})
}

// GetBindingRule is used to retrieve a single ACL binding rule as defined by
// its ID.
func (a *ACL) GetBindingRule(
	args *structs.ACLBindingRuleRequest, reply *structs.ACLBindingRuleResponse) error {

	// Only allow operators to read an ACL binding rule when ACLs are enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	authErr := a.srv.Authenticate(a.ctx, args)
	if done, err := a.srv.forward(structs.ACLGetBindingRuleRPCMethod, args, args, reply); done {
		return err
	}
	if authErr != nil {
		return structs.ErrPermissionDenied
	}
	defer metrics.MeasureSince([]string{"nomad", "acl", "get_binding_rule"}, time.Now())

	// Check management level permissions.
	if acl, err := a.srv.ResolveACL(args); err != nil {
		return err
	} else if acl == nil || !acl.IsManagement() {
		return structs.ErrPermissionDenied
	}

	// Set up and return the blocking query.
	return a.srv.blockingRPC(&blockingOptions{
		queryOpts: &args.QueryOptions,
		queryMeta: &reply.QueryMeta,
		run: func(ws memdb.WatchSet, stateStore *state.StateStore) error {

			// Perform a lookup for the ACL role.
			out, err := stateStore.GetACLBindingRule(ws, args.ACLBindingRuleID)
			if err != nil {
				return err
			}

			// Set the index correctly depending on whether the ACL binding
			// rule was found.
			switch out {
			case nil:
				index, err := stateStore.Index(state.TableACLBindingRules)
				if err != nil {
					return err
				}
				reply.Index = index
			default:
				reply.Index = out.ModifyIndex
			}

			// We didn't encounter an error looking up the index; set the ACL
			// binding rule on the reply and exit successfully.
			reply.ACLBindingRule = out
			return nil
		},
	})
}

// OIDCAuthURL starts the OIDC login workflow. The response URL should be used
// by the caller to authenticate the user. Once this has been completed,
// OIDCCompleteAuth can be used for the remainder of the workflow.
func (a *ACL) OIDCAuthURL(args *structs.ACLOIDCAuthURLRequest, reply *structs.ACLOIDCAuthURLResponse) error {

	// The OIDC flow can only be used when the Nomad cluster has ACL enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	// Perform the initial forwarding within the region. This ensures we
	// respect stale queries.
	if done, err := a.srv.forward(structs.ACLOIDCAuthURLRPCMethod, args, args, reply); done {
		return err
	}

	// There is not a perfect place to run this defer since we potentially
	// forward twice. It is likely there will be two distinct patterns to this
	// timing in clusters that utilise a mixture of local and global with
	// methods.
	defer metrics.MeasureSince([]string{"nomad", "acl", "oidc_auth_url"}, time.Now())

	// Validate the request arguments to ensure it contains all the data it
	// needs. Whether the data provided is correct will be handled by the OIDC
	// provider.
	if err := args.Validate(); err != nil {
		return structs.NewErrRPCCodedf(http.StatusBadRequest, "invalid OIDC auth-url request: %v", err)
	}

	// Grab a snapshot of the state, so we can query it safely.
	stateSnapshot, err := a.srv.fsm.State().Snapshot()
	if err != nil {
		return err
	}

	// Lookup the auth method from state, so we have the entire object
	// available to us. It's important to check for nil on the auth method
	// object, as it is possible the request was made with an incorrectly named
	// auth method.
	authMethod, err := stateSnapshot.GetACLAuthMethodByName(nil, args.AuthMethodName)
	if err != nil {
		return err
	}
	if authMethod == nil {
		return structs.NewErrRPCCodedf(http.StatusBadRequest, "auth-method %q not found", args.AuthMethodName)
	}

	// If the authentication method generates global ACL tokens, we need to
	// forward the request onto the authoritative regional leader.
	if authMethod.TokenLocalityIsGlobal() {
		args.Region = a.srv.config.AuthoritativeRegion

		if done, err := a.srv.forward(structs.ACLOIDCAuthURLRPCMethod, args, args, reply); done {
			return err
		}
	}

	// Generate our OIDC request.
	oidcReqOpts := []capOIDC.Option{
		capOIDC.WithNonce(args.ClientNonce),
	}

	if len(authMethod.Config.OIDCScopes) > 0 {
		oidcReqOpts = append(oidcReqOpts, capOIDC.WithScopes(authMethod.Config.OIDCScopes...))
	}

	oidcReq, err := capOIDC.NewRequest(
		aclOIDCAuthURLRequestExpiryTime,
		args.RedirectURI,
		oidcReqOpts...,
	)
	if err != nil {
		return fmt.Errorf("failed to generate OIDC request: %v", err)
	}

	// Use the cache to provide us with an OIDC provider for the auth method
	// that was resolved from state.
	oidcProvider, err := a.oidcProviderCache.Get(authMethod)
	if err != nil {
		return fmt.Errorf("failed to generate OIDC provider: %v", err)
	}

	// Generate a context. This argument is required by the OIDC provider lib,
	// but is not used in any way. This therefore acts for future proofing, if
	// the provider lib uses the context.
	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(aclOIDCAuthURLRequestExpiryTime))
	defer cancel()

	// Generate the URL, handling any error along with the URL.
	authURL, err := oidcProvider.AuthURL(ctx, oidcReq)
	if err != nil {
		return fmt.Errorf("failed to generate auth URL: %v", err)
	}

	reply.AuthURL = authURL
	return nil
}

// OIDCCompleteAuth complete the OIDC login workflow. It will exchange the OIDC
// provider token for a Nomad ACL token, using the configured ACL role and
// policy claims to provide authorization.
func (a *ACL) OIDCCompleteAuth(
	args *structs.ACLOIDCCompleteAuthRequest, reply *structs.ACLOIDCCompleteAuthResponse) error {

	// The OIDC flow can only be used when the Nomad cluster has ACL enabled.
	if !a.srv.config.ACLEnabled {
		return aclDisabled
	}

	// Perform the initial forwarding within the region. This ensures we
	// respect stale queries.
	if done, err := a.srv.forward(structs.ACLOIDCCompleteAuthRPCMethod, args, args, reply); done {
		return err
	}

	// There is not a perfect place to run this defer since we potentially
	// forward twice. It is likely there will be two distinct patterns to this
	// timing in clusters that utilise a mixture of local and global with
	// methods.
	defer metrics.MeasureSince([]string{"nomad", "acl", "oidc_complete_auth"}, time.Now())

	// Validate the request arguments to ensure it contains all the data it
	// needs. Whether the data provided is correct will be handled by the OIDC
	// provider.
	if err := args.Validate(); err != nil {
		return structs.NewErrRPCCodedf(http.StatusBadRequest, "invalid OIDC complete-auth request: %v", err)
	}

	// Grab a snapshot of the state, so we can query it safely.
	stateSnapshot, err := a.srv.fsm.State().Snapshot()
	if err != nil {
		return err
	}

	// Lookup the auth method from state, so we have the entire object
	// available to us. It's important to check for nil on the auth method
	// object, as it is possible the request was made with an incorrectly named
	// auth method.
	authMethod, err := stateSnapshot.GetACLAuthMethodByName(nil, args.AuthMethodName)
	if err != nil {
		return err
	}
	if authMethod == nil {
		return structs.NewErrRPCCodedf(http.StatusBadRequest, "auth-method %q not found", args.AuthMethodName)
	}

	// If the authentication method generates global ACL tokens, we need to
	// forward the request onto the authoritative regional leader.
	if authMethod.TokenLocalityIsGlobal() {
		args.Region = a.srv.config.AuthoritativeRegion

		if done, err := a.srv.forward(structs.ACLOIDCCompleteAuthRPCMethod, args, args, reply); done {
			return err
		}
	}

	// Use the cache to provide us with an OIDC provider for the auth method
	// that was resolved from state.
	oidcProvider, err := a.oidcProviderCache.Get(authMethod)
	if err != nil {
		return fmt.Errorf("failed to generate OIDC provider: %v", err)
	}

	// Build our OIDC request options and request object.
	oidcReqOpts := []capOIDC.Option{
		capOIDC.WithNonce(args.ClientNonce),
		capOIDC.WithState(args.State),
	}

	if len(authMethod.Config.OIDCScopes) > 0 {
		oidcReqOpts = append(oidcReqOpts, capOIDC.WithScopes(authMethod.Config.OIDCScopes...))
	}
	if len(authMethod.Config.BoundAudiences) > 0 {
		oidcReqOpts = append(oidcReqOpts, capOIDC.WithAudiences(authMethod.Config.BoundAudiences...))
	}

	oidcReq, err := capOIDC.NewRequest(aclOIDCCallbackRequestExpiryTime, args.RedirectURI, oidcReqOpts...)
	if err != nil {
		return fmt.Errorf("failed to generate OIDC request: %v", err)
	}

	// Generate a context with a deadline. This is passed to the OIDC provider
	// and used when making remote HTTP requests.
	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(aclOIDCCallbackRequestExpiryTime))
	defer cancel()

	// Exchange the state and code for an OIDC provider token.
	oidcToken, err := oidcProvider.Exchange(ctx, oidcReq, args.State, args.Code)
	if err != nil {
		return fmt.Errorf("failed to exchange token with provider: %v", err)
	}
	if !oidcToken.Valid() {
		return errors.New("exchanged token is not valid; potentially expired or empty")
	}

	var idTokenClaims map[string]interface{}
	if err := oidcToken.IDToken().Claims(&idTokenClaims); err != nil {
		return fmt.Errorf("failed to retrieve the ID token claims: %v", err)
	}

	var userClaims map[string]interface{}
	if userTokenSource := oidcToken.StaticTokenSource(); userTokenSource != nil {
		if err := oidcProvider.UserInfo(ctx, userTokenSource, idTokenClaims["sub"].(string), &userClaims); err != nil {
			return fmt.Errorf("failed to retrieve the user info claims: %v", err)
		}
	}

	// Generate the data used by the go-bexpr selector that is an internal
	// representation of the claims that can be understood by Nomad.
	oidcInternalClaims, err := oidc.SelectorData(authMethod, idTokenClaims, userClaims)
	if err != nil {
		return err
	}

	// Create a new binder object based on the current state snapshot to
	// provide consistency within the RPC handler.
	oidcBinder := oidc.NewBinder(stateSnapshot)

	// Generate the role and policy bindings that will be assigned to the ACL
	// token. Ensure we have at least 1 role or policy, otherwise the RPC will
	// fail anyway.
	tokenBindings, err := oidcBinder.Bind(authMethod, oidc.NewIdentity(authMethod.Config, oidcInternalClaims))
	if err != nil {
		return err
	}
	if tokenBindings.None() {
		return structs.NewErrRPCCoded(http.StatusBadRequest, "no role or policy bindings matched")
	}

	// Build our token RPC request. The RPC handler includes a lot of specific
	// logic, so we do not want to call Raft directly or copy that here. In the
	// future we should try and extract out the logic into an interface, or at
	// least a separate function.
	tokenUpsertRequest := structs.ACLTokenUpsertRequest{
		Tokens: []*structs.ACLToken{
			{
				Name:          "OIDC-" + authMethod.Name,
				Type:          structs.ACLClientToken,
				Policies:      tokenBindings.Policies,
				Roles:         tokenBindings.Roles,
				Global:        authMethod.TokenLocalityIsGlobal(),
				ExpirationTTL: authMethod.MaxTokenTTL,
			},
		},
		WriteRequest: structs.WriteRequest{
			Region:    a.srv.Region(),
			AuthToken: a.srv.getLeaderAcl(),
		},
	}

	var tokenUpsertReply structs.ACLTokenUpsertResponse

	if err := a.srv.RPC(structs.ACLUpsertTokensRPCMethod, &tokenUpsertRequest, &tokenUpsertReply); err != nil {
		return err
	}

	// The way the UpsertTokens RPC currently works, if we get no error, then
	// we will have exactly the same number of tokens returned as we sent. It
	// is therefore safe to assume we have 1 token.
	reply.ACLToken = tokenUpsertReply.Tokens[0]
	return nil
}