From e3b1c400e5474a55978d2243ec2b8aa1cecaefee Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Sun, 15 Apr 2018 22:11:04 +0200
Subject: [PATCH] agent/cache-types: got basic CA leaf caching work, major
 problems still

---
 agent/cache-types/connect_ca.go      | 182 ++++++++++++++++++++++++-
 agent/cache-types/connect_ca_test.go | 195 +++++++++++++++++++++++++++
 agent/cache-types/testing.go         |  48 +++++++
 3 files changed, 422 insertions(+), 3 deletions(-)

diff --git a/agent/cache-types/connect_ca.go b/agent/cache-types/connect_ca.go
index 5b72a47a7..22549ed49 100644
--- a/agent/cache-types/connect_ca.go
+++ b/agent/cache-types/connect_ca.go
@@ -2,15 +2,27 @@ package cachetype
 
 import (
 	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
 
 	"github.com/hashicorp/consul/agent/cache"
+	"github.com/hashicorp/consul/agent/connect"
 	"github.com/hashicorp/consul/agent/structs"
+
+	// NOTE(mitcehllh): This is temporary while certs are stubbed out.
+	"github.com/mitchellh/go-testing-interface"
 )
 
-// Recommended name for registration for ConnectCARoot
-const ConnectCARootName = "connect-ca"
+// Recommended name for registration.
+const (
+	ConnectCARootName = "connect-ca-root"
+	ConnectCALeafName = "connect-ca-leaf"
+)
 
-// ConnectCARoot supports fetching the Connect CA roots.
+// ConnectCARoot supports fetching the Connect CA roots. This is a
+// straightforward cache type since it only has to block on the given
+// index and return the data.
 type ConnectCARoot struct {
 	RPC RPC
 }
@@ -39,3 +51,167 @@ func (c *ConnectCARoot) Fetch(opts cache.FetchOptions, req cache.Request) (cache
 	result.Index = reply.QueryMeta.Index
 	return result, nil
 }
+
+// ConnectCALeaf supports fetching and generating Connect leaf
+// certificates.
+type ConnectCALeaf struct {
+	caIndex uint64 // Current index for CA roots
+
+	issuedCertsLock sync.RWMutex
+	issuedCerts     map[string]*structs.IssuedCert
+
+	RPC   RPC          // RPC client for remote requests
+	Cache *cache.Cache // Cache that has CA root certs via ConnectCARoot
+}
+
+func (c *ConnectCALeaf) Fetch(opts cache.FetchOptions, req cache.Request) (cache.FetchResult, error) {
+	var result cache.FetchResult
+
+	// Get the correct type
+	reqReal, ok := req.(*ConnectCALeafRequest)
+	if !ok {
+		return result, fmt.Errorf(
+			"Internal cache failure: request wrong type: %T", req)
+	}
+
+	// This channel watches our overall timeout. The other goroutines
+	// launched in this function should end all around the same time so
+	// they clean themselves up.
+	timeoutCh := time.After(opts.Timeout)
+
+	// Kick off the goroutine that waits for new CA roots. The channel buffer
+	// is so that the goroutine doesn't block forever if we return for other
+	// reasons.
+	newRootCACh := make(chan error, 1)
+	go c.waitNewRootCA(newRootCACh, opts.Timeout)
+
+	// Get our prior cert (if we had one) and use that to determine our
+	// expiration time. If no cert exists, we expire immediately since we
+	// need to generate.
+	c.issuedCertsLock.RLock()
+	lastCert := c.issuedCerts[reqReal.Service]
+	c.issuedCertsLock.RUnlock()
+
+	var leafExpiryCh <-chan time.Time
+	if lastCert != nil {
+		// Determine how long we wait until triggering. If we've already
+		// expired, we trigger immediately.
+		if expiryDur := lastCert.ValidBefore.Sub(time.Now()); expiryDur > 0 {
+			leafExpiryCh = time.After(expiryDur - 1*time.Hour)
+			// TODO(mitchellh): 1 hour buffer is hardcoded above
+		}
+	}
+
+	if leafExpiryCh == nil {
+		// If the channel is still nil then it means we need to generate
+		// a cert no matter what: we either don't have an existing one or
+		// it is expired.
+		leafExpiryCh = time.After(0)
+	}
+
+	// Block on the events that wake us up.
+	select {
+	case <-timeoutCh:
+		// TODO: what is the right error for a timeout?
+		return result, fmt.Errorf("timeout")
+
+	case err := <-newRootCACh:
+		// A new root CA triggers us to refresh the leaf certificate.
+		// If there was an error while getting the root CA then we return.
+		// Otherwise, we leave the select statement and move to generation.
+		if err != nil {
+			return result, err
+		}
+
+	case <-leafExpiryCh:
+		// The existing leaf certificate is expiring soon, so we generate a
+		// new cert with a healthy overlapping validity period (determined
+		// by the above channel).
+	}
+
+	// Create a CSR.
+	// TODO(mitchellh): This is obviously not production ready!
+	csr, pk := connect.TestCSR(&testing.RuntimeT{}, &connect.SpiffeIDService{
+		Host:       "1234.consul",
+		Namespace:  "default",
+		Datacenter: reqReal.Datacenter,
+		Service:    reqReal.Service,
+	})
+
+	// Request signing
+	var reply structs.IssuedCert
+	args := structs.CASignRequest{CSR: csr}
+	if err := c.RPC.RPC("ConnectCA.Sign", &args, &reply); err != nil {
+		return result, err
+	}
+	reply.PrivateKeyPEM = pk
+
+	// Lock the issued certs map so we can insert it. We only insert if
+	// we didn't happen to get a newer one. This should never happen since
+	// the Cache should ensure only one Fetch per service, but we sanity
+	// check just in case.
+	c.issuedCertsLock.Lock()
+	defer c.issuedCertsLock.Unlock()
+	lastCert = c.issuedCerts[reqReal.Service]
+	if lastCert == nil || lastCert.ModifyIndex < reply.ModifyIndex {
+		if c.issuedCerts == nil {
+			c.issuedCerts = make(map[string]*structs.IssuedCert)
+		}
+		c.issuedCerts[reqReal.Service] = &reply
+		lastCert = &reply
+	}
+
+	result.Value = lastCert
+	result.Index = lastCert.ModifyIndex
+	return result, nil
+}
+
+// waitNewRootCA blocks until a new root CA is available or the timeout is
+// reached (on timeout ErrTimeout is returned on the channel).
+func (c *ConnectCALeaf) waitNewRootCA(ch chan<- error, timeout time.Duration) {
+	// Fetch some new roots. This will block until our MinQueryIndex is
+	// matched or the timeout is reached.
+	rawRoots, err := c.Cache.Get(ConnectCARootName, &structs.DCSpecificRequest{
+		Datacenter: "",
+		QueryOptions: structs.QueryOptions{
+			MinQueryIndex: atomic.LoadUint64(&c.caIndex),
+			MaxQueryTime:  timeout,
+		},
+	})
+	if err != nil {
+		ch <- err
+		return
+	}
+
+	roots, ok := rawRoots.(*structs.IndexedCARoots)
+	if !ok {
+		// This should never happen but we don't want to even risk a panic
+		ch <- fmt.Errorf(
+			"internal error: CA root cache returned bad type: %T", rawRoots)
+		return
+	}
+
+	// Set the new index
+	atomic.StoreUint64(&c.caIndex, roots.QueryMeta.Index)
+
+	// Trigger the channel since we updated.
+	ch <- nil
+}
+
+// ConnectCALeafRequest is the cache.Request implementation for the
+// COnnectCALeaf cache type. This is implemented here and not in structs
+// since this is only used for cache-related requests and not forwarded
+// directly to any Consul servers.
+type ConnectCALeafRequest struct {
+	Datacenter    string
+	Service       string // Service name, not ID
+	MinQueryIndex uint64
+}
+
+func (r *ConnectCALeafRequest) CacheInfo() cache.RequestInfo {
+	return cache.RequestInfo{
+		Key:        r.Service,
+		Datacenter: r.Datacenter,
+		MinIndex:   r.MinQueryIndex,
+	}
+}
diff --git a/agent/cache-types/connect_ca_test.go b/agent/cache-types/connect_ca_test.go
index 24c37f313..43953e7f8 100644
--- a/agent/cache-types/connect_ca_test.go
+++ b/agent/cache-types/connect_ca_test.go
@@ -1,6 +1,8 @@
 package cachetype
 
 import (
+	"fmt"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -55,3 +57,196 @@ func TestConnectCARoot_badReqType(t *testing.T) {
 	require.Contains(err.Error(), "wrong type")
 
 }
+
+// Test that after an initial signing, new CA roots (new ID) will
+// trigger a blocking query to execute.
+func TestConnectCALeaf_changingRoots(t *testing.T) {
+	t.Parallel()
+
+	require := require.New(t)
+	rpc := TestRPC(t)
+	defer rpc.AssertExpectations(t)
+
+	typ, rootsCh := testCALeafType(t, rpc)
+	defer close(rootsCh)
+	rootsCh <- structs.IndexedCARoots{
+		ActiveRootID: "1",
+		QueryMeta:    structs.QueryMeta{Index: 1},
+	}
+
+	// Instrument ConnectCA.Sign to
+	var resp *structs.IssuedCert
+	var idx uint64
+	rpc.On("RPC", "ConnectCA.Sign", mock.Anything, mock.Anything).Return(nil).
+		Run(func(args mock.Arguments) {
+			reply := args.Get(2).(*structs.IssuedCert)
+			reply.ValidBefore = time.Now().Add(12 * time.Hour)
+			reply.CreateIndex = atomic.AddUint64(&idx, 1)
+			reply.ModifyIndex = reply.CreateIndex
+			resp = reply
+		})
+
+	// We'll reuse the fetch options and request
+	opts := cache.FetchOptions{MinIndex: 0, Timeout: 10 * time.Second}
+	req := &ConnectCALeafRequest{Datacenter: "dc1", Service: "web"}
+
+	// First fetch should return immediately
+	fetchCh := TestFetchCh(t, typ, opts, req)
+	select {
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("shouldn't block waiting for fetch")
+	case result := <-fetchCh:
+		require.Equal(cache.FetchResult{
+			Value: resp,
+			Index: 1,
+		}, result)
+	}
+
+	// Second fetch should block with set index
+	fetchCh = TestFetchCh(t, typ, opts, req)
+	select {
+	case result := <-fetchCh:
+		t.Fatalf("should not return: %#v", result)
+	case <-time.After(100 * time.Millisecond):
+	}
+
+	// Let's send in new roots, which should trigger the sign req
+	rootsCh <- structs.IndexedCARoots{
+		ActiveRootID: "2",
+		QueryMeta:    structs.QueryMeta{Index: 2},
+	}
+	select {
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("shouldn't block waiting for fetch")
+	case result := <-fetchCh:
+		require.Equal(cache.FetchResult{
+			Value: resp,
+			Index: 2,
+		}, result)
+	}
+
+	// Third fetch should block
+	fetchCh = TestFetchCh(t, typ, opts, req)
+	select {
+	case result := <-fetchCh:
+		t.Fatalf("should not return: %#v", result)
+	case <-time.After(100 * time.Millisecond):
+	}
+}
+
+// Test that after an initial signing, an expiringLeaf will trigger a
+// blocking query to resign.
+func TestConnectCALeaf_expiringLeaf(t *testing.T) {
+	t.Parallel()
+
+	require := require.New(t)
+	rpc := TestRPC(t)
+	defer rpc.AssertExpectations(t)
+
+	typ, rootsCh := testCALeafType(t, rpc)
+	defer close(rootsCh)
+	rootsCh <- structs.IndexedCARoots{
+		ActiveRootID: "1",
+		QueryMeta:    structs.QueryMeta{Index: 1},
+	}
+
+	// Instrument ConnectCA.Sign to
+	var resp *structs.IssuedCert
+	var idx uint64
+	rpc.On("RPC", "ConnectCA.Sign", mock.Anything, mock.Anything).Return(nil).
+		Run(func(args mock.Arguments) {
+			reply := args.Get(2).(*structs.IssuedCert)
+			reply.CreateIndex = atomic.AddUint64(&idx, 1)
+			reply.ModifyIndex = reply.CreateIndex
+
+			// This sets the validity to 0 on the first call, and
+			// 12 hours+ on subsequent calls. This means that our first
+			// cert expires immediately.
+			reply.ValidBefore = time.Now().Add((12 * time.Hour) *
+				time.Duration(reply.CreateIndex-1))
+
+			resp = reply
+		})
+
+	// We'll reuse the fetch options and request
+	opts := cache.FetchOptions{MinIndex: 0, Timeout: 10 * time.Second}
+	req := &ConnectCALeafRequest{Datacenter: "dc1", Service: "web"}
+
+	// First fetch should return immediately
+	fetchCh := TestFetchCh(t, typ, opts, req)
+	select {
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("shouldn't block waiting for fetch")
+	case result := <-fetchCh:
+		require.Equal(cache.FetchResult{
+			Value: resp,
+			Index: 1,
+		}, result)
+	}
+
+	// Second fetch should return immediately despite there being
+	// no updated CA roots, because we issued an expired cert.
+	fetchCh = TestFetchCh(t, typ, opts, req)
+	select {
+	case <-time.After(100 * time.Millisecond):
+		t.Fatal("shouldn't block waiting for fetch")
+	case result := <-fetchCh:
+		require.Equal(cache.FetchResult{
+			Value: resp,
+			Index: 2,
+		}, result)
+	}
+
+	// Third fetch should block since the cert is not expiring and
+	// we also didn't update CA certs.
+	fetchCh = TestFetchCh(t, typ, opts, req)
+	select {
+	case result := <-fetchCh:
+		t.Fatalf("should not return: %#v", result)
+	case <-time.After(100 * time.Millisecond):
+	}
+}
+
+// testCALeafType returns a *ConnectCALeaf that is pre-configured to
+// use the given RPC implementation for "ConnectCA.Sign" operations.
+func testCALeafType(t *testing.T, rpc RPC) (*ConnectCALeaf, chan structs.IndexedCARoots) {
+	// This creates an RPC implementation that will block until the
+	// value is sent on the channel. This lets us control when the
+	// next values show up.
+	rootsCh := make(chan structs.IndexedCARoots, 10)
+	rootsRPC := &testGatedRootsRPC{ValueCh: rootsCh}
+
+	// Create a cache
+	c := cache.TestCache(t)
+	c.RegisterType(ConnectCARootName, &ConnectCARoot{RPC: rootsRPC}, &cache.RegisterOptions{
+		// Disable refresh so that the gated channel controls the
+		// request directly. Otherwise, we get background refreshes and
+		// it screws up the ordering of the channel reads of the
+		// testGatedRootsRPC implementation.
+		Refresh: false,
+	})
+
+	// Create the leaf type
+	return &ConnectCALeaf{RPC: rpc, Cache: c}, rootsCh
+}
+
+// testGatedRootsRPC will send each subsequent value on the channel as the
+// RPC response, blocking if it is waiting for a value on the channel. This
+// can be used to control when background fetches are returned and what they
+// return.
+//
+// This should be used with Refresh = false for the registration options so
+// automatic refreshes don't mess up the channel read ordering.
+type testGatedRootsRPC struct {
+	ValueCh chan structs.IndexedCARoots
+}
+
+func (r *testGatedRootsRPC) RPC(method string, args interface{}, reply interface{}) error {
+	if method != "ConnectCA.Roots" {
+		return fmt.Errorf("invalid RPC method: %s", method)
+	}
+
+	replyReal := reply.(*structs.IndexedCARoots)
+	*replyReal = <-r.ValueCh
+	return nil
+}
diff --git a/agent/cache-types/testing.go b/agent/cache-types/testing.go
index bf68ec478..fcffe45a9 100644
--- a/agent/cache-types/testing.go
+++ b/agent/cache-types/testing.go
@@ -1,6 +1,10 @@
 package cachetype
 
 import (
+	"reflect"
+	"time"
+
+	"github.com/hashicorp/consul/agent/cache"
 	"github.com/mitchellh/go-testing-interface"
 )
 
@@ -10,3 +14,47 @@ func TestRPC(t testing.T) *MockRPC {
 	// perform some initialization later.
 	return &MockRPC{}
 }
+
+// TestFetchCh returns a channel that returns the result of the Fetch call.
+// This is useful for testing timing and concurrency with Fetch calls.
+// Errors will show up as an error type on the resulting channel so a
+// type switch should be used.
+func TestFetchCh(
+	t testing.T,
+	typ cache.Type,
+	opts cache.FetchOptions,
+	req cache.Request) <-chan interface{} {
+	resultCh := make(chan interface{})
+	go func() {
+		result, err := typ.Fetch(opts, req)
+		if err != nil {
+			resultCh <- err
+			return
+		}
+
+		resultCh <- result
+	}()
+
+	return resultCh
+}
+
+// TestFetchChResult tests that the result from TestFetchCh matches
+// within a reasonable period of time (it expects it to be "immediate" but
+// waits some milliseconds).
+func TestFetchChResult(t testing.T, ch <-chan interface{}, expected interface{}) {
+	t.Helper()
+
+	select {
+	case result := <-ch:
+		if err, ok := result.(error); ok {
+			t.Fatalf("Result was error: %s", err)
+			return
+		}
+
+		if !reflect.DeepEqual(result, expected) {
+			t.Fatalf("Result doesn't match!\n\n%#v\n\n%#v", result, expected)
+		}
+
+	case <-time.After(50 * time.Millisecond):
+	}
+}