open-consul/command/intention/finder/finder.go

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package finder
import (
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"fmt"
"strings"
"sync"
"github.com/hashicorp/consul/api"
)
// Finder finds intentions by a src/dst exact match. There is currently
// no direct API to do this so this struct downloads all intentions and
// caches them once, and searches in-memory for this. For now this works since
// even with a very large number of intentions, the size of the data gzipped
// over HTTP will be relatively small.
//
// The Finder will only download the intentions one time. This struct is
// not expected to be used over a long period of time. Though it may be
// reused multile times, the intentions list is only downloaded once.
type Finder struct {
// Client is the API client to use for any requests.
Client *api.Client
lock sync.Mutex
ixns []*api.Intention // cached list of intentions
}
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// ID returns the intention ID for the given CLI args. An error is returned
// if args is not 1 or 2 elements.
func (f *Finder) IDFromArgs(args []string) (string, error) {
switch len(args) {
case 1:
return args[0], nil
case 2:
ixn, err := f.Find(args[0], args[1])
if err != nil {
return "", err
}
if ixn == nil {
return "", fmt.Errorf(
"Intention with source %q and destination %q not found.",
args[0], args[1])
}
return ixn.ID, nil
default:
return "", fmt.Errorf("command requires exactly 1 or 2 arguments")
}
}
// Find finds the intention that matches the given src and dst. This will
// return nil when the result is not found.
func (f *Finder) Find(src, dst string) (*api.Intention, error) {
src = StripDefaultNS(src)
dst = StripDefaultNS(dst)
f.lock.Lock()
defer f.lock.Unlock()
// If the list of ixns is nil, then we haven't fetched yet, so fetch
if f.ixns == nil {
ixns, _, err := f.Client.Connect().Intentions(nil)
if err != nil {
return nil, err
}
f.ixns = ixns
}
// Go through the intentions and find an exact match
for _, ixn := range f.ixns {
if ixn.SourceString() == src && ixn.DestinationString() == dst {
return ixn, nil
}
}
return nil, nil
}
// StripDefaultNS strips the default namespace from an argument. For now,
// the API and lookups strip this value from string output so we strip it.
func StripDefaultNS(v string) string {
if idx := strings.IndexByte(v, '/'); idx > 0 {
if v[:idx] == api.IntentionDefaultNamespace {
return v[idx+1:]
}
}
return v
}