add method to parse /ipfs/ addresses into a peerinfo

peerinfo.go

@@ -2,6 +2,8 @@ package peerstore
 
 import (
 	"encoding/json"
+	"fmt"
+	"strings"
 
 	"github.com/libp2p/go-libp2p-peer"
 	ma "github.com/multiformats/go-multiaddr"
@@ -16,6 +18,38 @@ type PeerInfo struct {
 	Addrs []ma.Multiaddr
 }
 
+var ErrInvalidAddr = fmt.Errorf("invalid p2p multiaddr")
+
+func InfoFromP2pAddr(m ma.Multiaddr) (*PeerInfo, error) {
+	if m == nil {
+		return nil, ErrInvalidAddr
+	}
+
+	// make sure it's an IPFS addr
+	parts := ma.Split(m)
+	if len(parts) < 1 {
+		return nil, ErrInvalidAddr
+	}
+
+	ipfspart := parts[len(parts)-1] // last part
+	if ipfspart.Protocols()[0].Code != ma.P_IPFS {
+		return nil, ErrInvalidAddr
+	}
+
+	// make sure 'ipfs id' parses as a peer.ID
+	peerIdParts := strings.Split(ipfspart.String(), "/")
+	peerIdStr := peerIdParts[len(peerIdParts)-1]
+	id, err := peer.IDB58Decode(peerIdStr)
+	if err != nil {
+		return nil, err
+	}
+
+	return &PeerInfo{
+		ID:    id,
+		Addrs: []ma.Multiaddr{ma.Join(parts[:len(parts)-1]...)},
+	}, nil
+}
+
 func (pi *PeerInfo) Loggable() map[string]interface{} {
 	return map[string]interface{}{
 		"peerID": pi.ID.Pretty(),

peerinfo_test.go

@@ -56,3 +56,30 @@ func TestPeerInfoMarshal(t *testing.T) {
 		t.Fatal("loggables gave wrong peerID output")
 	}
 }
+
+func TestP2pAddrParsing(t *testing.T) {
+	a := mustAddr(t, "/ip4/1.2.3.4/tcp/4536")
+	id, err := peer.IDB58Decode("QmaCpDMGvV2BGHeYERUEnRQAwe3N8SzbUtfsmvsqQLuvuJ")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	p2pa := a.String() + "/ipfs/" + id.Pretty()
+	p2pma, err := ma.NewMultiaddr(p2pa)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	pinfo, err := InfoFromP2pAddr(p2pma)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if pinfo.ID != id {
+		t.Fatal("didnt get expected peerID")
+	}
+
+	if !a.Equal(pinfo.Addrs[0]) {
+		t.Fatal("didnt get expected address")
+	}
+}