openpgp: move addUserID outside of ReadEntity

In change id Id992676ef2363779a7028f4799180efb027fcf47, "current" was
moved into the UserID packet handling scope. This was the only thing
preventing us to move the UserID packet handling code inside its own
function.

This patch moves the UserID packet handling code inside a new addUserID
function. This is consistent with the other existing addSubKey method.

"current" is renamed to "identity" for improved readability.

Change-Id: I5d58eb35ab5fa9fc7d9d111fa186fec6f5e11e79
Reviewed-on: https://go-review.googlesource.com/118959
Reviewed-by: Filippo Valsorda <filippo@golang.org>
Run-TryBot: Filippo Valsorda <filippo@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

openpgp/keys.go

@@ -345,36 +345,8 @@ EachPacket:
 
 		switch pkt := p.(type) {
 		case *packet.UserId:
-			// Make a new Identity object, that we might wind up throwing away.
-			// We'll only add it if we get a valid self-signature over this
-			// userID.
-			current := new(Identity)
-			current.Name = pkt.Id
-			current.UserId = pkt
-
-			for {
-				p, err = packets.Next()
-				if err == io.EOF {
-					break EachPacket
-				} else if err != nil {
-					return nil, err
-				}
-
-				sig, ok := p.(*packet.Signature)
-				if !ok {
-					packets.Unread(p)
-					continue EachPacket
-				}
-
-				if (sig.SigType == packet.SigTypePositiveCert || sig.SigType == packet.SigTypeGenericCert) && sig.IssuerKeyId != nil && *sig.IssuerKeyId == e.PrimaryKey.KeyId {
-					if err = e.PrimaryKey.VerifyUserIdSignature(pkt.Id, e.PrimaryKey, sig); err != nil {
-						return nil, errors.StructuralError("user ID self-signature invalid: " + err.Error())
-					}
-					current.SelfSignature = sig
-					e.Identities[pkt.Id] = current
-				} else {
-					current.Signatures = append(current.Signatures, sig)
-				}
+			if err := addUserID(e, packets, pkt); err != nil {
+				return nil, err
 			}
 		case *packet.Signature:
 			if pkt.SigType == packet.SigTypeKeyRevocation {
@@ -426,6 +398,42 @@ EachPacket:
 	return e, nil
 }
 
+func addUserID(e *Entity, packets *packet.Reader, pkt *packet.UserId) error {
+	// Make a new Identity object, that we might wind up throwing away.
+	// We'll only add it if we get a valid self-signature over this
+	// userID.
+	identity := new(Identity)
+	identity.Name = pkt.Id
+	identity.UserId = pkt
+
+	for {
+		p, err := packets.Next()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return err
+		}
+
+		sig, ok := p.(*packet.Signature)
+		if !ok {
+			packets.Unread(p)
+			break
+		}
+
+		if (sig.SigType == packet.SigTypePositiveCert || sig.SigType == packet.SigTypeGenericCert) && sig.IssuerKeyId != nil && *sig.IssuerKeyId == e.PrimaryKey.KeyId {
+			if err = e.PrimaryKey.VerifyUserIdSignature(pkt.Id, e.PrimaryKey, sig); err != nil {
+				return errors.StructuralError("user ID self-signature invalid: " + err.Error())
+			}
+			identity.SelfSignature = sig
+			e.Identities[pkt.Id] = identity
+		} else {
+			identity.Signatures = append(identity.Signatures, sig)
+		}
+	}
+
+	return nil
+}
+
 func addSubkey(e *Entity, packets *packet.Reader, pub *packet.PublicKey, priv *packet.PrivateKey) error {
 	var subKey Subkey
 	subKey.PublicKey = pub