Add Tor .onion address support and unit test cases

codec.go

 package multiaddr
 
 import (
+	"encoding/base32"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -165,6 +166,16 @@ func addressStringToBytes(p Protocol, s string) ([]byte, error) {
 		binary.BigEndian.PutUint16(b, uint16(i))
 		return b, nil
 
+	case P_TOR:
+		fields := strings.Split(s, ".onion")
+		if len(fields) != 2 {
+			return nil, fmt.Errorf("failed to parse ipfs addr: %s not a Tor .onion address.", s)
+		}
+		b, err := base32.StdEncoding.DecodeString(strings.ToUpper(fields[0]))
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse ipfs addr: %s %s", s, err)
+		}
+		return b, nil
 	case P_IPFS: // ipfs
 		// the address is a varint prefixed multihash string representation
 		m, err := mh.FromB58String(s)

multiaddr_test.go

@@ -25,6 +25,8 @@ func TestConstructFails(t *testing.T) {
 		"/sctp",
 		"/udp/65536",
 		"/tcp/65536",
+		"/tor/9imaq4ygg2iegci7.onion",
+		"/tor/aaimaq4ygg2iegci7.onion",
 		"/udp/1234/sctp",
 		"/udp/1234/udt/1234",
 		"/udp/1234/utp/1234",
@@ -49,6 +51,9 @@ func TestConstructSucceeds(t *testing.T) {
 		"/ip4/0.0.0.0",
 		"/ip6/::1",
 		"/ip6/2601:9:4f81:9700:803e:ca65:66e8:c21",
+		"/tor/timaq4ygg2iegci7.onion",
+		"/tor/timaq4ygg2iegci7.onion/tcp/1234",
+		"/tor/timaq4ygg2iegci7.onion/tcp/80/http",
 		"/udp/0",
 		"/tcp/0",
 		"/sctp/0",

protocols.csv

@@ -5,6 +5,7 @@ code	size	name
 33	16	dccp
 41	128	ip6
 132	16	sctp
+133     10      tor
 301	0	udt
 302	0	utp
 421	V	ipfs

protocols.go

@@ -25,6 +25,7 @@ const (
 	P_DCCP  = 33
 	P_IP6   = 41
 	P_SCTP  = 132
+	P_TOR   = 133
 	P_UTP   = 301
 	P_UDT   = 302
 	P_IPFS  = 421
@@ -46,6 +47,7 @@ var Protocols = []Protocol{
 	Protocol{P_IP6, 128, "ip6", CodeToVarint(P_IP6)},
 	// these require varint:
 	Protocol{P_SCTP, 16, "sctp", CodeToVarint(P_SCTP)},
+	Protocol{P_TOR, 10, "tor", CodeToVarint(P_TOR)},
 	Protocol{P_UTP, 0, "utp", CodeToVarint(P_UTP)},
 	Protocol{P_UDT, 0, "udt", CodeToVarint(P_UDT)},
 	Protocol{P_HTTP, 0, "http", CodeToVarint(P_HTTP)},