do sorting on addresses before sending them to stream

addr/sorting.go

@@ -0,0 +1,62 @@
+package addr
+
+import (
+	"bytes"
+
+	ma "github.com/jbenet/go-multiaddr"
+	manet "github.com/jbenet/go-multiaddr-net"
+	mafmt "github.com/whyrusleeping/mafmt"
+)
+
+func isFDCostlyTransport(a ma.Multiaddr) bool {
+	return mafmt.TCP.Matches(a)
+}
+
+type AddrList []ma.Multiaddr
+
+func (al AddrList) Len() int {
+	return len(al)
+}
+
+func (al AddrList) Swap(i, j int) {
+	al[i], al[j] = al[j], al[i]
+}
+
+func (al AddrList) Less(i, j int) bool {
+	a := al[i]
+	b := al[j]
+
+	// dial localhost addresses next, they should fail immediately
+	lba := manet.IsIPLoopback(a)
+	lbb := manet.IsIPLoopback(b)
+	if lba {
+		if !lbb {
+			return true
+		}
+	}
+
+	// dial utp and similar 'non-fd-consuming' addresses first
+	fda := isFDCostlyTransport(a)
+	fdb := isFDCostlyTransport(b)
+	if !fda {
+		if fdb {
+			return true
+		}
+
+		// if neither consume fd's, assume equal ordering
+		return false
+	}
+
+	// if 'b' doesnt take a file descriptor
+	if !fdb {
+		return false
+	}
+
+	// if 'b' is loopback and both take file descriptors
+	if lbb {
+		return false
+	}
+
+	// for the rest, just sort by bytes
+	return bytes.Compare(a.Bytes(), b.Bytes()) > 0
+}

addr_manager.go

@@ -1,9 +1,11 @@
 package peer
 
 import (
+	"sort"
 	"sync"
 	"time"
 
+	addr "github.com/ipfs/go-libp2p-peer/addr"
 	ma "github.com/jbenet/go-multiaddr"
 	"golang.org/x/net/context"
 )
@@ -258,7 +260,7 @@ func (mgr *AddrManager) AddrStream(ctx context.Context, p ID) <-chan ma.Multiadd
 		initial = append(initial, a.Addr)
 	}
 
-	// TODO: sort these?
+	sort.Sort(addr.AddrList(initial))
 
 	go func(buffer []ma.Multiaddr) {
 		defer close(out)