addr: proper filter + subtract

net/swarm/addr/addr.go

@@ -41,19 +41,27 @@ func init() {
 	SupportedTransportProtocols = transports
 }
 
-// FilterAddrs is a filter that removes certain addresses
-// from a list. the addresses removed are those known NOT
-// to work with our network. Namely, addresses with UTP.
-func FilterAddrs(a []ma.Multiaddr) []ma.Multiaddr {
+// FilterAddrs is a filter that removes certain addresses, according to filter.
+// if filter returns true, the address is kept.
+func FilterAddrs(a []ma.Multiaddr, filter func(ma.Multiaddr) bool) []ma.Multiaddr {
 	b := make([]ma.Multiaddr, 0, len(a))
 	for _, addr := range a {
-		if AddrUsable(addr, false) {
+		if filter(addr) {
 			b = append(b, addr)
 		}
 	}
 	return b
 }
 
+// FilterUsableAddrs removes certain addresses
+// from a list. the addresses removed are those known NOT
+// to work with our network. Namely, addresses with UTP.
+func FilterUsableAddrs(a []ma.Multiaddr) []ma.Multiaddr {
+	return FilterAddrs(a, func(m ma.Multiaddr) bool {
+		return AddrUsable(m, false)
+	})
+}
+
 // AddrOverNonLocalIP returns whether the addr uses a non-local ip link
 func AddrOverNonLocalIP(a ma.Multiaddr) bool {
 	split := ma.Split(a)
@@ -228,13 +236,19 @@ func AddrIsShareableOnWAN(addr ma.Multiaddr) bool {
 
 // WANShareableAddrs filters addresses based on whether they're shareable on WAN
 func WANShareableAddrs(inp []ma.Multiaddr) []ma.Multiaddr {
-	out := make([]ma.Multiaddr, 0, len(inp))
-	for _, a := range inp {
-		if AddrIsShareableOnWAN(a) {
-			out = append(out, a)
+	return FilterAddrs(inp, AddrIsShareableOnWAN)
+}
+
+// Subtract filters out all addrs in b from a
+func Subtract(a, b []ma.Multiaddr) []ma.Multiaddr {
+	return FilterAddrs(a, func(m ma.Multiaddr) bool {
+		for _, bb := range b {
+			if m.Equal(bb) {
+				return false
+			}
 		}
-	}
-	return out
+		return true
+	})
 }
 
 // CheckNATWarning checks if our observed addresses differ. if so,

net/swarm/addr/addr_test.go

@@ -53,9 +53,9 @@ func TestFilterAddrs(t *testing.T) {
 		}
 	}
 
-	subtestAddrsEqual(t, FilterAddrs(bad), []ma.Multiaddr{})
-	subtestAddrsEqual(t, FilterAddrs(good), good)
-	subtestAddrsEqual(t, FilterAddrs(goodAndBad), good)
+	subtestAddrsEqual(t, FilterUsableAddrs(bad), []ma.Multiaddr{})
+	subtestAddrsEqual(t, FilterUsableAddrs(good), good)
+	subtestAddrsEqual(t, FilterUsableAddrs(goodAndBad), good)
 }
 
 func subtestAddrsEqual(t *testing.T, a, b []ma.Multiaddr) {
@@ -196,3 +196,37 @@ func TestWANShareable(t *testing.T) {
 		t.Error("should be zero")
 	}
 }
+
+func TestSubtract(t *testing.T) {
+
+	a := []ma.Multiaddr{
+		newMultiaddr(t, "/ip4/127.0.0.1/tcp/1234"),
+		newMultiaddr(t, "/ip4/0.0.0.0/tcp/1234"),
+		newMultiaddr(t, "/ip6/::1/tcp/1234"),
+		newMultiaddr(t, "/ip6/::/tcp/1234"),
+		newMultiaddr(t, "/ip6/fe80::1/tcp/1234"),
+		newMultiaddr(t, "/ip6/fe80::/tcp/1234"),
+	}
+
+	b := []ma.Multiaddr{
+		newMultiaddr(t, "/ip4/127.0.0.1/tcp/1234"),
+		newMultiaddr(t, "/ip6/::1/tcp/1234"),
+		newMultiaddr(t, "/ip6/fe80::1/tcp/1234"),
+	}
+
+	c1 := []ma.Multiaddr{
+		newMultiaddr(t, "/ip4/0.0.0.0/tcp/1234"),
+		newMultiaddr(t, "/ip6/::/tcp/1234"),
+		newMultiaddr(t, "/ip6/fe80::/tcp/1234"),
+	}
+
+	c2 := Subtract(a, b)
+	if len(c1) != len(c2) {
+		t.Error("should be the same")
+	}
+	for i, ca := range c1 {
+		if !c2[i].Equal(ca) {
+			t.Error("should be the same", ca, c2[i])
+		}
+	}
+}

net/swarm/swarm.go

@@ -41,7 +41,7 @@ func NewSwarm(ctx context.Context, listenAddrs []ma.Multiaddr,
 	local peer.ID, peers peer.Peerstore) (*Swarm, error) {
 
 	if len(listenAddrs) > 0 {
-		filtered := addrutil.FilterAddrs(listenAddrs)
+		filtered := addrutil.FilterUsableAddrs(listenAddrs)
 		if len(filtered) < 1 {
 			return nil, fmt.Errorf("swarm cannot use any addr in: %s", listenAddrs)
 		}

net/swarm/swarm_addr_test.go

@@ -51,9 +51,9 @@ func TestFilterAddrs(t *testing.T) {
 		}
 	}
 
-	subtestAddrsEqual(t, addrutil.FilterAddrs(bad), []ma.Multiaddr{})
-	subtestAddrsEqual(t, addrutil.FilterAddrs(good), good)
-	subtestAddrsEqual(t, addrutil.FilterAddrs(goodAndBad), good)
+	subtestAddrsEqual(t, addrutil.FilterUsableAddrs(bad), []ma.Multiaddr{})
+	subtestAddrsEqual(t, addrutil.FilterUsableAddrs(good), good)
+	subtestAddrsEqual(t, addrutil.FilterUsableAddrs(goodAndBad), good)
 
 	// now test it with swarm
 

net/swarm/swarm_dial.go

@@ -41,7 +41,7 @@ func (s *Swarm) Dial(ctx context.Context, p peer.ID) (*Conn, error) {
 
 	remoteAddrs := s.peers.Addresses(p)
 	// make sure we can use the addresses.
-	remoteAddrs = addrutil.FilterAddrs(remoteAddrs)
+	remoteAddrs = addrutil.FilterUsableAddrs(remoteAddrs)
 	if len(remoteAddrs) == 0 {
 		return nil, errors.New("peer has no addresses")
 	}