config: simplify ipv6 link local address peering

from cli:

```
gobgp neighbor add fe80::902f:4eff:fe52:6985%eth0 as 65000
```

from configuration file:

```toml
[[neighbors]]
[[neighbors.afi-safis]]
[neighbors.config]
neighbor-address = "fe80::902f:4eff:fe52:6985%eth0"
peer-as = 65000
```

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>

4 files changed, 57 insertions, 28 deletions

diff --git a/config/default.go b/config/default.go
index e0564c0e..d2911036 100644
--- a/config/default.go
+++ b/config/default.go
@@ -52,6 +52,25 @@ func extractArray(intf interface{}) ([]interface{}, error) {
 	return nil, nil
 }
 
+func getIPv6LinkLocalAddress(ifname string) (string, error) {
+	ifi, err := net.InterfaceByName(ifname)
+	if err != nil {
+		return "", err
+	}
+	addrs, err := ifi.Addrs()
+	if err != nil {
+		return "", err
+	}
+	for _, addr := range addrs {
+		if ip, _, err := net.ParseCIDR(addr.String()); err != nil {
+			return "", err
+		} else if ip.To4() == nil && ip.IsLinkLocalUnicast() {
+			return fmt.Sprintf("%s%%%s", ip.String(), ifname), nil
+		}
+	}
+	return "", fmt.Errorf("no ipv6 link local address for %s", ifname)
+}
+
 func SetDefaultNeighborConfigValues(n *Neighbor, asn uint32) error {
 	return setDefaultNeighborConfigValuesWithViper(nil, n, asn)
 }
@@ -85,28 +104,33 @@ func setDefaultNeighborConfigValuesWithViper(v *viper.Viper, n *Neighbor, asn ui
 	}
 
 	if n.Transport.Config.LocalAddress == "" {
-		if n.Config.NeighborAddress != "" {
-			v6 := true
-			if ip := net.ParseIP(n.Config.NeighborAddress); ip.To4() != nil {
-				v6 = false
-			}
-			if v6 {
-				n.Transport.Config.LocalAddress = "::"
-			} else {
-				n.Transport.Config.LocalAddress = "0.0.0.0"
-			}
-		} else {
+		if n.Config.NeighborAddress == "" {
 			return fmt.Errorf("no neighbor address/interface specified")
 		}
+		ipAddr, err := net.ResolveIPAddr("ip", n.Config.NeighborAddress)
+		if err != nil {
+			return err
+		}
+		localAddress := "0.0.0.0"
+		if ipAddr.IP.To4() == nil {
+			localAddress = "::"
+			if ipAddr.Zone != "" {
+				localAddress, err = getIPv6LinkLocalAddress(ipAddr.Zone)
+				if err != nil {
+					return err
+				}
+			}
+		}
+		n.Transport.Config.LocalAddress = localAddress
 	}
 
 	if len(n.AfiSafis) == 0 {
-		if ip := net.ParseIP(n.Config.NeighborAddress); ip.To4() != nil {
+		if ipAddr, err := net.ResolveIPAddr("ip", n.Config.NeighborAddress); err != nil {
+			return fmt.Errorf("invalid neighbor address: %s", n.Config.NeighborAddress)
+		} else if ipAddr.IP.To4() != nil {
 			n.AfiSafis = []AfiSafi{defaultAfiSafi(AFI_SAFI_TYPE_IPV4_UNICAST, true)}
-		} else if ip.To16() != nil {
-			n.AfiSafis = []AfiSafi{defaultAfiSafi(AFI_SAFI_TYPE_IPV6_UNICAST, true)}
 		} else {
-			return fmt.Errorf("invalid neighbor address: %s", n.Config.NeighborAddress)
+			n.AfiSafis = []AfiSafi{defaultAfiSafi(AFI_SAFI_TYPE_IPV6_UNICAST, true)}
 		}
 	} else {
 		afs, err := extractArray(v.Get("neighbor.afi-safis"))
diff --git a/gobgp/cmd/common.go b/gobgp/cmd/common.go
index 9a4b8164..0c3e4c48 100644
--- a/gobgp/cmd/common.go
+++ b/gobgp/cmd/common.go
@@ -26,6 +26,7 @@ import (
 	"os"
 	"sort"
 	"strconv"
+	"strings"
 	"time"
 )
 
@@ -264,7 +265,7 @@ func extractReserved(args, keys []string) map[string][]string {
 }
 
 type PeerConf struct {
-	RemoteIp          net.IP                             `json:"remote_ip,omitempty"`
+	RemoteIp          string                             `json:"remote_ip,omitempty"`
 	Id                net.IP                             `json:"id,omitempty"`
 	RemoteAs          uint32                             `json:"remote_as,omitempty"`
 	LocalAs           uint32                             `json:"local-as,omitempty"`
@@ -294,8 +295,9 @@ func ApiStruct2Peer(p *gobgpapi.Peer) *Peer {
 		c, _ := bgp.DecodeCapability(buf)
 		remoteCaps = append(remoteCaps, c)
 	}
+	remoteIp, _ := net.ResolveIPAddr("ip", p.Conf.NeighborAddress)
 	conf := PeerConf{
-		RemoteIp:     net.ParseIP(p.Conf.NeighborAddress),
+		RemoteIp:     remoteIp.String(),
 		Id:           net.ParseIP(p.Conf.Id),
 		RemoteAs:     p.Conf.PeerAs,
 		LocalAs:      p.Conf.LocalAs,
@@ -325,8 +327,8 @@ func (p peers) Swap(i, j int) {
 func (p peers) Less(i, j int) bool {
 	p1 := p[i].Conf.RemoteIp
 	p2 := p[j].Conf.RemoteIp
-	p1Isv4 := p1.To4() != nil
-	p2Isv4 := p2.To4() != nil
+	p1Isv4 := !strings.Contains(p1, ":")
+	p2Isv4 := !strings.Contains(p2, ":")
 	if p1Isv4 != p2Isv4 {
 		if p1Isv4 {
 			return true
@@ -337,8 +339,8 @@ func (p peers) Less(i, j int) bool {
 	if p1Isv4 {
 		addrlen = 32
 	}
-	strings := sort.StringSlice{cidr2prefix(fmt.Sprintf("%s/%d", p1.String(), addrlen)),
-		cidr2prefix(fmt.Sprintf("%s/%d", p2.String(), addrlen))}
+	strings := sort.StringSlice{cidr2prefix(fmt.Sprintf("%s/%d", p1, addrlen)),
+		cidr2prefix(fmt.Sprintf("%s/%d", p2, addrlen))}
 	return strings.Less(0, 1)
 }
 
diff --git a/gobgp/cmd/neighbor.go b/gobgp/cmd/neighbor.go
index bf687772..3856949a 100644
--- a/gobgp/cmd/neighbor.go
+++ b/gobgp/cmd/neighbor.go
@@ -39,8 +39,8 @@ func getNeighbors() (peers, error) {
 	m := peers{}
 	for _, p := range r.Peers {
 		if neighborsOpts.Transport != "" {
-			addr := net.ParseIP(p.Conf.NeighborAddress)
-			if addr.To4() != nil {
+			addr, _ := net.ResolveIPAddr("ip", p.Conf.NeighborAddress)
+			if addr.IP.To4() != nil {
 				if neighborsOpts.Transport != "ipv4" {
 					continue
 				}
@@ -61,7 +61,7 @@ func getNeighbor(addr string) (*Peer, error) {
 		return nil, e
 	}
 	for _, p := range l {
-		if p.Conf.RemoteIp.String() == addr {
+		if p.Conf.RemoteIp == addr {
 			return p, nil
 		}
 	}
@@ -94,8 +94,8 @@ func showNeighbors() error {
 
 	now := time.Now()
 	for _, p := range m {
-		if len(p.Conf.RemoteIp) > maxaddrlen {
-			maxaddrlen = len(p.Conf.RemoteIp)
+		if l := len(p.Conf.RemoteIp); l > maxaddrlen {
+			maxaddrlen = l
 		}
 		if len(fmt.Sprint(p.Conf.RemoteAs)) > maxaslen {
 			maxaslen = len(fmt.Sprint(p.Conf.RemoteAs))
@@ -771,9 +771,12 @@ func modNeighbor(cmdType string, args []string) error {
 		usage += " as <VALUE>"
 	}
 
-	if len(m[""]) != 1 || net.ParseIP(m[""][0]) == nil {
+	if len(m[""]) != 1 {
 		return fmt.Errorf("%s", usage)
 	}
+	if _, err := net.ResolveIPAddr("ip", m[""][0]); err != nil {
+		return err
+	}
 	var err error
 	switch cmdType {
 	case CMD_ADD:
diff --git a/server/server.go b/server/server.go
index ee8374a6..cfbe514f 100644
--- a/server/server.go
+++ b/server/server.go
@@ -162,7 +162,7 @@ func (server *BgpServer) Serve() {
 		passConn := func(conn *net.TCPConn) {
 			host, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
 			ipaddr, _ := net.ResolveIPAddr("ip", host)
-			remoteAddr := ipaddr.IP.String()
+			remoteAddr := ipaddr.String()
 			peer, found := server.neighborMap[remoteAddr]
 			if found {
 				if peer.fsm.adminState != ADMIN_STATE_UP {