addrs: follow link state

addr.go

@@ -5,53 +5,134 @@ import (
 	"github.com/vishvananda/netlink"
 	"fmt"
 	"log"
+	"io"
 )
 
 type AddrSet struct {
+	linkAttrs	netlink.LinkAttrs
+	linkChan	chan netlink.LinkUpdate
+	addrChan	chan netlink.AddrUpdate
+
 	addrs	map[string]net.IP
 }
 
-func (as *AddrSet) ScanInterface(iface string, family Family) error {
-	link, err := netlink.LinkByName(iface)
-	if err != nil {
-		return fmt.Errorf("netlink.LinkByName %v: %v", iface, err)
-	}
-
-	addrList, err := netlink.AddrList(link, int(family))
-	if err != nil {
-		return fmt.Errorf("netlink.AddrList %v: %v", link, err)
-	}
-
-	// set
-	as.addrs = make(map[string]net.IP)
-
-	for _, addr := range addrList {
-		as.applyLinkAddr(link, addr)
-	}
-
-	return nil
+func (addrs *AddrSet) String() string {
+	return fmt.Sprintf("AddrSet iface=%v", addrs.linkAttrs.Name)
 }
 
-func (as *AddrSet) applyLinkAddr(link netlink.Link, addr netlink.Addr) {
-	linkUp := link.Attrs().Flags & net.FlagUp != 0
+func (addrs *AddrSet) testFlag(flag net.Flags) bool {
+	return addrs.linkAttrs.Flags & flag != 0
+}
 
+func (addrs *AddrSet) Up() bool {
+	return addrs.testFlag(net.FlagUp)
+}
+
+func InterfaceAddrs(iface string, family Family) (*AddrSet, error) {
+	var addrs AddrSet
+
+	link, err := netlink.LinkByName(iface)
+	if err != nil {
+		return nil, fmt.Errorf("netlink.LinkByName %v: %v", iface, err)
+	} else {
+		addrs.linkAttrs = *link.Attrs()
+	}
+
+	// list
+	if addrList, err := netlink.AddrList(link, int(family)); err != nil {
+		return nil, fmt.Errorf("netlink.AddrList %v: %v", link, err)
+	} else {
+		addrs.addrs = make(map[string]net.IP)
+
+		for _, addr := range addrList {
+			addrs.updateAddr(addr, true)
+		}
+	}
+
+	// update
+	addrs.linkChan = make(chan netlink.LinkUpdate)
+	addrs.addrChan = make(chan netlink.AddrUpdate)
+
+	if err := netlink.LinkSubscribe(addrs.linkChan, nil); err != nil {
+		return nil, fmt.Errorf("netlink.LinkSubscribe: %v", err)
+	}
+
+	if err := netlink.AddrSubscribe(addrs.addrChan, nil); err != nil {
+		return nil, fmt.Errorf("netlink.AddrSubscribe: %v", err)
+	}
+
+	return &addrs, nil
+}
+
+func (addrs *AddrSet) Read() error {
+	for {
+		select {
+		case linkUpdate, ok := <-addrs.linkChan:
+			if !ok {
+				return io.EOF
+			}
+
+			linkAttrs := linkUpdate.Attrs()
+
+			if linkAttrs.Index != addrs.linkAttrs.Index {
+				continue
+			}
+
+			// update state
+			addrs.updateLink(*linkAttrs)
+
+		case addrUpdate, ok := <-addrs.addrChan:
+			if !ok {
+				return io.EOF
+			}
+
+			if addrUpdate.LinkIndex != addrs.linkAttrs.Index {
+				continue
+			}
+
+			// XXX: scope and other filters?
+			addrs.updateAddr(addrUpdate.Addr, addrUpdate.NewAddr)
+
+			return nil
+		}
+	}
+}
+
+// Update state for address
+func (addrs *AddrSet) updateAddr(addr netlink.Addr, up bool) {
 	if addr.Scope >= int(netlink.SCOPE_LINK) {
 		return
 	}
 
-	as.applyAddr(addr.IP, linkUp)
-}
+	ip := addr.IP
 
-// Update state for address
-func (as *AddrSet) applyAddr(ip net.IP, up bool) {
 	if up {
-		log.Printf("update: up %v", ip)
+		log.Printf("%v: up %v", addrs, ip)
 
-		as.addrs[ip.String()] = ip
+		addrs.addrs[ip.String()] = ip
 
 	} else {
-		log.Printf("update: down %v", ip)
+		log.Printf("%v: down %v", addrs, ip)
 
-		delete(as.addrs, ip.String())
+		delete(addrs.addrs, ip.String())
+	}
+}
+
+func (addrs *AddrSet) updateLink(linkAttrs netlink.LinkAttrs) {
+	addrs.linkAttrs = linkAttrs
+
+	if !addrs.Up() {
+		log.Printf("%v: down", addrs)
+	}
+}
+
+func (addrs *AddrSet) Each(visitFunc func(net.IP)) {
+	if !addrs.Up() {
+		// link down has no up addrs
+		return
+	}
+
+	for _, ip := range addrs.addrs {
+		visitFunc(ip)
 	}
 }