route: add support for the manipulation of routing informaion

This change adds the Marshal method of RouteMessage to make it possible to exchange route messages between userspace processes and the kernel for the manipulation of routing information base inside the kernel. Change-Id: I0cf2c1a391820f41eb9c5eac1c172598cb2e1533 Reviewed-on: https://go-review.googlesource.com/36077 Reviewed-by: Ian Lance Taylor <iant@golang.org>

Author: cixtor

route/address.go

@@ -24,6 +24,39 @@ type LinkAddr struct {
 // Family implements the Family method of Addr interface.
 func (a *LinkAddr) Family() int { return sysAF_LINK }
 
+func (a *LinkAddr) lenAndSpace() (int, int) {
+l := 8 + len(a.Name) + len(a.Addr)
+return l, roundup(l)
+}
+
+func (a *LinkAddr) marshal(b []byte) (int, error) {
+l, ll := a.lenAndSpace()
+if len(b) < ll {
+return 0, errShortBuffer
+}
+nlen, alen := len(a.Name), len(a.Addr)
+if nlen > 255 || alen > 255 {
+return 0, errInvalidAddr
+}
+b[0] = byte(l)
+b[1] = sysAF_LINK
+if a.Index > 0 {
+nativeEndian.PutUint16(b[2:4], uint16(a.Index))
+}
+data := b[8:]
+if nlen > 0 {
+b[5] = byte(nlen)
+copy(data[:nlen], a.Addr)
+data = data[nlen:]
+}
+if alen > 0 {
+b[6] = byte(alen)
+copy(data[:alen], a.Name)
+data = data[alen:]
+}
+return ll, nil
+}
+
 func parseLinkAddr(b []byte) (Addr, error) {
 if len(b) < 8 {
 return nil, errInvalidAddr
@@ -90,6 +123,21 @@ type Inet4Addr struct {
 // Family implements the Family method of Addr interface.
 func (a *Inet4Addr) Family() int { return sysAF_INET }
 
+func (a *Inet4Addr) lenAndSpace() (int, int) {
+return sizeofSockaddrInet, roundup(sizeofSockaddrInet)
+}
+
+func (a *Inet4Addr) marshal(b []byte) (int, error) {
+l, ll := a.lenAndSpace()
+if len(b) < ll {
+return 0, errShortBuffer
+}
+b[0] = byte(l)
+b[1] = sysAF_INET
+copy(b[4:8], a.IP[:])
+return ll, nil
+}
+
 // An Inet6Addr represents an internet address for IPv6.
 type Inet6Addr struct {
 IP [16]byte // IP address
@@ -99,18 +147,36 @@ type Inet6Addr struct {
 // Family implements the Family method of Addr interface.
 func (a *Inet6Addr) Family() int { return sysAF_INET6 }
 
+func (a *Inet6Addr) lenAndSpace() (int, int) {
+return sizeofSockaddrInet6, roundup(sizeofSockaddrInet6)
+}
+
+func (a *Inet6Addr) marshal(b []byte) (int, error) {
+l, ll := a.lenAndSpace()
+if len(b) < ll {
+return 0, errShortBuffer
+}
+b[0] = byte(l)
+b[1] = sysAF_INET6
+copy(b[8:24], a.IP[:])
+if a.ZoneID > 0 {
+nativeEndian.PutUint32(b[24:28], uint32(a.ZoneID))
+}
+return ll, nil
+}
+
 // parseInetAddr parses b as an internet address for IPv4 or IPv6.
 func parseInetAddr(af int, b []byte) (Addr, error) {
 switch af {
 case sysAF_INET:
-if len(b) < 16 {
+if len(b) < sizeofSockaddrInet {
 return nil, errInvalidAddr
 }
 a := &Inet4Addr{}
 copy(a.IP[:], b[4:8])
 return a, nil
 case sysAF_INET6:
-if len(b) < 28 {
+if len(b) < sizeofSockaddrInet6 {
 return nil, errInvalidAddr
 }
 a := &Inet6Addr{ZoneID: int(nativeEndian.Uint32(b[24:28]))}
@@ -174,7 +240,7 @@ func parseKernelInetAddr(af int, b []byte) (int, Addr, error) {
 off6 = 8 // offset of in6_addr
 )
 switch {
-case b[0] == 28: // size of sockaddr_in6
+case b[0] == sizeofSockaddrInet6:
 a := &Inet6Addr{}
 copy(a.IP[:], b[off6:off6+16])
 return int(b[0]), a, nil
@@ -186,7 +252,7 @@ func parseKernelInetAddr(af int, b []byte) (int, Addr, error) {
 copy(a.IP[:], b[l-off6:l])
 }
 return int(b[0]), a, nil
-case b[0] == 16: // size of sockaddr_in
+case b[0] == sizeofSockaddrInet:
 a := &Inet4Addr{}
 copy(a.IP[:], b[off4:off4+4])
 return int(b[0]), a, nil
@@ -211,6 +277,24 @@ type DefaultAddr struct {
 // Family implements the Family method of Addr interface.
 func (a *DefaultAddr) Family() int { return a.af }
 
+func (a *DefaultAddr) lenAndSpace() (int, int) {
+l := len(a.Raw)
+return l, roundup(l)
+}
+
+func (a *DefaultAddr) marshal(b []byte) (int, error) {
+l, ll := a.lenAndSpace()
+if len(b) < ll {
+return 0, errShortBuffer
+}
+if l > 255 {
+return 0, errInvalidAddr
+}
+b[1] = byte(l)
+copy(b[:l], a.Raw)
+return ll, nil
+}
+
 func parseDefaultAddr(b []byte) (Addr, error) {
 if len(b) < 2 || len(b) < int(b[0]) {
 return nil, errInvalidAddr
@@ -219,6 +303,66 @@ func parseDefaultAddr(b []byte) (Addr, error) {
 return a, nil
 }
 
+func addrsSpace(as []Addr) int {
+var l int
+for _, a := range as {
+switch a := a.(type) {
+case *LinkAddr:
+_, ll := a.lenAndSpace()
+l += ll
+case *Inet4Addr:
+_, ll := a.lenAndSpace()
+l += ll
+case *Inet6Addr:
+_, ll := a.lenAndSpace()
+l += ll
+case *DefaultAddr:
+_, ll := a.lenAndSpace()
+l += ll
+}
+}
+return l
+}
+
+// marshalAddrs marshals as returns a bitmap indicating which address
+// is stored in b.
+func marshalAddrs(b []byte, as []Addr) (uint, error) {
+var attrs uint
+for i, a := range as {
+switch a := a.(type) {
+case *LinkAddr:
+l, err := a.marshal(b)
+if err != nil {
+return 0, err
+}
+b = b[l:]
+attrs |= 1 << uint(i)
+case *Inet4Addr:
+l, err := a.marshal(b)
+if err != nil {
+return 0, err
+}
+b = b[l:]
+attrs |= 1 << uint(i)
+case *Inet6Addr:
+l, err := a.marshal(b)
+if err != nil {
+return 0, err
+}
+b = b[l:]
+attrs |= 1 << uint(i)
+case *DefaultAddr:
+l, err := a.marshal(b)
+if err != nil {
+return 0, err
+}
+b = b[l:]
+attrs |= 1 << uint(i)
+}
+}
+return attrs, nil
+}
+
 func parseAddrs(attrs uint, fn func(int, []byte) (int, Addr, error), b []byte) ([]Addr, error) {
 var as [sysRTAX_MAX]Addr
 af := int(sysAF_UNSPEC)

route/defs_darwin.go

@@ -13,6 +13,8 @@ package route
 #include <net/if.h>
 #include <net/if_dl.h>
 #include <net/route.h>
+
+#include <netinet/in.h>
 */
 import "C"
 
@@ -23,6 +25,8 @@ const (
 sysAF_LINK = C.AF_LINK
 sysAF_INET6 = C.AF_INET6
 
+sysSOCK_RAW = C.SOCK_RAW
+
 sysNET_RT_DUMP = C.NET_RT_DUMP
 sysNET_RT_FLAGS = C.NET_RT_FLAGS
 sysNET_RT_IFLIST = C.NET_RT_IFLIST
@@ -103,4 +107,8 @@ const (
 sizeofRtMsghdrDarwin15 = C.sizeof_struct_rt_msghdr
 sizeofRtMsghdr2Darwin15 = C.sizeof_struct_rt_msghdr2
 sizeofRtMetricsDarwin15 = C.sizeof_struct_rt_metrics
+
+sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
+sizeofSockaddrInet = C.sizeof_struct_sockaddr_in
+sizeofSockaddrInet6 = C.sizeof_struct_sockaddr_in6
 )

route/defs_dragonfly.go

@@ -13,6 +13,8 @@ package route
 #include <net/if.h>
 #include <net/if_dl.h>
 #include <net/route.h>
+
+#include <netinet/in.h>
 */
 import "C"
 
@@ -23,6 +25,8 @@ const (
 sysAF_LINK = C.AF_LINK
 sysAF_INET6 = C.AF_INET6
 
+sysSOCK_RAW = C.SOCK_RAW
+
 sysNET_RT_DUMP = C.NET_RT_DUMP
 sysNET_RT_FLAGS = C.NET_RT_FLAGS
 sysNET_RT_IFLIST = C.NET_RT_IFLIST
@@ -102,4 +106,8 @@ const (
 
 sizeofRtMsghdrDragonFlyBSD4 = C.sizeof_struct_rt_msghdr
 sizeofRtMetricsDragonFlyBSD4 = C.sizeof_struct_rt_metrics
+
+sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
+sizeofSockaddrInet = C.sizeof_struct_sockaddr_in
+sizeofSockaddrInet6 = C.sizeof_struct_sockaddr_in6
 )

route/defs_freebsd.go

@@ -14,6 +14,8 @@ package route
 #include <net/if_dl.h>
 #include <net/route.h>
 
+#include <netinet/in.h>
+
 struct if_data_freebsd7 {
 u_char ifi_type;
 u_char ifi_physical;
@@ -222,6 +224,8 @@ const (
 sysAF_LINK = C.AF_LINK
 sysAF_INET6 = C.AF_INET6
 
+sysSOCK_RAW = C.SOCK_RAW
+
 sysNET_RT_DUMP = C.NET_RT_DUMP
 sysNET_RT_FLAGS = C.NET_RT_FLAGS
 sysNET_RT_IFLIST = C.NET_RT_IFLIST
@@ -326,4 +330,8 @@ const (
 sizeofIfDataFreeBSD9Emu = C.sizeof_struct_if_data_freebsd9
 sizeofIfDataFreeBSD10Emu = C.sizeof_struct_if_data_freebsd10
 sizeofIfDataFreeBSD11Emu = C.sizeof_struct_if_data_freebsd11
+
+sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
+sizeofSockaddrInet = C.sizeof_struct_sockaddr_in
+sizeofSockaddrInet6 = C.sizeof_struct_sockaddr_in6
 )

route/defs_netbsd.go

@@ -13,6 +13,8 @@ package route
 #include <net/if.h>
 #include <net/if_dl.h>
 #include <net/route.h>
+
+#include <netinet/in.h>
 */
 import "C"
 
@@ -23,6 +25,8 @@ const (
 sysAF_LINK = C.AF_LINK
 sysAF_INET6 = C.AF_INET6
 
+sysSOCK_RAW = C.SOCK_RAW
+
 sysNET_RT_DUMP = C.NET_RT_DUMP
 sysNET_RT_FLAGS = C.NET_RT_FLAGS
 sysNET_RT_IFLIST = C.NET_RT_IFLIST
@@ -101,4 +105,8 @@ const (
 
 sizeofRtMsghdrNetBSD7 = C.sizeof_struct_rt_msghdr
 sizeofRtMetricsNetBSD7 = C.sizeof_struct_rt_metrics
+
+sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
+sizeofSockaddrInet = C.sizeof_struct_sockaddr_in
+sizeofSockaddrInet6 = C.sizeof_struct_sockaddr_in6
 )

route/defs_openbsd.go

@@ -13,6 +13,8 @@ package route
 #include <net/if.h>
 #include <net/if_dl.h>
 #include <net/route.h>
+
+#include <netinet/in.h>
 */
 import "C"
 
@@ -23,6 +25,8 @@ const (
 sysAF_LINK = C.AF_LINK
 sysAF_INET6 = C.AF_INET6
 
+sysSOCK_RAW = C.SOCK_RAW
+
 sysNET_RT_DUMP = C.NET_RT_DUMP
 sysNET_RT_FLAGS = C.NET_RT_FLAGS
 sysNET_RT_IFLIST = C.NET_RT_IFLIST
@@ -91,3 +95,11 @@ const (
 sysRTAX_LABEL = C.RTAX_LABEL
 sysRTAX_MAX = C.RTAX_MAX
 )
+
+const (
+sizeofRtMsghdr = C.sizeof_struct_rt_msghdr
+
+sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
+sizeofSockaddrInet = C.sizeof_struct_sockaddr_in
+sizeofSockaddrInet6 = C.sizeof_struct_sockaddr_in6
+)

route/message.go

@@ -7,9 +7,6 @@
 package route
 
 // A Message represents a routing message.
-//
-// Note: This interface will be changed to support Marshal method in
-// future version.
 type Message interface {
 // Sys returns operating system-specific information.
 Sys() []Sys
@@ -52,11 +49,10 @@ func ParseRIB(typ RIBType, b []byte) ([]Message, error) {
 b = b[l:]
 continue
 }
-mtyp := int(b[3])
-if fn, ok := parseFns[mtyp]; !ok {
+if w, ok := wireFormats[int(b[3])]; !ok {
 nskips++
 } else {
-m, err := fn(typ, b)
+m, err := w.parse(typ, b)
 if err != nil {
 return nil, err
 }