diff -r d61ee475bdf5 src/pkg/net/fd.go
--- a/src/pkg/net/fd.go Thu Oct 07 16:10:48 2010 +0200
+++ b/src/pkg/net/fd.go Fri Oct 08 00:13:47 2010 +0200
@@ -12,6 +12,7 @@
    "sync"
    "syscall"
    "time"
+   "unsafe"
 )

 // Network file descriptor.
@@ -401,6 +402,61 @@
    return
 }

+func (fd *netFD) Recvmsg(p []byte, pancil []byte) (n int, nancil int, sa syscall.Sockaddr, err os.Error) {
+   if fd == nil || fd.sysfile == nil {
+       return 0, 0, nil, os.EINVAL
+   }
+   fd.rio.Lock()
+   defer fd.rio.Unlock()
+   fd.incref()
+   defer fd.decref()
+   if fd.rdeadline_delta > 0 {
+       fd.rdeadline = pollserver.Now() + fd.rdeadline_delta
+   } else {
+       fd.rdeadline = 0
+   }
+   var msghdr syscall.Msghdr
+   var rsa syscall.RawSockaddrAny
+   msghdr.Name = (*byte)(unsafe.Pointer(&rsa))
+   msghdr.Namelen = uint32(syscall.SizeofSockaddrAny)
+   var iov syscall.Iovec
+   // TODO test with zero-length or nil p
+   iov.Base = (*byte)(unsafe.Pointer(&p[0]))
+   iov.Len = uint64(len(p))
+   msghdr.Iov = &iov
+   msghdr.Iovlen = 1
+   if pancil != nil {
+       msghdr.Control = (*byte)(unsafe.Pointer(&p[0]))
+       msghdr.Controllen = uint64(len(pancil))
+   }
+   var oserr os.Error
+   var errno int
+   for {
+       n, errno = syscall.Recvmsg(fd.sysfd, &msghdr, 0)
+       if errno == syscall.EAGAIN && fd.rdeadline >= 0 {
+           pollserver.WaitRead(fd)
+           continue
+       }
+       if errno != 0 {
+           n = 0
+           nancil = 0
+           oserr = os.Errno(errno)
+       }
+       break
+   }
+   if oserr != nil {
+       err = &OpError{"read", fd.net, fd.laddr, oserr}
+       return
+   }
+   nancil = int(msghdr.Controllen)
+   sa, errno = syscall.AnyToSockaddr(&rsa)
+   if errno != 0 {
+       err = os.Errno(errno)
+       return
+   }
+   return
+}
+
 func (fd *netFD) Write(p []byte) (n int, err os.Error) {
    if fd == nil {
        return 0, os.EINVAL
@@ -481,6 +537,24 @@
    return
 }