// writeThenReadDatagram transmits ICMP for IPv4 datagrams to the
// loopback address or interface and captures the response datagrams
// from the protocol stack within the kernel.
func writeThenReadDatagram(t *testing.T, i int, c *ipv4.RawConn, wb []byte, src, dst net.Addr) []byte {
rb := make([]byte, ipv4.HeaderLen+len(wb))
wh := &ipv4.Header{
Version: ipv4.Version,
Len: ipv4.HeaderLen,
TOS: i + 1,
TotalLen: ipv4.HeaderLen + len(wb),
TTL: i + 1,
Protocol: 1,
}
if src != nil {
wh.Src = src.(*net.IPAddr).IP
}
if dst != nil {
wh.Dst = dst.(*net.IPAddr).IP
}
c.SetDeadline(time.Now().Add(100 * time.Millisecond))
if err := c.WriteTo(wh, wb, nil); err != nil {
t.Fatalf("ipv4.RawConn.WriteTo failed: %v", err)
}
rh, b, cm, err := c.ReadFrom(rb)
if err != nil {
t.Fatalf("ipv4.RawConn.ReadFrom failed: %v", err)
}
t.Logf("rcvd cmsg: %v", cm.String())
t.Logf("rcvd hdr: %v", rh.String())
return b
}
// runDatagramTransponder transmits ICMP for IPv4 datagrams to the
// loopback address or interface and captures the response datagrams
// from the protocol stack within the kernel.
func runDatagramTransponder(t *testing.T, c *ipv4.RawConn, wb []byte, src, dst net.Addr) {
cf := ipv4.FlagTTL | ipv4.FlagDst | ipv4.FlagInterface
rb := make([]byte, ipv4.HeaderLen+len(wb))
for i, toggle := range []bool{true, false, true} {
if err := c.SetControlMessage(cf, toggle); err != nil {
t.Fatalf("ipv4.RawConn.SetControlMessage failed: %v", err)
}
wh := &ipv4.Header{}
wh.Version = ipv4.Version
wh.Len = ipv4.HeaderLen
wh.TOS = i + 1
wh.TotalLen = ipv4.HeaderLen + len(wb)
wh.TTL = i + 1
wh.Protocol = 1
if src != nil {
wh.Src = src.(*net.IPAddr).IP
}
if dst != nil {
wh.Dst = dst.(*net.IPAddr).IP
}
c.SetDeadline(time.Now().Add(100 * time.Millisecond))
if err := c.WriteTo(wh, wb, nil); err != nil {
t.Fatalf("ipv4.RawConn.WriteTo failed: %v", err)
}
rh, _, cm, err := c.ReadFrom(rb)
if err != nil {
t.Fatalf("ipv4.RawConn.ReadFrom failed: %v", err)
}
t.Logf("rcvd cmsg: %v", cm.String())
t.Logf("rcvd hdr: %v", rh.String())
}
}