don't allow links to be used with --net=host

Docker-DCO-1.1-Signed-off-by: Cristian Staretu <cristian.staretu@gmail.com> (github: unclejack)

integration-cli/docker_cli_run_test.go

@@ -722,6 +722,20 @@ func TestLoopbackWhenNetworkDisabled(t *testing.T) {
 	logDone("run - test container loopback when networking disabled")
 }
 
+func TestNetHostNotAllowedWithLinks(t *testing.T) {
+	_, _, err := cmd(t, "run", "--name", "linked", "busybox", "true")
+
+	cmd := exec.Command(dockerBinary, "run", "--net=host", "--link", "linked:linked", "busybox", "true")
+	_, _, err = runCommandWithOutput(cmd)
+	if err == nil {
+		t.Fatal("Expected error")
+	}
+
+	deleteAllContainers()
+
+	logDone("run - don't allow --net=host to be used with links")
+}
+
 func TestLoopbackOnlyExistsWhenNetworkingDisabled(t *testing.T) {
 	cmd := exec.Command(dockerBinary, "run", "--net=none", "busybox", "ip", "-o", "-4", "a", "show", "up")
 	out, _, err := runCommandWithOutput(cmd)

runconfig/parse.go

@@ -19,6 +19,7 @@ var (
 	ErrConflictAttachDetach        = fmt.Errorf("Conflicting options: -a and -d")
 	ErrConflictDetachAutoRemove    = fmt.Errorf("Conflicting options: --rm and -d")
 	ErrConflictNetworkHostname     = fmt.Errorf("Conflicting options: -h and the network mode (--net)")
+	ErrConflictHostNetworkAndLinks = fmt.Errorf("Conflicting options: --net=host can't be used with links. This would result in undefined behavior.")
 )
 
 //FIXME Only used in tests
@@ -115,6 +116,10 @@ func parseRun(cmd *flag.FlagSet, args []string, sysInfo *sysinfo.SysInfo) (*Conf
 		return nil, nil, cmd, ErrConflictNetworkHostname
 	}
 
+	if *flNetMode == "host" && flLinks.Len() > 0 {
+		return nil, nil, cmd, ErrConflictHostNetworkAndLinks
+	}
+
 	// If neither -d or -a are set, attach to everything by default
 	if flAttach.Len() == 0 && !*flDetach {
 		if !*flDetach {