Re: [ANNOUNCE] Git v2.16.0-rc0

[Jonathan Nieder <jrnieder@gmail.com>]

Hi Bryan,

Bryan Turner wrote:

> Our test environment is still on Ubuntu 12.04 LTS (it's a long story,
> but one I doubt is unique to us), which means it's using OpenSSH 5.9.
> ssh -G was added in OpenSSH 6.8 [1], circa March 2015, which means the
> "auto" detection "fails" and chooses "simple" instead of "ssh". But
> OpenSSH 5.9 _does_ support -4, -6 and -p. As a result, commands which
> have been working without issue on all previous versions of Git start
> to fail saying
>
> git -c gc.auto=0 -c credential.helper= fetch --force --prune --progress ssh://localhost:64281/repo.git +refs/*:refs/*' exited with code 128 saying: fatal: ssh variant 'simple' does not support setting port

Hm, that's not expected.  git-config(1) says:

	By default, Git determines the command line arguments to use
	based on the basename of the configured SSH command
	(configured using the environment variable GIT_SSH or
	GIT_SSH_COMMAND or the config setting core.sshCommand). If the
	basename is unrecognized, Git will attempt to detect support
	of OpenSSH options by [...]

So my first question is why the basename detection is not working for
you.  What value of GIT_SSH, GIT_SSH_COMMAND, or core.sshCommand are
you using?

> I know Ubuntu 12.04 LTS is end-of-life, but 14.04 LTS, which is
> running OpenSSH 6.6 [2], has the same issue. The following is from a
> fully patched 14.04.5:
>
> bturner@ubuntu:~$ cat /etc/*ease | head -4
> DISTRIB_ID=Ubuntu
> DISTRIB_RELEASE=14.04
> DISTRIB_CODENAME=trusty
> DISTRIB_DESCRIPTION="Ubuntu 14.04.5 LTS"
>
> bturner@ubuntu:~$ ssh -V
> OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8, OpenSSL 1.0.1f 6 Jan 2014
>
> bturner@ubuntu:~$ ssh -G -p 7999 localhost
> unknown option -- G

It's good you caught this flaw in the detection.  Would something like
the following make sense?  If so, I can resend with a commit message
and tests tomorrow or the day after.

diff --git i/Documentation/config.txt w/Documentation/config.txt
index 64c1dbba94..75eafd8db6 100644
--- i/Documentation/config.txt
+++ w/Documentation/config.txt
@@ -2118,8 +2118,8 @@ ssh.variant::
 	unrecognized, Git will attempt to detect support of OpenSSH
 	options by first invoking the configured SSH command with the
 	`-G` (print configuration) option and will subsequently use
-	OpenSSH options (if that is successful) or no options besides
-	the host and remote command (if it fails).
+	OpenSSH options if that is successful or a conservative set of
+	OpenSSH-style options if it fails.
 +
 The config variable `ssh.variant` can be set to override this detection.
 Valid values are `ssh` (to use OpenSSH options), `plink`, `putty`,
diff --git i/connect.c w/connect.c
index c3a014c5ba..3784c2be53 100644
--- i/connect.c
+++ w/connect.c
@@ -941,10 +941,9 @@ static void push_ssh_options(struct argv_array *args, struct argv_array *env,
 
 	if (flags & CONNECT_IPV4) {
 		switch (variant) {
-		case VARIANT_AUTO:
-			BUG("VARIANT_AUTO passed to push_ssh_options");
 		case VARIANT_SIMPLE:
 			die("ssh variant 'simple' does not support -4");
+		case VARIANT_AUTO:
 		case VARIANT_SSH:
 		case VARIANT_PLINK:
 		case VARIANT_PUTTY:
@@ -953,10 +952,9 @@ static void push_ssh_options(struct argv_array *args, struct argv_array *env,
 		}
 	} else if (flags & CONNECT_IPV6) {
 		switch (variant) {
-		case VARIANT_AUTO:
-			BUG("VARIANT_AUTO passed to push_ssh_options");
 		case VARIANT_SIMPLE:
 			die("ssh variant 'simple' does not support -6");
+		case VARIANT_AUTO:
 		case VARIANT_SSH:
 		case VARIANT_PLINK:
 		case VARIANT_PUTTY:
@@ -970,10 +968,9 @@ static void push_ssh_options(struct argv_array *args, struct argv_array *env,
 
 	if (port) {
 		switch (variant) {
-		case VARIANT_AUTO:
-			BUG("VARIANT_AUTO passed to push_ssh_options");
 		case VARIANT_SIMPLE:
 			die("ssh variant 'simple' does not support setting port");
+		case VARIANT_AUTO:
 		case VARIANT_SSH:
 			argv_array_push(args, "-p");
 			break;
@@ -1026,7 +1023,7 @@ static void fill_ssh_args(struct child_process *conn, const char *ssh_host,
 				 VARIANT_SSH, port, flags);
 		argv_array_push(&detect.args, ssh_host);
 
-		variant = run_command(&detect) ? VARIANT_SIMPLE : VARIANT_SSH;
+		variant = run_command(&detect) ? VARIANT_AUTO : VARIANT_SSH;
 	}
 
 	argv_array_push(&conn->args, ssh);
diff --git i/t/t5601-clone.sh w/t/t5601-clone.sh
index 0f895478f0..0224edc85b 100755
--- i/t/t5601-clone.sh
+++ w/t/t5601-clone.sh
@@ -365,6 +365,11 @@ test_expect_success 'OpenSSH variant passes -4' '
 	expect_ssh "-4 -p 123" myhost src
 '
 
+test_expect_success 'OpenSSH passes GIT_PROTOCOL envvar' '
+	git -c protocol.version=1 clone [myhost:123]:src ssh-v1-clone &&
+	expect_ssh "-o SendEnv=GIT_PROTOCOL -p 123" myhost src
+'
+
 test_expect_success 'variant can be overridden' '
 	copy_ssh_wrapper_as "$TRASH_DIRECTORY/putty" &&
 	git -c ssh.variant=putty clone -4 "[myhost:123]:src" ssh-putty-clone &&
@@ -377,19 +382,32 @@ test_expect_success 'variant=auto picks based on basename' '
 	expect_ssh "-4 -P 123" myhost src
 '
 
-test_expect_success 'simple does not support -4/-6' '
+test_expect_success 'variant=simple does not support -4/-6' '
 	copy_ssh_wrapper_as "$TRASH_DIRECTORY/simple" &&
-	test_must_fail git clone -4 "myhost:src" ssh-4-clone-simple
+	test_must_fail git -c ssh.variant=simple clone -4 "myhost:src" ssh-4-clone-simple
 '
 
-test_expect_success 'simple does not support port' '
+test_expect_success 'variant=simple does not support port' '
 	copy_ssh_wrapper_as "$TRASH_DIRECTORY/simple" &&
-	test_must_fail git clone "[myhost:123]:src" ssh-bracket-clone-simple
+	test_must_fail git -c ssh.variant=simple clone "[myhost:123]:src" ssh-bracket-clone-simple
+'
+
+test_expect_success 'old OpenSSH passes -4 and -p' '
+	copy_ssh_wrapper_as "$TRASH_DIRECTORY/old" &&
+	git -c ssh.variant=auto clone -4 "[myhost:123]:src" old-ssh-clone &&
+	expect_ssh "-4 -p 123" myhost src
 '
 
-test_expect_success 'uplink is treated as simple' '
+test_expect_success 'old OpenSSH does not pass GIT_PROTOCOL envvar' '
+	copy_ssh_wrapper_as "$TRASH_DIRECTORY/old" &&
+	git -c protocol.version=1 -c ssh.variant=auto clone "[myhost:123]:src" old-ssh-protocol-v1 &&
+	expect_ssh "-p 123" myhost src
+'
+
+test_expect_success 'uplink is treated as old OpenSSH' '
 	copy_ssh_wrapper_as "$TRASH_DIRECTORY/uplink" &&
-	test_must_fail git clone "[myhost:123]:src" ssh-bracket-clone-uplink &&
+	git -c protocol.version=1 clone "[myhost:123]:src" ssh-bracket-clone-uplink &&
+	expect_ssh "-p 123" myhost src &&
 	git clone "myhost:src" ssh-clone-uplink &&
 	expect_ssh myhost src
 '
@@ -405,8 +423,8 @@ test_expect_success 'OpenSSH-like uplink is treated as ssh' '
 	test_when_finished "rm -f \"\$TRASH_DIRECTORY/uplink\"" &&
 	GIT_SSH="$TRASH_DIRECTORY/uplink" &&
 	test_when_finished "GIT_SSH=\"\$TRASH_DIRECTORY/ssh\$X\"" &&
-	git clone "[myhost:123]:src" ssh-bracket-clone-sshlike-uplink &&
-	expect_ssh "-p 123" myhost src
+	git -c protocol.version=1 clone "[myhost:123]:src" ssh-bracket-clone-sshlike-uplink &&
+	expect_ssh "-o SendEnv=GIT_PROTOCOL -p 123" myhost src
 '
 
 test_expect_success 'plink is treated specially (as putty)' '