ssh: implement Git SSH variant selection

We'd implemented Git's autodetection of SSH variants in the past, but we hadn't implemented the newer explicit SSH selection. Since we're about to pass some additional options to our ssh binaries, let's implement the proper variant using GIT_SSH_VARIANT and ssh.variant. Roughly, the algorithm is this: GIT_SSH_VARIANT overrides ssh.variant, and if neither is set, autodetection occurs. A user can specify either "ssh" (OpenSSH), "putty" (or its synonym "plink"), "tortoiseplink", or "simple", or, if they'd like the autodetection behavior, "auto". If the value is not any of these, then it is interpreted as "ssh".
git-lfs · Mar 31, 2021 · 9114a57 · 9114a57
1 parent 4e9391c
commit 9114a57
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Showing 2 changed files with 158 additions and 14 deletions.
diff --git a/ssh/ssh.go b/ssh/ssh.go
@@ -12,6 +12,15 @@ import (
 	"github.com/rubyist/tracerx"
 )
 
+type sshVariant string
+
+const (
+	variantSSH      = sshVariant("ssh")
+	variantSimple   = sshVariant("simple")
+	variantPutty    = sshVariant("putty")
+	variantTortoise = sshVariant("tortoiseplink")
+)
+
 type SSHMetadata struct {
 	UserAndHost string
 	Port        string
@@ -47,14 +56,59 @@ func parseShellCommand(command string, existing string) (ssh string, cmd string,
 	return
 }
 
+func findVariant(variant string) (bool, sshVariant) {
+	switch variant {
+	case "ssh", "simple", "putty", "tortoiseplink":
+		return false, sshVariant(variant)
+	case "plink":
+		return false, variantPutty
+	case "auto":
+		return true, ""
+	default:
+		return false, variantSSH
+	}
+}
+
+func autodetectVariant(osEnv config.Environment, gitEnv config.Environment, basessh string) sshVariant {
+	if basessh != defaultSSHCmd {
+		// Strip extension for easier comparison
+		if ext := filepath.Ext(basessh); len(ext) > 0 {
+			basessh = basessh[:len(basessh)-len(ext)]
+		}
+		if strings.EqualFold(basessh, "plink") {
+			return variantPutty
+		}
+		if strings.EqualFold(basessh, "tortoiseplink") {
+			return variantTortoise
+		}
+	}
+	return "ssh"
+}
+
+func getVariant(osEnv config.Environment, gitEnv config.Environment, basessh string) sshVariant {
+	variant, ok := osEnv.Get("GIT_SSH_VARIANT")
+	autodetect, val := findVariant(variant)
+	if ok {
+		if autodetect {
+			return autodetectVariant(osEnv, gitEnv, basessh)
+		}
+		return val
+	}
+	variant, ok = gitEnv.Get("GIT_SSH_VARIANT")
+	if autodetect, val := findVariant(variant); ok {
+		if autodetect {
+			return autodetectVariant(osEnv, gitEnv, basessh)
+		}
+		return val
+	}
+	return autodetectVariant(osEnv, gitEnv, basessh)
+}
+
 // Return the executable name for ssh on this machine and the base args
 // Base args includes port settings, user/host, everything pre the command to execute
 func getExeAndArgs(osEnv config.Environment, gitEnv config.Environment, meta *SSHMetadata) (exe string, baseargs []string, needShell bool) {
 	var cmd string
 
-	isPlink := false
-	isTortoise := false
-
 	ssh, _ := osEnv.Get("GIT_SSH")
 	sshCmd, _ := osEnv.Get("GIT_SSH_COMMAND")
 	ssh, cmd, needShell = parseShellCommand(sshCmd, ssh)
@@ -69,25 +123,17 @@ func getExeAndArgs(osEnv config.Environment, gitEnv config.Environment, meta *SS
 	}
 
 	basessh := filepath.Base(ssh)
-
-	if basessh != defaultSSHCmd {
-		// Strip extension for easier comparison
-		if ext := filepath.Ext(basessh); len(ext) > 0 {
-			basessh = basessh[:len(basessh)-len(ext)]
-		}
-		isPlink = strings.EqualFold(basessh, "plink")
-		isTortoise = strings.EqualFold(basessh, "tortoiseplink")
-	}
+	variant := getVariant(osEnv, gitEnv, basessh)
 
 	args := make([]string, 0, 7)
 
-	if isTortoise {
+	if variant == variantTortoise {
 		// TortoisePlink requires the -batch argument to behave like ssh/plink
 		args = append(args, "-batch")
 	}
 
 	if len(meta.Port) > 0 {
-		if isPlink || isTortoise {
+		if variant == variantPutty || variant == variantTortoise {
 			args = append(args, "-P")
 		} else {
 			args = append(args, "-p")

diff --git a/ssh/ssh_test.go b/ssh/ssh_test.go
@@ -117,6 +117,44 @@ func TestSSHGetExeAndArgsPlinkCustomPort(t *testing.T) {
 	assert.Equal(t, []string{"-P", "8888", "[email protected]"}, args)
 }
 
+func TestSSHGetExeAndArgsPlinkCustomPortExplicitEnvironment(t *testing.T) {
+	plink := filepath.Join("Users", "joebloggs", "bin", "ssh")
+
+	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
+		"GIT_SSH_COMMAND": "",
+		"GIT_SSH":         plink,
+		"GIT_SSH_VARIANT": "plink",
+	}, nil))
+	require.Nil(t, err)
+
+	meta := SSHMetadata{}
+	meta.UserAndHost = "[email protected]"
+	meta.Port = "8888"
+
+	exe, args := formatArgs(getExeAndArgs(cli.OSEnv(), cli.GitEnv(), &meta))
+	assert.Equal(t, plink, exe)
+	assert.Equal(t, []string{"-P", "8888", "[email protected]"}, args)
+}
+
+func TestSSHGetExeAndArgsPlinkCustomPortExplicitEnvironmentPutty(t *testing.T) {
+	plink := filepath.Join("Users", "joebloggs", "bin", "ssh")
+
+	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
+		"GIT_SSH_COMMAND": "",
+		"GIT_SSH":         plink,
+		"GIT_SSH_VARIANT": "putty",
+	}, nil))
+	require.Nil(t, err)
+
+	meta := SSHMetadata{}
+	meta.UserAndHost = "[email protected]"
+	meta.Port = "8888"
+
+	exe, args := formatArgs(getExeAndArgs(cli.OSEnv(), cli.GitEnv(), &meta))
+	assert.Equal(t, plink, exe)
+	assert.Equal(t, []string{"-P", "8888", "[email protected]"}, args)
+}
+
 func TestSSHGetExeAndArgsTortoisePlink(t *testing.T) {
 	plink := filepath.Join("Users", "joebloggs", "bin", "tortoiseplink.exe")
 
@@ -152,6 +190,66 @@ func TestSSHGetExeAndArgsTortoisePlinkCustomPort(t *testing.T) {
 	assert.Equal(t, []string{"-batch", "-P", "8888", "[email protected]"}, args)
 }
 
+func TestSSHGetExeAndArgsTortoisePlinkCustomPortExplicitEnvironment(t *testing.T) {
+	plink := filepath.Join("Users", "joebloggs", "bin", "ssh")
+
+	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
+		"GIT_SSH_COMMAND": "",
+		"GIT_SSH":         plink,
+		"GIT_SSH_VARIANT": "tortoiseplink",
+	}, nil))
+	require.Nil(t, err)
+
+	meta := SSHMetadata{}
+	meta.UserAndHost = "[email protected]"
+	meta.Port = "8888"
+
+	exe, args := formatArgs(getExeAndArgs(cli.OSEnv(), cli.GitEnv(), &meta))
+	assert.Equal(t, plink, exe)
+	assert.Equal(t, []string{"-batch", "-P", "8888", "[email protected]"}, args)
+}
+
+func TestSSHGetExeAndArgsTortoisePlinkCustomPortExplicitConfig(t *testing.T) {
+	plink := filepath.Join("Users", "joebloggs", "bin", "ssh")
+
+	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
+		"GIT_SSH_COMMAND": "",
+		"GIT_SSH":         plink,
+		"GIT_SSH_VARIANT": "tortoiseplink",
+	}, map[string]string{
+		"ssh.variant": "tortoiseplink",
+	}))
+	require.Nil(t, err)
+
+	meta := SSHMetadata{}
+	meta.UserAndHost = "[email protected]"
+	meta.Port = "8888"
+
+	exe, args := formatArgs(getExeAndArgs(cli.OSEnv(), cli.GitEnv(), &meta))
+	assert.Equal(t, plink, exe)
+	assert.Equal(t, []string{"-batch", "-P", "8888", "[email protected]"}, args)
+}
+
+func TestSSHGetExeAndArgsTortoisePlinkCustomPortExplicitConfigOverride(t *testing.T) {
+	plink := filepath.Join("Users", "joebloggs", "bin", "ssh")
+
+	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
+		"GIT_SSH_COMMAND": "",
+		"GIT_SSH":         plink,
+	}, map[string]string{
+		"ssh.variant": "putty",
+	}))
+	require.Nil(t, err)
+
+	meta := SSHMetadata{}
+	meta.UserAndHost = "[email protected]"
+	meta.Port = "8888"
+
+	exe, args := formatArgs(getExeAndArgs(cli.OSEnv(), cli.GitEnv(), &meta))
+	assert.Equal(t, plink, exe)
+	assert.Equal(t, []string{"-batch", "-P", "8888", "[email protected]"}, args)
+}
+
 func TestSSHGetExeAndArgsSshCommandPrecedence(t *testing.T) {
 	cli, err := lfshttp.NewClient(lfshttp.NewContext(nil, map[string]string{
 		"GIT_SSH_COMMAND": "sshcmd",