Merge branch 'dt/send-email-client-cert' into next

"git send-email" learns to support use of client-side certificates.

* dt/send-email-client-cert:
  send-email: add client certificate options

Author: gitster

Documentation/config/sendemail.adoc

@@ -12,6 +12,22 @@ sendemail.smtpSSLCertPath::
 	Path to ca-certificates (either a directory or a single file).
 	Set it to an empty string to disable certificate verification.
 
+sendemail.smtpSSLClientCert::
+	Path to the client certificate file to present if requested by the
+	server. This is required when the server is set up to verify client
+	certificates. If the corresponding private key is not included in the
+	file, it must be supplied using `sendemail.smtpSSLClientKey` or the
+	`--smtp-ssl-client-key` option.
+
+sendemail.smtpSSLClientKey::
+	Path to the client private key file that corresponds to the client
+	certificate. To avoid misconfiguration, this configuration must be used
+	in conjunction with `sendemail.smtpSSLClientKey` or the
+	`--smtp-ssl-client-cert` option. If the client key is included in the
+	client certificate, the choice of private key depends on the format of
+	the certificate. Visit https://metacpan.org/pod/IO::Socket::SSL for more
+	details.
+
 sendemail.<identity>.*::
 	Identity-specific versions of the `sendemail.*` parameters
 	found below, taking precedence over those when this

Documentation/git-send-email.adoc

@@ -290,6 +290,25 @@ must be used for each option.
 	variable, if set, or the backing SSL library's compiled-in default
 	otherwise (which should be the best choice on most platforms).
 
+--smtp-ssl-client-cert <path>::
+	Path to the client certificate file to present if requested by the
+	server. This option is required when the server is set up to verify
+	client certificates. If the corresponding private key is not included in
+	the file, it must be supplied using the `sendemail.smtpSSLClientKey`
+	configuration variable or the `--smtp-ssl-client-key` option. Defaults
+	to the value of the `sendemail.smtpSSLClientCert` configuration
+	variable, if set.
+
+--smtp-ssl-client-key <path>::
+	Path to the client private key file that corresponds to the client
+	certificate. To avoid misconfiguration, this option must be used in
+	conjunction with the `sendemail.smtpSSLClientKey` configuration variable
+	or the `--smtp-ssl-client-cert` option. If the client key is included in
+	the client certificate, the choice of private key depends on the format
+	of the certificate. Visit https://metacpan.org/pod/IO::Socket::SSL for
+	more details. Defaults to the value of the `sendemail.smtpSSLClientKey`
+	configuration variable, if set.
+
 --smtp-user=<user>::
 	Username for SMTP-AUTH. Default is the value of `sendemail.smtpUser`;
 	if a username is not specified (with `--smtp-user` or `sendemail.smtpUser`),

git-send-email.perl

@@ -66,6 +66,8 @@ sub usage {
     --smtp-ssl-cert-path    <str>  * Path to ca-certificates (either directory or file).
                                      Pass an empty string to disable certificate
                                      verification.
+    --smtp-ssl-client-cert  <str>  * Path to the client certificate file
+    --smtp-ssl-client-key   <str>  * Path to the private key file for the client certificate
     --smtp-domain           <str>  * The domain name sent to HELO/EHLO handshake
     --smtp-auth             <str>  * Space-separated list of allowed AUTH mechanisms, or
                                      "none" to disable authentication.
@@ -279,6 +281,7 @@ sub do_edit {
 my ($to_cmd, $cc_cmd, $header_cmd);
 my ($smtp_server, $smtp_server_port, @smtp_server_options);
 my ($smtp_authuser, $smtp_encryption, $smtp_ssl_cert_path);
+my ($smtp_ssl_client_cert, $smtp_ssl_client_key);
 my ($batch_size, $relogin_delay);
 my ($identity, $aliasfiletype, @alias_files, $smtp_domain, $smtp_auth);
 my ($imap_sent_folder);
@@ -350,6 +353,8 @@ sub do_edit {
 my %config_path_settings = (
     "aliasesfile" => \@alias_files,
     "smtpsslcertpath" => \$smtp_ssl_cert_path,
+    "smtpsslclientcert" => \$smtp_ssl_client_cert,
+    "smtpsslclientkey" => \$smtp_ssl_client_key,
     "mailmap.file" => \$mailmap_file,
     "mailmap.blob" => \$mailmap_blob,
 );
@@ -531,6 +536,8 @@ sub config_regexp {
 		    "smtp-ssl" => sub { $smtp_encryption = 'ssl' },
 		    "smtp-encryption=s" => \$smtp_encryption,
 		    "smtp-ssl-cert-path=s" => \$smtp_ssl_cert_path,
+		    "smtp-ssl-client-cert=s" => \$smtp_ssl_client_cert,
+		    "smtp-ssl-client-key=s" => \$smtp_ssl_client_key,
 		    "smtp-debug:i" => \$debug_net_smtp,
 		    "smtp-domain:s" => \$smtp_domain,
 		    "smtp-auth=s" => \$smtp_auth,
@@ -1522,6 +1529,8 @@ sub handle_smtp_error {
 }
 
 sub ssl_verify_params {
+	my %ret = ();
+
 	eval {
 		require IO::Socket::SSL;
 		IO::Socket::SSL->import(qw/SSL_VERIFY_PEER SSL_VERIFY_NONE/);
@@ -1533,20 +1542,36 @@ sub ssl_verify_params {
 
 	if (!defined $smtp_ssl_cert_path) {
 		# use the OpenSSL defaults
-		return (SSL_verify_mode => SSL_VERIFY_PEER());
+		$ret{SSL_verify_mode} = SSL_VERIFY_PEER();
+	}
+	else {
+		if ($smtp_ssl_cert_path eq "") {
+			$ret{SSL_verify_mode} = SSL_VERIFY_NONE();
+		} elsif (-d $smtp_ssl_cert_path) {
+			$ret{SSL_verify_mode} = SSL_VERIFY_PEER();
+			$ret{SSL_ca_path} = $smtp_ssl_cert_path;
+		} elsif (-f $smtp_ssl_cert_path) {
+			$ret{SSL_verify_mode} = SSL_VERIFY_PEER();
+			$ret{SSL_ca_file} = $smtp_ssl_cert_path;
+		} else {
+			die sprintf(__("CA path \"%s\" does not exist"), $smtp_ssl_cert_path);
+		}
 	}
 
-	if ($smtp_ssl_cert_path eq "") {
-		return (SSL_verify_mode => SSL_VERIFY_NONE());
-	} elsif (-d $smtp_ssl_cert_path) {
-		return (SSL_verify_mode => SSL_VERIFY_PEER(),
-			SSL_ca_path => $smtp_ssl_cert_path);
-	} elsif (-f $smtp_ssl_cert_path) {
-		return (SSL_verify_mode => SSL_VERIFY_PEER(),
-			SSL_ca_file => $smtp_ssl_cert_path);
-	} else {
-		die sprintf(__("CA path \"%s\" does not exist"), $smtp_ssl_cert_path);
+	if (defined $smtp_ssl_client_cert) {
+		$ret{SSL_cert_file} = $smtp_ssl_client_cert;
 	}
+	if (defined $smtp_ssl_client_key) {
+		if (!defined $smtp_ssl_client_cert) {
+			# Accept the client key only when a certificate is given.
+			# We die here because this case is a user error.
+			die sprintf(__("Only client key \"%s\" specified"),
+				    $smtp_ssl_client_key);
+		}
+		$ret{SSL_key_file} = $smtp_ssl_client_key;
+	}
+
+	return %ret;
 }
 
 sub file_name_is_absolute {