connect & http: support -4 and -6 switches for remote operations

Sometimes it is necessary to force IPv4-only or IPv6-only operation
on networks where name lookups may return a non-routable address and
stall remote operations.

The ssh(1) command has an equivalent switches which we may pass when
we run them.  There may be old ssh(1) implementations out there
which do not support these switches; they should report the
appropriate error in that case.

rsync support is untouched for now since it is deprecated and
scheduled to be removed.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Reviewed-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 18 insertions, 0 deletions

diff --git a/builtin/clone.c b/builtin/clone.c
index a0b3cd9..f3dee71 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -47,6 +47,7 @@ static const char *real_git_dir;
 static char *option_upload_pack = "git-upload-pack";
 static int option_verbosity;
 static int option_progress = -1;
+static enum transport_family family;
 static struct string_list option_config;
 static struct string_list option_reference;
 static int option_dissociate;
@@ -92,6 +93,10 @@ static struct option builtin_clone_options[] = {
 		   N_("separate git dir from working tree")),
 	OPT_STRING_LIST('c', "config", &option_config, N_("key=value"),
 			N_("set config inside the new repository")),
+	OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
+			TRANSPORT_FAMILY_IPV4),
+	OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
+			TRANSPORT_FAMILY_IPV6),
 	OPT_END()
 };
 
@@ -967,6 +972,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 	remote = remote_get(option_origin);
 	transport = transport_get(remote, remote->url[0]);
 	transport_set_verbosity(transport, option_verbosity, option_progress);
+	transport->family = family;
 
 	path = get_repo_path(remote->url[0], &is_bundle);
 	is_local = option_local != 0 && path && !is_bundle;
diff --git a/builtin/fetch.c b/builtin/fetch.c
index c85f347..89b71a8 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -37,6 +37,7 @@ static int prune = -1; /* unspecified */
 static int all, append, dry_run, force, keep, multiple, update_head_ok, verbosity;
 static int progress = -1, recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
 static int tags = TAGS_DEFAULT, unshallow, update_shallow;
+static enum transport_family family;
 static const char *depth;
 static const char *upload_pack;
 static struct strbuf default_rla = STRBUF_INIT;
@@ -124,6 +125,10 @@ static struct option builtin_fetch_options[] = {
 		 N_("accept refs that update .git/shallow")),
 	{ OPTION_CALLBACK, 0, "refmap", NULL, N_("refmap"),
 	  N_("specify fetch refmap"), PARSE_OPT_NONEG, parse_refmap_arg },
+	OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
+			TRANSPORT_FAMILY_IPV4),
+	OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
+			TRANSPORT_FAMILY_IPV6),
 	OPT_END()
 };
 
@@ -861,6 +866,7 @@ static struct transport *prepare_transport(struct remote *remote)
 	struct transport *transport;
 	transport = transport_get(remote, NULL);
 	transport_set_verbosity(transport, verbosity, progress);
+	transport->family = family;
 	if (upload_pack)
 		set_option(transport, TRANS_OPT_UPLOADPACK, upload_pack);
 	if (keep)
diff --git a/builtin/push.c b/builtin/push.c
index 8963dbd..833c983 100644
--- a/builtin/push.c
+++ b/builtin/push.c
@@ -23,6 +23,7 @@ static const char *receivepack;
 static int verbosity;
 static int progress = -1;
 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
+static enum transport_family family;
 
 static struct push_cas_option cas;
 
@@ -346,6 +347,7 @@ static int push_with_options(struct transport *transport, int flags)
 	unsigned int reject_reasons;
 
 	transport_set_verbosity(transport, verbosity, progress);
+	transport->family = family;
 
 	if (receivepack)
 		transport_set_option(transport,
@@ -565,6 +567,10 @@ int cmd_push(int argc, const char **argv, const char *prefix)
 		  0, "signed", &push_cert, "yes|no|if-asked", N_("GPG sign the push"),
 		  PARSE_OPT_OPTARG, option_parse_push_signed },
 		OPT_BIT(0, "atomic", &flags, N_("request atomic transaction on remote side"), TRANSPORT_PUSH_ATOMIC),
+		OPT_SET_INT('4', "ipv4", &family, N_("use IPv4 addresses only"),
+				TRANSPORT_FAMILY_IPV4),
+		OPT_SET_INT('6', "ipv6", &family, N_("use IPv6 addresses only"),
+				TRANSPORT_FAMILY_IPV6),
 		OPT_END()
 	};