[PATCH 1/3] connect.c: Improve parsing of literal IPV6 addresses

["Torsten Bögershausen" <tboegi@web.de>]

When parsing an URL, older Git versions did handle
URLs like ssh://2001:db8::1/repo.git the same way as
ssh://[2001:db8::1]/repo.git

Commit 83b058 broke the parsing of IPV6 adresses without "[]":
It was written in mind that the fist ':' in a URL was the beginning of a
port number, while the old code was more clever:
Literal IPV6 addresses have always at least two ':'.
When the "hostandport" had a ':' and the rest of the hostandport string
could be parsed into an integer between 0 and 65536, then it was used
as a port number, like "host:22".
Otherwise the first ':' was assumed to be part of a literal IPV6 address,
like "ssh://[2001:db8::1]/repo.git" or "ssh://[::1]/repo.git".

Re-introduce the old parsing in get_host_and_port().

Improve the parsing to handle URLs which have a user name and a literal
IPV6 like "ssh://user@[2001:db8::1]/repo.git".
(Thanks to Christian Taube <lists@hcf.yourweb.de> for reporting this long
standing issue)

Another regression was introduced in 83b058:
A non-RFC conform URL like "[localhost:222]" could be used in older versions
of Git to connect to run "ssh -p 222 localhost".
The new stricter parsing did not allow this any more.
See even 8d3d28f5dba why "[localhost:222]" should be declared a feature.

Signed-off-by: Torsten Bögershausen <tboegi@web.de>
---
Unfortunatly my attemps to improve connect.c introduced some
regressions:
- "git clone ssh://::1/repo" did not work anymore (for some reason I assumed
  that literall IPV6 addresses always should have brackets, but that was wrong)
- "ssh://host:2222/repo" written in the "unofficial short form"
  "[host:2222]:repo did not work anymore. I think that should be
  an "unoffical feature", because it worked in older Git versions

On top of that, the combination of ssh://username@[host] had never
be handled correctly, so fix that as well.
Thanks to Christian Taube for reporting it.


Comments and an extra pair of critical eyes are welcome.


 connect.c        | 63 ++++++++++++++++++++++++++++++++++----------------------
 t/t5601-clone.sh |  2 +-
 2 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/connect.c b/connect.c
index d47d0ec..b608976 100644
--- a/connect.c
+++ b/connect.c
@@ -274,28 +274,44 @@ static enum protocol get_protocol(const char *name)
 	die("I don't handle protocol '%s'", name);
 }
 
+static char *host_end(char **hoststart, int removebrackets)
+{
+	char *host = *hoststart;
+	char *end;
+	char *start = strstr(host, "@[");
+	if (start)
+		start++; /* Jump over '@' */
+	else
+		start = host;
+	if (start[0] == '[') {
+		end = strchr(start + 1, ']');
+		if (end) {
+			if (removebrackets) {
+				*end = 0;
+				memmove(start, start + 1, end - start);
+				end++;
+			}
+		} else
+			end = host;
+	} else
+		end = host;
+	return end;
+}
+
 #define STR_(s)	# s
 #define STR(s)	STR_(s)
 
 static void get_host_and_port(char **host, const char **port)
 {
 	char *colon, *end;
-
-	if (*host[0] == '[') {
-		end = strchr(*host + 1, ']');
-		if (end) {
-			*end = 0;
-			end++;
-			(*host)++;
-		} else
-			end = *host;
-	} else
-		end = *host;
+	end = host_end(host, 1);
 	colon = strchr(end, ':');
-
 	if (colon) {
-		*colon = 0;
-		*port = colon + 1;
+		long portnr = strtol(colon + 1, &end, 10);
+		if (end != colon + 1 && *end == '\0' && 0 <= portnr && portnr < 65536) {
+			*colon = 0;
+			*port = colon + 1;
+		}
 	}
 }
 
@@ -547,13 +563,16 @@ static struct child_process *git_proxy_connect(int fd[2], char *host)
 	return proxy;
 }
 
-static const char *get_port_numeric(const char *p)
+static char *get_port(char *host)
 {
 	char *end;
+	char *p = strchr(host, ':');
+
 	if (p) {
 		long port = strtol(p + 1, &end, 10);
 		if (end != p + 1 && *end == '\0' && 0 <= port && port < 65536) {
-			return p;
+			*p = '\0';
+			return p+1;
 		}
 	}
 
@@ -595,14 +614,7 @@ static enum protocol parse_connect_url(const char *url_orig, char **ret_host,
 	 * Don't do destructive transforms as protocol code does
 	 * '[]' unwrapping in get_host_and_port()
 	 */
-	if (host[0] == '[') {
-		end = strchr(host + 1, ']');
-		if (end) {
-			end++;
-		} else
-			end = host;
-	} else
-		end = host;
+	end = host_end(&host, 0);
 
 	if (protocol == PROTO_LOCAL)
 		path = end;
@@ -705,7 +717,8 @@ struct child_process *git_connect(int fd[2], const char *url,
 			char *ssh_host = hostandport;
 			const char *port = NULL;
 			get_host_and_port(&ssh_host, &port);
-			port = get_port_numeric(port);
+			if (!port)
+				port = get_port(ssh_host);
 
 			if (!ssh) ssh = "ssh";
 
diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index e4f10c0..f901b8a 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -326,7 +326,7 @@ test_expect_success !MINGW,!CYGWIN 'clone local path foo:bar' '
 
 test_expect_success 'bracketed hostnames are still ssh' '
 	git clone "[myhost:123]:src" ssh-bracket-clone &&
-	expect_ssh myhost:123 src
+	expect_ssh myhost '-p 123' src
 '
 
 counter=0
-- 
2.2.0.rc1.26.g3e3a70d