http: update curl http/2 info matching for curl 8.3.0

To redact header lines in http/2 curl traces, we have to parse past some
prefix bytes that curl sticks in the info lines it passes to us. That
changed once already, and we adapted in db30130165 (http: handle both
"h2" and "h2h3" in curl info lines, 2023-06-17).

Now it has changed again, in curl's fbacb14c4 (http2: cleanup trace
messages, 2023-08-04), which was released in curl 8.3.0. Running a build
of git linked against that version will fail to redact the trace (and as
before, t5559 notices and complains).

The format here is a little more complicated than the other ones, as it
now includes a "stream id". This is not constant but is always numeric,
so we can easily parse past it.

We'll continue to match the old versions, of course, since we want to
work with many different versions of curl. We can't even select one
format at compile time, because the behavior depends on the runtime
version of curl we use, not the version we build against.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

http.c

@@ -622,6 +622,8 @@ static int redact_sensitive_header(struct strbuf *header, size_t offset)
 
 static int match_curl_h2_trace(const char *line, const char **out)
 {
+	const char *p;
+
 	/*
 	 * curl prior to 8.1.0 gives us:
 	 *
@@ -633,6 +635,18 @@ static int match_curl_h2_trace(const char *line, const char **out)
 	    skip_iprefix(line, "h2 [", out))
 		return 1;
 
+	/*
+	 * curl 8.3.0 uses:
+	 *   [HTTP/2] [<stream-id>] [<header-name>: <header-val>]
+	 * where <stream-id> is numeric.
+	 */
+	if (skip_iprefix(line, "[HTTP/2] [", &p)) {
+		while (isdigit(*p))
+			p++;
+		if (skip_prefix(p, "] [", out))
+			return 1;
+	}
+
 	return 0;
 }