[RFC PATCH v2 12/16] Smart fetch and push over HTTP: server side

@@ -77,6 +77,152 @@ static NORETURN void not_found(const char *err, ...)
 	exit(0);
 }
 
+static NORETURN void forbidden(const char *err, ...)
+{
+	va_list params;
+
+	write_status(403, "Forbidden");
+	write_nocache();
+	end_headers();
+
+	va_start(params, err);
+	if (err && *err) {
+		vsnprintf(buffer, sizeof(buffer), err, params);
+		fprintf(stderr, "%s\n", buffer);
+	}
+	va_end(params);
+	exit(0);
+}
+
+struct http_service {
+	const char *name;
+	const char *config_name;
+	int enabled;
+};
+static struct http_service *service;
+
+static struct http_service http_service[] = {
+	{ "upload-pack", "uploadpack", 1 },
+	{ "receive-pack", "receivepack", 0 },
+};
+
+static int http_config(const char *var, const char *value, void *cb)
+{
+	if (!prefixcmp(var, "http.") &&
+	    !strcmp(var + 5, service->config_name)) {
+		service->enabled = git_config_bool(var, value);
+		return 0;
+	}
+
+	/* we are not interested in parsing any other configuration here */
+	return 0;
+}
+
+static void select_service(const char *name)
+{
+	int i;
+
+	if (prefixcmp(name, "git-"))
+		forbidden("Unsupported service: '%s'", name);
+
+	for (i = 0; i < ARRAY_SIZE(http_service); i++) {
+		service = &http_service[i];
+		if (!strcmp(service->name, name + 4)) {
+			git_config(http_config, NULL);
+			if (!service->enabled)
+				forbidden("Service not enabled: '%s'", name);
+			return;
+		}
+	}
+	forbidden("Unsupported service: '%s'", name);
+}
+
+static void inflate_request(const char *prog_name, int out)
+{
+	z_stream stream;
+	unsigned char in_buf[8192];
+	unsigned char out_buf[8192];
+	unsigned long cnt = 0;
+	int ret;
+
+	memset(&stream, 0, sizeof(stream));
+	ret = inflateInit2(&stream, (15 + 16));
+	if (ret != Z_OK)
+		die("cannot start zlib inflater, zlib err %d", ret);
+
+	while (1) {
+		ssize_t n = xread(0, in_buf, sizeof(in_buf));
+		if (n <= 0)
+			die("request ended in the middle of the gzip stream");
+
+		stream.next_in = in_buf;
+		stream.avail_in = n;
+
+		while (0 < stream.avail_in) {
+			int ret;
+
+			stream.next_out = out_buf;
+			stream.avail_out = sizeof(out_buf);
+
+			ret = inflate(&stream, Z_NO_FLUSH);
+			if (ret != Z_OK && ret != Z_STREAM_END)
+				die("zlib error inflating request, result %d", ret);
+
+			n = stream.total_out - cnt;
+			if (write_in_full(out, out_buf, n) != n)
+				die("%s aborted reading request", prog_name);
+			cnt += n;
+
+			if (ret == Z_STREAM_END)
+				goto done;
+		}
+	}
+
+done:
+	inflateEnd(&stream);
+	close(out);
+}
+
+static void run_service(const char **argv)
+{
+	const char *encoding = getenv("HTTP_CONTENT_ENCODING");
+	int use_gzip = 0;
+	struct child_process cld;
+
+	if (encoding && !strcmp(encoding, "gzip"))
+		use_gzip = 1;
+	else if (encoding && !strcmp(encoding, "x-gzip"))
+		use_gzip = 1;
+
+	memset(&cld, 0, sizeof(cld));
+	cld.argv = argv;
+	if (use_gzip)
+		cld.in = -1;
+	cld.git_cmd = 1;
+	if (start_command(&cld))
+		die_errno("Cannot start %s", argv[0]);
+
+	close(1);
+	if (use_gzip)
+		inflate_request(argv[0], cld.in);
+	else
+		close(0);
+
+	if (finish_command(&cld))
+		die("%s terminated with error", argv[0]);
+}
+
+static void require_content_type(const char *need_type)
+{
+	const char *input_type = getenv("CONTENT_TYPE");
+	if (!input_type || strcmp(input_type, need_type)) {
+		write_status(415, "Unsupported Media Type");
+		write_nocache();
+		end_headers();
+		exit(0);
+	}
+}
+
 static void write_file(const char *the_type, const char *name)
 {
 	const char *p = git_path("%s", name);

@@ -151,6 +297,25 @@ static int show_text_ref(const char *name, const unsigned char *sha1,
 
 static void get_info_refs(char *arg)
 {
+	char *query = getenv("QUERY_STRING");
+
+	if (query && !prefixcmp(query, "service=")) {
+		const char *argv[] = {NULL /* service name */,
+			"--one-shot-rpc", "--advertise-refs",
+			".", NULL};
+
+		select_service(query + 8);
+
+		write_nocache();
+		format_write("%s: application/x-git-%s-advertisement\r\n",
+			content_type, service->name);
+		end_headers();
+		packet_write(1, "# service=git-%s\n", service->name);
+
+		argv[0] = service->name;
+		run_service(argv);
+	}
+
 	write_nocache();
 	write_header(content_type, "text/plain; charset=utf-8");
 	end_headers();

@@ -176,6 +341,28 @@ static void get_info_packs(char *arg)
 	safe_write(1, "\n", 1);
 }
 
+static void post_to_service(char *service_name)
+{
+	const char *argv[] = {NULL, "--one-shot-rpc", ".", NULL};
+	unsigned n;
+
+	select_service(service_name);
+
+	n = snprintf(buffer, sizeof(buffer),
+		"application/x-git-%s-request", service->name);
+	if (n >= sizeof(buffer))
+		die("impossibly long service name");
+	require_content_type(buffer);
+
+	write_nocache();
+	format_write("%s: application/x-git-%s-result\r\n",
+		content_type, service->name);
+	end_headers();
+
+	argv[0] = service->name;
+	run_service(argv);
+}
+
 static NORETURN void die_webcgi(const char *err, va_list params)
 {
 	write_status(500, "Internal Server Error");

@@ -198,7 +385,10 @@ static struct service_cmd {
 	{"GET", "/objects/info/[^/]*$", get_text_file},
 	{"GET", "/objects/[0-9a-f]{2}/[0-9a-f]{38}$", get_loose_object},
 	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.pack$", get_pack_file},
-	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file}
+	{"GET", "/objects/pack/pack-[0-9a-f]{40}\\.idx$", get_idx_file},
+
+	{"POST", "/git-upload-pack$", post_to_service},
+	{"POST", "/git-receive-pack$", post_to_service}
 };
 
 int main(int argc, char **argv)