From 0f1dc53f45d307c8342bf547d79695b614cf9c26 Mon Sep 17 00:00:00 2001 From: Brandon Williams Date: Thu, 15 Mar 2018 10:31:41 -0700 Subject: remote-curl: implement stateless-connect command Teach remote-curl the 'stateless-connect' command which is used to establish a stateless connection with servers which support protocol version 2. This allows remote-curl to act as a proxy, allowing the git client to communicate natively with a remote end, simply using remote-curl as a pass through to convert requests to http. Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano --- remote-curl.c | 207 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 206 insertions(+), 1 deletion(-) (limited to 'remote-curl.c') diff --git a/remote-curl.c b/remote-curl.c index 66a53f74bb..87f5b77b29 100644 --- a/remote-curl.c +++ b/remote-curl.c @@ -188,7 +188,12 @@ static struct ref *parse_git_refs(struct discovery *heads, int for_push) heads->version = discover_version(&reader); switch (heads->version) { case protocol_v2: - die("support for protocol v2 not implemented yet"); + /* + * Do nothing. This isn't a list of refs but rather a + * capability advertisement. Client would have run + * 'stateless-connect' so we'll dump this capability listing + * and let them request the refs themselves. + */ break; case protocol_v1: case protocol_v0: @@ -1085,6 +1090,202 @@ static void parse_push(struct strbuf *buf) free(specs); } +/* + * Used to represent the state of a connection to an HTTP server when + * communicating using git's wire-protocol version 2. + */ +struct proxy_state { + char *service_name; + char *service_url; + struct curl_slist *headers; + struct strbuf request_buffer; + int in; + int out; + struct packet_reader reader; + size_t pos; + int seen_flush; +}; + +static void proxy_state_init(struct proxy_state *p, const char *service_name, + enum protocol_version version) +{ + struct strbuf buf = STRBUF_INIT; + + memset(p, 0, sizeof(*p)); + p->service_name = xstrdup(service_name); + + p->in = 0; + p->out = 1; + strbuf_init(&p->request_buffer, 0); + + strbuf_addf(&buf, "%s%s", url.buf, p->service_name); + p->service_url = strbuf_detach(&buf, NULL); + + p->headers = http_copy_default_headers(); + + strbuf_addf(&buf, "Content-Type: application/x-%s-request", p->service_name); + p->headers = curl_slist_append(p->headers, buf.buf); + strbuf_reset(&buf); + + strbuf_addf(&buf, "Accept: application/x-%s-result", p->service_name); + p->headers = curl_slist_append(p->headers, buf.buf); + strbuf_reset(&buf); + + p->headers = curl_slist_append(p->headers, "Transfer-Encoding: chunked"); + + /* Add the Git-Protocol header */ + if (get_protocol_http_header(version, &buf)) + p->headers = curl_slist_append(p->headers, buf.buf); + + packet_reader_init(&p->reader, p->in, NULL, 0, + PACKET_READ_GENTLE_ON_EOF); + + strbuf_release(&buf); +} + +static void proxy_state_clear(struct proxy_state *p) +{ + free(p->service_name); + free(p->service_url); + curl_slist_free_all(p->headers); + strbuf_release(&p->request_buffer); +} + +/* + * CURLOPT_READFUNCTION callback function. + * Attempts to copy over a single packet-line at a time into the + * curl provided buffer. + */ +static size_t proxy_in(char *buffer, size_t eltsize, + size_t nmemb, void *userdata) +{ + size_t max; + struct proxy_state *p = userdata; + size_t avail = p->request_buffer.len - p->pos; + + + if (eltsize != 1) + BUG("curl read callback called with size = %"PRIuMAX" != 1", + (uintmax_t)eltsize); + max = nmemb; + + if (!avail) { + if (p->seen_flush) { + p->seen_flush = 0; + return 0; + } + + strbuf_reset(&p->request_buffer); + switch (packet_reader_read(&p->reader)) { + case PACKET_READ_EOF: + die("unexpected EOF when reading from parent process"); + case PACKET_READ_NORMAL: + packet_buf_write_len(&p->request_buffer, p->reader.line, + p->reader.pktlen); + break; + case PACKET_READ_DELIM: + packet_buf_delim(&p->request_buffer); + break; + case PACKET_READ_FLUSH: + packet_buf_flush(&p->request_buffer); + p->seen_flush = 1; + break; + } + p->pos = 0; + avail = p->request_buffer.len; + } + + if (max < avail) + avail = max; + memcpy(buffer, p->request_buffer.buf + p->pos, avail); + p->pos += avail; + return avail; +} + +static size_t proxy_out(char *buffer, size_t eltsize, + size_t nmemb, void *userdata) +{ + size_t size; + struct proxy_state *p = userdata; + + if (eltsize != 1) + BUG("curl read callback called with size = %"PRIuMAX" != 1", + (uintmax_t)eltsize); + size = nmemb; + + write_or_die(p->out, buffer, size); + return size; +} + +/* Issues a request to the HTTP server configured in `p` */ +static int proxy_request(struct proxy_state *p) +{ + struct active_request_slot *slot; + + slot = get_active_slot(); + + curl_easy_setopt(slot->curl, CURLOPT_NOBODY, 0); + curl_easy_setopt(slot->curl, CURLOPT_POST, 1); + curl_easy_setopt(slot->curl, CURLOPT_URL, p->service_url); + curl_easy_setopt(slot->curl, CURLOPT_HTTPHEADER, p->headers); + + /* Setup function to read request from client */ + curl_easy_setopt(slot->curl, CURLOPT_READFUNCTION, proxy_in); + curl_easy_setopt(slot->curl, CURLOPT_READDATA, p); + + /* Setup function to write server response to client */ + curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, proxy_out); + curl_easy_setopt(slot->curl, CURLOPT_WRITEDATA, p); + + if (run_slot(slot, NULL) != HTTP_OK) + return -1; + + return 0; +} + +static int stateless_connect(const char *service_name) +{ + struct discovery *discover; + struct proxy_state p; + + /* + * Run the info/refs request and see if the server supports protocol + * v2. If and only if the server supports v2 can we successfully + * establish a stateless connection, otherwise we need to tell the + * client to fallback to using other transport helper functions to + * complete their request. + */ + discover = discover_refs(service_name, 0); + if (discover->version != protocol_v2) { + printf("fallback\n"); + fflush(stdout); + return -1; + } else { + /* Stateless Connection established */ + printf("\n"); + fflush(stdout); + } + + proxy_state_init(&p, service_name, discover->version); + + /* + * Dump the capability listing that we got from the server earlier + * during the info/refs request. + */ + write_or_die(p.out, discover->buf, discover->len); + + /* Peek the next packet line. Until we see EOF keep sending POSTs */ + while (packet_reader_peek(&p.reader) != PACKET_READ_EOF) { + if (proxy_request(&p)) { + /* We would have an err here */ + break; + } + } + + proxy_state_clear(&p); + return 0; +} + int cmd_main(int argc, const char **argv) { struct strbuf buf = STRBUF_INIT; @@ -1153,12 +1354,16 @@ int cmd_main(int argc, const char **argv) fflush(stdout); } else if (!strcmp(buf.buf, "capabilities")) { + printf("stateless-connect\n"); printf("fetch\n"); printf("option\n"); printf("push\n"); printf("check-connectivity\n"); printf("\n"); fflush(stdout); + } else if (skip_prefix(buf.buf, "stateless-connect ", &arg)) { + if (!stateless_connect(arg)) + break; } else { error("remote-curl: unknown command '%s' from git", buf.buf); return 1; -- cgit v1.2.3