From 296b847c0d6de63353e236cfbf94163d24155529 Mon Sep 17 00:00:00 2001 From: David Turner Date: Fri, 18 Nov 2016 15:30:49 -0500 Subject: remote-curl: don't hang when a server dies before any output In the event that a HTTP server closes the connection after giving a 200 but before giving any packets, we don't want to hang forever waiting for a response that will never come. Instead, we should die immediately. One case where this happens is when attempting to fetch a dangling object by its object name. In this case, the server dies before sending any data. Prior to this patch, fetch-pack would wait for data from the server, and remote-curl would wait for fetch-pack, causing a deadlock. Despite this patch, there is other possible malformed input that could cause the same deadlock (e.g. a half-finished pktline, or a pktline but no trailing flush). There are a few possible solutions to this: 1. Allowing remote-curl to tell fetch-pack about the EOF (so that fetch-pack could know that no more data is coming until it says something else). This is tricky because an out-of-band signal would be required, or the http response would have to be re-framed inside another layer of pkt-line or something. 2. Make remote-curl understand some of the protocol. It turns out that in addition to understanding pkt-line, it would need to watch for ack/nak. This is somewhat fragile, as information about the protocol would end up in two places. Also, pkt-lines which are already at the length limit would need special handling. Both of these solutions would require a fair amount of work, whereas this hack is easy and solves at least some of the problem. Still to do: it would be good to give a better error message than "fatal: The remote end hung up unexpectedly". Signed-off-by: David Turner Signed-off-by: Junio C Hamano --- remote-curl.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'remote-curl.c') diff --git a/remote-curl.c b/remote-curl.c index f14c41f4c0..ee4423659f 100644 --- a/remote-curl.c +++ b/remote-curl.c @@ -400,6 +400,7 @@ struct rpc_state { size_t pos; int in; int out; + int any_written; struct strbuf result; unsigned gzip_request : 1; unsigned initial_buffer : 1; @@ -456,6 +457,8 @@ static size_t rpc_in(char *ptr, size_t eltsize, { size_t size = eltsize * nmemb; struct rpc_state *rpc = buffer_; + if (size) + rpc->any_written = 1; write_or_die(rpc->in, ptr, size); return size; } @@ -659,6 +662,8 @@ retry: curl_easy_setopt(slot->curl, CURLOPT_WRITEFUNCTION, rpc_in); curl_easy_setopt(slot->curl, CURLOPT_FILE, rpc); + + rpc->any_written = 0; err = run_slot(slot, NULL); if (err == HTTP_REAUTH && !large_request) { credential_fill(&http_auth); @@ -667,6 +672,9 @@ retry: if (err != HTTP_OK) err = -1; + if (!rpc->any_written) + err = -1; + curl_slist_free_all(headers); free(gzip_body); return err; -- cgit v1.2.1