BUG/MEDIUM: http: Drop the connection establishment when a redirect is performed
This bug occurs when a redirect rule is applied during the request analysis on a
persistent connection, on a proxy without any server. This means, in a frontend
section or in a listen/backend section with no "server" line.
Because the transaction processing is shortened, no server can be selected to
perform the connection. So if we try to establish it, this fails and a 503 error
is returned, while a 3XX was already sent. So, in this case, HAProxy generates 2
replies and only the first one is expected.
Here is the configuration snippet to easily reproduce the problem:
listen www
bind :8080
mode http
timeout connect 5s
timeout client 3s
timeout server 6s
redirect location /
A simple HTTP/1.1 request without body will trigger the bug:
$ telnet 0 8080
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
GET / HTTP/1.1
HTTP/1.1 302 Found
Cache-Control: no-cache
Content-length: 0
Location: /
HTTP/1.0 503 Service Unavailable
Cache-Control: no-cache
Connection: close
Content-Type: text/html
<html><body><h1>503 Service Unavailable</h1>
No server is available to handle this request.
</body></html>
Connection closed by foreign host.
[wt: only 1.8-dev is impacted though the bug is present in older ones]
diff --git a/src/proto_http.c b/src/proto_http.c
index 24d034a..6c940f1 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -4261,6 +4261,8 @@
/* Trim any possible response */
res->chn->buf->i = 0;
res->next = res->sov = 0;
+ /* If not already done, don't perform any connection establishment */
+ channel_dont_connect(req->chn);
} else {
/* keep-alive not possible */
if (unlikely(txn->flags & TX_USE_PX_CONN)) {