commit 2e9bd5cb1a3122326a3b347a6febc7da047b58ad
from: Omar Polo <op@omarpolo.com>
via: Thomas Adam <thomas@xteddy.org>
date: Fri Mar 10 21:44:31 2023 UTC

gotwebd: handle short reads and timeouts

If a short read happens, or if all the fastcgi record to read don't fit
in the buffer, gotwebd fails to continue reading and hits the timeout.
If this happens before gotweb_process_request is called, it will crash
in gotweb_free_transport since c->t will be NULL.

This register the event with EV_PERSIST so fcgi_request is called again
when there's more to read and guards gotweb_free_transport.  It also
makes spaces for the records as soon as they're successfully parsed.

With lots of help from stsp

ok stsp@

commit - a928faa132d1d2e179dcfc5d3f3210263b067ac9
commit + 2e9bd5cb1a3122326a3b347a6febc7da047b58ad
blob - 0ca99d2850d2590cd57a086459f7e8e5b2e77a74
blob + a2a198890cf78469d183c3223cdce1833f9e6be9
--- gotwebd/fcgi.c
+++ gotwebd/fcgi.c
@@ -97,14 +97,14 @@ fcgi_request(int fd, short events, void *arg)
 			c->buf_pos += parsed;
 			c->buf_len -= parsed;
 		}
-	} while (parsed > 0 && c->buf_len > 0);
 
-	/* Make space for further reads */
-	if (parsed != 0)
-		if (c->buf_len > 0) {
+		/* drop the parsed record */
+		if (parsed != 0 && c->buf_len > 0) {
 			bcopy(c->buf + c->buf_pos, c->buf, c->buf_len);
 			c->buf_pos = 0;
 		}
+	} while (parsed > 0 && c->buf_len > 0);
+
 	return;
 fail:
 	fcgi_cleanup_request(c);
@@ -506,7 +506,8 @@ fcgi_cleanup_request(struct request *c)
 
 	close(c->fd);
 	template_free(c->tp);
-	gotweb_free_transport(c->t);
+	if (c->t != NULL)
+		gotweb_free_transport(c->t);
 	free(c);
 }
 
blob - b57ade9f4b857c2f3544b8ba769c7a33509fac96
blob + c70fe81742e688cd82a6449ebb48174fdc111dc1
--- gotwebd/sockets.c
+++ gotwebd/sockets.c
@@ -647,7 +647,7 @@ sockets_socket_accept(int fd, short event, void *arg)
 	c->request_started = 0;
 	c->sock->client_status = CLIENT_CONNECT;
 
-	event_set(&c->ev, s, EV_READ, fcgi_request, c);
+	event_set(&c->ev, s, EV_READ|EV_PERSIST, fcgi_request, c);
 	event_add(&c->ev, NULL);
 
 	evtimer_set(&c->tmo, fcgi_timeout, c);