fb_mqtt_cb_read: change read size to be remz, hopefully fixing timeouts

It was mqtt->rbuf->len previously, the length of the bytearray, which
doesn't make a lot of sense - it resulted in reading 2, 4, 8, 16, 32
bytes and when it reached a high enough number, ssl_read would either:

1. Stop because the socket buffer got empty (the main reason it kinda
worked most of the time), or
2. Continue reading into the next packet

And continuing to read means not just a desync but also that remz - rize
(remaining bytes - read bytes) is negative, or more precisely, a huge
number, since remz is unsigned.

So it gets stuck reading ~2**64 bytes into that buffer, thinking it's a
neverending packet, and that means not getting pongs. So it timeouts.

The fix is trivial - just make it read exactly the amount of bytes it
needs to read (remz), never more than that.

1 files changed, 1 insertions, 1 deletions

diff --git a/facebook/facebook-mqtt.c b/facebook/facebook-mqtt.c
index a4dde5b..6e85b29 100644
--- a/facebook/facebook-mqtt.c
+++ b/facebook/facebook-mqtt.c
@@ -281,7 +281,7 @@ static gboolean fb_mqtt_cb_read(gpointer data, gint fd,
     }
 
     if (mqtt->remz > 0) {
-        rize = ssl_read(mqtt->ssl, buf, MIN(mqtt->rbuf->len, sizeof buf));
+        rize = ssl_read(mqtt->ssl, buf, MIN(mqtt->remz, sizeof buf));
 
         if (rize < 1)
             goto error;