In Pan, we use GIOChannel to communicate with the NNTP server. We've
noticed that, when sending a large post, GIOChannel loses data when it's in
buffered mode (see bug #119285).

The workaround is to switch to non-buffered mode when sending, though I'd
like to understand whether this behaviour isn't a glib bug and if not, why
we're seeing this.

I'll attach two programs that reproduce this problem. server.c is a pure
libc-based server and client.c is a glib-based client, implementing both
buffered and non-buffered sending.  The client uses gnet to establish the
connection, though that's easily changed, if you do not have gnet installed.

The protocol is NNTP-like:

--> DATA <n>     (number of bytes to expect)
<-- OK <n>       (number of bytes to expect)
--> XXXX...X     (n bytes of data)
<-- OK <n>       (number of bytes received)

This works OK over loopback (lo), but going over an ADSL line, the server
will not receive all data most of the time.

Compile as:
$ cc -g -Wall -o server server.c
$ cc -g -Wall `pkg-config --cflags gnet-2.0` -o ../bin/glib client.c
`pkg-config --libs gnet-2.0`
$ cc -g -Wall `pkg-config --cflags gnet-2.0` -o ../bin/glib-unbuf client.c
`pkg-config --libs gnet-2.0` -DUNBUFFERED