[pkg-lynx-maint] Bug#1033423: lynx: Status line stuck on "HTTP/1.1 200 OK", body not rendered, no input accepted when receiving a specifically-formatted response

[Thomas Dickey]

On Mon, Mar 27, 2023 at 07:20:25PM -0400, Thomas Dickey wrote:
> On Fri, Mar 24, 2023 at 08:36:26PM +0100, наб wrote:
> > Package: lynx
> > Version: 2.9.0dev.6-3~deb11u1
> > Version: 2.9.0dev.12-1
> > Severity: normal
> ...
> > I get the same thing when I run
> >   echo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| base16 -d | nc -lp 8000
> > and open localhost:8000, for a cheaper repro.
> 
> thanks - I can reproduce this case (trace shows it reads the whole file)

The basic problem is that using nc in this way differs from a real webserver,
because it leaves the connection open and inactive.  Lynx actually will
time out in that case, but it is a long time by default, to provide for
slow connections.

man lynx:
       -read_timeout=N
              Sets the read-timeout, where N is given in seconds.

lynx.cfg:
	.h2 READ_TIMEOUT
	# Specifies (in seconds) read-timeout. Default value is rather huge.
	#READ_TIMEOUT:18000

(30 minutes).  Some other programs (not all) work around this by either
using multiple threads (and providing for partial updates), or polling
for activity (for the same purpose).  Lynx does neither.

As an alternative, one can interrupt the read, e.g., using ^G.
In the existing Lynx, that has the drawback that the connection
is abandoned (which is a problem if you run it to just connect
to a certain page -- Lynx exits).  To work around that problem,
I modified the behavior to gracefully close (no exit) if you
interrupt the read loop.  That keeps ^G in its existing behavior
for interrupting connection attempts, and makes this example work
as intended.

The workaround is in Lynx 2.9.0

-- 
Thomas E. Dickey <dickey at invisible-island.net>
https://invisible-island.net
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