To protect against a rogue server reading your files, the client
honors C_EXECUTE only when it matches recent player input.
This has a somewhat troubled history, detailed in the previous commit.
The remaining major issue comes from commit 8b7d0b9 (v4.3.11): any
suffix of a recent line of input is accepted as C_EXECUTE text.
Before, only text that looked like an argument of an execute command
or a redirection was accepted.
Fix by again requiring the text to be preceded by something that looks
like an execute command. But do it more carefully: don't break
execute with a prompted for argument, and prevent abuse of
redirections for execute.
Signed-off-by: Markus Armbruster <armbru@pond.sub.org>
Why upgrade? I'm not a lawyer, but here's my take on the differences
to version 2:
* Software patents: better protection against abuse of patents to
prevent users from exercising the rights under the GPL. I doubt
we'll get hit with a patent suit, but it's a good move just on
general principles.
* License compatibility: compatible with more free licenses, i.e. can
"steal" more free software for use in Empire. I don't expect to steal
much, but it's nice to have the option.
* Definition of "source code": modernization of some details for today's
networked world, to make it easier to distribute the software. Not
really relevant to us now, as we normally distribute full source code.
* Tivoization: this is about putting GPL-licensed software in hardware,
then make the hardware refuse to run modified software. "Neat" trick
to effectively deny its users their rights under the GPL. Abuse was
"pioneered" by TiVo (popular digital video recorders). GPLv3 forbids
it. Unlikely to become a problem for us.
* Internationalization: more careful wording, to harden the license
outside the US. The lawyers tell us it better be done that way.
* License violations: friendlier way to deal with license violations.
This has come out of past experience enforcing the GPL.
* Additional permissions: Probably not relevant to us.
Also include myself in the list of principal authors.
(EOF_COOKIE, INTR_COOKIE, input_fd, send_intr, recv_output)
(recv_input, intr, play): New playing phase code. No native Windows
support yet. Sends just one EOF cookie on EOF on standard input
instead of up to three. Old servers (before recvclient.c rev. 1.16)
fail to terminate the session when they receive an EOF cookie at an
argument prompt. The session then hangs; use SIGINT to get out. No
longer blocks on sending input, which could deadlock the session.
Closes#827090. Fixes error handling for select(). Fixes race
condition that could cause server output to be discarded on EOF on
standard input.
(main): Replace old playing phase code by a call to play().
(intr, sock, interrupt, handleintr): Replaced by play(), remove.
[_WIN32] (hStdIn): Ditto.
(auxfp): New.
(servercmd, prompt, doexecute): Remove parameter auxfi, use auxfp.
(eight_bit_clean): Move to servcmd.c.
(servercmd): Work on a single non-C_DATA line instead of getting lines
from an ioqueue.
(servercmd, output, screen, outch): Deal with all ids in servercmd()
rather than some there and some in output(). Don't treat C_NOECHO,
C_ABORT, C_CMDERR, C_BADCMD specially. Fix C_FLASH and C_EXIT to
ignore redirections; they used to ignore them only for some parts.
Replace output() by outch(), fold screen into outch().
(servercmd): Truncate long prompts and telegram infos to prevent
buffer overflow.
(prompt): Use new parameters code, prompt, teles instead of global
variables mode, the_prompt, num_teles.
(num_teles, the_prompt, mode, nbtu, nmin): Remove.
(prompt): Don't write an empty line before argument prompts to auxfp.
(servercmd): Don't strip newline from redirections and execute,
doredir(), dopipe() and doexecute() need it now.
(doredir, dopipe, doexecute): Use new seen_input() instead of gettag().
(doexecute): Set input_fd and leave reading the script file to play().
(serverio, termio, sendeof): Replaced by play(), remove.
(LBUF_LEN_MAX, lbuf, lbuf_init, lbuf_len, lbuf_full, lbuf_line)
(lbuf_putc): New.
(RING_SIZE, ring, ring_init, ring_len, ring_space, ring_peek)
(ring_getc, ring_putc, ring_putm, ring_discard, ring_search)
(ring_from_file, ring_to_file): New.
(clear_recent_input, save_input, seen_input): New.
(MAX): New.
(ioqueue, io, ioq_init, ioq_dequeue, ioq_read, ioq_write, ioq_qsize)
(ioq_drain, ioq_gets, ioqtobuf, enqueuecc, dequeuecc): Unused, remove.
(QEMPTY, qelem, insque, remque, initque): Unused, remove.
(tagstruct, taglist, io_init, gettag): Unused, remove.
