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putty-source/proxy/interactor.c
Simon Tatham 5d58931b51 Fix trust status when Interactor returns a seat.
While testing the unrelated pile of commits just past, I accidentally
started a Cygwin saved session I hadn't run in ages which used the old
Telnet-based cygtermd as a local proxy command, and found that it
presented the Cygwin prompt with a trust sigil. Oops!

It turns out that this is because interactor_return_seat does two
things that can change the real seat's trust status, and it does them
in the wrong order: it defaults the status back to trusted (as if the
seat was brand new, because that's how they start out), and it calls
tempseat_flush which may have buffered a trust-status reset while the
seat was borrowed. The former should not override the latter!
2022-03-12 21:05:07 +00:00

120 lines
3.6 KiB
C

/*
* Centralised functions for the Interactor trait.
*/
#include "putty.h"
Seat *interactor_borrow_seat(Interactor *itr)
{
Seat *clientseat = interactor_get_seat(itr);
if (!clientseat)
return NULL;
/* If the client has already had its Seat borrowed, then look
* through the existing TempSeat to find the underlying one. */
if (is_tempseat(clientseat))
return tempseat_get_real(clientseat);
/* Otherwise, make a new TempSeat and give that to the client. */
Seat *tempseat = tempseat_new(clientseat);
interactor_set_seat(itr, tempseat);
return clientseat;
}
static Interactor *interactor_toplevel(Interactor *itr, unsigned *level_out)
{
/*
* Find the Interactor at the top of the chain, so that all the
* Interactors in a stack can share that one's last-to-talk field.
* Also, count how far we had to go to get to it, to put in the
* message.
*/
Interactor *itr_top = itr;
unsigned level = 0;
while (itr_top->parent) {
itr_top = itr_top->parent;
level++;
}
if (level_out)
*level_out = level;
return itr_top;
}
void interactor_return_seat(Interactor *itr)
{
Seat *tempseat = interactor_get_seat(itr);
if (!is_tempseat(tempseat))
return; /* no-op */
/*
* We're about to hand this seat back to the parent Interactor to
* do its own thing with. It will typically expect to start in the
* same state as if the seat had never been borrowed, i.e. in the
* starting trust state.
*
* However, this may be overridden by the tempseat_flush call.
*/
Seat *realseat = tempseat_get_real(tempseat);
seat_set_trust_status(realseat, true);
tempseat_flush(tempseat);
interactor_set_seat(itr, realseat);
tempseat_free(tempseat);
/*
* If we have a parent Interactor, and anyone has ever called
* interactor_announce, then all Interactors from now on will
* announce themselves even if they have nothing to say.
*/
Interactor *itr_top = interactor_toplevel(itr, NULL);
if (itr_top->last_to_talk)
interactor_announce(itr);
}
InteractionReadySeat interactor_announce(Interactor *itr)
{
Seat *seat = interactor_get_seat(itr);
assert(!is_tempseat(seat) &&
"Shouldn't call announce when someone else is using our seat");
InteractionReadySeat iseat;
iseat.seat = seat;
unsigned level;
Interactor *itr_top = interactor_toplevel(itr, &level);
/*
* Generally, we should announce ourself if the previous
* Interactor that said anything was not us. That includes if
* there was no previous Interactor to talk (i.e. if we're the
* first to say anything) - *except* that the primary Interactor
* doesn't need to announce itself, if no proxy has intervened
* before it.
*/
bool need_announcement = (itr_top->last_to_talk != itr);
if (!itr->parent && !itr_top->last_to_talk)
need_announcement = false;
if (need_announcement) {
const char *prefix = "";
if (itr_top->last_to_talk != NULL)
seat_antispoof_msg(iseat, ""); /* leave a separating blank line */
char *desc = interactor_description(itr);
char *adjective = (level == 0 ? dupstr("primary") :
level == 1 ? dupstr("proxy") :
dupprintf("proxy^%u", level));
char *msg = dupprintf("%sMaking %s %s", prefix, adjective, desc);
sfree(adjective);
sfree(desc);
seat_antispoof_msg(iseat, msg);
sfree(msg);
itr_top->last_to_talk = itr;
}
return iseat;
}