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Allow new_connection to take an optional Seat. (NFC)

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This is working towards allowing the subsidiary SSH connection in an
SshProxy to share the main user-facing Seat, so as to be able to pass
through interactive prompts.

This is more difficult than the similar change with LogPolicy, because
Seats are stateful. In particular, the trust-sigil status will need to
be controlled by the SshProxy until it's ready to pass over control to
the main SSH (or whatever) connection.

To make this work, I've introduced a thing called a TempSeat, which is
(yet) another Seat implementation. When a backend hands its Seat to
new_connection(), it does it in a way that allows new_connection() to
borrow it completely, and replace it in the main backend structure
with a TempSeat, which acts as a temporary placeholder. If the main
backend tries to do things like changing trust status or sending
output, the TempSeat will buffer them; later on, when the connection
is established, TempSeat will replay the changes into the real Seat.

So, in each backend, I've made the following changes:
 - pass &foo->seat to new_connection, which may overwrite it with a
   TempSeat.
 - if it has done so (which we can tell via the is_tempseat() query
   function), then we have to free the TempSeat and reinstate our main
   Seat. The signal that we can do so is the PLUGLOG_CONNECT_SUCCESS
   notification, which indicates that SshProxy has finished all its
   connection setup work.
 - we also have to remember to free the TempSeat if our backend is
   disposed of without that having happened (e.g. because the
   connection _doesn't_ succeed).
 - in backends which have no local auth phase to worry about, ensure
   we don't call seat_set_trust_status on the main Seat _before_ it
   gets potentially replaced with a TempSeat. Moved some calls of
   seat_set_trust_status to just after new_connection(), so that now
   the initial trust status setup will go into the TempSeat (if
   appropriate) and be buffered until that seat is relinquished.

In all other uses of new_connection, where we don't have a Seat
available at all, we just pass NULL.

This is NFC, because neither new_connection() nor any of its delegates
will _actually_ do this replacement yet. We're just setting up the
framework to enable it to do so in the next commit.
This commit is contained in:
Simon Tatham
2021-09-13 17:17:20 +01:00
parent a08f953bd6
commit 6d272ee007
14 changed files with 465 additions and 21 deletions
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19
otherbackends/raw.c
View File

@ -39,8 +39,15 @@ static void raw_log(Plug *plug, PlugLogType type, SockAddr *addr, int port,
Raw *raw = container_of(plug, Raw, plug);
backend_socket_log(raw->seat, raw->logctx, type, addr, port, error_msg,
error_code, raw->conf, raw->socket_connected);
if (type == PLUGLOG_CONNECT_SUCCESS)
if (type == PLUGLOG_CONNECT_SUCCESS) {
raw->socket_connected = true;
if (is_tempseat(raw->seat)) {
Seat *ts = raw->seat;
tempseat_flush(ts);
raw->seat = tempseat_get_real(ts);
tempseat_free(ts);
}
}
}
static void raw_check_close(Raw *raw)
@ -132,9 +139,6 @@ static char *raw_init(const BackendVtable *vt, Seat *seat,
int addressfamily;
char *loghost;
/* No local authentication phase in this protocol */
seat_set_trust_status(seat, false);
raw = snew(Raw);
raw->plug.vt = &Raw_plugvt;
raw->backend.vt = vt;
@ -168,10 +172,13 @@ static char *raw_init(const BackendVtable *vt, Seat *seat,
*/
raw->s = new_connection(addr, *realhost, port, false, true, nodelay,
keepalive, &raw->plug, conf,
log_get_policy(logctx));
log_get_policy(logctx), &raw->seat);
if ((err = sk_socket_error(raw->s)) != NULL)
return dupstr(err);
/* No local authentication phase in this protocol */
seat_set_trust_status(raw->seat, false);
loghost = conf_get_str(conf, CONF_loghost);
if (*loghost) {
char *colon;
@ -191,6 +198,8 @@ static void raw_free(Backend *be)
{
Raw *raw = container_of(be, Raw, backend);
if (is_tempseat(raw->seat))
tempseat_free(raw->seat);
if (raw->s)
sk_close(raw->s);
conf_free(raw->conf);