-/* Fork a new exim process to deliver the message, and do a re-exec, both to
-get a clean delivery process, and to regain root privilege in cases where it
-has been given away.
-
-Arguments:
- transport_name to pass to the new process
- hostname ditto
- hostaddress ditto
- id the new message to process
- socket_fd the connected socket
-
-Returns: FALSE if fork fails; TRUE otherwise
-*/
-
-BOOL
-transport_pass_socket(const uschar *transport_name, const uschar *hostname,
- const uschar *hostaddress, uschar *id, int socket_fd
-#ifndef DISABLE_ESMTP_LIMITS
- , unsigned peer_limit_mail, unsigned peer_limit_rcpt, unsigned peer_limit_rcptdom
-#endif
- )
-{
-pid_t pid;
-int status;
-
-DEBUG(D_transport) debug_printf("transport_pass_socket entered\n");
-
-/*XXX we'd prefer this never happens, by not calling here for this
-case (instead, passing back the next-id. But in case it does... */
-if (continue_wait_db)
- { dbfn_close_multi(continue_wait_db); continue_wait_db = NULL; }
-if (continue_retry_db)
- { dbfn_close_multi(continue_retry_db); continue_retry_db = NULL; }
-
-#ifndef DISABLE_ESMTP_LIMITS
-continue_limit_mail = peer_limit_mail;
-continue_limit_rcpt = peer_limit_rcpt;
-continue_limit_rcptdom = peer_limit_rcptdom;
-#endif
-
-if ((pid = exim_fork(US"continued-transport")) == 0)
- {
- /* If we are running in the test harness, wait for a bit to allow the
- previous process time to finish, write the log, etc., so that the output is
- always in the same order for automatic comparison. */
- /* The double-fork goes back at least as far as 0.53 (June 1996). As of
- 2024 I'm unclear why it is needed, especially given the following exec.
- I suppose it means that the parent [caller of transport_pass_socket()]
- [ that would be the "transport" proc ]
- has no direct extant child procs, from this operation. Does it wait
- for children? Not obviously so far, and a quick test has is working
- apparently ok with a single fork. Further: The "transport" proc goes
- on to only send results back up the pipe to its parent, the "delivery"
- proc. It'd be kinda nice to swap the sequence around: send the results back,
- omit the forking entrely, and exec the new transport. But the code
- it all in the wrong place (the pipe-write in deliver.c and here we're
- down in the transport). Perhaps we could pass the suggested next
- msgid back up the pipe?
-
- How would this interact with the existing TLS proxy process?
- Probably the way continue_more does at present. That feature is
- for the case where a single message has more (recip) addrs than
- can be handled in a single call to the transport. The continue-more
- flag is set; the transport avoids doing a continue-transport fork/exec,
- closes TLS and passes back to the deliver proc and exits. The deliver proc
- makes a further call to the transport. An RSET is sent on the conn;
- and the still-open conn is left for the deliver proc to make another
- call to the transport with it open. That only works because it was
- originally a continued-conn, also, so the deliver proc has the conn.
- - So if already a continued-conn, could pass back the next-message-id
- rather than doing a further continued-conn - but we'd have to re-establish
- TLS.
- [ Which is a pity, and should also be worked on. ]
- We do not need to pass the wait-tpt hintsdb handle across an exec-for-
- continued-conn because the deliver proc can know what tpt will be used,
- so the name is predictable and it cam open it. May as well do that for
- any remote tpt, and skip the open/close code in the tpt. Perhaps local
- tpts also for consistency. But... only for transaction-capable DB providers
- (and we will be assuming they are sequential-fork-safe).
-
- Architecture. The transport is a separate proc so that it can
- - go badly wrong and die, being monitored from a safer parent
- - manipulate privs, to deliver to local files. But here, we're smtp
- and don't to that!
- */
-
- testharness_pause_ms(500);
- transport_do_pass_socket(transport_name, hostname, hostaddress,
- id, socket_fd);
- /*NOTREACHED*/
- }
-
-if (pid > 0)
- return TRUE;
-
-DEBUG(D_transport) debug_printf("transport_pass_socket failed to fork: %s\n",
- strerror(errno));
-return FALSE;
-}
-
-
git://git.exim.org / exim.git / commitdiff