Hi Christian,
That's a larger fix than I was contemplating but it simplifies the code
greatly. It solves the problem for me.
Thank you for the quick fix.
Mike.
On Monday 14 July 2025 at 17:11:07 +0200, Christian Grothoff wrote:
> Dear Mike,
>
> Thanks for reporting, I've pushed a fix and released libmicrohttpd 1.0.2.
>
> Happy hacking!
>
> Christian
>
> On 7/12/25 18:49, Mike Crowe via libmicrohttpd wrote:
> > This problem was detected by Valgrind 3.25.1 when running one of the test
> > cases for our code that uses libmicrohttpd.
> >
> > In v1.0.1 if the bind() call in MHD_start_daemon_va fails then listen_fd is
> > closed and set to an invalid value at daemon.c line 8433:
> >
> > if (0 != bind (listen_fd, pservaddr, addrlen))
> > {
> > #ifdef HAVE_MESSAGES
> > MHD_DLOG (daemon,
> > _ ("Failed to bind to port %u: %s\n"),
> > (unsigned int) port,
> > MHD_socket_last_strerr_ ());
> > #endif
> > MHD_socket_close_chk_ (listen_fd);
> > listen_fd = MHD_INVALID_SOCKET;
> > goto free_and_fail;
> > }
> >
> > Unfortunately, listen_fd has already been copied to daemon->listen_fd by
> > daemon.c line 8399:
> >
> > /* check for user supplied sockaddr */
> > daemon->listen_fd = listen_fd;
> >
> > That copy is closed again at the end of MHD_start_daemon_va at
> > daemon.c line 9041:
> >
> > if ((MHD_INVALID_SOCKET != daemon->listen_fd) &&
> > (listen_fd != daemon->listen_fd))
> > (void) MHD_socket_close_ (daemon->listen_fd);
> >
> > It doesn't look like the code has changed in this area on current master.
> >
> > My instinct is to push copying listen_fd to daemon->listen_fd close to the
> > end of MHD_start_daemon_va. Unfortunately it seems that listen_fd is read
> > back from daemon->listen_fd in certain circumstances. It is not a simple
> > function!
> >
> > Is there a straightforward fix for this that I've missed?
> >
> > Thanks.
> >
> > Mike.
> >
> > Original Valgrind report:
> > --8<--
> > ==2700784== File descriptor 13: AF_INET6 socket 13: <unbound> <->
> > <unbound> is already closed
> > ==2700784== at 0x792BD6C: close (close.c:27)
> > ==2700784== by 0x4E5AE64: MHD_start_daemon_va (daemon.c:9041)
> > ==2700784== by 0x4E5AF1A: MHD_start_daemon (daemon.c:6116)
> > ==2700784== Previously closed
> > ==2700784== at 0x792BD6C: close (close.c:27)
> > ==2700784== by 0x4E59B9F: MHD_start_daemon_va (daemon.c:8433)
> > ==2700784== by 0x4E5AF1A: MHD_start_daemon (daemon.c:6116)
> >
