c++ howto create and use a websocket to a remote machine

On Mon, 26 Jan 2026 at 16:37, Ben Engbers via BaseX-Talk < basex-talk at mailman.uni-konstanz.de> wrote: > Hi, > > Thanks to an increasing number of grandchildren, as a retiree I have had > little time in recent years to continue working on my C++ client for > Basex. It therefore took a lot of time to find and fix a very persistent > memory leak, but I finally succeeded. > On a local machine, running basexserver, the entire server protocol can > be handled without error messages. The only thing I couldn't test yet > was the use of a websocket to a remote machine, and that now appears to > be causing problems. > On an old PC, I installed a minimal version of Fedora 43 that does not > use GNOME. Basexserver runs without any problems and I can create new > users in basexclient. Local use of my client does not cause any > problems. But when I want to create a websocket to the test machine, I > get the error message “setsockopt: Bad file descriptor”. After several > attempts using the IP address instead of the machine name, both my > laptop and the test PC crashed, and I had to reinstall basex. > In C++, I use the following code to create a socket (the starting point > for this code was Alexander Holupirek's C code “basexdbc.c”): > > BasexSocket & BasexSocket::CreateSocket (string host, string port) { // > @suppress("Name convention for function") > cout << __FUNCTION__ << " : " << host << " | " << port << " | " > << endl; > if (host.empty () || port.empty ()) { > cout << "ERROR: Invalid hostname/port\n" << endl; > exit(0); > } > /* > if (host.empty () || port.empty ()) { > Master_sfd = -1; > return *this; > } > */ > > struct addrinfo hints; > struct addrinfo * result = NULL, *rp; > memset (&hints, 0, sizeof (struct addrinfo)); // Initialize hints > hints.ai_family = AF_INET; // Accept both AF_INET and > AF_INET6 > hints.ai_socktype = SOCK_STREAM; > hints.ai_flags = AI_NUMERICSERV; // Port must be specified as number > > int rc; > rc = getaddrinfo (host.c_str (), port.c_str (), &hints, &result); > if (rc != 0) > perror (gai_strerror (rc)); > > for (rp = result; rp != NULL; rp = rp->ai_next) { // result is a > linked > list of address structures. > Master_sfd = socket (rp->ai_family, rp->ai_socktype, rp->ai_protocol); > if (Master_sfd == -1) > continue; > if (connect (Master_sfd, rp->ai_addr, rp->ai_addrlen) != -1) > break; > // Try to connect. Return the first successfull connect > or abort > close (Master_sfd); > } > set_nonblock_flag (Master_sfd, 1); > int opt = true; > if (setsockopt > (Master_sfd, SOL_SOCKET, SO_REUSEADDR, (char *) &opt, sizeof (opt)) < 0) > { > perror ("setsockopt"); > exit (EXIT_FAILURE); > } > if (rp == NULL) { > warnx ("Can not connect to Basex server"); > } > freeaddrinfo (result); > cout << "Master_sfd: " << Master_sfd << endl; > return *this; > }; > > Can anyone explain to me how I can successfully build a websocket to the > test PC? > > Ben > >

Op 26-01-2026 om 20:53 schreef Andy Bunce via BaseX-Talk: > Hi Ben, > > I can't speak to any C++ issues, but you might check if this is not just > a permissions or network/firewall issue by: > > From the BaseX GUI on your laptop, execute: > > |client:connect('test-pc', 1984, 'admin', '...') ||(:will return id if can connect else error :)| > > Or from a laptop terminal window > > |basexclient -n test-pc -p1984 > | > > Happy retirement. > > /Andy > > | > | > > > > > On Mon, 26 Jan 2026 at 16:37, Ben Engbers via BaseX-Talk <basex- > talk at mailman.uni-konstanz.de <mailto:basex-talk at mailman.uni- > konstanz.de>> wrote: > > Hi, > > Thanks to an increasing number of grandchildren, as a retiree I have > had > little time in recent years to continue working on my C++ client for > Basex. It therefore took a lot of time to find and fix a very > persistent > memory leak, but I finally succeeded. > On a local machine, running basexserver, the entire server protocol can > be handled without error messages. The only thing I couldn't test yet > was the use of a websocket to a remote machine, and that now appears to > be causing problems. > On an old PC, I installed a minimal version of Fedora 43 that does not > use GNOME. Basexserver runs without any problems and I can create new > users in basexclient. Local use of my client does not cause any > problems. But when I want to create a websocket to the test machine, I > get the error message “setsockopt: Bad file descriptor”. After several > attempts using the IP address instead of the machine name, both my > laptop and the test PC crashed, and I had to reinstall basex. > In C++, I use the following code to create a socket (the starting point > for this code was Alexander Holupirek's C code “basexdbc.c”): > > BasexSocket & BasexSocket::CreateSocket (string host, string port) { // > @suppress("Name convention for function") > cout << __FUNCTION__ << " : " << host << " | " << port << > " | " << endl; > if (host.empty () || port.empty ()) { > cout << "ERROR: Invalid hostname/port\n" << endl; > exit(0); > } > /* > if (host.empty () || port.empty ()) { > Master_sfd = -1; > return *this; > } > */ > > struct addrinfo hints; > struct addrinfo * result = NULL, *rp; > memset (&hints, 0, sizeof (struct addrinfo)); // Initialize hints > hints.ai_family = AF_INET; // Accept both > AF_INET and AF_INET6 > hints.ai_socktype = SOCK_STREAM; > hints.ai_flags = AI_NUMERICSERV; // Port must be specified as > number > > int rc; > rc = getaddrinfo (host.c_str (), port.c_str (), &hints, &result); > if (rc != 0) > perror (gai_strerror (rc)); > > for (rp = result; rp != NULL; rp = rp->ai_next) { // result is > a linked > list of address structures. > Master_sfd = socket (rp->ai_family, rp->ai_socktype, rp->ai_protocol); > if (Master_sfd == -1) > continue; > if (connect (Master_sfd, rp->ai_addr, rp->ai_addrlen) != -1) > break; > // Try to connect. Return the first successfull > connect > or abort > close (Master_sfd); > } > set_nonblock_flag (Master_sfd, 1); > int opt = true; > if (setsockopt > (Master_sfd, SOL_SOCKET, SO_REUSEADDR, (char *) &opt, sizeof (opt)) < 0) > { > perror ("setsockopt"); > exit (EXIT_FAILURE); > } > if (rp == NULL) { > warnx ("Can not connect to Basex server"); > } > freeaddrinfo (result); > cout << "Master_sfd: " << Master_sfd << endl; > return *this; > }; > > Can anyone explain to me how I can successfully build a websocket to > the > test PC? > > Ben >

Op 26-01-2026 om 20:53 schreef Andy Bunce: > Hi Ben, > > I can't speak to any C++ issues, but you might check if this is not just > a permissions or network/firewall issue by: > > From the BaseX GUI on your laptop, execute: > > |client:connect('test-pc', 1984, 'admin', '...') ||(:will return id if can connect else error :)| > > Or from a laptop terminal window > > |basexclient -n test-pc -p1984 > | > > Happy retirement. > > /Andy

On Wed, 28 Jan 2026 at 12:44, Ben Engbers <Ben.Engbers at be-logical.nl> wrote: > Hi, > > It showed that with a Fedora 43 minimal install, ports 1984 and 8080 > were closed in the firewall. > After opening these ports, my code can also handle remote connections. > > I also asked Gemini is there were errors in my code. There were no real > errors but Gemini suggested some improvements. I'll implement them and > hopefully in one of the next few days I'll be able to upload a working > beta version. > > Ben > PS. While installing then server, I have been recording all the commands > that were issued on the server. If someone wants to have that file, let > me know. > > Op 26-01-2026 om 20:53 schreef Andy Bunce: > > Hi Ben, > > > > I can't speak to any C++ issues, but you might check if this is not just > > a permissions or network/firewall issue by: > > > > From the BaseX GUI on your laptop, execute: > > > > |client:connect('test-pc', 1984, 'admin', '...') ||(:will return id if > can connect else error :)| > > > > Or from a laptop terminal window > > > > |basexclient -n test-pc -p1984 > > | > > > > Happy retirement. > > > > /Andy >