sockets/us_xfr_sv.c

+/* us_xfr_sv.c
+
+   An example UNIX stream socket server. Accepts incoming connections
+   and copies data sent from clients to stdout.
+
+   See also us_xfr_cl.c.
+*/
 #include "us_xfr.h"
 #define BACKLOG 5
 
 int
 main(int argc, char *argv[])
 {
     struct sockaddr_un addr;
     int sfd, cfd;
     ssize_t numRead;
     char buf[BUF_SIZE];
 
     sfd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (sfd == -1)
         errExit("socket");
 
     /* Construct server socket address, bind socket to it,
        and make this a listening socket */
 
+    /* For an explanation of the following check, see the errata notes for
+       pages 1168 and 1172 at http://www.man7.org/tlpi/errata/. */
+
+    if (strlen(SV_SOCK_PATH) > sizeof(addr.sun_path) - 1)
+        fatal("Server socket path too long: %s", SV_SOCK_PATH);
+
     if (remove(SV_SOCK_PATH) == -1 && errno != ENOENT)
         errExit("remove-%s", SV_SOCK_PATH);
 
     memset(&addr, 0, sizeof(struct sockaddr_un));
     addr.sun_family = AF_UNIX;
     strncpy(addr.sun_path, SV_SOCK_PATH, sizeof(addr.sun_path) - 1);
 
     if (bind(sfd, (struct sockaddr *) &addr, sizeof(struct sockaddr_un)) == -1)
         errExit("bind");
 
     if (listen(sfd, BACKLOG) == -1)
         errExit("listen");
 
     for (;;) {          /* Handle client connections iteratively */
 
         /* Accept a connection. The connection is returned on a new
            socket, 'cfd'; the listening socket ('sfd') remains open
            and can be used to accept further connections. */
 
         cfd = accept(sfd, NULL, NULL);
         if (cfd == -1)
             errExit("accept");
 
         /* Transfer data from connected socket to stdout until EOF */
 
         while ((numRead = read(cfd, buf, BUF_SIZE)) > 0)
             if (write(STDOUT_FILENO, buf, numRead) != numRead)
                 fatal("partial/failed write");
 
         if (numRead == -1)
             errExit("read");
 
         if (close(cfd) == -1)
             errMsg("close");
     }
 }