Choose a different Port when 655 isn't available when doing "tinc init".

If port 655 cannot be bound to when using the init command, tinc will try to
find a random port number that can be bound to, and will add the appropriate
Port variable to its host config file. A warning will be printed as well.

diff --git a/src/tincctl.c b/src/tincctl.c
index a49654847f158d74c0cbafce1e9307a45c768122..16fa4b18bc4896cd00bba02f6db9f670d8bbbdf9 100644 (file)
--- a/src/tincctl.c
+++ b/src/tincctl.c
@@ -1657,6 +1657,35 @@ bool check_id(const char *name) {
        return true;
 }
 
+static bool try_bind(int port) {
+       struct addrinfo *ai = NULL;
+       struct addrinfo hint = {
+               .ai_flags = AI_PASSIVE,
+               .ai_family = AF_UNSPEC,
+               .ai_socktype = SOCK_STREAM,
+               .ai_protocol = IPPROTO_TCP,
+       };
+
+       char portstr[16];
+       snprintf(portstr, sizeof portstr, "%d", port);
+
+       if(getaddrinfo(NULL, portstr, &hint, &ai) || !ai)
+               return false;
+
+       while(ai) {
+               int fd = socket(ai->ai_family, SOCK_STREAM, IPPROTO_TCP);
+               if(!fd)
+                       return false;
+               int result = bind(fd, ai->ai_addr, ai->ai_addrlen);
+               closesocket(fd);
+               if(result)
+                       return false;
+               ai = ai->ai_next;
+       }
+
+       return true;
+}
+
 static int cmd_init(int argc, char *argv[]) {
        if(!access(tinc_conf, F_OK)) {
                fprintf(stderr, "Configuration file %s already exists!\n", tinc_conf);
@@ -1725,6 +1754,35 @@ static int cmd_init(int argc, char *argv[]) {
        if(!rsa_keygen(2048, false) || !ecdsa_keygen(false))
                return 1;
 
+
+       if(!try_bind(655)) {
+               srand(time(NULL));
+               int port = 0;
+               for(int i = 0; i < 100; i++) {
+                       port = 0x1000 + (rand() & 0x7fff);
+                       if(try_bind(port))
+                               break;
+                       port = 0;
+               }
+               if(port) {
+                       char *filename;
+                       xasprintf(&filename, "%s" SLASH "hosts" SLASH "%s", confbase, name);
+                       FILE *f = fopen(filename, "a");
+                       free(filename);
+                       if(!f) {
+                               port = 0;
+                       } else {
+                               fprintf(f, "Port = %d\n", port);
+                               fclose(f);
+                       }
+               }
+
+               if(!port)
+                       fprintf(stderr, "Warning: could not bind to port 655. Please change tinc's Port manually.\n");
+               else
+                       fprintf(stderr, "Warning: could not bind to port 655. Tinc will instead listen on port %d.\n", port);
+       }
+
 #ifndef HAVE_MINGW
        char *filename;
        xasprintf(&filename, "%s" SLASH "tinc-up", confbase);