Add bind option to net/connect

This will allow us to set the address we use for outgoing connections.

Builds, haven't checked it passes current tests, haven't checked it
actually works either.

src/core/net.c

@@ -259,8 +259,9 @@ static int janet_get_sockettype(Janet *argv, int32_t argc, int32_t n) {
 }
 
 /* Needs argc >= offset + 2 */
-/* For unix paths, just rertuns a single sockaddr and sets *is_unix to 1, otherwise 0 */
+/* For unix paths, just rertuns a single sockaddr and sets *is_unix to 1,
-static struct addrinfo *janet_get_addrinfo(Janet *argv, int32_t offset, int socktype, int passive, int *is_unix) {
+ * otherwise 0. Also, ignores is_bind when is a unix socket. */
+static struct addrinfo *janet_get_addrinfo(Janet *argv, int32_t offset, int socktype, int passive, int *is_unix, int is_bind) {
     /* Unix socket support - not yet supported on windows. */
 #ifndef JANET_WINDOWS
     if (janet_keyeq(argv[offset], "unix")) {
@@ -285,12 +286,29 @@ static struct addrinfo *janet_get_addrinfo(Janet *argv, int32_t offset, int sock
     }
 #endif
     /* Get host and port */
-    const char *host = janet_getcstring(argv, offset);
+    char *host = NULL, *port = NULL;
-    const char *port;
+    char *err = NULL;
+    /* if is_bind is set, skip offsets and ports! */
+    if (!is_bind) {
+        host = (char *)janet_getcstring(argv, offset);
         if (janet_checkint(argv[offset + 1])) {
-        port = (const char *)janet_to_string(argv[offset + 1]);
+            port = (char *)janet_to_string(argv[offset + 1]);
         } else {
-        port = janet_optcstring(argv, offset + 2, offset + 1, NULL);
+            port = (char *)janet_optcstring(argv, offset + 2, offset + 1, NULL);
+        }
+        err = "could not get address info: %s";
+    } else {
+        /* when is_bind is set, we're performing a connect, but wanting to
+         * specify from where we connect, and in general don't care about a
+         * port */
+        int32_t current_offset = 3;
+        if (janet_keyeq(argv[current_offset], "stream") ||
+            janet_keyeq(argv[current_offset], "datagram")) {
+           current_offset = 4;
+        }
+        host = (char *)janet_getcstring(argv, current_offset);
+        port = NULL;
+        err = "could not get address info for connect bind: %s";
     }
     /* getaddrinfo */
     struct addrinfo *ai = NULL;
@@ -301,7 +319,7 @@ static struct addrinfo *janet_get_addrinfo(Janet *argv, int32_t offset, int sock
     hints.ai_flags = passive ? AI_PASSIVE : 0;
     int status = getaddrinfo(host, port, &hints, &ai);
     if (status) {
-        janet_panicf("could not get address info: %s", gai_strerror(status));
+        janet_panicf(err, gai_strerror(status));
     }
     *is_unix = 0;
     return ai;
@@ -322,7 +340,7 @@ JANET_CORE_FN(cfun_net_sockaddr,
     int socktype = janet_get_sockettype(argv, argc, 2);
     int is_unix = 0;
     int make_arr = (argc >= 3 && janet_truthy(argv[3]));
-    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 0, &is_unix);
+    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 0, &is_unix, 0);
 #ifndef JANET_WINDOWS
     /* no unix domain socket support on windows yet */
     if (is_unix) {
@@ -361,11 +379,11 @@ JANET_CORE_FN(cfun_net_connect,
               "Open a connection to communicate with a server. Returns a duplex stream "
               "that can be used to communicate with the server. Type is an optional keyword "
               "to specify a connection type, either :stream or :datagram. The default is :stream. ") {
-    janet_arity(argc, 2, 3);
+    janet_arity(argc, 2, 4);
 
     int socktype = janet_get_sockettype(argv, argc, 2);
     int is_unix = 0;
-    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 0, &is_unix);
+    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 0, &is_unix, 0);
 
     /* Create socket */
     JSock sock = JSOCKDEFAULT;
@@ -401,6 +419,35 @@ JANET_CORE_FN(cfun_net_connect,
         }
     }
 
+    /* TODO: check if need bind and bind! */
+    ai = NULL;
+    if (argc >= 3 && is_unix == 0) {
+        if (argc == 4 ||
+            (!janet_keyeq(argv[3], "stream") &&
+             !janet_keyeq(argv[3], "datagram"))) {
+            ai = janet_get_addrinfo(argv, 0, socktype, 0, &is_unix, 1);
+        }
+    }
+
+    /* Check all addrinfos in a loop for the first that we can bind to. */
+    struct addrinfo *rp = NULL;
+    for (rp = ai; rp != NULL; rp = rp->ai_next) {
+#ifdef JANET_WINDOWS
+        sock = WSASocketW(rp->ai_family, rp->ai_socktype | JSOCKFLAGS, rp->ai_protocol, NULL, 0, WSA_FLAG_OVERLAPPED);
+#else
+        sock = socket(rp->ai_family, rp->ai_socktype | JSOCKFLAGS, rp->ai_protocol);
+#endif
+        if (!JSOCKVALID(sock)) continue;
+
+        /* Bind */
+        if (bind(sock, rp->ai_addr, (int) rp->ai_addrlen) == 0) break;
+        JSOCKCLOSE(sock);
+    }
+    freeaddrinfo(ai);
+    if (NULL == rp) {
+        janet_panic("could not bind to any sockets");
+    }
+
     /* Connect to socket */
 #ifdef JANET_WINDOWS
     int status = WSAConnect(sock, addr, addrlen, NULL, NULL, NULL, NULL);
@@ -502,7 +549,7 @@ JANET_CORE_FN(cfun_net_listen,
     /* Get host, port, and handler*/
     int socktype = janet_get_sockettype(argv, argc, 2);
     int is_unix = 0;
-    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 1, &is_unix);
+    struct addrinfo *ai = janet_get_addrinfo(argv, 0, socktype, 1, &is_unix, 0);
 
     JSock sfd = JSOCKDEFAULT;
 #ifndef JANET_WINDOWS