feat: more powerful port check

src/network.c

@@ -12,30 +12,68 @@ int get_random_num(int range_start, int range_end) { // create a random number i
     return range_start + (rand() % (range_end - range_start + 1));
 }
 
-int check_port_available(unsigned short port) { // test a port is available or not
-    struct sockaddr_in server_addr; 
-    memset(&server_addr, 0, sizeof(server_addr)); // struct init
-    server_addr.sin_family = AF_INET; // set as IP communication
-    server_addr.sin_addr.s_addr = htonl(INADDR_ANY); // allow any connection
-    server_addr.sin_port = htons(port); // set telnet port
-    int server_sockfd = socket(AF_INET, SOCK_STREAM, 0); // socket created
-    if (server_sockfd < 0) { // create failed
-        return 0;
+int check_port_available(unsigned int port, int is_udp, int is_ipv6) { // test a port is available or not
+    int ipv4_tcp_sock, ipv4_udp_sock;
+    int ipv6_tcp_sock, ipv6_udp_sock;
+    struct sockaddr_in ipv4_tcp_addr, ipv4_udp_addr;
+    struct sockaddr_in6 ipv6_tcp_addr, ipv6_udp_addr;
+
+    ipv4_tcp_sock = socket(AF_INET, SOCK_STREAM, 0);
+    bzero(&ipv4_tcp_addr, sizeof(ipv4_tcp_addr));
+    ipv4_tcp_addr.sin_family = AF_INET;
+    ipv4_tcp_addr.sin_port = htons(port);
+    ipv4_tcp_addr.sin_addr.s_addr = INADDR_ANY;
+    if (bind(ipv4_tcp_sock, (struct sockaddr*)&ipv4_tcp_addr, sizeof(ipv4_tcp_addr)) < 0) {
+        return 0; // false
+    }
+    close(ipv4_tcp_sock);
+
+    if (is_udp) { // udp check
+        ipv4_udp_sock = socket(AF_INET, SOCK_DGRAM, 0);
+        bzero(&ipv4_udp_addr, sizeof(ipv4_udp_addr));
+        ipv4_udp_addr.sin_family = AF_INET;
+        ipv4_udp_addr.sin_port = htons(port);
+        ipv4_udp_addr.sin_addr.s_addr = INADDR_ANY;
+        if (bind(ipv4_udp_sock, (struct sockaddr*)&ipv4_udp_addr, sizeof(ipv4_udp_addr)) < 0) {
+            return 0; // false
+        }
+        close(ipv4_udp_sock);
+    }
+
+    if (!is_ipv6) { // ipv6 ignore
+        return 1; // true
     }
-    if (bind(server_sockfd, (struct sockaddr*)&server_addr, sizeof(struct sockaddr)) < 0) { // bind failed
-        return 0;
+
+    ipv6_tcp_sock = socket(AF_INET6, SOCK_STREAM, 0);
+    bzero(&ipv6_tcp_addr, sizeof(ipv6_tcp_addr));
+    ipv6_tcp_addr.sin6_family = AF_INET6;
+    ipv6_tcp_addr.sin6_port = htons(port);
+    ipv6_tcp_addr.sin6_addr = in6addr_any;
+    if (bind(ipv6_tcp_sock, (struct sockaddr*)&ipv6_tcp_addr, sizeof(ipv6_tcp_addr)) < 0) {
+        return 0; // false
     }
-    if (close(server_sockfd) != 0) { // close failed
-        return 0;
+    close(ipv6_tcp_sock);
+
+    if (is_udp) { // udp check
+        ipv6_udp_sock = socket(AF_INET6, SOCK_DGRAM, 0);
+        bzero(&ipv6_udp_addr, sizeof(ipv6_udp_addr));
+        ipv6_udp_addr.sin6_family = AF_INET6;
+        ipv6_udp_addr.sin6_port = htons(port);
+        ipv6_udp_addr.sin6_addr = in6addr_any;
+        if (bind(ipv6_udp_sock, (struct sockaddr*)&ipv6_udp_addr, sizeof(ipv6_udp_addr)) < 0) {
+            return 0; // false
+        }
+        close(ipv6_udp_sock);
     }
-    return 1; // port available
+
+    return 1; // true
 }
 
 int get_available_port(unsigned short range_start, unsigned short range_end) { // get a available port
     unsigned short port;
     for (;;) { // wait until a available port in range
         port = get_random_num(range_start, range_end); // get a random port in range
-        if (check_port_available(port)) { // port available
+        if (check_port_available(port, 1, 1)) { // port available
             return (int)port;
         }
     }