platform_compat: выбирать глобальный IPv6 (2000::/3) вместо ULA при выборе адреса интерфейса

lib/platform_compat.c

@@ -60,6 +60,12 @@ int random_bytes(uint8_t *buffer, size_t len) {
 #endif
 }
 
+/* Глобальный unicast IPv6 (2000::/3). При выборе адреса интерфейса предпочитаем его
+ * ULA (fc00::/7) и link-local (fe80::/10). */
+static int ipv6_is_global_unicast(const uint8_t* a) {
+    return (a[0] & 0xe0) == 0x20;
+}
+
 #ifndef _WIN32
 uint32_t get_interface_ip_by_index(uint32_t netif_index) {
     struct ifaddrs *ifaddr, *ifa;
@@ -89,7 +95,8 @@ int get_interface_ipv6_by_index(uint32_t netif_index, int temporary, uint8_t* ad
     struct ifaddrs *ifaddr, *ifa;
     if (getifaddrs(&ifaddr) == -1) return -1;
 
-    int found = 0;
+    uint8_t global_match[16], local_match[16];
+    int has_global = 0, has_local = 0;
     for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
         if (ifa->ifa_addr == NULL) continue;
         if (ifa->ifa_name == NULL) continue;
@@ -100,20 +107,18 @@ int get_interface_ipv6_by_index(uint32_t netif_index, int temporary, uint8_t* ad
         struct sockaddr_in6* sin6 = (struct sockaddr_in6*)ifa->ifa_addr;
         if ((sin6->sin6_addr.s6_addr[0] & 0xfe) == 0xfe && sin6->sin6_addr.s6_addr[1] == 0x80) continue;
         int is_temporary = (ifa->ifa_flags & IFA_F_TEMPORARY) ? 1 : 0;
-        if (temporary && is_temporary) {
-            memcpy(addr_out, &sin6->sin6_addr, 16);
-            found = 1;
-            break;
-        }
-        if (!temporary && !is_temporary) {
-            memcpy(addr_out, &sin6->sin6_addr, 16);
-            found = 1;
-            break;
+        if ((temporary && !is_temporary) || (!temporary && is_temporary)) continue;
+        if (ipv6_is_global_unicast(sin6->sin6_addr.s6_addr)) {
+            if (!has_global) { memcpy(global_match, &sin6->sin6_addr, 16); has_global = 1; }
+        } else {
+            if (!has_local) { memcpy(local_match, &sin6->sin6_addr, 16); has_local = 1; }
         }
     }
 
     freeifaddrs(ifaddr);
-    return found ? 0 : -1;
+    if (has_global) { memcpy(addr_out, global_match, 16); return 0; }
+    if (has_local)  { memcpy(addr_out, local_match, 16);  return 0; }
+    return -1;
 }
 
 #ifdef __linux__
@@ -151,8 +156,8 @@ int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t*
 
     if (send(nl_sock, &req, req.nlh.nlmsg_len, 0) < 0) { close(nl_sock); return -1; }
 
-    uint8_t fallback[16], stable_addr[16], temp_addr[16];
-    int has_fallback = 0, has_stable = 0, has_temp = 0;
+    uint8_t fallback[16], g_stable[16], g_temp[16], l_stable[16], l_temp[16];
+    int has_fallback = 0, has_g_stable = 0, has_g_temp = 0, has_l_stable = 0, has_l_temp = 0;
 
     char buf[8192];
     int done = 0;
@@ -181,19 +186,32 @@ int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t*
 
             int is_temp = (ifa_flags & IFA_F_TEMPORARY) != 0;
             int is_mngtmp = (ifa_flags & IFA_F_MANAGETEMPADDR) != 0;
+            int is_global = ipv6_is_global_unicast(addr);
 
             if (!has_fallback) { memcpy(fallback, addr, 16); has_fallback = 1; }
 
-            if (!has_stable && (!is_temp || is_mngtmp)) { memcpy(stable_addr, addr, 16); has_stable = 1; }
-            if (!has_temp && is_temp && !is_mngtmp) { memcpy(temp_addr, addr, 16); has_temp = 1; }
+            if (is_global) {
+                if (!has_g_stable && (!is_temp || is_mngtmp)) { memcpy(g_stable, addr, 16); has_g_stable = 1; }
+                if (!has_g_temp && is_temp && !is_mngtmp) { memcpy(g_temp, addr, 16); has_g_temp = 1; }
+            } else {
+                if (!has_l_stable && (!is_temp || is_mngtmp)) { memcpy(l_stable, addr, 16); has_l_stable = 1; }
+                if (!has_l_temp && is_temp && !is_mngtmp) { memcpy(l_temp, addr, 16); has_l_temp = 1; }
+            }
         }
     }
     close(nl_sock);
 
-    if (prefer_stable && has_stable) { memcpy(addr_out, stable_addr, 16); return 0; }
-    if (!prefer_stable && has_temp) { memcpy(addr_out, temp_addr, 16); return 0; }
-    if (has_stable) { memcpy(addr_out, stable_addr, 16); return 0; }
-    if (has_temp) { memcpy(addr_out, temp_addr, 16); return 0; }
+    if (prefer_stable) {
+        if (has_g_stable) { memcpy(addr_out, g_stable, 16); return 0; }
+        if (has_g_temp)   { memcpy(addr_out, g_temp, 16);   return 0; }
+        if (has_l_stable) { memcpy(addr_out, l_stable, 16); return 0; }
+        if (has_l_temp)   { memcpy(addr_out, l_temp, 16);   return 0; }
+    } else {
+        if (has_g_temp)   { memcpy(addr_out, g_temp, 16);   return 0; }
+        if (has_g_stable) { memcpy(addr_out, g_stable, 16); return 0; }
+        if (has_l_temp)   { memcpy(addr_out, l_temp, 16);   return 0; }
+        if (has_l_stable) { memcpy(addr_out, l_stable, 16); return 0; }
+    }
     if (has_fallback) { memcpy(addr_out, fallback, 16); return 0; }
     return -1;
 }
@@ -335,6 +353,7 @@ int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t*
     PIP_ADAPTER_ADDRESSES adapters = plat_win_get_adapters(AF_INET6);
     if (!adapters) return -1;
     int found = 0;
+    uint8_t local_match[16]; int has_local = 0;
     PIP_ADAPTER_ADDRESSES a = plat_win_find_adapter(adapters, netif_index);
     if (a) {
         for (PIP_ADAPTER_UNICAST_ADDRESS u = a->FirstUnicastAddress; u; u = u->Next) {
@@ -344,12 +363,12 @@ int get_interface_ipv6_addr_nl(uint32_t netif_index, int prefer_stable, uint8_t*
             { static const uint8_t lb[16] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1};
               if (memcmp(b, lb, 16) == 0) continue; }                /* loopback */
             { static const uint8_t z[16]; if (memcmp(b, z, 16) == 0) continue; } /* :: */
-            memcpy(addr_out, b, 16);
-            found = 1;
-            break;
+            if (ipv6_is_global_unicast(b)) { memcpy(addr_out, b, 16); found = 1; break; }
+            if (!has_local) { memcpy(local_match, b, 16); has_local = 1; }
         }
     }
     free(adapters);
+    if (!found && has_local) { memcpy(addr_out, local_match, 16); found = 1; }
     return found ? 0 : -1;
 }