evgeny
38c9f229bc
- u_async.c: process immediate_queue BEFORE epoll_wait in uasync_poll - stcp_link.c: defensive NULL etcp_conn/etcp_link in stcp_link_close - utun_instance.c: move stcp_server_list_destroy_all to Phase J (before ETCP), add deferred drain in both Phase J and L - stcp.h/c: STCP_HS_ENC_CLIENT 6→38, STCP_HS_ENC_SERVER 7→39, exchange ed25519_pubkey in both handshake directions - etcp_connections.c: copy peer_ed25519 from STCP to ETCP_CONN in etcp_link_enter_ready_tcp; guard link->etcp in tcp_link_close_cb - chat_sync.c: fix lk->conn NULL dereference for TCP links - test_stcp.c: update stcp_server_create/stcp_client_connect callsites - tools/chat_tcp_test: change transport udp→tcp
236 lines
7.3 KiB
C
236 lines
7.3 KiB
C
/* outgoing_iface.c
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*
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* Определяет IPv4-адрес и индекс/имя исходящего интерфейса,
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* который ОС выберет при отправке на заданный destination
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* после bind на 0.0.0.0 (INADDR_ANY).
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*
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* Сборка:
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* Linux / BSD: gcc -o out out.c
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* Windows (MSVC): cl out.c /link ws2_32.lib iphlpapi.lib
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* Windows (MinGW): gcc -o out.exe out.c -lws2_32 -liphlpapi
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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/* ===================== Платформенные заголовки ===================== */
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#ifdef _WIN32
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# ifndef WIN32_LEAN_AND_MEAN
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# define WIN32_LEAN_AND_MEAN
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# endif
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# include <winsock2.h>
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# include <ws2tcpip.h>
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# include <iphlpapi.h>
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# pragma comment(lib, "ws2_32.lib")
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# pragma comment(lib, "iphlpapi.lib")
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typedef SOCKET socket_t;
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# define SOCKET_INVALID INVALID_SOCKET
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# define SOCKET_ERRNO WSAGetLastError()
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/* На Windows нет IFNAMSIZ; берём с запасом */
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# ifndef IF_NAMESIZE
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# define IF_NAMESIZE 256
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# endif
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#else /* Linux, FreeBSD, OpenBSD, NetBSD, macOS, … */
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# include <unistd.h>
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# include <sys/types.h>
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# include <sys/socket.h>
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# include <netinet/in.h>
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# include <arpa/inet.h>
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# include <ifaddrs.h>
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# include <net/if.h>
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# include <errno.h>
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typedef int socket_t;
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# define SOCKET_INVALID (-1)
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# define SOCKET_ERRNO errno
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# ifndef IF_NAMESIZE
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# define IF_NAMESIZE IFNAMSIZ /* обычно 16 */
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# endif
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#endif
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/* ===================== Структура результата ===================== */
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typedef struct {
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char ip[INET_ADDRSTRLEN]; /* IP строкой, например "192.168.1.5" */
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char name[IF_NAMESIZE]; /* имя интерфейса: "eth0", "em0", "Wi-Fi" … */
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uint32_t ifindex; /* числовой ifindex (if_nametoindex) */
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} iface_info_t;
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/* ===================== Утилиты ===================== */
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static int net_init(void)
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{
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#ifdef _WIN32
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static int done = 0;
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if (!done) {
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WSADATA wsa;
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if (WSAStartup(MAKEWORD(2, 2), &wsa) != 0)
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return -1;
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done = 1;
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}
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#endif
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return 0;
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}
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static void socket_close(socket_t s)
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{
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#ifdef _WIN32
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if (s != SOCKET_INVALID)
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closesocket(s);
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#else
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if (s >= 0)
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close(s);
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#endif
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}
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/* ===================== Основная функция ===================== */
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/*
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* dst_ip — адрес назначения (например, "8.8.8.8" или IP вашего VPN-сервера)
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* dst_port — любой открытый порт (например, 53 или 123), реальных пакетов не уйдёт
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* info — заполняемая структура
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*
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* Возвращает 0 при успехе, -1 при ошибке.
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*/
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int get_outgoing_iface(const char *dst_ip, int dst_port, iface_info_t *info)
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{
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socket_t sock = SOCKET_INVALID;
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int ret = -1;
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struct sockaddr_in dst, src;
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socklen_t src_len = sizeof(src);
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memset(info, 0, sizeof(*info));
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if (net_init() != 0)
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return -1;
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/* 1. UDP-сокет */
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sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
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if (sock == SOCKET_INVALID)
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return -1;
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/* 2. Bind на 0.0.0.0 — именно так, как в вопросе */
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memset(&dst, 0, sizeof(dst));
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dst.sin_family = AF_INET;
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dst.sin_addr.s_addr = INADDR_ANY; /* 0.0.0.0 */
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dst.sin_port = 0; /* система выберет порт */
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if (bind(sock, (struct sockaddr *)&dst, sizeof(dst)) != 0)
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goto end;
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/* 3. "Соединяемся" с destination.
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* Для UDP это НЕ шлёт реальных пакетов, но ядро просчитывает
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* маршрут и фиксирует выбранный source IP в сокете. */
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memset(&dst, 0, sizeof(dst));
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dst.sin_family = AF_INET;
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dst.sin_port = htons((uint16_t)dst_port);
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if (inet_pton(AF_INET, dst_ip, &dst.sin_addr) != 1)
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goto end;
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if (connect(sock, (struct sockaddr *)&dst, sizeof(dst)) != 0)
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goto end;
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/* 4. Забираем выбранный локальный адрес */
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if (getsockname(sock, (struct sockaddr *)&src, &src_len) != 0)
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goto end;
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if (!inet_ntop(AF_INET, &src.sin_addr, info->ip, sizeof(info->ip)))
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goto end;
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/* 5. По source IP ищем интерфейс в системном списке */
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#ifdef _WIN32
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{
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ULONG size = 0;
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DWORD rv;
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PIP_ADAPTER_ADDRESSES adapters = NULL, a;
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PIP_ADAPTER_UNICAST_ADDRESS u;
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/* первый вызов — узнать размер буфера */
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rv = GetAdaptersAddresses(AF_INET, GAA_FLAG_INCLUDE_PREFIX,
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NULL, NULL, &size);
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if (rv != ERROR_BUFFER_OVERFLOW)
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goto end;
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adapters = (PIP_ADAPTER_ADDRESSES)malloc(size);
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if (!adapters)
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goto end;
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rv = GetAdaptersAddresses(AF_INET, GAA_FLAG_INCLUDE_PREFIX,
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NULL, adapters, &size);
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if (rv != NO_ERROR) {
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free(adapters);
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goto end;
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}
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for (a = adapters; a != NULL; a = a->Next) {
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for (u = a->FirstUnicastAddress; u; u = u->Next) {
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struct sockaddr_in *ua =
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(struct sockaddr_in *)u->Address.lpSockaddr;
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if (ua->sin_addr.s_addr == src.sin_addr.s_addr) {
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info->ifindex = (uint32_t)a->IfIndex;
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/* FriendlyName — WCHAR, приводим к UTF-8 */
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WideCharToMultiByte(CP_UTF8, 0, a->FriendlyName, -1,
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info->name, IF_NAMESIZE,
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NULL, NULL);
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ret = 0;
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goto win_done;
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}
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}
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}
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win_done:
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free(adapters);
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}
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#else /* Linux / BSD / macOS */
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{
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struct ifaddrs *ifap, *ifa;
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if (getifaddrs(&ifap) != 0)
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goto end;
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for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
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if (!ifa->ifa_addr || ifa->ifa_addr->sa_family != AF_INET)
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continue;
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struct sockaddr_in *addr = (struct sockaddr_in *)ifa->ifa_addr;
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if (addr->sin_addr.s_addr == src.sin_addr.s_addr) {
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strncpy(info->name, ifa->ifa_name, IF_NAMESIZE - 1);
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info->ifindex = if_nametoindex(ifa->ifa_name);
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ret = 0;
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break;
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}
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}
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freeifaddrs(ifap);
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}
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#endif
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end:
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socket_close(sock);
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return ret;
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}
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/* ===================== Пример использования =====================
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int main(int argc, char **argv)
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{
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iface_info_t info;
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const char *dst = (argc > 1) ? argv[1] : "8.8.8.8";
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int port = (argc > 2) ? atoi(argv[2]) : 53;
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if (get_outgoing_iface(dst, port, &info) == 0) {
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printf("Destination : %s:%d\n", dst, port);
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printf("Source IP : %s\n", info.ip);
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printf("Iface name : %s\n", info.name);
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printf("Iface index : %u\n", info.ifindex);
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return 0;
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}
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fprintf(stderr, "Failed to determine outgoing interface (errno=%d)\n",
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#ifdef _WIN32
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(int)WSAGetLastError()
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#else
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errno
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#endif
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);
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return 1;
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}
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*/ |