+/*
+ splice.c -- Splice two outgoing tinc connections together
+ Copyright (C) 2018 Guus Sliepen <guus@tinc-vpn.org>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <stdio.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+
+#ifdef HAVE_MINGW
+extern const char *winerror(int);
+#define strerror(x) ((x)>0?strerror(x):winerror(GetLastError()))
+#define sockerrno WSAGetLastError()
+#define sockstrerror(x) winerror(x)
+#else
+#define sockerrno errno
+#define sockstrerror(x) strerror(x)
+#endif
+
+int main(int argc, char *argv[]) {
+ if(argc < 7) {
+ fprintf(stderr, "Usage: %s name1 host1 port1 name2 host2 port2 [protocol]\n", argv[0]);
+ return 1;
+ }
+
+ const char *protocol;
+
+ if(argc >= 8) {
+ protocol = argv[7];
+ } else {
+ protocol = "17.7";
+ }
+
+#ifdef HAVE_MINGW
+ static struct WSAData wsa_state;
+
+ if(WSAStartup(MAKEWORD(2, 2), &wsa_state)) {
+ return 1;
+ }
+
+#endif
+ int sock[2];
+ char buf[1024];
+
+ struct addrinfo *ai, hint;
+ memset(&hint, 0, sizeof(hint));
+
+ hint.ai_family = AF_UNSPEC;
+ hint.ai_socktype = SOCK_STREAM;
+ hint.ai_protocol = IPPROTO_TCP;
+ hint.ai_flags = 0;
+
+ for (int i = 0; i < 2; i++) {
+ if(getaddrinfo(argv[2 + 3 * i], argv[3 + 3 * i], &hint, &ai) || !ai) {
+ fprintf(stderr, "getaddrinfo() failed: %s\n", sockstrerror(sockerrno));
+ return 1;
+ }
+
+ sock[i] = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+
+ if(sock[i] == -1) {
+ fprintf(stderr, "Could not create socket: %s\n", sockstrerror(sockerrno));
+ return 1;
+ }
+
+ if(connect(sock[i], ai->ai_addr, ai->ai_addrlen)) {
+ fprintf(stderr, "Could not connect to %s: %s\n", argv[i + 3 * i], sockstrerror(sockerrno));
+ return 1;
+ }
+
+ fprintf(stderr, "Connected to %s\n", argv[1 + 3 * i]);
+
+ /* Pretend to be the other one */
+ int len = snprintf(buf, sizeof buf, "0 %s %s\n", argv[4 - 3 * i], protocol);
+ if (send(sock[i], buf, len, 0) != len) {
+ fprintf(stderr, "Error sending data to %s: %s\n", argv[1 + 3 * i], sockstrerror(sockerrno));
+ return 1;
+ }
+
+ /* Ignore the response */
+ do {
+ if (recv(sock[i], buf, 1, 0) != 1) {
+ fprintf(stderr, "Error reading data from %s: %s\n", argv[1 + 3 * i], sockstrerror(sockerrno));
+ return 1;
+ }
+ } while(*buf != '\n');
+ }
+
+ fprintf(stderr, "Splicing...\n");
+
+ int nfds = (sock[0] > sock[1] ? sock[0] : sock[1]) + 1;
+
+ while(true) {
+ fd_set fds;
+ FD_ZERO(&fds);
+ FD_SET(sock[0], &fds);
+ FD_SET(sock[1], &fds);
+
+ if(select(nfds, &fds, NULL, NULL, NULL) <= 0) {
+ return 1;
+ }
+
+ for(int i = 0; i < 2; i++ ) {
+ if(FD_ISSET(sock[i], &fds)) {
+ ssize_t len = recv(sock[i], buf, sizeof buf, 0);
+
+ if(len < 0) {
+ fprintf(stderr, "Error while reading from %s: %s\n", argv[1 + i * 3], sockstrerror(sockerrno));
+ return 1;
+ }
+
+ if(len == 0) {
+ fprintf(stderr, "Connection closed by %s\n", argv[1 + i * 3]);
+ return 0;
+ }
+
+ if(send(sock[i ^ 1], buf, len, 0) != len) {
+ fprintf(stderr, "Error while writing to %s: %s\n", argv[4 - i * 3], sockstrerror(sockerrno));
+ return 1;
+ }
+ }
+ }
+ }
+
+ return 0;
+}