tcprpf-client.c - net/tcprpf - Rivoreo Source Code Repositories

 /*
  * Copyright 2015-2018 Rivoreo
  *
  * 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.
  */

 #include "common.h"
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <sys/wait.h>
 #include <netdb.h>
 #include <unistd.h>
 #include "syncrw.h"
 #include <signal.h>
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <errno.h>
 #include <time.h>

 extern int forward(int, int);

 static int alrm = 0;

 static void signal_handler(int sig) {
 	switch(sig) {
 		case SIGCHLD:
 			while(1) switch(waitpid(-1, NULL, WNOHANG)) {
 				case -1:
 					if(errno == EINTR) continue;
 					if(errno == ECHILD) return;
 					perror("waitpid");
 					return;
 				case 0:
 					return;
 				//default:
 			}
 			return;
 		case SIGALRM:
 			alrm = 1;
 			return;
 	}
 }

 int main(int argc, char **argv) {
 	const char *name = strchr(argv[0], '/');
 	if(name) name++; else name = argv[0];

 	if(argc != 3) {
 		fprintf(stderr, "Usage: %s <forward-host>:<forward-port> <rpf-server>:<server-port>\n", name);
 		return -1;
 	}

 	struct sigaction orig_act;
 	struct sigaction act = { .sa_handler = SIG_IGN };
 	if(sigaction(SIGPIPE, &act, NULL) < 0) {
 		perror("sigaction");
 		return 1;
 	}
 	act.sa_handler = signal_handler;
 	sigaction(SIGCHLD, &act, NULL);

 	int server_address_is_name = 0;
 	struct addrinfo *server_name_info = NULL, *orig_addr_info_p = NULL;
 	struct in_addr forward_host_address, rpf_server_address;

 	char *col = strchr(argv[1], ':');
 	if(!col) {
 		fprintf(stderr, "%s: Missing ':' in forward-host\n", argv[0]);
 		return -1;
 	}
 	int forward_host_port = atoi(col + 1);
 	if(forward_host_port < 1) {
 		fprintf(stderr, "%s: Wrong port of forward host; port number must greater that 0\n", argv[0]);
 		return -1;
 	}
 	*col = 0;
 	if(inet_pton(AF_INET, argv[1], &forward_host_address) < 1) {
 		fprintf(stderr, "%s: Invalid forward host address '%s'\n", argv[0], argv[1]);
 		return -1;
 	}

 	col = strchr(argv[2], ':');
 	if(!col) {
 		fprintf(stderr, "%s: Missing ':' in rpf-server\n", argv[0]);
 		return -1;
 	}
 	int rpf_server_port = atoi(col + 1);
 	if(rpf_server_port < 1) {
 		fprintf(stderr, "%s: Wrong port of rpf server; port number must greater that 0\n", argv[0]);
 		return -1;
 	}

 	fprintf(stderr, "\nTCP Reverse Port Forwarding Client - %s\n"
 		RIVOREO_COPYRIGHT_NOTICE "\n"
 		LICENSE_INFORMATION "\n\n", name);

 	*col = 0;
 	if(inet_pton(AF_INET, argv[2], &rpf_server_address) < 1) {
 		fprintf(stderr, "%s: Invalid rpf server address '%s', trying getaddrinfo\n", argv[0], argv[2]);
 		server_address_is_name = 1;
 	}

 	int fd = -1;
 	fd_set fdset;
 	struct timeval read_timeout;
 	struct sockaddr_in server_addr = {
 		.sin_family = AF_INET,
 		.sin_port = htons(rpf_server_port)
 	};
 	if(!server_address_is_name) server_addr.sin_addr = rpf_server_address;
 	while(1) {
 		if(server_address_is_name) {
 			if(!server_name_info) {
 				freeaddrinfo(orig_addr_info_p);
 				struct addrinfo hints = {
 					.ai_family = AF_INET,
 					.ai_socktype = 0,
 					.ai_protocol = 0
 				};
 				int e = getaddrinfo(argv[2], NULL, &hints, &server_name_info);
 				if(e) {
 					fprintf(stderr, "%s: Cannot resolv server name '%s': %s\n", argv[0], argv[2], gai_strerror(e));
 					orig_addr_info_p = NULL;
 					sleep(4);
 					continue;
 				}
 				orig_addr_info_p = server_name_info;
 			}
 			server_addr.sin_addr = ((struct sockaddr_in *)server_name_info->ai_addr)->sin_addr;
 		}
 		//if(fd != -1) close(fd);
 		fd = socket(AF_INET, SOCK_STREAM, 0);
 		if(fd == -1) {
 			perror("socket");
 			return 1;
 		}
 		static const int keepalive = 1;
 		if(setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof keepalive) < 0) perror("setsockopt");
 		static const struct timeval sendtimeout = { .tv_sec = 10 };
 		if(setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &sendtimeout, sizeof sendtimeout) < 0) perror("setsockopt");
 		fprintf(stderr, "%s: Connecting to rpf server %s", argv[0], argv[2]);
 		if(server_address_is_name) fprintf(stderr, " (%s)\n", inet_ntoa(server_addr.sin_addr));
 		else fputc('\n', stderr);
 		sigaction(SIGALRM, &act, &orig_act);
 		alarm(20);
 		alrm = 0;
 		while(connect(fd, (struct sockaddr *)&server_addr, sizeof server_addr) < 0) {
 			if(errno == EINTR || errno == EINPROGRESS || errno == EALREADY) {
 				if(alrm) {
 					alarm(0);
 					sigaction(SIGALRM, &orig_act, NULL);
 					alrm = 0;
 					fprintf(stderr, "%s: Connection to rpf server %s timed out\n", argv[0], argv[2]);
 					if(server_address_is_name) server_name_info = server_name_info->ai_next;
 					goto close_and_recreate_socket;
 				}
 				continue;
 			}
 			perror("connect: rpf server");
 			alarm(0);
 			sigaction(SIGALRM, &orig_act, NULL);
 			//alrm = 0;
 #if defined __APPLE__ && defined __MACH__
 			if(errno == EISCONN) goto close_and_recreate_socket;
 #endif
 			if(server_address_is_name) server_name_info = server_name_info->ai_next;
 			sleep(10);
 			goto close_and_recreate_socket;
 		}
 		alarm(0);
 		sigaction(SIGALRM, &orig_act, NULL);

 		int keep_alive_sent = 0;

 		while(1) {
 			char magic[sizeof MAGIC - 1];
 			FD_ZERO(&fdset);
 			FD_SET(fd, &fdset);
 			read_timeout.tv_sec = 120;
 			read_timeout.tv_usec = 0;
 			int n = select(fd + 1, &fdset, NULL, NULL, &read_timeout);
 			if(n < 0) {
 				if(errno == EINTR) continue;
 				perror("select");
 				sleep(1);
 				break;
 			} else if(!n) {
 #if 1
 				if(keep_alive_sent) {
 					fprintf(stderr, "%s: Waiting for data from server timed out after keep alive is sent\n", argv[0]);
 					break;
 				}
 #endif
 				uint16_t packet_type = htons(KEEP_ALIVE);
 				if(sync_write(fd, MAGIC, sizeof MAGIC - 1) < 0 || sync_write(fd, &packet_type, sizeof packet_type) < 0) {
 					perror("write");
 					sleep(1);
 					break;
 				}
 				keep_alive_sent++;
 				continue;
 			}
 			int s = sync_read(fd, magic, sizeof magic);
 			//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
 			if(s < 0) {
 				perror("read");
 				sleep(1);
 				break;
 			}
 			if(s < (int)sizeof magic) {
 				fprintf(stderr, "%s: Server closed connection\n", argv[0]);
 				break;
 			}
 			if(memcmp(magic, MAGIC, sizeof magic)) {
 				fprintf(stderr, "%s: Protocol mismatch\n", argv[0]);
 				sleep(1);
 				break;
 			}
 			uint16_t packet_type;
 			s = sync_read(fd, &packet_type, sizeof packet_type);
 			//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
 			if(s < 0) {
 				perror("read");
 				sleep(1);
 				break;
 			}
 			if(s < (int)sizeof packet_type) {
 				fprintf(stderr, "%s: Server closed connection\n", argv[0]);
 				break;
 			}
 			//fprintf(stderr, "%s debug: " __FILE__ ":%d: packet_type = %hu\n", argv[0], __LINE__, packet_type);
 			packet_type = ntohs(packet_type);
 			//fprintf(stderr, "%s debug: " __FILE__ ":%d: packet_type = %hu\n", argv[0], __LINE__, packet_type);
 			if(packet_type == KEEP_ALIVE) {
 				fprintf(stderr, "%s: Keep alive from server\n", argv[0]);
 				packet_type = htons(KEEP_ALIVE_REPLY);
 				if(sync_write(fd, MAGIC, sizeof MAGIC - 1) < 0 || sync_write(fd, &packet_type, sizeof packet_type) < 0) {
 					perror("write");
 					sleep(1);
 					break;
 				}
 				continue;
 			}
 			if(packet_type == KEEP_ALIVE_REPLY) {
 				if(!keep_alive_sent) {
 					fprintf(stderr, "%s: Unexpected keep alive reply from server, disconnecting\n", argv[0]);
 					sleep(2);
 					break;
 				}
 				keep_alive_sent--;
 				continue;
 			}
 			if(packet_type == NEW_CONNECTION) {
 				//fprintf(stderr, "%s debug: " __FILE__ ":%d: server has got a new connection\n", argv[0], __LINE__);
 				struct new_connection_packet packet;
 				s = sync_read(fd, &packet.len, sizeof packet.len);
 				//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
 				if(s < 0) {
 					perror("read");
 					sleep(1);
 					break;
 				}
 				if(s < (int)sizeof packet.len) break;
 				size_t remain_len = ntohl(packet.len) - sizeof packet.len;
 				//fprintf(stderr, "%s debug: " __FILE__ ":%d: remain_len = %zu\n", argv[0], __LINE__, remain_len);
 				if(remain_len < INITIAL_NEW_CONN_PACKET_LENGTH - sizeof packet.len) {
 					fprintf(stderr, "%s: Recevied packet too short, disconnecting\n", argv[0]);
 					break;
 				}
 				size_t extra_len = 0;
 				if(remain_len > sizeof packet - sizeof packet.len) {
 					fprintf(stderr, "%s: Recevied packet too long, skipping extra parts\n", argv[0]);
 					extra_len = remain_len - (sizeof packet - sizeof packet.len);
 					remain_len = sizeof packet - sizeof packet.len;
 				}

 				s = sync_read(fd, (char *)&packet + sizeof packet.len, remain_len);
 				//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
 				if(s < (int)remain_len) {
 					if(s < 0) perror("read");
 					sleep(1);
 					break;
 				}
 				fprintf(stderr, "%s: New connection recevied on server %s from %s port %hu",
 					argv[0], argv[2], inet_ntoa(packet.address), ntohs(packet.port));
 				if(ntohl(packet.len) >= INITIAL_NEW_CONN_PACKET_LENGTH + sizeof(struct in_addr) + sizeof(uint16_t)) {
 					fprintf(stderr, " to %s port %hu\n",
 						inet_ntoa(packet.dest_address), ntohs(packet.dest_port));
 				} else {
 					fputc('\n', stderr);
 				}
 				if(extra_len) {
 					//size_t chunk_len = MIN(extra_len, 16384);
 					size_t chunk_len = MIN(extra_len, 4096);
 					char buffer[chunk_len];
 					do {
 						int len = MIN(chunk_len, extra_len);
 						s = sync_read(fd, buffer, len);
 						//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
 						if(s < 0) {
 							perror("read");
 							sleep(1);
 							break;
 						}
 						if(s < len) {
 							goto close_and_recreate_socket;
 						}
 						extra_len -= len;
 					} while(extra_len > 0);
 				}

 				pid_t pid = fork();
 				if(pid) {
 					if(pid < 0) perror("fork");
 					break;
 				} else {
 					int forward_host_socket = socket(AF_INET, SOCK_STREAM, 0);
 					if(forward_host_socket == -1) {
 						perror("socket");
 						exit(1);
 					}
 					struct sockaddr_in addr = {
 						.sin_family = AF_INET,
 						.sin_addr = forward_host_address,
 						.sin_port = htons(forward_host_port)
 					};
 					pid = getpid();
 					fprintf(stderr, "%s: %d: Connecting to %s:%d\n", argv[0], (int)pid, argv[1], forward_host_port);
 					while(connect(forward_host_socket, (struct sockaddr *)&addr, sizeof addr) < 0) {
 						if(errno == EINTR) continue;
 						perror("connect: forwarding");
 						exit(1);
 					}
 					struct sockaddr_in local_addr;
 					socklen_t len = sizeof local_addr;
 					if(getsockname(forward_host_socket, (struct sockaddr *)&local_addr, &len) < 0) {
 						perror("getsockname");
 					} else {
 						fprintf(stderr, "%s: %d: Connected to %s:%d, local port %d\n",
 							argv[0], (int)pid, argv[1], forward_host_port, ntohs(local_addr.sin_port));
 					}
 					int status = forward(fd, forward_host_socket) < 0 ? 1 : 0;
 					fprintf(stderr, "%s: %d: Exiting with status %d\n", argv[0], (int)pid, status);
 					exit(status);
 				}
 			} else {
 				fprintf(stderr, "%s: Unknown packet type %hu\n", argv[0], packet_type);
 				break;
 			}
 		}
 close_and_recreate_socket:
 		close(fd);
 	}
 }
	/*
	* Copyright 2015-2018 Rivoreo
	*
	* 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.
	*/

	#include "common.h"
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <netinet/in.h>
	#include <arpa/inet.h>
	#include <sys/wait.h>
	#include <netdb.h>
	#include <unistd.h>
	#include "syncrw.h"
	#include <signal.h>
	#include <string.h>
	#include <stdlib.h>
	#include <stdio.h>
	#include <errno.h>
	#include <time.h>

	extern int forward(int, int);

	static int alrm = 0;

	static void signal_handler(int sig) {
	switch(sig) {
	case SIGCHLD:
	while(1) switch(waitpid(-1, NULL, WNOHANG)) {
	case -1:
	if(errno == EINTR) continue;
	if(errno == ECHILD) return;
	perror("waitpid");
	return;
	case 0:
	return;
	//default:
	}
	return;
	case SIGALRM:
	alrm = 1;
	return;
	}
	}

	int main(int argc, char **argv) {
	const char *name = strchr(argv[0], '/');
	if(name) name++; else name = argv[0];

	if(argc != 3) {
	fprintf(stderr, "Usage: %s <forward-host>:<forward-port> <rpf-server>:<server-port>\n", name);
	return -1;
	}

	struct sigaction orig_act;
	struct sigaction act = { .sa_handler = SIG_IGN };
	if(sigaction(SIGPIPE, &act, NULL) < 0) {
	perror("sigaction");
	return 1;
	}
	act.sa_handler = signal_handler;
	sigaction(SIGCHLD, &act, NULL);

	int server_address_is_name = 0;
	struct addrinfo server_name_info = NULL, orig_addr_info_p = NULL;
	struct in_addr forward_host_address, rpf_server_address;

	char *col = strchr(argv[1], ':');
	if(!col) {
	fprintf(stderr, "%s: Missing ':' in forward-host\n", argv[0]);
	return -1;
	}
	int forward_host_port = atoi(col + 1);
	if(forward_host_port < 1) {
	fprintf(stderr, "%s: Wrong port of forward host; port number must greater that 0\n", argv[0]);
	return -1;
	}
	*col = 0;
	if(inet_pton(AF_INET, argv[1], &forward_host_address) < 1) {
	fprintf(stderr, "%s: Invalid forward host address '%s'\n", argv[0], argv[1]);
	return -1;
	}

	col = strchr(argv[2], ':');
	if(!col) {
	fprintf(stderr, "%s: Missing ':' in rpf-server\n", argv[0]);
	return -1;
	}
	int rpf_server_port = atoi(col + 1);
	if(rpf_server_port < 1) {
	fprintf(stderr, "%s: Wrong port of rpf server; port number must greater that 0\n", argv[0]);
	return -1;
	}

	fprintf(stderr, "\nTCP Reverse Port Forwarding Client - %s\n"
	RIVOREO_COPYRIGHT_NOTICE "\n"
	LICENSE_INFORMATION "\n\n", name);

	*col = 0;
	if(inet_pton(AF_INET, argv[2], &rpf_server_address) < 1) {
	fprintf(stderr, "%s: Invalid rpf server address '%s', trying getaddrinfo\n", argv[0], argv[2]);
	server_address_is_name = 1;
	}

	int fd = -1;
	fd_set fdset;
	struct timeval read_timeout;
	struct sockaddr_in server_addr = {
	.sin_family = AF_INET,
	.sin_port = htons(rpf_server_port)
	};
	if(!server_address_is_name) server_addr.sin_addr = rpf_server_address;
	while(1) {
	if(server_address_is_name) {
	if(!server_name_info) {
	freeaddrinfo(orig_addr_info_p);
	struct addrinfo hints = {
	.ai_family = AF_INET,
	.ai_socktype = 0,
	.ai_protocol = 0
	};
	int e = getaddrinfo(argv[2], NULL, &hints, &server_name_info);
	if(e) {
	fprintf(stderr, "%s: Cannot resolv server name '%s': %s\n", argv[0], argv[2], gai_strerror(e));
	orig_addr_info_p = NULL;
	sleep(4);
	continue;
	}
	orig_addr_info_p = server_name_info;
	}
	server_addr.sin_addr = ((struct sockaddr_in *)server_name_info->ai_addr)->sin_addr;
	}
	//if(fd != -1) close(fd);
	fd = socket(AF_INET, SOCK_STREAM, 0);
	if(fd == -1) {
	perror("socket");
	return 1;
	}
	static const int keepalive = 1;
	if(setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof keepalive) < 0) perror("setsockopt");
	static const struct timeval sendtimeout = { .tv_sec = 10 };
	if(setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &sendtimeout, sizeof sendtimeout) < 0) perror("setsockopt");
	fprintf(stderr, "%s: Connecting to rpf server %s", argv[0], argv[2]);
	if(server_address_is_name) fprintf(stderr, " (%s)\n", inet_ntoa(server_addr.sin_addr));
	else fputc('\n', stderr);
	sigaction(SIGALRM, &act, &orig_act);
	alarm(20);
	alrm = 0;
	while(connect(fd, (struct sockaddr *)&server_addr, sizeof server_addr) < 0) {
	if(errno == EINTR \|\| errno == EINPROGRESS \|\| errno == EALREADY) {
	if(alrm) {
	alarm(0);
	sigaction(SIGALRM, &orig_act, NULL);
	alrm = 0;
	fprintf(stderr, "%s: Connection to rpf server %s timed out\n", argv[0], argv[2]);
	if(server_address_is_name) server_name_info = server_name_info->ai_next;
	goto close_and_recreate_socket;
	}
	continue;
	}
	perror("connect: rpf server");
	alarm(0);
	sigaction(SIGALRM, &orig_act, NULL);
	//alrm = 0;
	#if defined __APPLE__ && defined __MACH__
	if(errno == EISCONN) goto close_and_recreate_socket;
	#endif
	if(server_address_is_name) server_name_info = server_name_info->ai_next;
	sleep(10);
	goto close_and_recreate_socket;
	}
	alarm(0);
	sigaction(SIGALRM, &orig_act, NULL);

	int keep_alive_sent = 0;

	while(1) {
	char magic[sizeof MAGIC - 1];
	FD_ZERO(&fdset);
	FD_SET(fd, &fdset);
	read_timeout.tv_sec = 120;
	read_timeout.tv_usec = 0;
	int n = select(fd + 1, &fdset, NULL, NULL, &read_timeout);
	if(n < 0) {
	if(errno == EINTR) continue;
	perror("select");
	sleep(1);
	break;
	} else if(!n) {
	#if 1
	if(keep_alive_sent) {
	fprintf(stderr, "%s: Waiting for data from server timed out after keep alive is sent\n", argv[0]);
	break;
	}
	#endif
	uint16_t packet_type = htons(KEEP_ALIVE);
	if(sync_write(fd, MAGIC, sizeof MAGIC - 1) < 0 \|\| sync_write(fd, &packet_type, sizeof packet_type) < 0) {
	perror("write");
	sleep(1);
	break;
	}
	keep_alive_sent++;
	continue;
	}
	int s = sync_read(fd, magic, sizeof magic);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
	if(s < 0) {
	perror("read");
	sleep(1);
	break;
	}
	if(s < (int)sizeof magic) {
	fprintf(stderr, "%s: Server closed connection\n", argv[0]);
	break;
	}
	if(memcmp(magic, MAGIC, sizeof magic)) {
	fprintf(stderr, "%s: Protocol mismatch\n", argv[0]);
	sleep(1);
	break;
	}
	uint16_t packet_type;
	s = sync_read(fd, &packet_type, sizeof packet_type);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
	if(s < 0) {
	perror("read");
	sleep(1);
	break;
	}
	if(s < (int)sizeof packet_type) {
	fprintf(stderr, "%s: Server closed connection\n", argv[0]);
	break;
	}
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: packet_type = %hu\n", argv[0], __LINE__, packet_type);
	packet_type = ntohs(packet_type);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: packet_type = %hu\n", argv[0], __LINE__, packet_type);
	if(packet_type == KEEP_ALIVE) {
	fprintf(stderr, "%s: Keep alive from server\n", argv[0]);
	packet_type = htons(KEEP_ALIVE_REPLY);
	if(sync_write(fd, MAGIC, sizeof MAGIC - 1) < 0 \|\| sync_write(fd, &packet_type, sizeof packet_type) < 0) {
	perror("write");
	sleep(1);
	break;
	}
	continue;
	}
	if(packet_type == KEEP_ALIVE_REPLY) {
	if(!keep_alive_sent) {
	fprintf(stderr, "%s: Unexpected keep alive reply from server, disconnecting\n", argv[0]);
	sleep(2);
	break;
	}
	keep_alive_sent--;
	continue;
	}
	if(packet_type == NEW_CONNECTION) {
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: server has got a new connection\n", argv[0], __LINE__);
	struct new_connection_packet packet;
	s = sync_read(fd, &packet.len, sizeof packet.len);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
	if(s < 0) {
	perror("read");
	sleep(1);
	break;
	}
	if(s < (int)sizeof packet.len) break;
	size_t remain_len = ntohl(packet.len) - sizeof packet.len;
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: remain_len = %zu\n", argv[0], __LINE__, remain_len);
	if(remain_len < INITIAL_NEW_CONN_PACKET_LENGTH - sizeof packet.len) {
	fprintf(stderr, "%s: Recevied packet too short, disconnecting\n", argv[0]);
	break;
	}
	size_t extra_len = 0;
	if(remain_len > sizeof packet - sizeof packet.len) {
	fprintf(stderr, "%s: Recevied packet too long, skipping extra parts\n", argv[0]);
	extra_len = remain_len - (sizeof packet - sizeof packet.len);
	remain_len = sizeof packet - sizeof packet.len;
	}

	s = sync_read(fd, (char *)&packet + sizeof packet.len, remain_len);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
	if(s < (int)remain_len) {
	if(s < 0) perror("read");
	sleep(1);
	break;
	}
	fprintf(stderr, "%s: New connection recevied on server %s from %s port %hu",
	argv[0], argv[2], inet_ntoa(packet.address), ntohs(packet.port));
	if(ntohl(packet.len) >= INITIAL_NEW_CONN_PACKET_LENGTH + sizeof(struct in_addr) + sizeof(uint16_t)) {
	fprintf(stderr, " to %s port %hu\n",
	inet_ntoa(packet.dest_address), ntohs(packet.dest_port));
	} else {
	fputc('\n', stderr);
	}
	if(extra_len) {
	//size_t chunk_len = MIN(extra_len, 16384);
	size_t chunk_len = MIN(extra_len, 4096);
	char buffer[chunk_len];
	do {
	int len = MIN(chunk_len, extra_len);
	s = sync_read(fd, buffer, len);
	//fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
	if(s < 0) {
	perror("read");
	sleep(1);
	break;
	}
	if(s < len) {
	goto close_and_recreate_socket;
	}
	extra_len -= len;
	} while(extra_len > 0);
	}

	pid_t pid = fork();
	if(pid) {
	if(pid < 0) perror("fork");
	break;
	} else {
	int forward_host_socket = socket(AF_INET, SOCK_STREAM, 0);
	if(forward_host_socket == -1) {
	perror("socket");
	exit(1);
	}
	struct sockaddr_in addr = {
	.sin_family = AF_INET,
	.sin_addr = forward_host_address,
	.sin_port = htons(forward_host_port)
	};
	pid = getpid();
	fprintf(stderr, "%s: %d: Connecting to %s:%d\n", argv[0], (int)pid, argv[1], forward_host_port);
	while(connect(forward_host_socket, (struct sockaddr *)&addr, sizeof addr) < 0) {
	if(errno == EINTR) continue;
	perror("connect: forwarding");
	exit(1);
	}
	struct sockaddr_in local_addr;
	socklen_t len = sizeof local_addr;
	if(getsockname(forward_host_socket, (struct sockaddr *)&local_addr, &len) < 0) {
	perror("getsockname");
	} else {
	fprintf(stderr, "%s: %d: Connected to %s:%d, local port %d\n",
	argv[0], (int)pid, argv[1], forward_host_port, ntohs(local_addr.sin_port));
	}
	int status = forward(fd, forward_host_socket) < 0 ? 1 : 0;
	fprintf(stderr, "%s: %d: Exiting with status %d\n", argv[0], (int)pid, status);
	exit(status);
	}
	} else {
	fprintf(stderr, "%s: Unknown packet type %hu\n", argv[0], packet_type);
	break;
	}
	}
	close_and_recreate_socket:
	close(fd);
	}
	}