tcprpf-client.c

/*
 * Copyright 2015-2017 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 <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 void signal_handler(int sig) {
	if(sig != SIGCHLD) return;
	//while(wait(NULL) < 0) {
	while(waitpid(-1, NULL, WNOHANG) < 0) {
		if(errno == EINTR) continue;
		perror("waitpid");
		return;
	}
}

int main(int argc, char **argv) {
	if(argc != 3) {
		fprintf(stderr, "Usage: %s <forward-host>:<forward-port> <rpf-server>:<server-port>\n", argv[0]);
		return -1;
	}

	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);

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

	int fd = -1;
	struct sockaddr_in server_addr = {
		.sin_family = AF_INET,
		.sin_addr = rpf_server_address,
		.sin_port = htons(rpf_server_port)
	};
	while(1) {
		if(fd != -1) close(fd);
		fd = socket(AF_INET, SOCK_STREAM, 0);
		if(fd == -1) {
			perror("socket");
			return 1;
		}
		fprintf(stderr, "%s: Connecting to rpf server %s\n", argv[0], argv[2]);
		while(connect(fd, (struct sockaddr *)&server_addr, sizeof server_addr) < 0) {
			if(errno == EINTR) continue;
			perror("connect");
			//return 1;
			sleep(10);
		}

		while(1) {
			char magic[sizeof MAGIC - 1];
			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");
				//return 1;
				sleep(1);
				break;
			}
			if(s < sizeof magic) {
				fprintf(stderr, "%s: Server closed connection\n", argv[0]);
				//return 0;
				break;
			}
			if(memcmp(magic, MAGIC, sizeof magic)) {
				fprintf(stderr, "%s: Protocol mismatch\n", argv[0]);
				//return 1;
				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");
				//return 1;
				sleep(1);
				break;
			}
			if(s < sizeof packet_type) {
				fprintf(stderr, "%s: Server closed connection\n", argv[0]);
				//return 0;
				break;
			}
			fprintf(stderr, "%s debug: " __FILE__ ":%d: packet_type = %hu\n", argv[0], __LINE__, packet_type);
/*
			switch(ntohs(packet_type)) {
				case KEEP_ALIVE:
					fprintf(stderr, "%s: Keep alive from server\n", argv[0]);
					break;
				case NEW_CONNECTION:
					fork_and_start_forwarding(fd, &forward_host_address, &forward_host_port);
			}*/
			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]);
				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 < 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 > sizeof packet - sizeof packet.len) {
					fprintf(stderr, "%s: Recevied packet too long, skipping\n", argv[0]);
					char buffer[remain_len];
					s = sync_read(fd, buffer, remain_len);
					fprintf(stderr, "%s debug: " __FILE__ ":%d: s = %d\n", argv[0], __LINE__, s);
					if(s < 0) {
						perror("read");
						sleep(1);
						break;
					}
					if(s < remain_len) break;
				} else {
					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 < remain_len) {
						if(s < 0) perror("read");
						sleep(1);
						break;
					}
					struct sockaddr_in *addr = (struct sockaddr_in *)&packet.addr;
					fprintf(stderr, "%s: New connection recevied on server time %s from %s port %d\n",
						argv[0], ctime(&packet.tv.tv_sec), inet_ntoa(addr->sin_addr), ntohs(addr->sin_port));
				}

				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)
					};
					fprintf(stderr, "%s: Connecting to %s:%d\n", argv[0], argv[1], forward_host_port);
					while(connect(forward_host_socket, (struct sockaddr *)&addr, sizeof addr) < 0) {
						if(errno == EINTR) continue;
						perror("connect");
						exit(1);
					}
					exit(forward(fd, forward_host_socket) < 0 ? 1 : 0);
				}
			} else {
				fprintf(stderr, "%s: Unknown packet type %hu\n", argv[0], packet_type);
				break;
			}
		}
	}
}