raw/forward.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/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <unistd.h>
//#include "syncrw.h"
#include <stdio.h>
#include <errno.h>

#ifndef MAX
#define MAX(A,B) ((A)>(B)?(A):(B))
#endif

static int send_chunk(int wfd, int rfd) {
	//fprintf(stderr, "function: send_chunk(%d, %d)\n", wfd, rfd);
	char buffer[4096];
	int rs;
	do {
		rs = read(rfd, buffer, sizeof buffer);
	} while(rs < 0 && errno == EINTR);
	if(rs < 0) return -1;
	if(!rs) return 0;
	int wss = 0;
	do {
		int ws = write(wfd, buffer + wss, rs - wss);
		if(ws < 0) {
			if(errno == EINTR) continue;
			return -1;
		}
		wss += ws;
	} while(wss < rs);
	return wss;
}

int forward(int fd1, int fd2) {
	//fprintf(stderr, "function: forward(%d, %d)\n", fd1, fd2);
	fd_set fdset;
	int max_fd = MAX(fd1, fd2);
	int fd1_eof = 0, fd2_eof = 0;
	do {
		FD_ZERO(&fdset);
		if(!fd1_eof) FD_SET(fd1, &fdset);
		if(!fd2_eof) FD_SET(fd2, &fdset);
		switch(select(max_fd + 1, &fdset, NULL, NULL, NULL)) {
			case -1:
				if(errno == EINTR) continue;
				perror("select");
				return -1;
			case 0:
				continue;
			default:
				if(FD_ISSET(fd1, &fdset)) {
					switch(send_chunk(fd2, fd1)) {
						case -1:
							return -1;
						case 0:
							fd1_eof = 1;
							break;
					}
				} else if(FD_ISSET(fd2, &fdset)) {
					switch(send_chunk(fd1, fd2)) {
						case -1:
							return -1;
						case 0:
							fd2_eof = 1;
							break;
					}
				}
		}
	//} while(!fd1_eof || !fd2_eof);
	} while(!fd1_eof && !fd2_eof);
	return 0;
}