diff options
Diffstat (limited to 'gre.c')
| -rw-r--r-- | gre.c | 398 |
1 files changed, 199 insertions, 199 deletions
@@ -1,7 +1,7 @@ /* * gre.c - userspace GRE tunnel * - * Copyright (C) 2015, Xiaoxiao <i@xiaoxiao.im> + * Copyright (C) 2015 - 2017, Xiaoxiao <i@pxx.io> * * 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 @@ -50,231 +50,231 @@ static int daemonize(void); int main(int argc, char **argv) { - fd_set readset; - - if (argc != 4) - { - printf("usage: %s <tun> remote local\n", argv[0]); - return EXIT_FAILURE; - } - - tun = tun_new(argv[1]); - if (tun < 0) - { - printf("failed to init tun device\n"); - return EXIT_FAILURE; - } - - sock = socket(AF_INET, SOCK_RAW, IPPROTO_GRE); - if (sock < 0) - { - perror("socket"); - return EXIT_FAILURE; - } - - struct sockaddr_in local; - local.sin_family = AF_INET; - local.sin_port = htons(IPPROTO_GRE); - local.sin_addr.s_addr = inet_addr(argv[3]); - if (local.sin_addr.s_addr == INADDR_NONE) - { - fprintf(stderr, "bad local address\n"); - return EXIT_FAILURE; - } - else - { - if (bind(sock, (struct sockaddr *)&local, sizeof(local)) != 0) - { - perror("bind"); - return EXIT_FAILURE; - } - } - - remote.sin_family = AF_INET; - remote.sin_port = htons(IPPROTO_GRE); - remote.sin_addr.s_addr = inet_addr(argv[2]); - if (remote.sin_addr.s_addr == INADDR_NONE) - { - fprintf(stderr, "bad remote address\n"); - return EXIT_FAILURE; - } - - setnonblock(sock); - setnonblock(tun); - runas("nobody"); - daemonize(); - - int maxfd = (tun > sock ? tun : sock) + 1; - while (1) - { - FD_ZERO(&readset); - FD_SET(tun, &readset); - FD_SET(sock, &readset); - - int r = select(maxfd, &readset, NULL, NULL, NULL); - if (r < 0) - { - if (errno == EINTR) - { - continue; - } - else - { - perror("select"); - break; - } - } - - if (FD_ISSET(sock, &readset)) - { - gre_cb(); - } - - if (FD_ISSET(tun, &readset)) - { - tun_cb(); - } - } - - return 0; + fd_set readset; + + if (argc != 4) + { + printf("usage: %s <tun> remote local\n", argv[0]); + return EXIT_FAILURE; + } + + tun = tun_new(argv[1]); + if (tun < 0) + { + printf("failed to init tun device\n"); + return EXIT_FAILURE; + } + + sock = socket(AF_INET, SOCK_RAW, IPPROTO_GRE); + if (sock < 0) + { + perror("socket"); + return EXIT_FAILURE; + } + + struct sockaddr_in local; + local.sin_family = AF_INET; + local.sin_port = htons(IPPROTO_GRE); + local.sin_addr.s_addr = inet_addr(argv[3]); + if (local.sin_addr.s_addr == INADDR_NONE) + { + fprintf(stderr, "bad local address\n"); + return EXIT_FAILURE; + } + else + { + if (bind(sock, (struct sockaddr *)&local, sizeof(local)) != 0) + { + perror("bind"); + return EXIT_FAILURE; + } + } + + remote.sin_family = AF_INET; + remote.sin_port = htons(IPPROTO_GRE); + remote.sin_addr.s_addr = inet_addr(argv[2]); + if (remote.sin_addr.s_addr == INADDR_NONE) + { + fprintf(stderr, "bad remote address\n"); + return EXIT_FAILURE; + } + + setnonblock(sock); + setnonblock(tun); + runas("nobody"); + daemonize(); + + int maxfd = (tun > sock ? tun : sock) + 1; + while (1) + { + FD_ZERO(&readset); + FD_SET(tun, &readset); + FD_SET(sock, &readset); + + int r = select(maxfd, &readset, NULL, NULL, NULL); + if (r < 0) + { + if (errno == EINTR) + { + continue; + } + else + { + perror("select"); + break; + } + } + + if (FD_ISSET(sock, &readset)) + { + gre_cb(); + } + + if (FD_ISSET(tun, &readset)) + { + tun_cb(); + } + } + + return 0; } static void gre_cb(void) { - int ihl; // IP header length - int n; - - n = recv(sock, buf, sizeof(buf), 0); - if (n < 0) - { - perror("recv"); - return; - } - ihl = 4 * (buf[0] & 0x0f); - if (ihl > 60 || ihl < 20) - { - printf("IPv4 header too long\n"); - return; - } - // check source IPv4 address - if (*(uint32_t *)(buf + 12) != remote.sin_addr.s_addr) - { - return; - } - - // parse GRE header - if (*(uint16_t *)(buf + ihl) != 0) - { - return; - } - uint16_t protocol = ntohs(*(uint16_t *)(buf + ihl + 2)); - if (protocol != 0x0800) - { - return; - } - - write(tun, buf + ihl + 4, n - ihl - 4); + int ihl; // IP header length + int n; + + n = recv(sock, buf, sizeof(buf), 0); + if (n < 0) + { + perror("recv"); + return; + } + ihl = 4 * (buf[0] & 0x0f); + if (ihl > 60 || ihl < 20) + { + printf("IPv4 header too long\n"); + return; + } + // check source IPv4 address + if (*(uint32_t *)(buf + 12) != remote.sin_addr.s_addr) + { + return; + } + + // parse GRE header + if (*(uint16_t *)(buf + ihl) != 0) + { + return; + } + uint16_t protocol = ntohs(*(uint16_t *)(buf + ihl + 2)); + if (protocol != 0x0800) + { + return; + } + + write(tun, buf + ihl + 4, n - ihl - 4); } static void tun_cb(void) { - int n; - - n = read(tun, buf + 4, sizeof(buf) - 4); - if (n < 0) - { - perror("read"); - return; - } - *(uint16_t *)(buf) = 0; - *(uint16_t *)(buf + 2) = htons(0x0800); - sendto(sock, buf, n + 4, 0, (struct sockaddr *)&remote, sizeof(struct sockaddr)); + int n; + + n = read(tun, buf + 4, sizeof(buf) - 4); + if (n < 0) + { + perror("read"); + return; + } + *(uint16_t *)(buf) = 0; + *(uint16_t *)(buf + 2) = htons(0x0800); + sendto(sock, buf, n + 4, 0, (struct sockaddr *)&remote, sizeof(struct sockaddr)); } static int tun_new(const char *dev) { - struct ifreq ifr; - int fd, err; - - fd = open("/dev/net/tun", O_RDWR); - if (fd < 0) - { - return -1; - } - - bzero(&ifr, sizeof(struct ifreq)); - - ifr.ifr_flags = IFF_TUN | IFF_NO_PI; - if (*dev != '\0') - { - strncpy(ifr.ifr_name, dev, IFNAMSIZ); - } - - err = ioctl(fd, TUNSETIFF, (void *)&ifr); - if (err < 0) - { - return err; - } - return fd; + struct ifreq ifr; + int fd, err; + + fd = open("/dev/net/tun", O_RDWR); + if (fd < 0) + { + return -1; + } + + bzero(&ifr, sizeof(struct ifreq)); + + ifr.ifr_flags = IFF_TUN | IFF_NO_PI; + if (*dev != '\0') + { + strncpy(ifr.ifr_name, dev, IFNAMSIZ); + } + + err = ioctl(fd, TUNSETIFF, (void *)&ifr); + if (err < 0) + { + return err; + } + return fd; } static int setnonblock(int fd) { - int flags; - flags = fcntl(fd, F_GETFL, 0); - if (flags == -1) - { - return -1; - } - if (-1 == fcntl(fd, F_SETFL, flags | O_NONBLOCK)) - { - return -1; - } - return 0; + int flags; + flags = fcntl(fd, F_GETFL, 0); + if (flags == -1) + { + return -1; + } + if (-1 == fcntl(fd, F_SETFL, flags | O_NONBLOCK)) + { + return -1; + } + return 0; } static int runas(const char *user) { - struct passwd *pw_ent = getpwnam(user); - - if (pw_ent != NULL) - { - if (setegid(pw_ent->pw_gid) != 0) - { - return -1; - } - if (seteuid(pw_ent->pw_uid) != 0) - { - return -1; - } - } - - return 0; + struct passwd *pw_ent = getpwnam(user); + + if (pw_ent != NULL) + { + if (setegid(pw_ent->pw_gid) != 0) + { + return -1; + } + if (seteuid(pw_ent->pw_uid) != 0) + { + return -1; + } + } + + return 0; } static int daemonize(void) { - pid_t pid; + pid_t pid; - pid = fork(); - if (pid < 0) - { - perror("fork"); - return -1; - } + pid = fork(); + if (pid < 0) + { + perror("fork"); + return -1; + } - if (pid > 0) - { - exit(0); - } + if (pid > 0) + { + exit(0); + } - umask(0); + umask(0); - if (setsid() < 0) - { - perror("setsid"); - return -1; - } + if (setsid() < 0) + { + perror("setsid"); + return -1; + } - return 0; + return 0; } |