diff options
Diffstat (limited to 'ct_client.c')
| -rw-r--r-- | ct_client.c | 440 |
1 files changed, 440 insertions, 0 deletions
diff --git a/ct_client.c b/ct_client.c new file mode 100644 index 0000000..dbf07c5 --- /dev/null +++ b/ct_client.c @@ -0,0 +1,440 @@ +/* + * curvetun - the cipherspace wormhole creator + * Part of the netsniff-ng project + * Copyright 2011 Daniel Borkmann <daniel@netsniff-ng.org>, + * Subject to the GPL, version 2. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <netdb.h> +#include <fcntl.h> +#include <signal.h> +#include <syslog.h> +#include <limits.h> +#include <netinet/in.h> +#include <arpa/inet.h> +#include <sys/types.h> +#include <sys/socket.h> +#include <sys/ioctl.h> +#include <sys/stat.h> +#include <sys/poll.h> +#include <netinet/tcp.h> +#include <netinet/udp.h> +#include <linux/if_tun.h> + +#include "built_in.h" +#include "die.h" +#include "xio.h" +#include "xutils.h" +#include "curve.h" +#include "xmalloc.h" +#include "curvetun.h" +#include "ct_servmgmt.h" +#include "ct_usermgmt.h" +#include "crypto_auth_hmacsha512256.h" + +extern volatile sig_atomic_t sigint; +static volatile sig_atomic_t closed_by_server = 0; + +static void handler_udp_tun_to_net(int sfd, int dfd, struct curve25519_proto *p, + struct curve25519_struct *c, char *buff, + size_t len) +{ + char *cbuff; + ssize_t rlen, clen; + struct ct_proto *hdr; + size_t off = sizeof(struct ct_proto) + crypto_box_zerobytes; + + if (!buff || len <= off) + return; + + memset(buff, 0, len); + while ((rlen = read(sfd, buff + off, len - off)) > 0) { + hdr = (struct ct_proto *) buff; + + memset(hdr, 0, sizeof(*hdr)); + hdr->flags = 0; + + clen = curve25519_encode(c, p, (unsigned char *) (buff + off - + crypto_box_zerobytes), (rlen + + crypto_box_zerobytes), (unsigned char **) + &cbuff); + if (unlikely(clen <= 0)) + goto close; + + hdr->payload = htons((uint16_t) clen); + + set_udp_cork(dfd); + + write_exact(dfd, hdr, sizeof(struct ct_proto), 0); + write_exact(dfd, cbuff, clen, 0); + + set_udp_uncork(dfd); + + memset(buff, 0, len); + } + + return; +close: + closed_by_server = 1; +} + +static void handler_udp_net_to_tun(int sfd, int dfd, struct curve25519_proto *p, + struct curve25519_struct *c, char *buff, + size_t len) +{ + char *cbuff; + ssize_t rlen, clen; + struct ct_proto *hdr; + struct sockaddr_storage naddr; + + socklen_t nlen = sizeof(naddr); + + if (!buff || !len) + return; + + memset(&naddr, 0, sizeof(naddr)); + while ((rlen = recvfrom(sfd, buff, len, 0, (struct sockaddr *) &naddr, + &nlen)) > 0) { + hdr = (struct ct_proto *) buff; + + if (unlikely(rlen < sizeof(struct ct_proto))) + goto close; + if (unlikely(rlen - sizeof(*hdr) != ntohs(hdr->payload))) + goto close; + if (unlikely(ntohs(hdr->payload) == 0)) + goto close; + if (hdr->flags & PROTO_FLAG_EXIT) + goto close; + + clen = curve25519_decode(c, p, (unsigned char *) buff + + sizeof(struct ct_proto), + rlen - sizeof(struct ct_proto), + (unsigned char **) &cbuff, NULL); + if (unlikely(clen <= 0)) + goto close; + + cbuff += crypto_box_zerobytes; + clen -= crypto_box_zerobytes; + + if (write(dfd, cbuff, clen)) { ; } + } + + return; +close: + closed_by_server = 1; +} + +static void handler_tcp_tun_to_net(int sfd, int dfd, struct curve25519_proto *p, + struct curve25519_struct *c, char *buff, + size_t len) +{ + char *cbuff; + ssize_t rlen, clen; + struct ct_proto *hdr; + size_t off = sizeof(struct ct_proto) + crypto_box_zerobytes; + + if (!buff || len <= off) + return; + + memset(buff, 0, len); + while ((rlen = read(sfd, buff + off, len - off)) > 0) { + hdr = (struct ct_proto *) buff; + + memset(hdr, 0, sizeof(*hdr)); + hdr->flags = 0; + + clen = curve25519_encode(c, p, (unsigned char *) (buff + off - + crypto_box_zerobytes), (rlen + + crypto_box_zerobytes), (unsigned char **) + &cbuff); + if (unlikely(clen <= 0)) + goto close; + + hdr->payload = htons((uint16_t) clen); + + set_tcp_cork(dfd); + + write_exact(dfd, hdr, sizeof(struct ct_proto), 0); + write_exact(dfd, cbuff, clen, 0); + + set_tcp_uncork(dfd); + + memset(buff, 0, len); + } + + return; +close: + closed_by_server = 1; +} + +extern ssize_t handler_tcp_read(int fd, char *buff, size_t len); + +static void handler_tcp_net_to_tun(int sfd, int dfd, struct curve25519_proto *p, + struct curve25519_struct *c, char *buff, + size_t len) +{ + char *cbuff; + ssize_t rlen, clen; + struct ct_proto *hdr; + + if (!buff || !len) + return; + + while ((rlen = handler_tcp_read(sfd, buff, len)) > 0) { + hdr = (struct ct_proto *) buff; + + if (unlikely(rlen < sizeof(struct ct_proto))) + goto close; + if (unlikely(rlen - sizeof(*hdr) != ntohs(hdr->payload))) + goto close; + if (unlikely(ntohs(hdr->payload) == 0)) + goto close; + if (hdr->flags & PROTO_FLAG_EXIT) + goto close; + + clen = curve25519_decode(c, p, (unsigned char *) buff + + sizeof(struct ct_proto), + rlen - sizeof(struct ct_proto), + (unsigned char **) &cbuff, NULL); + if (unlikely(clen <= 0)) + goto close; + + cbuff += crypto_box_zerobytes; + clen -= crypto_box_zerobytes; + + if (write(dfd, cbuff, clen)) { ; } + } + + return; +close: + closed_by_server = 1; +} + +static void notify_init(int fd, int udp, struct curve25519_proto *p, + struct curve25519_struct *c, char *home) +{ + int fd2, i; + ssize_t err, clen; + size_t us_len, msg_len, pad; + struct ct_proto hdr; + char username[256], path[PATH_MAX], *us, *cbuff, *msg; + unsigned char auth[crypto_auth_hmacsha512256_BYTES], *token; + + memset(&hdr, 0, sizeof(hdr)); + hdr.flags |= PROTO_FLAG_INIT; + + memset(path, 0, sizeof(path)); + slprintf(path, sizeof(path), "%s/%s", home, FILE_USERNAM); + + fd2 = open_or_die(path, O_RDONLY); + + memset(username, 0, sizeof(username)); + err = read(fd2, username, sizeof(username)); + username[sizeof(username) - 1] = 0; + + close(fd2); + + token = get_serv_store_entry_auth_token(); + if (!token) + syslog_panic("Cannot find auth token for server!\n"); + + us_len = sizeof(struct username_struct) + crypto_box_zerobytes; + us = xzmalloc(us_len); + + err = username_msg(username, strlen(username) + 1, + us + crypto_box_zerobytes, + us_len - crypto_box_zerobytes); + if (unlikely(err)) + syslog_panic("Cannot create init message!\n"); + + clen = curve25519_encode(c, p, (unsigned char *) us, us_len, + (unsigned char **) &cbuff); + if (unlikely(clen <= 0)) + syslog_panic("Init encrypt error!\n"); + + err = crypto_auth_hmacsha512256(auth, (unsigned char *) cbuff, clen, token); + if (unlikely(err)) + syslog_panic("Cannot create init hmac message!\n"); + + pad = ((uint32_t) secrand()) % 200; + msg_len = clen + sizeof(auth) + pad; + + msg = xzmalloc(msg_len); + memcpy(msg, auth, sizeof(auth)); + memcpy(msg + sizeof(auth), cbuff, clen); + + for (i = sizeof(auth) + clen; i < msg_len; ++i) + msg[i] = (uint8_t) secrand(); + + hdr.payload = htons((uint16_t) msg_len); + + set_sock_cork(fd, udp); + + write_exact(fd, &hdr, sizeof(struct ct_proto), 0); + write_exact(fd, msg, msg_len, 0); + + set_sock_uncork(fd, udp); + + xfree(msg); + xfree(us); +} + +static void notify_close(int fd) +{ + struct ct_proto hdr; + + memset(&hdr, 0, sizeof(hdr)); + + hdr.flags |= PROTO_FLAG_EXIT; + hdr.payload = 0; + + write_exact(fd, &hdr, sizeof(hdr), 0); +} + +int client_main(char *home, char *dev, char *host, char *port, int udp) +{ + int fd = -1, tunfd = 0, retry_server = 0; + int ret, try = 1, i; + struct addrinfo hints, *ahead, *ai; + struct pollfd fds[2]; + struct curve25519_proto *p; + struct curve25519_struct *c; + char *buff; + size_t blen = TUNBUFF_SIZ; //FIXME + +retry: + if (!retry_server) { + openlog("curvetun", LOG_PID | LOG_CONS | LOG_NDELAY, LOG_DAEMON); + syslog(LOG_INFO, "curvetun client booting!\n"); + } + + c = xmalloc(sizeof(struct curve25519_struct)); + + curve25519_alloc_or_maybe_die(c); + + p = get_serv_store_entry_proto_inf(); + if (!p) + syslog_panic("Cannot proto!\n"); + + memset(&hints, 0, sizeof(hints)); + hints.ai_family = PF_UNSPEC; + hints.ai_socktype = udp ? SOCK_DGRAM : SOCK_STREAM; + hints.ai_protocol = udp ? IPPROTO_UDP : IPPROTO_TCP; + hints.ai_flags = AI_NUMERICSERV; + + ret = getaddrinfo(host, port, &hints, &ahead); + if (ret < 0) { + syslog(LOG_ERR, "Cannot get address info! Retry!\n"); + curve25519_free(c); + xfree(c); + fd = -1; + retry_server = 1; + closed_by_server = 0; + sleep(1); + goto retry; + } + + for (ai = ahead; ai != NULL && fd < 0; ai = ai->ai_next) { + fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol); + if (fd < 0) + continue; + ret = connect(fd, ai->ai_addr, ai->ai_addrlen); + if (ret < 0) { + syslog(LOG_ERR, "Cannot connect to remote, try %d: %s!\n", + try++, strerror(errno)); + close(fd); + fd = -1; + continue; + } + + set_socket_keepalive(fd); + set_mtu_disc_dont(fd); + if (!udp) + set_tcp_nodelay(fd); + } + + freeaddrinfo(ahead); + + if (fd < 0) { + syslog(LOG_ERR, "Cannot create socket! Retry!\n"); + curve25519_free(c); + xfree(c); + fd = -1; + retry_server = 1; + closed_by_server = 0; + sleep(1); + goto retry; + } + + if (!retry_server) + tunfd = tun_open_or_die(dev ? dev : DEVNAME_CLIENT, + IFF_TUN | IFF_NO_PI); + + set_nonblocking_sloppy(fd); + set_nonblocking_sloppy(tunfd); + + memset(fds, 0, sizeof(fds)); + fds[0].fd = fd; + fds[1].fd = tunfd; + fds[0].events = POLLIN; + fds[1].events = POLLIN; + + buff = xmalloc_aligned(blen, 64); + + notify_init(fd, udp, p, c, home); + + syslog(LOG_INFO, "curvetun client ready!\n"); + + while (likely(!sigint && !closed_by_server)) { + poll(fds, 2, -1); + for (i = 0; i < 2; ++i) { + if ((fds[i].revents & POLLIN) != POLLIN) + continue; + if (fds[i].fd == tunfd) { + if (udp) + handler_udp_tun_to_net(tunfd, fd, p, c, + buff, blen); + else + handler_tcp_tun_to_net(tunfd, fd, p, c, + buff, blen); + } else if (fds[i].fd == fd) { + if (udp) + handler_udp_net_to_tun(fd, tunfd, p, c, + buff, blen); + else + handler_tcp_net_to_tun(fd, tunfd, p, c, + buff, blen); + } + } + } + + syslog(LOG_INFO, "curvetun client prepare shut down!\n"); + + if (!closed_by_server) + notify_close(fd); + + xfree(buff); + close(fd); + curve25519_free(c); + xfree(c); + + /* tundev still active */ + if (closed_by_server && !sigint) { + syslog(LOG_ERR, "curvetun connection retry attempt!\n"); + fd = -1; + retry_server = 1; + closed_by_server = 0; + sleep(1); + goto retry; + } + + close(tunfd); + syslog(LOG_INFO, "curvetun client shut down!\n"); + closelog(); + + return 0; +} |