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iodine/src/client.c
Erik Ekman 92b160a416 Fix mtu fragment size probing
2012-02-04 20:34:04 +01:00

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/*
* Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <ctype.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/time.h>
#include <fcntl.h>
#include <zlib.h>
#include <time.h>
#ifdef WINDOWS32
#include "windows.h"
#include <winsock2.h>
#else
#include <arpa/nameser.h>
#ifdef DARWIN
#define BIND_8_COMPAT
#include <arpa/nameser_compat.h>
#endif
#include <grp.h>
#include <pwd.h>
#include <netdb.h>
#endif
#include "common.h"
#include "encoding.h"
#include "base32.h"
#include "base64.h"
#include "dns.h"
#include "login.h"
#include "tun.h"
#include "version.h"
#include "client.h"
#define PING_TIMEOUT(t) ((t) >= (conn == CONN_DNS_NULL ? 1 : 20))
static int running;
static const char *password;
static struct sockaddr_in nameserv;
static struct sockaddr_in raw_serv;
static const char *topdomain;
static uint16_t rand_seed;
static int downstream_seqno;
static int downstream_fragment;
static int down_ack_seqno;
static int down_ack_fragment;
/* Current up/downstream IP packet */
static struct packet outpkt;
static struct packet inpkt;
/* My userid at the server */
static char userid;
/* DNS id for next packet */
static uint16_t chunkid;
/* Base32 encoder used for non-data packets and replies */
static struct encoder *b32;
/* Base64 encoder for replies */
static struct encoder *b64;
/* The encoder used for data packets
* Defaults to Base32, can be changed after handshake */
static struct encoder *dataenc;
/* The encoder to use for downstream data */
static char downenc = ' ';
/* set query type to send */
static unsigned short do_qtype = T_NULL;
/* My connection mode */
static enum connection conn;
void
client_init()
{
running = 1;
outpkt.seqno = 0;
inpkt.len = 0;
downstream_seqno = 0;
downstream_fragment = 0;
down_ack_seqno = 0;
down_ack_fragment = 0;
chunkid = ((unsigned int) rand()) & 0xFFFF;
b32 = get_base32_encoder();
b64 = get_base64_encoder();
dataenc = get_base32_encoder();
rand_seed = ((unsigned int) rand()) & 0xFFFF;
conn = CONN_DNS_NULL;
}
void
client_stop()
{
running = 0;
}
enum connection
client_get_conn()
{
return conn;
}
void
client_set_nameserver(const char *cp, int port)
{
struct in_addr addr;
if (inet_aton(cp, &addr) != 1)
errx(1, "error parsing nameserver address: '%s'", cp);
memset(&nameserv, 0, sizeof(nameserv));
nameserv.sin_family = AF_INET;
nameserv.sin_port = htons(port);
nameserv.sin_addr = addr;
}
void
client_set_topdomain(const char *cp)
{
topdomain = cp;
}
void
client_set_password(const char *cp)
{
password = cp;
}
void
set_qtype(char *qtype)
{
if (!strcasecmp(qtype, "NULL"))
do_qtype = T_NULL;
else if (!strcasecmp(qtype, "CNAME"))
do_qtype = T_CNAME;
else if (!strcasecmp(qtype, "A"))
do_qtype = T_A;
else if (!strcasecmp(qtype, "MX"))
do_qtype = T_MX;
else if (!strcasecmp(qtype, "TXT"))
do_qtype = T_TXT;
}
void
set_downenc(char *encoding)
{
if (!strcasecmp(encoding, "base32"))
downenc = 'T';
else if (!strcasecmp(encoding, "base64"))
downenc = 'S';
else if (!strcasecmp(encoding, "raw"))
downenc = 'R';
}
const char *
client_get_raw_addr()
{
return inet_ntoa(raw_serv.sin_addr);
}
static void
send_query(int fd, char *hostname)
{
char packet[4096];
struct query q;
size_t len;
chunkid += 7727;
if (chunkid == 0)
/* 0 is used as "no-query" in iodined.c */
chunkid = 7727;
q.id = chunkid;
q.type = do_qtype;
len = dns_encode(packet, sizeof(packet), &q, QR_QUERY, hostname, strlen(hostname));
if (len < 1) {
warnx("dns_encode doesn't fit");
return;
}
sendto(fd, packet, len, 0, (struct sockaddr*)&nameserv, sizeof(nameserv));
}
static void
send_raw(int fd, char *buf, int buflen, int user, int cmd)
{
char packet[4096];
int len;
len = MIN(sizeof(packet) - RAW_HDR_LEN, buflen);
memcpy(packet, raw_header, RAW_HDR_LEN);
if (len) {
memcpy(&packet[RAW_HDR_LEN], buf, len);
}
len += RAW_HDR_LEN;
packet[RAW_HDR_CMD] = cmd | (user & 0x0F);
sendto(fd, packet, len, 0, (struct sockaddr*)&raw_serv, sizeof(raw_serv));
}
static void
send_raw_data(int dns_fd)
{
send_raw(dns_fd, outpkt.data, outpkt.len, userid, RAW_HDR_CMD_DATA);
}
static void
send_packet(int fd, char cmd, const char *data, const size_t datalen)
{
char buf[4096];
buf[0] = cmd;
build_hostname(buf + 1, sizeof(buf) - 1, data, datalen, topdomain, b32);
send_query(fd, buf);
}
static int
is_sending()
{
return (outpkt.len != 0);
}
static void
send_chunk(int fd)
{
char hex[] = "0123456789abcdef";
char buf[4096];
int avail;
int code;
char *p;
p = outpkt.data;
p += outpkt.offset;
avail = outpkt.len - outpkt.offset;
outpkt.sentlen = build_hostname(buf + 4, sizeof(buf) - 4, p, avail, topdomain, dataenc);
/* Build upstream data header (see doc/proto_xxxxxxxx.txt) */
buf[0] = hex[userid & 15]; /* First byte is 4 bits userid */
code = ((outpkt.seqno & 7) << 2) | ((outpkt.fragment & 15) >> 2);
buf[1] = b32_5to8(code); /* Second byte is 3 bits seqno, 2 upper bits fragment count */
code = ((outpkt.fragment & 3) << 3) | (downstream_seqno & 7);
buf[2] = b32_5to8(code); /* Third byte is 2 bits lower fragment count, 3 bits downstream packet seqno */
code = ((downstream_fragment & 15) << 1) | (outpkt.sentlen == avail);
buf[3] = b32_5to8(code); /* Fourth byte is 4 bits downstream fragment count, 1 bit last frag flag */
down_ack_seqno = downstream_seqno;
down_ack_fragment = downstream_fragment;
outpkt.fragment++;
send_query(fd, buf);
}
static void
send_ping(int fd)
{
if (conn == CONN_DNS_NULL) {
char data[4];
if (is_sending()) {
outpkt.sentlen = 0;
outpkt.offset = 0;
outpkt.len = 0;
}
data[0] = userid;
data[1] = ((downstream_seqno & 7) << 4) | (downstream_fragment & 15);
data[2] = (rand_seed >> 8) & 0xff;
data[3] = (rand_seed >> 0) & 0xff;
down_ack_seqno = downstream_seqno;
down_ack_fragment = downstream_fragment;
rand_seed++;
send_packet(fd, 'p', data, sizeof(data));
} else {
send_raw(fd, NULL, 0, userid, RAW_HDR_CMD_PING);
}
}
static int
read_dns(int dns_fd, int tun_fd, char *buf, int buflen) /* FIXME: tun_fd needed for raw handling */
{
struct sockaddr_in from;
char data[64*1024];
socklen_t addrlen;
struct query q;
int r;
addrlen = sizeof(struct sockaddr);
if ((r = recvfrom(dns_fd, data, sizeof(data), 0,
(struct sockaddr*)&from, &addrlen)) == -1) {
warn("recvfrom");
return 0;
}
if (conn == CONN_DNS_NULL) {
int rv;
rv = dns_decode(buf, buflen, &q, QR_ANSWER, data, r);
if ((q.type == T_CNAME || q.type == T_MX || q.type == T_TXT)
&& rv >= 1)
/* CNAME an also be returned from an A (or MX) question */
{
size_t space;
/*
* buf is a hostname or txt stream that we still need to
* decode to binary
*
* also update rv with the number of valid bytes
*
* data is unused here, and will certainly hold the smaller binary
*/
switch (buf[0]) {
case 'h': /* Hostname with base32 */
case 'H':
if (rv < 5) {
/* 1 byte H, 3 bytes ".xy", >=1 byte data */
rv = 0;
break;
}
rv -= 3; /* rv=strlen, strip ".xy" */
rv = unpack_data (data, sizeof(data), buf + 1, rv - 1, b32);
/* this also does undotify */
rv = MIN(rv, buflen);
memcpy(buf, data, rv);
break;
case 'i': /* Hostname++ with base64 */
case 'I':
if (rv < 5) {
/* 1 byte H, 3 bytes ".xy", >=1 byte data */
rv = 0;
break;
}
rv -= 3; /* rv=strlen, strip ".xy" */
rv = unpack_data (data, sizeof(data), buf + 1, rv - 1, b64);
/* this also does undotify */
rv = MIN(rv, buflen);
memcpy(buf, data, rv);
break;
case 't': /* plain base32(Thirty-two) from TXT */
case 'T':
if (rv < 2) {
rv = 0;
break;
}
space = sizeof(data);
rv = b32->decode (data, &space, buf + 1, rv - 1);
rv = MIN(rv, buflen);
memcpy(buf, data, rv);
break;
case 's': /* plain base64(Sixty-four) from TXT */
case 'S':
if (rv < 2) {
rv = 0;
break;
}
space = sizeof(data);
rv = b64->decode (data, &space, buf + 1, rv - 1);
rv = MIN(rv, buflen);
memcpy(buf, data, rv);
break;
case 'r': /* Raw binary from TXT */
case 'R':
rv--; /* rv>=1 already checked */
memmove(buf, buf+1, rv);
break;
default:
warnx("Received unsupported encoding");
rv = 0;
break;
}
}
/* decode the data header, update seqno and frag before next request */
if (rv >= 2) {
downstream_seqno = (buf[1] >> 5) & 7;
downstream_fragment = (buf[1] >> 1) & 15;
}
if (is_sending()) {
if (chunkid == q.id) {
/* Got ACK on sent packet */
outpkt.offset += outpkt.sentlen;
if (outpkt.offset == outpkt.len) {
/* Packet completed */
outpkt.offset = 0;
outpkt.len = 0;
outpkt.sentlen = 0;
/* If the ack contains unacked frag number but no data,
* send a ping to ack the frag number and get more data*/
if (rv == 2 && (
downstream_seqno != down_ack_seqno ||
downstream_fragment != down_ack_fragment
)) {
send_ping(dns_fd);
}
} else {
/* More to send */
send_chunk(dns_fd);
}
}
}
return rv;
} else { /* CONN_RAW_UDP */
unsigned long datalen;
char buf[64*1024];
/* minimum length */
if (r < RAW_HDR_LEN) return 0;
/* should start with header */
if (memcmp(data, raw_header, RAW_HDR_IDENT_LEN)) return 0;
/* should be data packet */
if (RAW_HDR_GET_CMD(data) != RAW_HDR_CMD_DATA) return 0;
/* should be my user id */
if (RAW_HDR_GET_USR(data) != userid) return 0;
r -= RAW_HDR_LEN;
datalen = sizeof(buf);
if (uncompress((uint8_t*)buf, &datalen, (uint8_t*) &data[RAW_HDR_LEN], r) == Z_OK) {
write_tun(tun_fd, buf, datalen);
}
return 0;
}
}
static int
tunnel_tun(int tun_fd, int dns_fd)
{
unsigned long outlen;
unsigned long inlen;
char out[64*1024];
char in[64*1024];
ssize_t read;
if ((read = read_tun(tun_fd, in, sizeof(in))) <= 0)
return -1;
outlen = sizeof(out);
inlen = read;
compress2((uint8_t*)out, &outlen, (uint8_t*)in, inlen, 9);
memcpy(outpkt.data, out, MIN(outlen, sizeof(outpkt.data)));
outpkt.sentlen = 0;
outpkt.offset = 0;
outpkt.len = outlen;
outpkt.seqno++;
outpkt.fragment = 0;
if (conn == CONN_DNS_NULL) {
send_chunk(dns_fd);
} else {
send_raw_data(dns_fd);
}
return read;
}
static int
tunnel_dns(int tun_fd, int dns_fd)
{
unsigned long datalen;
char buf[64*1024];
size_t read;
if ((read = read_dns(dns_fd, tun_fd, buf, sizeof(buf))) <= 2)
return -1;
if (downstream_seqno != inpkt.seqno) {
/* New packet */
inpkt.seqno = downstream_seqno;
inpkt.fragment = downstream_fragment;
inpkt.len = 0;
} else if (downstream_fragment <= inpkt.fragment) {
/* Duplicate fragment */
return -1;
}
inpkt.fragment = downstream_fragment;
datalen = MIN(read - 2, sizeof(inpkt.data) - inpkt.len);
/* Skip 2 byte data header and append to packet */
memcpy(&inpkt.data[inpkt.len], &buf[2], datalen);
inpkt.len += datalen;
if (buf[1] & 1) { /* If last fragment flag is set */
/* Uncompress packet and send to tun */
datalen = sizeof(buf);
if (uncompress((uint8_t*)buf, &datalen, (uint8_t*) inpkt.data, inpkt.len) == Z_OK) {
write_tun(tun_fd, buf, datalen);
}
inpkt.len = 0;
}
/* If we have nothing to send, send a ping to get more data */
if (!is_sending())
send_ping(dns_fd);
return read;
}
int
client_tunnel(int tun_fd, int dns_fd)
{
struct timeval tv;
fd_set fds;
int rv;
int i;
int seconds;
rv = 0;
seconds = 0;
while (running) {
tv.tv_sec = 1;
tv.tv_usec = 0;
FD_ZERO(&fds);
if ((!is_sending()) || conn == CONN_RAW_UDP) {
FD_SET(tun_fd, &fds);
}
FD_SET(dns_fd, &fds);
i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv);
if (running == 0)
break;
if (i < 0)
err(1, "select");
if (i == 0) { /* timeout */
seconds++;
} else {
if (FD_ISSET(tun_fd, &fds)) {
seconds = 0;
if (tunnel_tun(tun_fd, dns_fd) <= 0)
continue;
}
if (FD_ISSET(dns_fd, &fds)) {
if (tunnel_dns(tun_fd, dns_fd) <= 0)
continue;
}
}
if (PING_TIMEOUT(seconds)) {
send_ping(dns_fd);
seconds = 0;
}
}
return rv;
}
static void
send_login(int fd, char *login, int len)
{
char data[19];
memset(data, 0, sizeof(data));
data[0] = userid;
memcpy(&data[1], login, MIN(len, 16));
data[17] = (rand_seed >> 8) & 0xff;
data[18] = (rand_seed >> 0) & 0xff;
rand_seed++;
send_packet(fd, 'l', data, sizeof(data));
}
static void
send_fragsize_probe(int fd, int fragsize)
{
char probedata[256];
char buf[4096];
/*
* build a large query domain which is random and maximum size,
* will also take up maximal space in the return packet
*/
memset(probedata, MAX(1, rand_seed & 0xff), sizeof(probedata));
probedata[1] = MAX(1, (rand_seed >> 8) & 0xff);
rand_seed++;
build_hostname(buf + 4, sizeof(buf) - 4, probedata, sizeof(probedata), topdomain, dataenc);
fragsize &= 2047;
buf[0] = 'r'; /* Probe downstream fragsize packet */
buf[1] = b32_5to8((userid << 1) | ((fragsize >> 10) & 1));
buf[2] = b32_5to8((fragsize >> 5) & 31);
buf[3] = b32_5to8(fragsize & 31);
send_query(fd, buf);
}
static void
send_set_downstream_fragsize(int fd, int fragsize)
{
char data[5];
data[0] = userid;
data[1] = (fragsize & 0xff00) >> 8;
data[2] = (fragsize & 0x00ff);
data[3] = (rand_seed >> 8) & 0xff;
data[4] = (rand_seed >> 0) & 0xff;
rand_seed++;
send_packet(fd, 'n', data, sizeof(data));
}
static void
send_version(int fd, uint32_t version)
{
char data[6];
data[0] = (version >> 24) & 0xff;
data[1] = (version >> 16) & 0xff;
data[2] = (version >> 8) & 0xff;
data[3] = (version >> 0) & 0xff;
data[4] = (rand_seed >> 8) & 0xff;
data[5] = (rand_seed >> 0) & 0xff;
rand_seed++;
send_packet(fd, 'V', data, sizeof(data));
}
static void
send_ip_request(int fd, int userid)
{
char buf[512] = "I____.";
buf[1] = b32_5to8(userid);
buf[2] = b32_5to8((rand_seed >> 10) & 0x1f);
buf[3] = b32_5to8((rand_seed >> 5) & 0x1f);
buf[4] = b32_5to8((rand_seed ) & 0x1f);
rand_seed++;
strncat(buf, topdomain, 512 - strlen(buf));
send_query(fd, buf);
}
static void
send_raw_udp_login(int dns_fd, int userid, int seed)
{
char buf[16];
login_calculate(buf, 16, password, seed + 1);
send_raw(dns_fd, buf, sizeof(buf), userid, RAW_HDR_CMD_LOGIN);
}
static void
send_case_check(int fd)
{
/* The '+' plus character is not allowed according to RFC.
* Expect to get SERVFAIL or similar if it is rejected.
*/
char buf[512] = "zZ+-aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyY1234.";
strncat(buf, topdomain, 512 - strlen(buf));
send_query(fd, buf);
}
static void
send_codec_switch(int fd, int userid, int bits)
{
char buf[512] = "s_____.";
buf[1] = b32_5to8(userid);
buf[2] = b32_5to8(bits);
buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
buf[5] = b32_5to8((rand_seed ) & 0x1f);
rand_seed++;
strncat(buf, topdomain, 512 - strlen(buf));
send_query(fd, buf);
}
static void
send_downenc_switch(int fd, int userid)
{
char buf[512] = "o_____.";
buf[1] = b32_5to8(userid);
buf[2] = tolower(downenc);
buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
buf[5] = b32_5to8((rand_seed ) & 0x1f);
rand_seed++;
strncat(buf, topdomain, 512 - strlen(buf));
send_query(fd, buf);
}
static int
handshake_version(int dns_fd, int *seed)
{
struct timeval tv;
char in[4096];
fd_set fds;
uint32_t payload;
int i;
int r;
int read;
for (i = 0; running && i < 5; i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_version(dns_fd, VERSION);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if(read <= 0) {
if (read == 0) {
warn("handshake read");
}
/* if read < 0 then warning has been printed already */
continue;
}
if (read >= 9) {
payload = (((in[4] & 0xff) << 24) |
((in[5] & 0xff) << 16) |
((in[6] & 0xff) << 8) |
((in[7] & 0xff)));
if (strncmp("VACK", in, 4) == 0) {
*seed = payload;
userid = in[8];
fprintf(stderr, "Version ok, both using protocol v 0x%08x. You are user #%d\n", VERSION, userid);
return 0;
} else if (strncmp("VNAK", in, 4) == 0) {
warnx("You use protocol v 0x%08x, server uses v 0x%08x. Giving up",
VERSION, payload);
return 1;
} else if (strncmp("VFUL", in, 4) == 0) {
warnx("Server full, all %d slots are taken. Try again later", payload);
return 1;
}
} else
warnx("did not receive proper login challenge");
}
fprintf(stderr, "Retrying version check...\n");
}
warnx("couldn't connect to server (maybe other -T options will work)");
return 1;
}
static int
handshake_login(int dns_fd, int seed)
{
struct timeval tv;
char in[4096];
char login[16];
char server[65];
char client[65];
int mtu;
fd_set fds;
int i;
int r;
int read;
login_calculate(login, 16, password, seed);
for (i=0; running && i<5 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_login(dns_fd, login, 16);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if(read <= 0) {
warn("read");
continue;
}
if (read > 0) {
int netmask;
if (strncmp("LNAK", in, 4) == 0) {
fprintf(stderr, "Bad password\n");
return 1;
} else if (sscanf(in, "%64[^-]-%64[^-]-%d-%d",
server, client, &mtu, &netmask) == 4) {
server[64] = 0;
client[64] = 0;
if (tun_setip(client, netmask) == 0 &&
tun_setmtu(mtu) == 0) {
fprintf(stderr, "Server tunnel IP is %s\n", server);
return 0;
} else {
errx(4, "Failed to set IP and MTU");
}
} else {
fprintf(stderr, "Received bad handshake\n");
}
}
}
fprintf(stderr, "Retrying login...\n");
}
warnx("couldn't login to server");
return 1;
}
static int
handshake_raw_udp(int dns_fd, int seed)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int len;
unsigned remoteaddr = 0;
struct in_addr server;
fprintf(stderr, "Testing raw UDP data to the server (skip with -r)\n");
for (i=0; running && i<3 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_ip_request(dns_fd, userid);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
len = read_dns(dns_fd, 0, in, sizeof(in));
if (len == 5 && in[0] == 'I') {
/* Received IP address */
remoteaddr = (in[1] & 0xff);
remoteaddr <<= 8;
remoteaddr |= (in[2] & 0xff);
remoteaddr <<= 8;
remoteaddr |= (in[3] & 0xff);
remoteaddr <<= 8;
remoteaddr |= (in[4] & 0xff);
server.s_addr = ntohl(remoteaddr);
break;
}
} else {
fprintf(stderr, ".");
fflush(stderr);
}
}
if (!remoteaddr) {
fprintf(stderr, "Failed to get raw server IP, will use DNS mode.\n");
return 0;
}
fprintf(stderr, "Server is at %s, trying raw login: ", inet_ntoa(server));
fflush(stderr);
/* Store address to iodined server */
memset(&raw_serv, 0, sizeof(raw_serv));
raw_serv.sin_family = AF_INET;
raw_serv.sin_port = htons(53);
raw_serv.sin_addr = server;
/* do login against port 53 on remote server
* based on the old seed. If reply received,
* switch to raw udp mode */
for (i=0; running && i<4 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_raw_udp_login(dns_fd, userid, seed);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
/* recv() needed for windows, dont change to read() */
len = recv(dns_fd, in, sizeof(in), 0);
if (len >= (16 + RAW_HDR_LEN)) {
char hash[16];
login_calculate(hash, 16, password, seed - 1);
if (memcmp(in, raw_header, RAW_HDR_IDENT_LEN) == 0
&& RAW_HDR_GET_CMD(in) == RAW_HDR_CMD_LOGIN
&& memcmp(&in[RAW_HDR_LEN], hash, sizeof(hash)) == 0) {
fprintf(stderr, "OK\n");
return 1;
}
}
}
fprintf(stderr, ".");
fflush(stderr);
}
fprintf(stderr, "failed\n");
return 0;
}
static int
handshake_case_check(int dns_fd)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int read;
int case_preserved;
case_preserved = 0;
for (i=0; running && i<5 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_case_check(dns_fd);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if (read > 0) {
if (in[0] == 'z' || in[0] == 'Z') {
if (read < (27 * 2)) {
fprintf(stderr, "Received short case check reply. Will use base32 encoder\n");
return case_preserved;
} else {
int k;
/* TODO enhance this, base128 is probably also possible */
case_preserved = 1;
for (k = 0; k < 27 && case_preserved; k += 2) {
if (in[k] == in[k+1]) {
/* test string: zZ+-aAbBcCdDeE... */
case_preserved = 0;
}
}
return case_preserved;
}
} else {
fprintf(stderr, "Received bad case check reply\n");
}
} else {
fprintf(stderr, "Got error on case check, will use base32\n");
return case_preserved;
}
}
fprintf(stderr, "Retrying case check...\n");
}
fprintf(stderr, "No reply on case check, continuing\n");
return case_preserved;
}
static void
handshake_switch_codec(int dns_fd)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int read;
dataenc = get_base64_encoder();
fprintf(stderr, "Switching upstream to %s codec\n", dataenc->name);
/* Send to server that this user will use base64 from now on */
for (i=0; running && i<5 ;i++) {
int bits;
tv.tv_sec = i + 1;
tv.tv_usec = 0;
bits = 6; /* base64 = 6 bits per byte */
send_codec_switch(dns_fd, userid, bits);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if (read > 0) {
if (strncmp("BADLEN", in, 6) == 0) {
fprintf(stderr, "Server got bad message length. ");
goto codec_revert;
} else if (strncmp("BADIP", in, 5) == 0) {
fprintf(stderr, "Server rejected sender IP address. ");
goto codec_revert;
} else if (strncmp("BADCODEC", in, 8) == 0) {
fprintf(stderr, "Server rejected the selected codec. ");
goto codec_revert;
}
in[read] = 0; /* zero terminate */
fprintf(stderr, "Server switched upstream to codec %s\n", in);
return;
}
}
fprintf(stderr, "Retrying codec switch...\n");
}
fprintf(stderr, "No reply from server on codec switch. ");
codec_revert:
fprintf(stderr, "Falling back to base32\n");
dataenc = get_base32_encoder();
}
static void
handshake_switch_downenc(int dns_fd)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int read;
char *dname;
dname = "Base32";
if (downenc == 'S')
dname = "Base64";
else if (downenc == 'R')
dname = "Raw";
fprintf(stderr, "Switching downstream to codec %s\n", dname);
for (i=0; running && i<5 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_downenc_switch(dns_fd, userid);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if (read > 0) {
if (strncmp("BADLEN", in, 6) == 0) {
fprintf(stderr, "Server got bad message length. ");
goto codec_revert;
} else if (strncmp("BADIP", in, 5) == 0) {
fprintf(stderr, "Server rejected sender IP address. ");
goto codec_revert;
} else if (strncmp("BADCODEC", in, 8) == 0) {
fprintf(stderr, "Server rejected the selected codec. ");
goto codec_revert;
}
in[read] = 0; /* zero terminate */
fprintf(stderr, "Server switched downstream to codec %s\n", in);
return;
}
}
fprintf(stderr, "Retrying codec switch...\n");
}
fprintf(stderr, "No reply from server on codec switch. ");
codec_revert:
fprintf(stderr, "Falling back to base32\n");
}
static int
fragsize_check(char *in, int read, int proposed_fragsize, int *max_fragsize)
/* Returns: 0: keep checking, 1: break loop (either okay or definitely wrong) */
{
int acked_fragsize = ((in[0] & 0xff) << 8) | (in[1] & 0xff);
static int nocheck_warned = 0;
if (read >= 5 && strncmp("BADIP", in, 5) == 0) {
fprintf(stderr, "got BADIP (Try iodined -c)..\n");
fflush(stderr);
return 0; /* maybe temporary error */
}
if (acked_fragsize != proposed_fragsize) {
/*
* got ack for wrong fragsize, maybe late response for
* earlier query, or ack corrupted
*/
return 0;
}
if (read != proposed_fragsize) {
/*
* correctly acked fragsize but read too little (or too
* much): this fragsize is definitely not reliable
*/
return 1;
}
/* here: read == proposed_fragsize == acked_fragsize */
/* test: */
/* in[123] = 123; */
/* Check for corruption */
if ((in[2] & 0xff) == 107) {
int okay = 1;
int i;
unsigned int v = in[3] & 0xff;
for (i = 3; i < read; i++, v += 107)
if ((in[i] & 0xff) != (v & 0xff)) {
okay = 0;
break;
}
if (okay) {
fprintf(stderr, "%d ok.. ", acked_fragsize);
fflush(stderr);
*max_fragsize = acked_fragsize;
return 1;
} else {
if (downenc != ' ' && downenc != 'T') {
fprintf(stderr, "%d corrupted at %d.. (Try -O Base32)\n", acked_fragsize, i);
} else {
fprintf(stderr, "%d corrupted at %d.. ", acked_fragsize, i);
fflush(stderr);
}
return 1;
}
} /* always returns */
/* here when uncheckable, so assume correct */
if (read >= 3 && nocheck_warned == 0) {
fprintf(stderr, "(Old server version, cannot check for corruption)\n");
fflush(stderr);
nocheck_warned = 1;
}
fprintf(stderr, "%d ok.. ", acked_fragsize);
fflush(stderr);
*max_fragsize = acked_fragsize;
return 1;
}
static int
handshake_autoprobe_fragsize(int dns_fd)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int read;
int proposed_fragsize = 768;
int range = 768;
int max_fragsize;
max_fragsize = 0;
fprintf(stderr, "Autoprobing max downstream fragment size... (skip with -m fragsize)\n");
while (running && range > 0 && (range >= 8 || max_fragsize < 300)) {
/* stop the slow probing early when we have enough bytes anyway */
for (i=0; running && i<3 ;i++) {
tv.tv_sec = 1;
tv.tv_usec = 0;
send_fragsize_probe(dns_fd, proposed_fragsize);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if (read > 0) {
/* We got a reply */
if (fragsize_check(in, read, proposed_fragsize, &max_fragsize) == 1)
break;
}
}
fprintf(stderr, ".");
fflush(stderr);
}
range >>= 1;
if (max_fragsize == proposed_fragsize) {
/* Try bigger */
proposed_fragsize += range;
} else {
/* Try smaller */
fprintf(stderr, "%d not ok.. ", proposed_fragsize);
fflush(stderr);
proposed_fragsize -= range;
}
}
if (!running) {
fprintf(stderr, "\n");
warnx("stopped while autodetecting fragment size (Try setting manually with -m)");
return 0;
}
if (max_fragsize <= 2) {
/* Tried all the way down to 2 and found no good size */
fprintf(stderr, "\n");
warnx("found no accepted fragment size. (Try forcing with -m, or try other -T or -O options)");
return 0;
}
/* data header adds 2 bytes */
fprintf(stderr, "will use %d-2=%d\n", max_fragsize, max_fragsize - 2);
if (do_qtype != T_NULL && downenc == ' ')
fprintf(stderr, "(Maybe other -O options will increase throughput)\n");
return max_fragsize - 2;
}
static void
handshake_set_fragsize(int dns_fd, int fragsize)
{
struct timeval tv;
char in[4096];
fd_set fds;
int i;
int r;
int read;
fprintf(stderr, "Setting downstream fragment size to max %d...\n", fragsize);
for (i=0; running && i<5 ;i++) {
tv.tv_sec = i + 1;
tv.tv_usec = 0;
send_set_downstream_fragsize(dns_fd, fragsize);
FD_ZERO(&fds);
FD_SET(dns_fd, &fds);
r = select(dns_fd + 1, &fds, NULL, NULL, &tv);
if(r > 0) {
read = read_dns(dns_fd, 0, in, sizeof(in));
if (read > 0) {
int accepted_fragsize;
if (strncmp("BADFRAG", in, 7) == 0) {
fprintf(stderr, "Server rejected fragsize. Keeping default.");
return;
} else if (strncmp("BADIP", in, 5) == 0) {
fprintf(stderr, "Server rejected sender IP address.\n");
return;
}
accepted_fragsize = ((in[0] & 0xff) << 8) | (in[1] & 0xff);
return;
}
}
fprintf(stderr, "Retrying set fragsize...\n");
}
fprintf(stderr, "No reply from server when setting fragsize. Keeping default.\n");
}
int
client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsize)
{
int seed;
int case_preserved;
int r;
r = handshake_version(dns_fd, &seed);
if (r) {
return r;
}
r = handshake_login(dns_fd, seed);
if (r) {
return r;
}
if (raw_mode && handshake_raw_udp(dns_fd, seed)) {
conn = CONN_RAW_UDP;
} else {
if (raw_mode == 0) {
fprintf(stderr, "Skipping raw mode\n");
}
case_preserved = handshake_case_check(dns_fd);
if (case_preserved) {
handshake_switch_codec(dns_fd);
}
if (downenc != ' ') {
handshake_switch_downenc(dns_fd);
}
if (autodetect_frag_size) {
fragsize = handshake_autoprobe_fragsize(dns_fd);
if (!fragsize) {
return 1;
}
}
handshake_set_fragsize(dns_fd, fragsize);
}
return 0;
}
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