From 282a508f2b8c8d427572d615a07b74442f921dd0 Mon Sep 17 00:00:00 2001 From: Erik Ekman Date: Sun, 20 Sep 2009 21:10:44 +0000 Subject: [PATCH] #76 merge client code --- src/client.c | 670 +++++++++++++++++++++++++++++++++++++++------------ src/client.h | 2 + src/iodine.c | 32 ++- 3 files changed, 551 insertions(+), 153 deletions(-) diff --git a/src/client.c b/src/client.c index 42f44d4..ae4187a 100644 --- a/src/client.c +++ b/src/client.c @@ -51,7 +51,7 @@ #include "version.h" #include "client.h" -#define PING_TIMEOUT(t) ((t) >= (conn == CONN_DNS_NULL ? 1 : 20)) +static void handshake_lazyoff(int dns_fd); static int running; static const char *password; @@ -61,20 +61,21 @@ 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; +int outchunkresent = 0; /* My userid at the server */ static char userid; +static char userid_char; /* used when sending (uppercase) */ +static char userid_char2; /* also accepted when receiving (lowercase) */ /* DNS id for next packet */ static uint16_t chunkid; +static uint16_t chunkid_prev; +static uint16_t chunkid_prev2; /* Base32 encoder used for non-data packets and replies */ static struct encoder *b32; @@ -94,22 +95,36 @@ static unsigned short do_qtype = T_NULL; /* My connection mode */ static enum connection conn; +int selecttimeout; /* RFC says timeout minimum 5sec */ + +int lazymode; + +long send_ping_soon; + +time_t lastdownstreamtime; + 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; + send_ping_soon = 1; /* send ping immediately after startup */ conn = CONN_DNS_NULL; + + chunkid = ((unsigned int) rand()) & 0xFFFF; + chunkid_prev = 0; + chunkid_prev2 = 0; + + outpkt.len = 0; + outpkt.seqno = 0; + outpkt.fragment = 0; + outchunkresent = 0; + inpkt.len = 0; + inpkt.seqno = 0; + inpkt.fragment = 0; } void @@ -176,6 +191,17 @@ set_downenc(char *encoding) downenc = 'R'; } +void +client_set_selecttimeout(int select_timeout) +{ + selecttimeout = select_timeout; +} + +void +client_set_lazymode(int lazy_mode) { + lazymode = lazymode; +} + const char * client_get_raw_addr() { @@ -189,6 +215,8 @@ send_query(int fd, char *hostname) struct query q; size_t len; + chunkid_prev2 = chunkid_prev; + chunkid_prev = chunkid; chunkid += 7727; if (chunkid == 0) /* 0 is used as "no-query" in iodined.c */ @@ -229,6 +257,7 @@ static void send_raw_data(int dns_fd) { send_raw(dns_fd, outpkt.data, outpkt.len, userid, RAW_HDR_CMD_DATA); + outpkt.len = 0; } @@ -243,7 +272,7 @@ send_packet(int fd, char cmd, const char *data, const size_t datalen) send_query(fd, buf); } -static int +static inline int is_sending() { return (outpkt.len != 0); @@ -252,7 +281,6 @@ is_sending() static void send_chunk(int fd) { - char hex[] = "0123456789abcdef"; char buf[4096]; int avail; int code; @@ -266,21 +294,23 @@ send_chunk(int fd) /* Build upstream data header (see doc/proto_xxxxxxxx.txt) */ - buf[0] = hex[userid & 15]; /* First byte is 4 bits userid */ - + buf[0] = userid_char; /* First byte is hex 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); + code = ((outpkt.fragment & 3) << 3) | (inpkt.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); + code = ((inpkt.fragment & 15) << 1) | (outpkt.sentlen == avail); buf[3] = b32_5to8(code); /* Fourth byte is 4 bits downstream fragment count, 1 bit last frag flag */ + +#if 0 + fprintf(stderr, " Send: down %d/%d up %d/%d, %d bytes\n", + inpkt.seqno, inpkt.fragment, outpkt.seqno, outpkt.fragment, + outpkt.sentlen); +#endif - down_ack_seqno = downstream_seqno; - down_ack_fragment = downstream_fragment; - - outpkt.fragment++; send_query(fd, buf); } @@ -290,22 +320,18 @@ 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[1] = ((inpkt.seqno & 7) << 4) | (inpkt.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++; +#if 0 + fprintf(stderr, " Send: down %d/%d (ping)\n", + inpkt.seqno, inpkt.fragment); +#endif + send_packet(fd, 'p', data, sizeof(data)); } else { send_raw(fd, NULL, 0, userid, RAW_HDR_CMD_PING); @@ -313,28 +339,31 @@ send_ping(int fd) } static int -read_dns(int dns_fd, int tun_fd, char *buf, int buflen) /* FIXME: tun_fd needed for raw handling */ +read_dns_withq(int dns_fd, int tun_fd, char *buf, int buflen, struct query *q) /* 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) { + (struct sockaddr*)&from, &addrlen)) < 0) { warn("recvfrom"); - return 0; + return -1; } if (conn == CONN_DNS_NULL) { int rv; + if (r <= 0) + /* useless packet */ + return 0; - rv = dns_decode(buf, buflen, &q, QR_ANSWER, data, r); + rv = dns_decode(buf, buflen, q, QR_ANSWER, data, r); + if (rv <= 0) + return rv; - if ((q.type == T_CNAME || q.type == T_MX || q.type == T_TXT) - && rv >= 1) + if (q->type == T_CNAME || q->type == T_MX || q->type == T_TXT) /* CNAME an also be returned from an A (or MX) question */ { size_t space; @@ -415,38 +444,6 @@ read_dns(int dns_fd, int tun_fd, char *buf, int buflen) /* FIXME: tun_fd needed } } - /* 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; @@ -470,6 +467,22 @@ read_dns(int dns_fd, int tun_fd, char *buf, int buflen) /* FIXME: tun_fd needed } } +static inline int +read_dns_namecheck(int dns_fd, int tun_fd, char *buf, int buflen, char c1, char c2) +/* Only returns >0 when the query hostname in the received packet matches + either c1 or c2; used to tell handshake-dupes apart. +*/ +{ + struct query q; + int rv; + + rv = read_dns_withq(dns_fd, tun_fd, buf, buflen, &q); + + if (rv > 0 && q.name[0] != c1 && q.name[0] != c2) + return 0; + + return rv; /* may also be 0 = useless or -1 = error (printed) */ +} static int tunnel_tun(int tun_fd, int dns_fd) @@ -483,6 +496,11 @@ tunnel_tun(int tun_fd, int dns_fd) if ((read = read_tun(tun_fd, in, sizeof(in))) <= 0) return -1; + /* We may be here only to empty the tun device; then return -1 + to force continue in select loop. */ + if (is_sending()) + return -1; + outlen = sizeof(out); inlen = read; compress2((uint8_t*)out, &outlen, (uint8_t*)in, inlen, 9); @@ -490,12 +508,15 @@ tunnel_tun(int tun_fd, int dns_fd) memcpy(outpkt.data, out, MIN(outlen, sizeof(outpkt.data))); outpkt.sentlen = 0; outpkt.offset = 0; + outpkt.seqno = (outpkt.seqno + 1) & 7; outpkt.len = outlen; - outpkt.seqno++; outpkt.fragment = 0; + outchunkresent = 0; if (conn == CONN_DNS_NULL) { send_chunk(dns_fd); + + send_ping_soon = 0; } else { send_raw_data(dns_fd); } @@ -506,43 +527,251 @@ tunnel_tun(int tun_fd, int dns_fd) static int tunnel_dns(int tun_fd, int dns_fd) { + static long packrecv = 0; + static long packrecv_oos = 0; + int up_ack_seqno; + int up_ack_fragment; + int new_down_seqno; + int new_down_fragment; + struct query q; unsigned long datalen; char buf[64*1024]; - size_t read; + int read; + int send_something_now = 0; - 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; + if ((read = read_dns_withq(dns_fd, tun_fd, buf, sizeof(buf), &q)) < 2) { + /* Maybe SERVFAIL etc. Send ping to get things back in order, + but wait a bit to prevent fast ping-pong loops. */ + send_ping_soon = 900; + return -1; /* nothing done */ } - inpkt.fragment = downstream_fragment; - datalen = MIN(read - 2, sizeof(inpkt.data) - inpkt.len); + /* Don't process anything that isn't data; already checked read>=2 */ + if (q.name[0] != 'P' && q.name[0] != 'p' && + q.name[0] != userid_char && q.name[0] != userid_char2) + return -1; /* nothing done */ - /* Skip 2 byte data header and append to packet */ - memcpy(&inpkt.data[inpkt.len], &buf[2], datalen); - inpkt.len += datalen; + if (read == 5 && !strncmp("BADIP", buf, 5)) { + warnx("BADIP: Server rejected sender IP address (maybe iodined -c will help), or server kicked us due to timeout. Will exit if no downstream data is received in 60 seconds."); + return -1; /* nothing done */ + } - 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); + + if (send_ping_soon) { + send_something_now = 1; + send_ping_soon = 0; + } + + + /* Decode the data header, update seqno and frag; + already checked read>=2 + Note that buf[] gets overwritten when down-pkt complete */ + new_down_seqno = (buf[1] >> 5) & 7; + new_down_fragment = (buf[1] >> 1) & 15; + up_ack_seqno = (buf[0] >> 4) & 7; + up_ack_fragment = buf[0] & 15; + +#if 0 + fprintf(stderr, " Recv: down %d/%d up %d/%d, %d bytes\n", + new_down_seqno, new_down_fragment, up_ack_seqno, + up_ack_fragment, read); +#endif + + /* Downstream data traffic */ + + if (read > 2 && new_down_seqno != inpkt.seqno && + recent_seqno(inpkt.seqno, new_down_seqno)) { + /* This is the previous seqno, or a bit earlier. + Probably out-of-sequence dupe due to unreliable + intermediary DNS. Don't get distracted, but send + ping quickly to get things back in order. + Ping will send our current seqno idea. + If it's really a new packet that skipped multiple seqnos + (why??), server will re-send and drop a few times and + eventually everything will work again. */ + read = 2; + send_ping_soon = 500; + /* Still process upstream ack, if any */ + } + + packrecv++; + + /* Don't process any non-recent stuff any further */ + if (q.id != chunkid && q.id != chunkid_prev && q.id != chunkid_prev2) { + packrecv_oos++; +#if 0 + fprintf(stderr, " q=%c Packs received = %8ld Out-of-sequence = %8ld\n", q.name[0], packrecv, packrecv_oos); +#endif + if (lazymode && packrecv < 600 && packrecv_oos == 5) + warnx("Hmm, getting some out-of-sequence DNS replies. You may want to try -I1 or -L0 if you notice hiccups in the data traffic."); + if (lazymode && packrecv < 600 && packrecv_oos == 15) { + warnx("Your DNS server connection causes severe re-ordering of DNS traffic. Lazy mode doesn't work well here, switching off. Next time on this network, start with -L0."); + lazymode = 0; + selecttimeout = 1; + handshake_lazyoff(dns_fd); } - inpkt.len = 0; + + if (send_something_now) { + send_ping(dns_fd); + send_ping_soon = 0; + } + return -1; /* nothing done */ + } +#if 0 + fprintf(stderr, " q=%c Packs received = %8ld Out-of-sequence = %8ld\n", q.name[0], packrecv, packrecv_oos); +#endif + + /* Okay, we have a recent downstream packet */ + lastdownstreamtime = time(NULL); + + /* In lazy mode, we shouldn't get much replies to our most-recent + query, only during heavy data transfer. Except when severe packet + reordering occurs, such as opendns... Since this means the server + doesn't have any packets left, send one relatively fast (but not + too fast, to avoid runaway ping-pong loops..) */ + if (q.id == chunkid && lazymode) { + if (!send_ping_soon || send_ping_soon > 900) + send_ping_soon = 900; } - /* If we have nothing to send, send a ping to get more data */ - if (!is_sending()) + if (read == 2 && new_down_seqno != inpkt.seqno && + !recent_seqno(inpkt.seqno, new_down_seqno)) { + /* This is a seqno that we didn't see yet, but it has + no data any more. Possible since iodined will send + fitting packs just once and not wait for ack. + Real data got lost, or will arrive shortly. + Update our idea of the seqno, and drop any waiting + old pack. Send ping to get things back on track. */ + inpkt.seqno = new_down_seqno; + inpkt.fragment = new_down_fragment; + inpkt.len = 0; + send_ping_soon = 500; + } + + while (read > 2) { + /* "if" with easy exit */ + + if (new_down_seqno != inpkt.seqno) { + /* New packet (and not dupe of recent; checked above) */ + /* Forget any old packet, even if incomplete */ + inpkt.seqno = new_down_seqno; + inpkt.fragment = new_down_fragment; /* hopefully 0 */ + inpkt.len = 0; + } else if (inpkt.fragment == 0 && new_down_fragment == 0 && + inpkt.len == 0) { + /* Weird situation: we probably got a no-data reply + for this seqno (see above), and the actual data + is following now. */ + /* okay, nothing to do here, just so that next else-if + doesn't trigger */ + } else if (new_down_fragment <= inpkt.fragment) { + /* Same packet but duplicate fragment, ignore. + If the server didn't get our ack for it, the next + ping or chunk will do that. */ + send_ping_soon = 500; + break; + } else if (new_down_fragment > inpkt.fragment + 1) { + /* Quite impossible. We missed a fragment, but the + server got our ack for it and is sending the next + fragment already. Don't handle it but let server + re-send and drop. */ + send_ping_soon = 500; + break; + } + inpkt.fragment = new_down_fragment; + + datalen = MIN(read - 2, sizeof(inpkt.data) - inpkt.len); + + /* we are here only when read > 2, so datalen "always" >=1 */ + + /* 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 */ + /* RE-USES buf[] */ + 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; + /* Keep .seqno and .fragment as is, so that we won't + reassemble from duplicate fragments */ + } + + /* Send anything to ack the received seqno/frag, and get more */ + if (inpkt.len == 0) { + /* was last frag; wait just a trifle because our + tun will probably return TCP-ack immediately. + 5msec = 200 DNSreq/sec */ + send_ping_soon = 5; + } else { + /* server certainly has more data */ + send_something_now = 1; + } + + break; + } + + /* NOTE: buf[] was overwritten when down-packet complete */ + + + /* Upstream data traffic */ + + if (is_sending()) { + /* already checked read>=2 */ +#if 0 + fprintf(stderr, "Got ack for %d,%d - expecting %d,%d - id=%d cur=%d prev=%d prev2=%d\n", + up_ack_seqno, up_ack_fragment, outpkt.seqno, outpkt.fragment, + q.id, chunkid, chunkid_prev, chunkid_prev2); +#endif + + if (up_ack_seqno == outpkt.seqno && + up_ack_fragment == outpkt.fragment) { + /* Okay, previously sent fragment has arrived */ + + outpkt.offset += outpkt.sentlen; + if (outpkt.offset >= outpkt.len) { + /* Packet completed */ + outpkt.offset = 0; + outpkt.len = 0; + outpkt.sentlen = 0; + outchunkresent = 0; + + /* Normally, server still has a query in queue, + but sometimes not. So send a ping. + (Comment this out and you'll see occasional + hiccups.) + But since the server often still has a + query and we can expect a TCP-ack returned + from our tun device quickly in many cases, + don't be too fast. + 20msec still is 50 DNSreq/second... */ + if (!send_ping_soon || send_ping_soon > 20) + send_ping_soon = 20; + } else { + /* More to send */ + outpkt.fragment++; + outchunkresent = 0; + send_chunk(dns_fd); + send_ping_soon = 0; + send_something_now = 0; + } + } + /* else: Some wrong fragment has arrived, or old fragment is + acked again, mostly by ping responses. + Don't resend chunk, usually not needed; select loop will + re-send on timeout (1sec if is_sending()). */ + } + + + /* Send ping if we didn't send anything yet */ + if (send_something_now) { send_ping(dns_fd); - + send_ping_soon = 0; + } + return read; } @@ -553,23 +782,43 @@ client_tunnel(int tun_fd, int dns_fd) fd_set fds; int rv; int i; - int seconds; rv = 0; - seconds = 0; + lastdownstreamtime = time(NULL); while (running) { - tv.tv_sec = 1; + tv.tv_sec = selecttimeout; tv.tv_usec = 0; + if (is_sending()) { + /* fast timeout for retransmits */ + tv.tv_sec = 1; + tv.tv_usec = 0; + } + + if (send_ping_soon) { + tv.tv_sec = 0; + tv.tv_usec = send_ping_soon * 1000; + } FD_ZERO(&fds); - if ((!is_sending()) || conn == CONN_RAW_UDP) { + if (!is_sending() || outchunkresent >= 2) { + /* If re-sending upstream data, chances are that + we're several seconds behind already and TCP + will start filling tun buffer with (useless) + retransmits. + Get up-to-date fast by simply dropping stuff, + that's what TCP is designed to handle. */ FD_SET(tun_fd, &fds); } FD_SET(dns_fd, &fds); i = select(MAX(tun_fd, dns_fd) + 1, &fds, NULL, NULL, &tv); + + if (lastdownstreamtime + 60 < time(NULL)) { + warnx("No downstream data received in 60 seconds, shutting down."); + running = 0; + } if (running == 0) break; @@ -577,24 +826,48 @@ client_tunnel(int tun_fd, int dns_fd) if (i < 0) err(1, "select"); - if (i == 0) { /* timeout */ - seconds++; + if (i == 0) { + /* timeout */ + if (is_sending()) { + /* Re-send current fragment; either frag + or ack probably dropped somewhere. + But problem: no cache-miss-counter, + so hostname will be identical. + Just drop whole packet after 3 retries, + and TCP retransmit will solve it. + NOTE: tun dropping above should be + >=(value_here - 1) */ + if (outchunkresent < 3) { + outchunkresent++; + send_chunk(dns_fd); + } else { + outpkt.offset = 0; + outpkt.len = 0; + outpkt.sentlen = 0; + outchunkresent = 0; + + send_ping(dns_fd); + } + } else { + send_ping(dns_fd); + } + send_ping_soon = 0; + } else { + if (FD_ISSET(tun_fd, &fds)) { - seconds = 0; if (tunnel_tun(tun_fd, dns_fd) <= 0) continue; + /* Returns -1 on error OR when quickly + dropping data in case of DNS congestion; + we need to _not_ do tunnel_dns() then. + If chunk sent, sets send_ping_soon=0. */ } 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; @@ -744,10 +1017,27 @@ send_downenc_switch(int fd, int userid) strncat(buf, topdomain, 512 - strlen(buf)); send_query(fd, buf); } - + +static void +send_lazy_switch(int fd, int userid) +{ + char buf[512] = "o__."; + buf[1] = b32_5to8(userid); + + if (lazymode) + buf[2] = 'l'; + else + buf[2] = 'i'; + + strncat(buf, topdomain, 512 - strlen(buf)); + send_query(fd, buf); +} + static int handshake_version(int dns_fd, int *seed) { + char hex[] = "0123456789abcdef"; + char hex2[] = "0123456789ABCDEF"; struct timeval tv; char in[4096]; fd_set fds; @@ -768,15 +1058,10 @@ handshake_version(int dns_fd, int *seed) 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 */ + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'v', 'V'); + + if(read <= 0) continue; - } if (read >= 9) { payload = (((in[4] & 0xff) << 24) | @@ -787,6 +1072,8 @@ handshake_version(int dns_fd, int *seed) if (strncmp("VACK", in, 4) == 0) { *seed = payload; userid = in[8]; + userid_char = hex[userid & 15]; + userid_char2 = hex2[userid & 15]; fprintf(stderr, "Version ok, both using protocol v 0x%08x. You are user #%d\n", VERSION, userid); return 0; @@ -836,12 +1123,10 @@ handshake_login(int dns_fd, int seed) 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"); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'l', 'L'); + + if(read <= 0) continue; - } if (read > 0) { int netmask; @@ -898,7 +1183,7 @@ handshake_raw_udp(int dns_fd, int seed) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - len = read_dns(dns_fd, 0, in, sizeof(in)); + len = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'i', 'I'); if (len == 5 && in[0] == 'I') { /* Received IP address */ remoteaddr = (in[1] & 0xff); @@ -991,28 +1276,24 @@ handshake_case_check(int dns_fd) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - read = read_dns(dns_fd, 0, in, sizeof(in)); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'z', 'Z'); 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; - } + if (read < (27 * 2)) { + fprintf(stderr, "Received short case check reply. Will use base32 encoder\n"); + return case_preserved; } else { - fprintf(stderr, "Received bad case check reply\n"); + 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, "Got error on case check, will use base32\n"); @@ -1055,7 +1336,7 @@ handshake_switch_codec(int dns_fd) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - read = read_dns(dns_fd, 0, in, sizeof(in)); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 's', 'S'); if (read > 0) { if (strncmp("BADLEN", in, 6) == 0) { @@ -1112,7 +1393,7 @@ handshake_switch_downenc(int dns_fd) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - read = read_dns(dns_fd, 0, in, sizeof(in)); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'o', 'O'); if (read > 0) { if (strncmp("BADLEN", in, 6) == 0) { @@ -1138,6 +1419,94 @@ codec_revert: fprintf(stderr, "Falling back to base32\n"); } +static void +handshake_try_lazy(int dns_fd) +{ + struct timeval tv; + char in[4096]; + fd_set fds; + int i; + int r; + int read; + + fprintf(stderr, "Switching to lazy mode for low-latency\n"); + for (i=0; running && i<3; i++) { + tv.tv_sec = i + 1; + tv.tv_usec = 0; + + send_lazy_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_namecheck(dns_fd, 0, in, sizeof(in), 'o', 'O'); + + 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 lazy mode. "); + goto codec_revert; + } else if (strncmp("Lazy", in, 4) == 0) { + fprintf(stderr, "Server switched to lazy mode\n"); + lazymode = 1; + return; + } + } + } + fprintf(stderr, "Retrying lazy mode switch...\n"); + } + fprintf(stderr, "No reply from server on lazy switch, probably old server version. "); + +codec_revert: + fprintf(stderr, "Falling back to legacy mode\n"); + lazymode = 0; + selecttimeout = 1; +} + +static void +handshake_lazyoff(int dns_fd) +/* Used in the middle of data transfer, timing is different and no error msgs */ +{ + struct timeval tv; + char in[4096]; + fd_set fds; + int i; + int r; + int read; + + for (i=0; running && i<5; i++) { + tv.tv_sec = 0; + tv.tv_usec = 500000; + + send_lazy_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_namecheck(dns_fd, 0, in, sizeof(in), 'o', 'O'); + + if (read > 0) { + if (read == 4 && strncmp("Immediate", in, 9) == 0) { + fprintf(stderr, "Server switched back to legacy mode.\n"); + lazymode = 0; + selecttimeout = 1; + return; + } + } + } + } +} static int fragsize_check(char *in, int read, int proposed_fragsize, int *max_fragsize) @@ -1243,7 +1612,7 @@ handshake_autoprobe_fragsize(int dns_fd) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - read = read_dns(dns_fd, 0, in, sizeof(in)); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'r', 'R'); if (read > 0) { /* We got a reply */ @@ -1308,7 +1677,7 @@ handshake_set_fragsize(int dns_fd, int fragsize) r = select(dns_fd + 1, &fds, NULL, NULL, &tv); if(r > 0) { - read = read_dns(dns_fd, 0, in, sizeof(in)); + read = read_dns_namecheck(dns_fd, 0, in, sizeof(in), 'n', 'N'); if (read > 0) { int accepted_fragsize; @@ -1349,6 +1718,7 @@ client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsiz if (raw_mode && handshake_raw_udp(dns_fd, seed)) { conn = CONN_RAW_UDP; + selecttimeout = 20; } else { if (raw_mode == 0) { fprintf(stderr, "Skipping raw mode\n"); @@ -1363,6 +1733,10 @@ client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsiz handshake_switch_downenc(dns_fd); } + if (lazymode) { + handshake_try_lazy(dns_fd); + } + if (autodetect_frag_size) { fragsize = handshake_autoprobe_fragsize(dns_fd); if (!fragsize) { diff --git a/src/client.h b/src/client.h index e20c281..e4141bf 100644 --- a/src/client.h +++ b/src/client.h @@ -28,6 +28,8 @@ void client_set_topdomain(const char *cp); void client_set_password(const char *cp); void set_qtype(char *qtype); void set_downenc(char *encoding); +void client_set_selecttimeout(int select_timeout); +void client_set_lazymode(int lazy_mode); int client_handshake(int dns_fd, int raw_mode, int autodetect_frag_size, int fragsize); int client_tunnel(int tun_fd, int dns_fd); diff --git a/src/iodine.c b/src/iodine.c index c5c097f..97bb5d2 100644 --- a/src/iodine.c +++ b/src/iodine.c @@ -61,8 +61,8 @@ usage() { extern char *__progname; fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] " - "[-P password] [-m maxfragsize] [-T type] [-O enc] [-z context] [-F pidfile] " - "[nameserver] topdomain\n", __progname); + "[-P password] [-m maxfragsize] [-T type] [-O enc] [-L 0|1] [-I sec] " + "[-z context] [-F pidfile] [nameserver] topdomain\n", __progname); exit(2); } @@ -72,8 +72,8 @@ help() { fprintf(stderr, "iodine IP over DNS tunneling client\n"); fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] " - "[-P password] [-m maxfragsize] [-T type] [-O enc] [-z context] [-F pidfile] " - "[nameserver] topdomain\n", __progname); + "[-P password] [-m maxfragsize] [-T type] [-O enc] [-L 0|1] [-I sec] " + "[-z context] [-F pidfile] [nameserver] topdomain\n", __progname); fprintf(stderr, " -v to print version info and exit\n"); fprintf(stderr, " -h to print this help and exit\n"); fprintf(stderr, " -f to keep running in foreground\n"); @@ -85,6 +85,8 @@ help() { fprintf(stderr, " -m maxfragsize, to limit size of downstream packets\n"); fprintf(stderr, " -T dns type: NULL (default, fastest), TXT, CNAME, A (CNAME answer), MX\n"); fprintf(stderr, " -O downstream encoding (!NULL): Base32(default), Base64, or Raw (only TXT)\n"); + fprintf(stderr, " -L 1: try lazy mode for low-latency (default). 0: don't (implies -I1)\n"); + fprintf(stderr, " -I max interval between requests (default 4 sec) to prevent server timeouts\n"); fprintf(stderr, " -z context, to apply specified SELinux context after initialization\n"); fprintf(stderr, " -F pidfile to write pid to a file\n"); fprintf(stderr, "nameserver is the IP number of the relaying nameserver, if absent /etc/resolv.conf is used\n"); @@ -127,6 +129,8 @@ main(int argc, char **argv) int autodetect_frag_size; int retval; int raw_mode; + int lazymode; + int selecttimeout; nameserv_addr = NULL; topdomain = NULL; @@ -146,6 +150,8 @@ main(int argc, char **argv) max_downstream_frag_size = 3072; retval = 0; raw_mode = 1; + lazymode = 1; + selecttimeout = 4; #ifdef WINDOWS32 WSAStartup(req_version, &wsa_data); @@ -162,7 +168,7 @@ main(int argc, char **argv) __progname++; #endif - while ((choice = getopt(argc, argv, "vfhru:t:d:P:m:F:T:O:")) != -1) { + while ((choice = getopt(argc, argv, "vfhru:t:d:P:m:F:T:O:L:I:")) != -1) { switch(choice) { case 'v': version(); @@ -209,6 +215,20 @@ main(int argc, char **argv) case 'O': /* not -D, is Debug in server */ set_downenc(optarg); break; + case 'L': + lazymode = atoi(optarg); + if (lazymode > 1) + lazymode = 1; + if (lazymode < 0) + lazymode = 0; + if (!lazymode) + selecttimeout = 1; + break; + case 'I': + selecttimeout = atoi(optarg); + if (selecttimeout < 1) + selecttimeout = 1; + break; default: usage(); /* NOTREACHED */ @@ -260,6 +280,8 @@ main(int argc, char **argv) /* NOTREACHED */ } + client_set_selecttimeout(selecttimeout); + client_set_lazymode(lazymode); client_set_topdomain(topdomain); if (username != NULL) {