--- gvpe/src/vpn_dns.C 2005/03/03 08:38:32 1.6 +++ gvpe/src/vpn_dns.C 2005/03/04 04:52:38 1.9 @@ -1,8 +1,10 @@ /* vpn_dns.C -- handle the dns tunnel part of the protocol. - Copyright (C) 2003-2004 Marc Lehmann + Copyright (C) 2003-2005 Marc Lehmann - This program is free software; you can redistribute it and/or modify + This file is part of GVPE. + + GVPE 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. @@ -13,7 +15,7 @@ GNU General Public License for more details. You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software + along with gvpe; if not, write to the Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ @@ -37,126 +39,239 @@ #include +#include + #include "netcompat.h" #include "vpn.h" #define MIN_RETRY 1. -#define MAX_RETRY 60. +#define MAX_RETRY 6. -#define MAX_OUTSTANDING 40 // max. outstanding requests -#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING -#define MAX_RATE 1000 // requests/s +#define MAX_OUTSTANDING 400 // max. outstanding requests +#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING +#define MAX_RATE 100 // requests/s #define MAX_BACKLOG (10*1024) // size of protocol backlog, must be > MAXSIZE #define MAX_DOMAIN_SIZE 220 // 255 is legal limit, but bind doesn't compress well // 240 leaves about 4 bytes of server reply data // every two request byte sless give room for one reply byte -// seqno has 12 bits, but the lower bit is always left as zero -// as bind caches ttl=0 records and we have to generate -// sequence numbers that always differ case-insensitively -#define SEQNO_MASK 0x07ff +#define SEQNO_MASK 0xffff +#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) -/* +#define MAX_LBL_SIZE 63 +#define MAX_PKT_SIZE 512 -protocol, in shorthand :) +#define RR_TYPE_TXT 16 +#define RR_TYPE_ANY 255 +#define RR_CLASS_IN 1 -client -> server ANY? -server -> client TXT +// works for cmaps up to 255 (not 256!) +struct charmap +{ + enum { INVALID = (u8)255 }; - is dns64-encoded [] - is dns64-encoded <0:12>[] + char encode [256]; // index => char + u8 decode [256]; // char => index + unsigned int size; -if is zero, the connection will be configured: + charmap (const char *cmap); +}; -<0:12><0:4>client-id:12> +charmap::charmap (const char *cmap) +{ + char *enc = encode; + u8 *dec = decode; -*/ + memset (enc, (char) 0, 256); + memset (dec, (char)INVALID, 256); -#define MAX_LBL_SIZE 63 -#define MAX_PKT_SIZE 512 + for (size = 0; cmap [size]; size++) + { + enc [size] = cmap [size]; + dec [(u8)enc [size]] = size; + } -#define RR_TYPE_TXT 16 -#define RR_TYPE_ANY 255 -#define RR_CLASS_IN 1 + assert (size < 256); +} -// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) -struct dns64 +#define MAX_DEC_LEN 500 +#define MAX_ENC_LEN (MAX_DEC_LEN * 2) +#define MAX_LIMBS ((MAX_DEC_LEN * 8 + GMP_NUMB_BITS - 1) / GMP_NUMB_BITS) + +// ugly. minimum base is 16(!) +struct basecoder { - static const char encode_chars[64 + 1]; - static s8 decode_chars[256]; + charmap cmap; + unsigned int enc_len [MAX_DEC_LEN]; + unsigned int dec_len [MAX_ENC_LEN]; - static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } - static int decode_len (int bytes) { return (bytes * 6) / 8; } - static int encode (char *dst, u8 *src, int len); - static int decode (u8 *dst, char *src, int len); + unsigned int encode_len (unsigned int len); + unsigned int decode_len (unsigned int len); - dns64 (); -} dns64; + unsigned int encode (char *dst, u8 *src, unsigned int len); + unsigned int decode (u8 *dst, char *src, unsigned int len); -// the following sequence has been crafted to -// a) look somewhat random -// b) the even (and odd) indices never share the same character as upper/lowercase -const char dns64::encode_chars[64 + 1] = "_-dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"; -s8 dns64::decode_chars[256]; + basecoder (const char *cmap); +}; -dns64::dns64 () +basecoder::basecoder (const char *cmap) +: cmap (cmap) { - for (int i = 0; i < 64; i++) - decode_chars [encode_chars [i]] = i + 1; + for (unsigned int len = 0; len < MAX_DEC_LEN; ++len) + { + u8 src [MAX_DEC_LEN]; + u8 dst [MAX_ENC_LEN]; + + memset (src, 255, len); + + mp_limb_t m [MAX_LIMBS]; + mp_size_t n; + + n = mpn_set_str (m, src, len, 256); + n = mpn_get_str (dst, this->cmap.size, m, n); + + for (int i = 0; !dst [i]; ++i) + n--; + + enc_len [len] = n; + dec_len [n] = len; + } } -int dns64::encode (char *dst, u8 *src, int len) +unsigned int basecoder::encode_len (unsigned int len) { - // slow, but easy to debug - char *beg = dst; - unsigned int accum, bits = 0; + return enc_len [len]; +} - while (len--) - { - accum <<= 8; - accum |= *src++; - bits += 8; +unsigned int basecoder::decode_len (unsigned int len) +{ + while (len && !dec_len [len]) + --len; - while (bits >= 6) - { - *dst++ = encode_chars [(accum >> (bits - 6)) & 63]; - bits -= 6; - } + return dec_len [len]; +} + +unsigned int basecoder::encode (char *dst, u8 *src, unsigned int len) +{ + if (!len) + return 0; + + int elen = encode_len (len); + + mp_limb_t m [MAX_LIMBS]; + mp_size_t n; + + u8 dst_ [MAX_ENC_LEN]; + + n = mpn_set_str (m, src, len, 256); + n = mpn_get_str (dst_, cmap.size, m, n); + + int plen = elen; // for padding + + while (n < plen) + { + *dst++ = cmap.encode [0]; + plen--; } - if (bits) - *dst++ = encode_chars [(accum << (6 - bits)) & 63]; + for (unsigned int i = n - plen; i < n; ++i) + *dst++ = cmap.encode [dst_ [i]]; - return dst - beg; + return elen; } -int dns64::decode (u8 *dst, char *src, int len) +unsigned int basecoder::decode (u8 *dst, char *src, unsigned int len) { - // slow, but easy to debug - u8 *beg = dst; - unsigned int accum, bits = 0; + if (!len) + return 0; + + u8 src_ [MAX_ENC_LEN]; + unsigned int elen = 0; while (len--) { - s8 chr = decode_chars [(u8)*src++]; + u8 val = cmap.decode [(u8)*src++]; - if (!chr) - continue; + if (val != charmap::INVALID) + src_ [elen++] = val; + } - accum <<= 6; - accum |= chr - 1; - bits += 6; + int dlen = decode_len (elen); - while (bits >= 8) - { - *dst++ = accum >> (bits - 8); - bits -= 8; - } + mp_limb_t m [MAX_LIMBS]; + mp_size_t n; + + u8 dst_ [MAX_DEC_LEN]; + + n = mpn_set_str (m, src_, elen, cmap.size); + n = mpn_get_str (dst_, 256, m, n); + + if (n < dlen) + { + memset (dst, 0, dlen - n); + memcpy (dst + dlen - n, dst_, n); } + else + memcpy (dst, dst_ + n - dlen, dlen); + + return dlen; +} + +#if 0 +struct test { test (); } test; + +test::test () +{ + basecoder cdc ("0123456789abcdefghijklmnopqrstuvwxyz"); + + u8 in[] = "0123456789abcdefghijklmnopqrstuvwxyz"; + static char enc[200]; + static u8 dec[200]; + + for (int i = 1; i < 20; i++) + { + int elen = cdc.encode (enc, in, i); + int dlen = cdc.decode (dec, enc, elen); + + printf ("%d>%d>%d (%s>%s)\n", i, elen, dlen, enc, dec); + } + abort (); +} +#endif + +// the following sequence has been crafted to +// a) look somewhat random +// b) the even (and odd) indices never share the same character as upper/lowercase +// the "_" is not valid but widely accepted (all octets should be supported, but let's be conservative) +// the other sequences are obviously derived +//static basecoder cdc63 ("_dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); +static basecoder cdc62 ("dDpPhHzZrR06QqMmjJkKBb34TtSsvVlL81xXaAeEFf92WwGgYyoO57UucCNniI"); +//static basecoder cdc36 ("dphzr06qmjkb34tsvl81xaef92wgyo57ucni"); // unused as of yet +static basecoder cdc26 ("dPhZrQmJkBtSvLxAeFwGyO"); + +///////////////////////////////////////////////////////////////////////////// + +#define HDRSIZE 6 + +inline void encode_header (char *data, int clientid, int seqno) +{ + u8 hdr[3] = { clientid, seqno >> 8, seqno }; + + assert (clientid < 256); - return dst - beg; + cdc26.encode (data, hdr, 3); +} + +inline void decode_header (char *data, int &clientid, int &seqno) +{ + u8 hdr[3]; + + cdc26.decode (hdr, data, HDRSIZE); + + clientid = hdr[0]; + seqno = (hdr[1] << 8) | hdr[2]; } ///////////////////////////////////////////////////////////////////////////// @@ -246,7 +361,7 @@ #define FLAG_QUERY ( 0 << 15) #define FLAG_RESPONSE ( 1 << 15) -#define FLAG_OP_MASK (15 << 14) +#define FLAG_OP_MASK (15 << 11) #define FLAG_OP_QUERY ( 0 << 11) #define FLAG_AA ( 1 << 10) #define FLAG_TC ( 1 << 9) @@ -315,11 +430,11 @@ dns_packet *pkt; tstamp next; int retry; - connection *conn; + struct dns_connection *dns; int seqno; - dns_req (connection *c); - void gen_stream_req (int seqno, byte_stream *stream); + dns_req (dns_connection *dns); + void gen_stream_req (int seqno, byte_stream &stream); }; static u16 dns_id = 12098; // TODO: should be per-vpn @@ -336,8 +451,8 @@ return dns_id; } -dns_req::dns_req (connection *c) -: conn (c) +dns_req::dns_req (dns_connection *dns) +: dns (dns) { next = 0; retry = 0; @@ -347,7 +462,7 @@ pkt->id = next_id (); } -void dns_req::gen_stream_req (int seqno, byte_stream *stream) +void dns_req::gen_stream_req (int seqno, byte_stream &stream) { this->seqno = seqno; @@ -355,26 +470,20 @@ pkt->qdcount = htons (1); int offs = 6*2; - int dlen = MAX_DOMAIN_SIZE - strlen (THISNODE->domain) - 2; + int dlen = MAX_DOMAIN_SIZE - (strlen (THISNODE->domain) + 2); // MAX_DOMAIN_SIZE is technically 255, but bind doesn't compress responses well, // so we need to have space for 2*MAX_DOMAIN_SIZE + header + extra - u8 data[256]; //TODO - - data[0] = THISNODE->id; //TODO - data[1] = seqno >> 7; //TODO - data[2] = seqno << 1; //TODO + char enc[256], *encp = enc; + encode_header (enc, THISNODE->id, seqno); - int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3; + int datalen = cdc62.decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE - HDRSIZE); - if (datalen > stream->size ()) - datalen = stream->size (); + if (datalen > stream.size ()) + datalen = stream.size (); - char enc[256], *encp = enc; - - memcpy (data + 3, stream->begin (), datalen); - int enclen = dns64::encode (enc, data, datalen + 3); - stream->remove (datalen); + int enclen = cdc62.encode (enc + HDRSIZE, stream.begin (), datalen) + HDRSIZE; + stream.remove (datalen); while (enclen) { @@ -441,6 +550,45 @@ } ///////////////////////////////////////////////////////////////////////////// + +struct dns_connection +{ + connection *c; + struct vpn *vpn; + + vector rcvpq; + + int rcvseq; + int sndseq; + + byte_stream rcvdq; + byte_stream snddq; + + void time_cb (time_watcher &w); time_watcher tw; + void receive_rep (dns_rcv *r); + + dns_connection (connection *c); + ~dns_connection (); +}; + +dns_connection::dns_connection (connection *c) +: c (c) +, rcvdq (MAX_BACKLOG * 2) +, snddq (MAX_BACKLOG * 2) +, tw (this, &dns_connection::time_cb) +{ + vpn = c->vpn; + + rcvseq = sndseq = 0; +} + +dns_connection::~dns_connection () +{ + for (vector::iterator i = rcvpq.begin (); + i != rcvpq.end (); + ++i) + delete *i; +} struct dns_cfg { @@ -451,46 +599,42 @@ u8 flags1, flags2; }; -void connection::dnsv4_receive_rep (struct dns_rcv *r) +void dns_connection::receive_rep (dns_rcv *r) { - dns_rcvpq.push_back (r); + rcvpq.push_back (r); redo: - for (vector::iterator i = dns_rcvpq.begin (); - i != dns_rcvpq.end (); - ++i) - if (dns_rcvseq == (*i)->seqno) + // find next packet + for (vector::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) + if (SEQNO_EQ (rcvseq, (*i)->seqno)) { - dns_rcv *r = *i; - - dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; + // enter the packet into our input stream + r = *i; - if (!dns_snddq && !dns_rcvdq) - { - dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); - dns_snddq = new byte_stream (MAX_BACKLOG); + // remove the oldest packet, look forward, as it's oldest first + for (vector::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) + if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) + { + delete *j; + rcvpq.erase (j); + break; + } - dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); - } + rcvseq = (rcvseq + 1) & SEQNO_MASK; - if (!dns_rcvdq->put (r->data, r->datalen)) + if (!rcvdq.put (r->data, r->datalen)) abort (); // MUST never overflow, can be caused by data corruption, TODO - while (vpn_packet *pkt = dns_rcvdq->get ()) + while (vpn_packet *pkt = rcvdq.get ()) { sockinfo si; si.host = 0; si.port = 0; si.prot = PROT_DNSv4; vpn->recv_vpn_packet (pkt, si); } - } - else if ((u32)(*i)->seqno - (u32)dns_rcvseq + MAX_WINDOW > MAX_WINDOW * 2) - { - //D - //abort(); - printf ("%d erasing %d (%d)\n", THISNODE->id, (u32)(*i)->seqno, dns_rcvseq); - dns_rcvpq.erase (i); + + // check for further packets goto redo; } } @@ -505,7 +649,7 @@ pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); - if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) + if (0 == (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) && pkt->qdcount == htons (1)) { char qname[MAXSIZE]; @@ -525,40 +669,41 @@ if (qclass == RR_CLASS_IN && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT) - && qlen > dlen + 1 + && qlen > dlen + 1 + HDRSIZE && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) { // correct class, domain: parse - u8 data[MAXSIZE]; - int datalen = dns64::decode (data, qname, qlen - dlen - 1); + int client, seqno; + decode_header (qname, client, seqno); - int client = data[0]; - int seqno = ((data[1] << 7) | (data[2] >> 1)) & SEQNO_MASK; + u8 data[MAXSIZE]; + int datalen = cdc62.decode (data, qname + HDRSIZE, qlen - (dlen + 1 + HDRSIZE)); if (0 < client && client <= conns.size ()) { connection *c = conns [client - 1]; - redo: + if (!c->dns) + c->dns = new dns_connection (c); + + dns_connection *dns = c->dns; - for (vector::iterator i = c->dns_rcvpq.begin (); - i != c->dns_rcvpq.end (); - ++i) - if ((*i)->seqno == seqno) + for (vector::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) + if (SEQNO_EQ ((*i)->seqno, seqno)) { // already seen that request: simply reply with the cached reply dns_rcv *r = *i; printf ("DUPLICATE %d\n", htons (r->pkt->id));//D - offs = r->pkt->len; - memcpy (pkt->at (0), r->pkt->at (0), offs); + memcpy (pkt->at (0), r->pkt->at (0), offs = r->pkt->len); + pkt->id = r->pkt->id; goto duplicate_request; } // new packet, queue - dns_rcv *rcv = new dns_rcv (seqno, data + 3, datalen - 3); - c->dnsv4_receive_rep (rcv); + dns_rcv *rcv = new dns_rcv (seqno, data, datalen); + dns->receive_rep (rcv); // now generate reply pkt->ancount = htons (1); // one answer RR @@ -580,19 +725,17 @@ int rdlen_offs = offs += 2; - while (c->dns_snddq - && !c->dns_snddq->empty () - && dlen > 1) + while (dlen > 1 && !dns->snddq.empty ()) { int txtlen = dlen <= 255 ? dlen - 1 : 255; - if (txtlen > c->dns_snddq->size ()) - txtlen = c->dns_snddq->size (); + if (txtlen > dns->snddq.size ()) + txtlen = dns->snddq.size (); (*pkt)[offs++] = txtlen; - memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen); + memcpy (pkt->at (offs), dns->snddq.begin (), txtlen); offs += txtlen; - c->dns_snddq->remove (txtlen); + dns->snddq.remove (txtlen); dlen -= txtlen + 1; } @@ -637,14 +780,14 @@ ++i) if ((*i)->pkt->id == pkt->id) { - connection *c = (*i)->conn; + dns_connection *dns = (*i)->dns; int seqno = (*i)->seqno; u8 data[MAXSIZE], *datap = data; delete *i; dns_sndpq.erase (i); - if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) + if (flags & FLAG_RESPONSE && !(flags & (FLAG_OP_MASK | FLAG_TC))) { char qname[MAXSIZE]; @@ -654,9 +797,9 @@ offs += 4; // skip qtype, qclass } - while (pkt->ancount-- && offs < MAXSIZE - 10) + while (pkt->ancount-- && offs < MAXSIZE - 10 && datap) { - pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); + int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; @@ -682,14 +825,27 @@ rdlen -= txtlen + 1; } - } + int client, rseqno; + decode_header (qname, client, rseqno); + + if (client != THISNODE->id) + { + slog (L_INFO, _("got dns tunnel response with wrong clientid, ignoring")); + datap = 0; + } + else if (rseqno != seqno) + { + slog (L_DEBUG, _("got dns tunnel response with wrong seqno, badly caching nameserver?")); + datap = 0; + } } } // todo: pkt now used - c->dnsv4_receive_rep (new dns_rcv (seqno, data, datap - data)); + if (datap) + dns->receive_rep (new dns_rcv (seqno, data, datap - data)); break; } @@ -730,29 +886,21 @@ bool connection::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) { - // never initialized - if (!dns_snddq && !dns_rcvdq) - { - dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); - dns_snddq = new byte_stream (MAX_BACKLOG); - - //dns_rcvseq = dns_sndseq = 0; - - dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); - } + if (!dns) + dns = new dns_connection (this); - if (!dns_snddq->put (pkt)) + if (!dns->snddq.put (pkt)) return false; // start timer if neccessary - if (!THISNODE->dns_port && !dnsv4_tw.active) - dnsv4_cb (dnsv4_tw); + if (!THISNODE->dns_port && !dns->tw.active) + dns->tw.trigger (); return true; } void -connection::dnsv4_cb (time_watcher &w) +dns_connection::time_cb (time_watcher &w) { // check for timeouts and (re)transmit tstamp next = NOW + 60; @@ -771,7 +919,7 @@ send = r; if (r->retry)//D - printf ("req %d, retry %d\n", r->pkt->id, r->retry); + printf ("req %d:%d, retry %d\n", r->seqno, r->pkt->id, r->retry); r->retry++; r->next = NOW + r->retry; } @@ -785,10 +933,10 @@ && vpn->dns_sndpq.size () < MAX_OUTSTANDING) { send = new dns_req (this); - send->gen_stream_req (dns_sndseq, dns_snddq); + send->gen_stream_req (sndseq, snddq); vpn->dns_sndpq.push_back (send); - dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK; + sndseq = (sndseq + 1) & SEQNO_MASK; } tstamp min_next = NOW + (1. / (tstamp)MAX_RATE); @@ -799,7 +947,8 @@ next = min_next; - sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ()); + sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, + vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); } else if (next < min_next) next = min_next;