--- gvpe/src/vpn_dns.C 2005/03/01 04:38:21 1.2 +++ gvpe/src/vpn_dns.C 2005/03/03 07:24:57 1.5 @@ -41,14 +41,19 @@ #include "vpn.h" -#if ENABLE_HTTP_PROXY -# include "conf.h" -#endif - #define MIN_RETRY 1. #define MAX_RETRY 60. -#define SERVER conf.dns_port +#define MAX_OUTSTANDING 40 // max. outstanding requests +#define MAX_WINDOW 100 // max. for MAX_OUTSTANDING +#define MAX_RATE 1000 // 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 + +#define SEQNO_MASK 0xffff /* @@ -81,13 +86,13 @@ static int encode_len (int bytes) { return (bytes * 8 + 5) / 6; } static int decode_len (int bytes) { return (bytes * 6) / 8; } - static void encode (char *dst, u8 *src, int len); - static void decode (u8 *dst, char *src, int len); + static int encode (char *dst, u8 *src, int len); + static int decode (u8 *dst, char *src, int len); dns64 (); } dns64; -const char dns64::encode_chars[64 + 1] = "0123456789-abcdefghijklmnopqrstuvwxyz_ABCDEFGHIJKLMNOPQRSTUVWXYZ"; +const char dns64::encode_chars[64 + 1] = "_4B9dLphHzrqQmGjkTbJt5svlZX8xSaReEYfwKgF1DP2W6NyVOU70IouACcMn3i-"; s8 dns64::decode_chars[256]; dns64::dns64 () @@ -96,9 +101,10 @@ decode_chars [encode_chars [i]] = i + 1; } -void dns64::encode (char *dst, u8 *src, int len) +int dns64::encode (char *dst, u8 *src, int len) { // slow, but easy to debug + char *beg = dst; unsigned int accum, bits = 0; while (len--) @@ -116,20 +122,22 @@ if (bits) *dst++ = encode_chars [(accum << (6 - bits)) & 63]; + + return dst - beg; } -void dns64::decode (u8 *dst, char *src, int len) +int dns64::decode (u8 *dst, char *src, int len) { // slow, but easy to debug + u8 *beg = dst; unsigned int accum, bits = 0; while (len--) { s8 chr = decode_chars [(u8)*src++]; - if (!chr) - break; + continue; accum <<= 6; accum |= chr - 1; @@ -141,8 +149,97 @@ bits -= 8; } } + + return dst - beg; } +///////////////////////////////////////////////////////////////////////////// + +struct byte_stream +{ + u8 *data; + int maxsize; + int fill; + + byte_stream (int maxsize); + ~byte_stream (); + + bool empty () { return !fill; } + int size () { return fill; } + + bool put (u8 *data, unsigned int datalen); + bool put (vpn_packet *pkt); + vpn_packet *get (); + + u8 *begin () { return data; } + void remove (int count); +}; + +byte_stream::byte_stream (int maxsize) +: maxsize (maxsize), fill (0) +{ + data = new u8 [maxsize]; +} + +byte_stream::~byte_stream () +{ + delete data; +} + +void byte_stream::remove (int count) +{ + if (count > fill) + abort (); + + memmove (data, data + count, fill -= count); +} + +bool byte_stream::put (u8 *data, unsigned int datalen) +{ + if (maxsize - fill < datalen) + return false; + + memcpy (this->data + fill, data, datalen); fill += datalen; + + return true; +} + +bool byte_stream::put (vpn_packet *pkt) +{ + if (maxsize - fill < pkt->len + 2) + return false; + + data [fill++] = pkt->len >> 8; + data [fill++] = pkt->len; + + memcpy (data + fill, &((*pkt)[0]), pkt->len); fill += pkt->len; + + return true; +} + +vpn_packet *byte_stream::get () +{ + int len = (data [0] << 8) | data [1]; + + printf ("get len %d, fill %d\n", len, fill);//D + + if (len > MAXSIZE && fill >= 2) + abort (); // TODO handle this gracefully, connection reset + + if (fill < len + 2) + return 0; + + vpn_packet *pkt = new vpn_packet; + + pkt->len = len; + memcpy (&((*pkt)[0]), data + 2, len); + remove (len + 2); + + return pkt; +} + +///////////////////////////////////////////////////////////////////////////// + #define FLAG_QUERY ( 0 << 15) #define FLAG_RESPONSE ( 1 << 15) #define FLAG_OP_MASK (15 << 14) @@ -151,6 +248,7 @@ #define FLAG_TC ( 1 << 9) #define FLAG_RD ( 1 << 8) #define FLAG_RA ( 1 << 7) +#define FLAG_AUTH ( 1 << 5) #define FLAG_RCODE_MASK (15 << 0) #define FLAG_RCODE_OK ( 0 << 0) #define FLAG_RCODE_FORMERR ( 1 << 0) @@ -159,7 +257,7 @@ #define FLAG_RCODE_REFUSED ( 5 << 0) #define DEFAULT_CLIENT_FLAGS (FLAG_QUERY | FLAG_OP_QUERY | FLAG_RD) -#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD) +#define DEFAULT_SERVER_FLAGS (FLAG_RESPONSE | FLAG_OP_QUERY | FLAG_AA | FLAG_RD | FLAG_RA) struct dns_packet : net_packet { @@ -206,6 +304,142 @@ return data - orig; } +///////////////////////////////////////////////////////////////////////////// + +struct dns_req +{ + dns_packet *pkt; + tstamp next; + int retry; + connection *conn; + int seqno; + + dns_req (connection *c); + void gen_stream_req (int seqno, byte_stream *stream); +}; + +static u16 dns_id = 12098; // TODO: should be per-vpn + +static u16 next_id () +{ + // the simplest lsfr with periodicity 65535 i could find + dns_id = (dns_id << 1) + | (((dns_id >> 1) + ^ (dns_id >> 2) + ^ (dns_id >> 4) + ^ (dns_id >> 15)) & 1); + + return dns_id; +} + +dns_req::dns_req (connection *c) +: conn (c) +{ + next = 0; + retry = 0; + + pkt = new dns_packet; + + pkt->id = next_id (); +} + +void dns_req::gen_stream_req (int seqno, byte_stream *stream) +{ + this->seqno = seqno; + + pkt->flags = htons (DEFAULT_CLIENT_FLAGS); + pkt->qdcount = htons (1); + + int offs = 6*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 >> 8; //TODO + data[2] = seqno; //TODO + + int datalen = dns64::decode_len (dlen - (dlen + MAX_LBL_SIZE - 1) / MAX_LBL_SIZE) - 3; + + 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); + + while (enclen) + { + int lbllen = enclen < MAX_LBL_SIZE ? enclen : MAX_LBL_SIZE; + + (*pkt)[offs++] = lbllen; + memcpy (pkt->at (offs), encp, lbllen); + + offs += lbllen; + encp += lbllen; + + enclen -= lbllen; + } + + const char *suffix = THISNODE->domain; + + // add tunnel domain + for (;;) + { + const char *end = strchr (suffix, '.'); + + if (!end) + end = suffix + strlen (suffix); + + int len = end - suffix; + + (*pkt)[offs++] = len; + memcpy (&((*pkt)[offs]), suffix, len); + offs += len; + + if (!*end) + break; + + suffix = end + 1; + } + + (*pkt)[offs++] = 0; + (*pkt)[offs++] = RR_TYPE_ANY >> 8; (*pkt)[offs++] = RR_TYPE_ANY; + (*pkt)[offs++] = RR_CLASS_IN >> 8; (*pkt)[offs++] = RR_CLASS_IN; + + pkt->len = offs; +} + +struct dns_rcv +{ + int seqno; + dns_packet *pkt; // reply packet + u8 data [MAXSIZE]; // actually part of the reply packet... + int datalen; + + dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen); + ~dns_rcv (); +}; + +dns_rcv::dns_rcv (int seqno, dns_packet *req, u8 *data, int datalen) +: seqno (seqno), pkt (new dns_packet), datalen (datalen) +{ + memcpy (this->data, data, datalen); + pkt->len = req->len; + memcpy (pkt->at (0), req->at (0), req->len); +} + +dns_rcv::~dns_rcv () +{ + delete pkt; +} + +///////////////////////////////////////////////////////////////////////////// + struct dns_cfg { u8 id1, id2, id3; @@ -215,99 +449,356 @@ u8 flags1, flags2; }; -// reply to client-poll -void dnsv4_poll (dns_packet *pkt, int &offs) +void connection::dnsv4_receive_rep (struct dns_rcv *r) { - int dlen = MAX_PKT_SIZE - offs - 2; - - (*pkt) [offs++] = 0; - (*pkt) [offs++] = 5; - memcpy (&((*pkt)[offs]), "\01H\02\xff\x00", 5); - offs += 5; + dns_rcvpq.push_back (r); - pkt->ancount = htons (1); - pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); + redo: - printf ("we have room for %d bytes\n", dlen); + for (vector::iterator i = dns_rcvpq.begin (); + i != dns_rcvpq.end (); + ++i) + if (dns_rcvseq == (*i)->seqno) + { + dns_rcv *r = *i; + + dns_rcvseq = (dns_rcvseq + 1) & SEQNO_MASK; + + if (!dns_snddq && !dns_rcvdq) + { + dns_rcvdq = new byte_stream (MAX_BACKLOG * 2); + dns_snddq = new byte_stream (MAX_BACKLOG); + + dns_si.set (::conf.dns_forw_host, ::conf.dns_forw_port, PROT_DNSv4); + } + + if (!dns_rcvdq->put (r->data, r->datalen)) + abort (); // MUST never overflow, can be caused by data corruption, TODO + + while (vpn_packet *pkt = dns_rcvdq->get ()) + { + sockinfo si; + si.host = 0; si.port = 0; si.prot = PROT_DNSv4; + + vpn->recv_vpn_packet (pkt, si); + } + } + else if ((u32)dns_rcvseq - MAX_WINDOW - (u32)(*i)->seqno < MAX_WINDOW * 2) + { + dns_rcvpq.erase (i); + goto redo; + } } -void -vpn::dnsv4_ev (io_watcher &w, short revents) +dns_packet * +vpn::dnsv4_server (dns_packet *pkt) { - if (revents & EVENT_READ) + u16 flags = ntohs (pkt->flags); + + //memcpy (&((*rep)[0]), &((*pkt)[0]), pkt->len); + int offs = 6 * 2; // skip header + + pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); + + if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) + && pkt->qdcount == htons (1)) { - dns_packet *pkt = new dns_packet; - struct sockaddr_in sa; - socklen_t sa_len = sizeof (sa); + char qname[MAXSIZE]; + 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++]; - int len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); - pkt->len = len; + pkt->qdcount = htons (1); + pkt->ancount = 0; + pkt->nscount = 0; // should be self, as other nameservers reply like this + pkt->arcount = 0; // a record for self, as other nameservers reply like this - u16 flags = ntohs (pkt->flags); + pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); - if (THISNODE->dns_port) + int dlen = strlen (THISNODE->domain); + + if (qclass == RR_CLASS_IN + && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT) + && qlen > dlen + 1 + && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) { - // server - pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); + // correct class, domain: parse + u8 data[MAXSIZE]; + int datalen = dns64::decode (data, qname, qlen - dlen - 1); - int offs = 6 * 2; // skip header + int client = data[0]; + int seqno = ((data[1] << 8) | data[2]) & SEQNO_MASK; - if (!(flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) - && pkt->qdcount == htons (1)) + if (0 < client && client <= conns.size ()) { - char qname[MAXSIZE]; - int qlen = pkt->decode_label ((char *)qname, MAXSIZE, offs); + connection *c = conns [client - 1]; - printf ("rcvd packet len %d, id%04x flags%04x q%04x a%04x n%04x a%04x <%s>\n", len, - pkt->id, flags, pkt->qdcount, pkt->ancount, pkt->nscount, pkt->arcount, qname);//D + for (vector::iterator i = c->dns_rcvpq.begin (); + i != c->dns_rcvpq.end (); + ++i) + if ((*i)->seqno == seqno) + { + // already seen that request, just reply with the original reply + dns_rcv *r = *i; - u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; - u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; + offs = r->pkt->len; + memcpy (pkt->at (0), r->pkt->at (0), offs); + goto duplicate_request; + } - pkt->qdcount = htons (1); - pkt->ancount = 0; - pkt->nscount = 0; // should be self, as other nameservers reply like this - pkt->arcount = 0; // a record for self, as other nameservers reply like this + // new packet, queue + c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data + 3, datalen - 3)); - pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_NXDOMAIN); + // now generate reply + pkt->ancount = htons (1); // one answer RR + pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_OK); - int dlen = strlen (THISNODE->domain); + (*pkt) [offs++] = 0xc0; + (*pkt) [offs++] = 6 * 2; // same as in query section - if (qclass == RR_CLASS_IN - && (qtype == RR_TYPE_ANY || qtype == RR_TYPE_TXT) - && qlen > dlen + 1 - && !memcmp (qname + qlen - dlen - 1, THISNODE->domain, dlen)) - { - // correct class, now generate reply - pkt->ancount = htons (1); // one answer RR + (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; + (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; + + (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; + (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL - (*pkt) [offs++] = 0xc0; - (*pkt) [offs++] = 6 * 2; // same as in query section + int dlen = MAX_PKT_SIZE - offs - 2; - (*pkt) [offs++] = RR_TYPE_TXT >> 8; (*pkt) [offs++] = RR_TYPE_TXT; - (*pkt) [offs++] = RR_CLASS_IN >> 8; (*pkt) [offs++] = RR_CLASS_IN; + // bind doesn't compress well, so reduce further by one label length + dlen -= qlen; - (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; - (*pkt) [offs++] = 0; (*pkt) [offs++] = 0; // TTL + int rdlen_offs = offs += 2; + + while (c->dns_snddq + && !c->dns_snddq->empty () + && dlen > 1) + { + int txtlen = dlen <= 255 ? dlen - 1 : 255; - dnsv4_poll (pkt, offs); - printf ("correct class\n"); + if (txtlen > c->dns_snddq->size ()) + txtlen = c->dns_snddq->size (); + + (*pkt)[offs++] = txtlen; + memcpy (pkt->at (offs), c->dns_snddq->begin (), txtlen); + offs += txtlen; + c->dns_snddq->remove (txtlen); + + dlen -= txtlen + 1; } - } - sendto (w.fd, &((*pkt)[0]), offs, 0, (sockaddr *)&sa, sa_len); + // avoid empty TXT rdata + if (offs == rdlen_offs) + (*pkt)[offs++] = 0; + + int rdlen = offs - rdlen_offs; + + (*pkt) [rdlen_offs - 2] = rdlen >> 8; + (*pkt) [rdlen_offs - 1] = rdlen; + + duplicate_request: ; + } + else + pkt->flags = htons (DEFAULT_SERVER_FLAGS | FLAG_RCODE_FORMERR); } - else + } + else + offs = pkt->len; + + pkt->len = offs; + return pkt; +} + +void +vpn::dnsv4_client (dns_packet *pkt) +{ + u16 flags = ntohs (pkt->flags); + int offs = 6 * 2; // skip header + + pkt->qdcount = ntohs (pkt->qdcount); + pkt->ancount = ntohs (pkt->ancount); + + // go through our request list and find the corresponding request + for (vector::iterator i = dns_sndpq.begin (); + i != dns_sndpq.end (); + ++i) + if ((*i)->pkt->id == pkt->id) + { + connection *c = (*i)->conn; + int seqno = (*i)->seqno; + u8 data[MAXSIZE], *datap = data; + + delete *i; + dns_sndpq.erase (i); + + if (flags & (FLAG_RESPONSE | FLAG_OP_MASK | FLAG_TC)) + { + char qname[MAXSIZE]; + + while (pkt->qdcount-- && offs < MAXSIZE - 4) + { + int qlen = pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); + offs += 4; // skip qtype, qclass + } + + while (pkt->ancount-- && offs < MAXSIZE - 10) + { + pkt->decode_label ((char *)qname, MAXSIZE - offs, offs); + + u16 qtype = (*pkt) [offs++] << 8; qtype |= (*pkt) [offs++]; + u16 qclass = (*pkt) [offs++] << 8; qclass |= (*pkt) [offs++]; + u32 ttl = (*pkt) [offs++] << 24; + ttl |= (*pkt) [offs++] << 16; + ttl |= (*pkt) [offs++] << 8; + ttl |= (*pkt) [offs++]; + + u16 rdlen = (*pkt) [offs++] << 8; rdlen |= (*pkt) [offs++]; + + if (rdlen <= MAXSIZE - offs) + { + // decode bytes, finally + + while (rdlen) + { + int txtlen = (*pkt) [offs++]; + + assert (txtlen + offs < MAXSIZE - 1); + + memcpy (datap, pkt->at (offs), txtlen); + datap += txtlen; offs += txtlen; + + rdlen -= txtlen + 1; + } + + } + + } + } + + if (datap != data) + printf ("%02x %02x %02x %02x\n", + data[0], + data[1], + data[2], + data[3]); + + printf ("recv %d,%d\n", pkt->id, seqno, datap - data);//D + c->dnsv4_receive_rep (new dns_rcv (seqno, pkt, data, datap - data)); + + break; + } + + delete pkt; +} + +void +vpn::dnsv4_ev (io_watcher &w, short revents) +{ + if (revents & EVENT_READ) + { + dns_packet *pkt = new dns_packet; + struct sockaddr_in sa; + socklen_t sa_len = sizeof (sa); + + pkt->len = recvfrom (w.fd, &((*pkt)[0]), MAXSIZE, 0, (sockaddr *)&sa, &sa_len); + + if (pkt->len > 0) { - // client + if (pkt->flags & htons (FLAG_TC)) + { + slog (L_WARN, _("DNS request/response truncated, check protocol settings.")); + //TODO connection reset + } + + if (THISNODE->dns_port) + { + pkt = dnsv4_server (pkt); + sendto (w.fd, &((*pkt)[0]), pkt->len, 0, (sockaddr *)&sa, sa_len); + } + else + dnsv4_client (pkt); } } } bool -vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) +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_snddq->put (pkt)) + return false; + + // start timer if neccessary + if (!THISNODE->dns_port && !dnsv4_tw.active) + dnsv4_cb (dnsv4_tw); + + return true; +} + +void +connection::dnsv4_cb (time_watcher &w) { - //return i->send_packet (pkt, tos); + // check for timeouts and (re)transmit + tstamp next = NOW + 60; + dns_req *send = 0; + + for (vector::iterator i = vpn->dns_sndpq.begin (); + i != vpn->dns_sndpq.end (); + ++i) + { + dns_req *r = *i; + + if (r->next <= NOW) + { + if (!send) + { + send = r; + + if (r->retry)//D + printf ("req %d, retry %d\n", r->pkt->id, r->retry); + r->retry++; + r->next = NOW + r->retry; + } + } + + if (r->next < next) + next = r->next; + } + + if (!send + && vpn->dns_sndpq.size () < MAX_OUTSTANDING) + { + send = new dns_req (this); + send->gen_stream_req (dns_sndseq, dns_snddq); + vpn->dns_sndpq.push_back (send); + + dns_sndseq = (dns_sndseq + 1) & SEQNO_MASK; + } + + tstamp min_next = NOW + (1. / (tstamp)MAX_RATE); + + if (send) + { + dns_packet *pkt = send->pkt; + + next = min_next; + + sendto (vpn->dnsv4_fd, &((*pkt)[0]), pkt->len, 0, dns_si.sav4 (), dns_si.salenv4 ()); + } + else if (next < min_next) + next = min_next; + + w.start (next); } #endif