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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.26 by pcg, Tue Mar 8 17:25:27 2005 UTC vs.
Revision 1.41 by pcg, Wed Nov 22 21:26:41 2006 UTC

… …
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details. 15 GNU General Public License for more details.
16 16
17 You should have received a copy of the GNU General Public License 17 You should have received a copy of the GNU General Public License
18 along with gvpe; if not, write to the Free Software 18 along with gvpe; if not, write to the Free Software
19 Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 Foundation, Inc. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20*/ 20*/
21
22// TODO: EDNS0 option to increase dns mtu?
23// TODO: re-write dns packet parsing/creation using a safe mem-buffer
24// to ensure no buffer overflows or similar problems.
21 25
22#include "config.h" 26#include "config.h"
23 27
24#if ENABLE_DNS 28#if ENABLE_DNS
25 29
… …
44 48
45#include "netcompat.h" 49#include "netcompat.h"
46 50
47#include "vpn.h" 51#include "vpn.h"
48 52
49#define MIN_POLL_INTERVAL .02 // how often to poll minimally when the server has data
50#define MAX_POLL_INTERVAL 6. // how often to poll minimally when the server has no data 53#define MAX_POLL_INTERVAL 5. // how often to poll minimally when the server has no data
51#define ACTIVITY_INTERVAL 5. 54#define ACTIVITY_INTERVAL 5.
52 55
53#define INITIAL_TIMEOUT 0.1 // retry timeouts 56#define INITIAL_TIMEOUT 0.1 // retry timeouts
54#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn 57#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
55 58
56#define MIN_SEND_INTERVAL 0.01 // wait at least this time between sending requests
57#define MAX_SEND_INTERVAL 0.5 // optimistic? 59#define MAX_SEND_INTERVAL 2. // optimistic?
58 60
59#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
60#define MAX_OUTSTANDING 20 // max. outstanding requests
61#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog 61#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
62#define MAX_BACKLOG (100*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE 62#define MAX_BACKLOG (64*1024) // size of gvpe protocol backlog (bytes), must be > MAXSIZE
63 63
64#define MAX_DOMAIN_SIZE 200 // 255 is legal limit, but bind doesn't compress well 64#define MAX_DOMAIN_SIZE 240 // 255 is legal limit, but bind doesn't compress well
65// 240 leaves about 4 bytes of server reply data 65// 240 leaves about 4 bytes of server reply data
66// every two request bytes less give room for one reply byte 66// every request byte less give room for two reply bytes
67 67
68#define SEQNO_MASK 0x3fff 68#define SEQNO_MASK 0x3fff
69#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 69#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
70 70
71#define MAX_LBL_SIZE 63 71#define MAX_LBL_SIZE 63
… …
424 u16 max_size; 424 u16 max_size;
425 u8 seq_cdc; 425 u8 seq_cdc;
426 u8 req_cdc; 426 u8 req_cdc;
427 427
428 u8 rep_cdc; 428 u8 rep_cdc;
429 u8 delay; // time in 0.01s units that the server may delay replying packets
429 u8 r2, r3, r4; 430 u8 r3, r4;
430 431
431 u8 r5, r6, r7, r8; 432 u8 r5, r6, r7, r8;
432 433
433 void reset (int clientid); 434 void reset (int clientid);
434 bool valid (); 435 bool valid ();
… …
449 flags = 0; 450 flags = 0;
450 def_ttl = 0; 451 def_ttl = 0;
451 seq_cdc = 26; 452 seq_cdc = 26;
452 req_cdc = 62; 453 req_cdc = 62;
453 rep_cdc = 0; 454 rep_cdc = 0;
454 max_size = ntohs (MAX_PKT_SIZE); 455 max_size = htons (MAX_PKT_SIZE);
455 client = ntohs (clientid); 456 client = htons (clientid);
456 uid = next_uid++; 457 uid = next_uid++;
458 delay = 0;
457 459
458 r2 = r3 = r4 = 0; 460 r3 = r4 = 0;
459 r4 = r5 = r6 = r7 = 0; 461 r4 = r5 = r6 = r7 = 0;
460} 462}
461 463
462bool dns_cfg::valid () 464bool dns_cfg::valid ()
463{ 465{
466 // although the protocol itself allows for some configurability,
467 // only the following encoding/decoding settings are implemented.
464 return id1 == 'G' 468 return id1 == 'G'
465 && id2 == 'V' 469 && id2 == 'V'
466 && id3 == 'P' 470 && id3 == 'P'
467 && id4 == 'E' 471 && id4 == 'E'
468 && seq_cdc == 26 472 && seq_cdc == 26
469 && req_cdc == 62 473 && req_cdc == 62
470 && rep_cdc == 0 474 && rep_cdc == 0
471 && version == 1 475 && version == 1;
472 && max_size == ntohs (MAX_PKT_SIZE);
473} 476}
474 477
475struct dns_packet : net_packet 478struct dns_packet : net_packet
476{ 479{
477 u16 id; 480 u16 id;
… …
553 double min_latency; 556 double min_latency;
554 double poll_interval, send_interval; 557 double poll_interval, send_interval;
555 558
556 vector<dns_rcv *> rcvpq; 559 vector<dns_rcv *> rcvpq;
557 560
558 byte_stream rcvdq; int rcvseq; 561 byte_stream rcvdq; int rcvseq; int repseq;
559 byte_stream snddq; int sndseq; 562 byte_stream snddq; int sndseq;
560 563
561 void time_cb (time_watcher &w); time_watcher tw; 564 void time_cb (time_watcher &w); time_watcher tw;
562 void receive_rep (dns_rcv *r); 565 void receive_rep (dns_rcv *r);
563 566
… …
720///////////////////////////////////////////////////////////////////////////// 723/////////////////////////////////////////////////////////////////////////////
721 724
722dns_connection::dns_connection (connection *c) 725dns_connection::dns_connection (connection *c)
723: c (c) 726: c (c)
724, rcvdq (MAX_BACKLOG * 2) 727, rcvdq (MAX_BACKLOG * 2)
725, snddq (MAX_BACKLOG * 2) 728, snddq (MAX_BACKLOG)
726, tw (this, &dns_connection::time_cb) 729, tw (this, &dns_connection::time_cb)
727{ 730{
728 vpn = c->vpn; 731 vpn = c->vpn;
729 732
730 established = false; 733 established = false;
731 734
732 rcvseq = sndseq = 0; 735 rcvseq = repseq = sndseq = 0;
733 736
734 last_sent = last_received = 0; 737 last_sent = last_received = 0;
735 poll_interval = MIN_POLL_INTERVAL; 738 poll_interval = 0.5; // starting here
736 send_interval = 0.5; // starting rate 739 send_interval = 0.5; // starting rate
737 min_latency = INITIAL_TIMEOUT; 740 min_latency = INITIAL_TIMEOUT;
738} 741}
739 742
740dns_connection::~dns_connection () 743dns_connection::~dns_connection ()
… …
768 771
769 // find next packet 772 // find next packet
770 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); ) 773 for (vector<dns_rcv *>::iterator i = rcvpq.end (); i-- != rcvpq.begin (); )
771 if (SEQNO_EQ (rcvseq, (*i)->seqno)) 774 if (SEQNO_EQ (rcvseq, (*i)->seqno))
772 { 775 {
776 //printf ("seqno eq %x %x\n", rcvseq, (*i)->seqno);//D
773 // enter the packet into our input stream 777 // enter the packet into our input stream
774 r = *i; 778 r = *i;
775 779
776 // remove the oldest packet, look forward, as it's oldest first 780 // remove the oldest packet, look forward, as it's oldest first
777 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j) 781 for (vector<dns_rcv *>::iterator j = rcvpq.begin (); j != rcvpq.end (); ++j)
778 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW)) 782 if (SEQNO_EQ ((*j)->seqno, rcvseq - MAX_WINDOW))
779 { 783 {
784 //printf ("seqno RR %x %x\n", (*j)->seqno, rcvseq - MAX_WINDOW);//D
780 delete *j; 785 delete *j;
781 rcvpq.erase (j); 786 rcvpq.erase (j);
782 break; 787 break;
783 } 788 }
784 789
… …
791 } 796 }
792 797
793 while (vpn_packet *pkt = rcvdq.get ()) 798 while (vpn_packet *pkt = rcvdq.get ())
794 { 799 {
795 sockinfo si; 800 sockinfo si;
796 si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4; 801 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
797 802
798 vpn->recv_vpn_packet (pkt, si); 803 vpn->recv_vpn_packet (pkt, si);
799 804
800 delete pkt; 805 delete pkt;
801 } 806 }
… …
855 if (0 < client && client <= conns.size ()) 860 if (0 < client && client <= conns.size ())
856 { 861 {
857 connection *c = conns [client - 1]; 862 connection *c = conns [client - 1];
858 dns_connection *dns = c->dns; 863 dns_connection *dns = c->dns;
859 dns_rcv *rcv; 864 dns_rcv *rcv;
860 bool in_seq;
861 865
862 if (dns) 866 if (dns)
863 { 867 {
864 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 868 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
865 if (SEQNO_EQ ((*i)->seqno, seqno)) 869 if (SEQNO_EQ ((*i)->seqno, seqno))
… …
876 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 880 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
877 881
878 goto duplicate_request; 882 goto duplicate_request;
879 } 883 }
880 884
881 in_seq = dns->rcvseq == seqno;
882
883 // new packet, queue 885 // new packet, queue
884 rcv = new dns_rcv (seqno, data, datalen); 886 rcv = new dns_rcv (seqno, data, datalen);
885 dns->receive_rep (rcv); 887 dns->receive_rep (rcv);
886 } 888 }
887 889
… …
894 pkt [offs++] = 0; pkt [offs++] = 0; 896 pkt [offs++] = 0; pkt [offs++] = 0;
895 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL 897 pkt [offs++] = 0; pkt [offs++] = dns ? dns->cfg.def_ttl : 0; // TTL
896 898
897 int rdlen_offs = offs += 2; 899 int rdlen_offs = offs += 2;
898 900
899 int dlen = (dns ? ntohs (dns->cfg.max_size) : MAX_PKT_SIZE) - offs;
900 // bind doesn't compress well, so reduce further by one label length
901 dlen -= qlen;
902
903 if (dns) 901 if (dns)
904 { 902 {
903 int dlen = ntohs (dns->cfg.max_size) - offs;
904
905 // bind doesn't compress well, so reduce further by one label length
906 dlen -= qlen;
907
905 // only put data into in-order sequence packets, if 908 // only put data into in-order sequence packets, if
906 // we receive out-of-order packets we generate empty 909 // we receive out-of-order packets we generate empty
907 // replies 910 // replies
908 while (dlen > 1 && !dns->snddq.empty () && in_seq) 911 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
912 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
909 { 913 {
914 dns->repseq = seqno;
915
916 while (dlen > 1 && !dns->snddq.empty ())
917 {
910 int txtlen = dlen <= 255 ? dlen - 1 : 255; 918 int txtlen = dlen <= 255 ? dlen - 1 : 255;
911 919
912 if (txtlen > dns->snddq.size ()) 920 if (txtlen > dns->snddq.size ())
913 txtlen = dns->snddq.size (); 921 txtlen = dns->snddq.size ();
914 922
915 pkt[offs++] = txtlen; 923 pkt[offs++] = txtlen;
916 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 924 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
917 offs += txtlen; 925 offs += txtlen;
918 dns->snddq.remove (txtlen); 926 dns->snddq.remove (txtlen);
919 927
920 dlen -= txtlen + 1; 928 dlen -= txtlen + 1;
929 }
921 } 930 }
922 931
923 // avoid empty TXT rdata 932 // avoid completely empty TXT rdata
924 if (offs == rdlen_offs) 933 if (offs == rdlen_offs)
925 pkt[offs++] = 0; 934 pkt[offs++] = 0;
926 935
927 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); 936 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
928 } 937 }
… …
1008 { 1017 {
1009 dns_connection *dns = (*i)->dns; 1018 dns_connection *dns = (*i)->dns;
1010 connection *c = dns->c; 1019 connection *c = dns->c;
1011 int seqno = (*i)->seqno; 1020 int seqno = (*i)->seqno;
1012 u8 data[MAXSIZE], *datap = data; 1021 u8 data[MAXSIZE], *datap = data;
1022 //printf ("rcv pkt %x\n", seqno);//D
1013 1023
1014 if ((*i)->retry) 1024 if ((*i)->retry)
1015 { 1025 {
1016 dns->send_interval *= 1.01; 1026 dns->send_interval *= 1.01;
1017 if (dns->send_interval > MAX_SEND_INTERVAL) 1027 if (dns->send_interval > MAX_SEND_INTERVAL)
… …
1020 else 1030 else
1021 { 1031 {
1022#if 0 1032#if 0
1023 dns->send_interval *= 0.999; 1033 dns->send_interval *= 0.999;
1024#endif 1034#endif
1025 if (dns->send_interval < MIN_SEND_INTERVAL)
1026 dns->send_interval = MIN_SEND_INTERVAL;
1027
1028 // the latency surely puts an upper bound on 1035 // the latency surely puts an upper bound on
1029 // the minimum send interval 1036 // the minimum send interval
1030 double latency = NOW - (*i)->sent; 1037 double latency = NOW - (*i)->sent;
1031 1038
1032 if (latency < dns->min_latency) 1039 if (latency < dns->min_latency)
1033 dns->min_latency = latency; 1040 dns->min_latency = latency;
1034 1041
1035 if (dns->send_interval > dns->min_latency * LATENCY_FACTOR) 1042 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1036 dns->send_interval = dns->min_latency * LATENCY_FACTOR; 1043 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1044
1045 if (dns->send_interval < conf.dns_send_interval)
1046 dns->send_interval = conf.dns_send_interval;
1037 } 1047 }
1038 1048
1039 delete *i; 1049 delete *i;
1040 dns_sndpq.erase (i); 1050 dns_sndpq.erase (i);
1041 1051
… …
1174} 1184}
1175 1185
1176bool 1186bool
1177vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1187vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1178{ 1188{
1179 int client = ntohs (si.port); 1189 int client = ntohl (si.host);
1180 1190
1181 assert (0 < client && client <= conns.size ()); 1191 assert (0 < client && client <= conns.size ());
1182 1192
1183 connection *c = conns [client - 1]; 1193 connection *c = conns [client - 1];
1184 1194
1185 if (!c->dns) 1195 if (!c->dns)
1186 c->dns = new dns_connection (c); 1196 c->dns = new dns_connection (c);
1187 1197
1188 if (!c->dns->snddq.put (pkt)) 1198 if (c->dns->snddq.put (pkt))
1189 return false;
1190
1191 c->dns->tw.trigger (); 1199 c->dns->tw.trigger ();
1192 1200
1201 // always return true even if the buffer overflows
1193 return true; 1202 return true;
1194} 1203}
1195 1204
1196void 1205void
1197connection::dnsv4_reset_connection () 1206connection::dnsv4_reset_connection ()
… …
1223 if (!send) 1232 if (!send)
1224 { 1233 {
1225 send = r; 1234 send = r;
1226 1235
1227 r->retry++; 1236 r->retry++;
1228 r->timeout = NOW + (r->retry * min_latency * 8.); 1237 r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
1238 //printf ("RETRY %x (%d, %f)\n", r->seqno, r->retry, r->timeout - NOW);//D
1229 1239
1230 // the following code changes the query section a bit, forcing 1240 // the following code changes the query section a bit, forcing
1231 // the forwarder to generate a new request 1241 // the forwarder to generate a new request
1232 if (r->stdhdr) 1242 if (r->stdhdr)
1233 {
1234 //printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);printf ("reencoded header for ID %d retry %d:%d:%d\n", htons (r->pkt->id), THISNODE->id, r->seqno, r->retry);
1235 //encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry); 1243 encode_header ((char *)r->pkt->at (6 * 2 + 1), THISNODE->id, r->seqno, r->retry);
1236 }
1237 } 1244 }
1238 } 1245 }
1239 else 1246 else
1240 NEXT (r->timeout); 1247 NEXT (r->timeout);
1241 } 1248 }
1242 1249
1243 if (last_sent + send_interval <= NOW)
1244 {
1245 if (!send) 1250 if (!send)
1251 {
1252 // generate a new packet, if wise
1253
1254 if (!established)
1246 { 1255 {
1247 // generate a new packet, if wise 1256 if (vpn->dns_sndpq.empty ())
1248
1249 if (!established)
1250 { 1257 {
1251 if (vpn->dns_sndpq.empty ())
1252 {
1253 send = new dns_snd (this); 1258 send = new dns_snd (this);
1254 1259
1255 cfg.reset (THISNODE->id); 1260 cfg.reset (THISNODE->id);
1256 send->gen_syn_req (); 1261 send->gen_syn_req ();
1257 }
1258 } 1262 }
1259 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING 1263 }
1264 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1260 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) 1265 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1266 {
1267 if (last_sent + send_interval <= NOW)
1261 { 1268 {
1262 //printf ("sending data request etc.\n"); //D 1269 //printf ("sending data request etc.\n"); //D
1263 if (!snddq.empty () || last_received + 1. > NOW) 1270 if (!snddq.empty () || last_received + 1. > NOW)
1264 { 1271 {
1265 poll_interval = send_interval; 1272 poll_interval = send_interval;
1266 NEXT (NOW + send_interval); 1273 NEXT (NOW + send_interval);
1267 } 1274 }
1268 1275
1269 send = new dns_snd (this); 1276 send = new dns_snd (this);
1270 send->gen_stream_req (sndseq, snddq); 1277 send->gen_stream_req (sndseq, snddq);
1271 send->timeout = NOW + min_latency * 8.; 1278 send->timeout = NOW + min_latency * conf.dns_timeout_factor;
1279 //printf ("SEND %x (%f)\n", send->seqno, send->timeout - NOW, min_latency, conf.dns_timeout_factor);//D
1272 1280
1273 sndseq = (sndseq + 1) & SEQNO_MASK; 1281 sndseq = (sndseq + 1) & SEQNO_MASK;
1274 } 1282 }
1275 1283 else
1276 if (send) 1284 NEXT (last_sent + send_interval);
1277 vpn->dns_sndpq.push_back (send);
1278 } 1285 }
1279 1286
1280 if (send) 1287 if (send)
1281 { 1288 vpn->dns_sndpq.push_back (send);
1289 }
1290
1291 if (send)
1292 {
1282 last_sent = NOW; 1293 last_sent = NOW;
1283 sendto (vpn->dnsv4_fd, 1294 sendto (vpn->dnsv4_fd,
1284 send->pkt->at (0), send->pkt->len, 0, 1295 send->pkt->at (0), send->pkt->len, 0,
1285 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ()); 1296 vpn->dns_forwarder.sav4 (), vpn->dns_forwarder.salenv4 ());
1286 }
1287 } 1297 }
1288 else
1289 NEXT (last_sent + send_interval);
1290 1298
1291 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d)", 1299 slog (L_NOISE, "DNS: pi %f si %f N %f (%d:%d %d)",
1292 poll_interval, send_interval, next - NOW, 1300 poll_interval, send_interval, next - NOW,
1293 vpn->dns_sndpq.size (), snddq.size ()); 1301 vpn->dns_sndpq.size (), snddq.size (),
1302 rcvpq.size ());
1294 1303
1295 // TODO: no idea when this happens, but when next < NOW, we have a problem 1304 // TODO: no idea when this happens, but when next < NOW, we have a problem
1305 // doesn't seem to happen anymore
1296 if (next < NOW + 0.0001) 1306 if (next < NOW + 0.001)
1297 next = NOW + 0.1; 1307 next = NOW + 0.1;
1298 1308
1299 w.start (next); 1309 w.start (next);
1300} 1310}
1301 1311

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