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/cvs/gvpe/src/vpn_dns.C
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Comparing gvpe/src/vpn_dns.C (file contents):
Revision 1.30 by pcg, Mon Mar 14 17:40:01 2005 UTC vs.
Revision 1.40 by pcg, Sat Jul 9 20:29:29 2005 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
… …
48 52
49#define MAX_POLL_INTERVAL 5. // 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
50#define ACTIVITY_INTERVAL 5. 54#define ACTIVITY_INTERVAL 5.
51 55
52#define INITIAL_TIMEOUT 0.1 // retry timeouts 56#define INITIAL_TIMEOUT 0.1 // retry timeouts
53#define INITIAL_SYN_TIMEOUT 10. // retry timeout for initial syn 57#define INITIAL_SYN_TIMEOUT 2. // retry timeout for initial syn
54 58
55#define MIN_SEND_INTERVAL 0.001 // wait at least this time between sending requests
56#define MAX_SEND_INTERVAL 2. // optimistic? 59#define MAX_SEND_INTERVAL 2. // optimistic?
57 60
58#define LATENCY_FACTOR 0.5 // RTT * LATENCY_FACTOR == sending rate
59#define MAX_OUTSTANDING 2 // max. outstanding requests
60#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog 61#define MAX_WINDOW 1000 // max. for MAX_OUTSTANDING, and backlog
61#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
62 63
63#define MAX_DOMAIN_SIZE 240 // 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
64// 240 leaves about 4 bytes of server reply data 65// 240 leaves about 4 bytes of server reply data
65// every two request bytes less give room for one reply byte 66// every request byte less give room for two reply bytes
66 67
67#define SEQNO_MASK 0x3fff 68#define SEQNO_MASK 0x3fff
68#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) ) 69#define SEQNO_EQ(a,b) ( 0 == ( ((a) ^ (b)) & SEQNO_MASK) )
69 70
70#define MAX_LBL_SIZE 63 71#define MAX_LBL_SIZE 63
… …
460 r4 = r5 = r6 = r7 = 0; 461 r4 = r5 = r6 = r7 = 0;
461} 462}
462 463
463bool dns_cfg::valid () 464bool dns_cfg::valid ()
464{ 465{
466 // although the protocol itself allows for some configurability,
467 // only the following encoding/decoding settings are implemented.
465 return id1 == 'G' 468 return id1 == 'G'
466 && id2 == 'V' 469 && id2 == 'V'
467 && id3 == 'P' 470 && id3 == 'P'
468 && id4 == 'E' 471 && id4 == 'E'
469 && seq_cdc == 26 472 && seq_cdc == 26
… …
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 = 0.5; // starting here 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;
… …
791 } 794 }
792 795
793 while (vpn_packet *pkt = rcvdq.get ()) 796 while (vpn_packet *pkt = rcvdq.get ())
794 { 797 {
795 sockinfo si; 798 sockinfo si;
796 si.host = 0x01010101; si.port = htons (c->conf->id); si.prot = PROT_DNSv4; 799 si.host = htonl (c->conf->id); si.port = 0; si.prot = PROT_DNSv4;
797 800
798 vpn->recv_vpn_packet (pkt, si); 801 vpn->recv_vpn_packet (pkt, si);
799 802
800 delete pkt; 803 delete pkt;
801 } 804 }
… …
855 if (0 < client && client <= conns.size ()) 858 if (0 < client && client <= conns.size ())
856 { 859 {
857 connection *c = conns [client - 1]; 860 connection *c = conns [client - 1];
858 dns_connection *dns = c->dns; 861 dns_connection *dns = c->dns;
859 dns_rcv *rcv; 862 dns_rcv *rcv;
860 bool in_seq;
861 863
862 if (dns) 864 if (dns)
863 { 865 {
864 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); ) 866 for (vector<dns_rcv *>::iterator i = dns->rcvpq.end (); i-- != dns->rcvpq.begin (); )
865 if (SEQNO_EQ ((*i)->seqno, seqno)) 867 if (SEQNO_EQ ((*i)->seqno, seqno))
… …
876 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len); 878 memcpy (pkt.at (0), r->pkt->at (0), offs = r->pkt->len);
877 879
878 goto duplicate_request; 880 goto duplicate_request;
879 } 881 }
880 882
881 in_seq = dns->rcvseq == seqno;
882
883 // new packet, queue 883 // new packet, queue
884 rcv = new dns_rcv (seqno, data, datalen); 884 rcv = new dns_rcv (seqno, data, datalen);
885 dns->receive_rep (rcv); 885 dns->receive_rep (rcv);
886 } 886 }
887 887
… …
904 dlen -= qlen; 904 dlen -= qlen;
905 905
906 // only put data into in-order sequence packets, if 906 // only put data into in-order sequence packets, if
907 // we receive out-of-order packets we generate empty 907 // we receive out-of-order packets we generate empty
908 // replies 908 // replies
909 while (dlen > 1 && !dns->snddq.empty () && in_seq) 909 //printf ("%d - %d & %x (=%d) < %d\n", seqno, dns->repseq, SEQNO_MASK, (seqno - dns->repseq) & SEQNO_MASK, MAX_WINDOW);//D
910 if (((seqno - dns->repseq) & SEQNO_MASK) <= MAX_WINDOW)
910 { 911 {
912 dns->repseq = seqno;
913
914 while (dlen > 1 && !dns->snddq.empty ())
915 {
911 int txtlen = dlen <= 255 ? dlen - 1 : 255; 916 int txtlen = dlen <= 255 ? dlen - 1 : 255;
912 917
913 if (txtlen > dns->snddq.size ()) 918 if (txtlen > dns->snddq.size ())
914 txtlen = dns->snddq.size (); 919 txtlen = dns->snddq.size ();
915 920
916 pkt[offs++] = txtlen; 921 pkt[offs++] = txtlen;
917 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen); 922 memcpy (pkt.at (offs), dns->snddq.begin (), txtlen);
918 offs += txtlen; 923 offs += txtlen;
919 dns->snddq.remove (txtlen); 924 dns->snddq.remove (txtlen);
920 925
921 dlen -= txtlen + 1; 926 dlen -= txtlen + 1;
927 }
922 } 928 }
923 929
924 // avoid empty TXT rdata 930 // avoid completely empty TXT rdata
925 if (offs == rdlen_offs) 931 if (offs == rdlen_offs)
926 pkt[offs++] = 0; 932 pkt[offs++] = 0;
927 933
928 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ()); 934 slog (L_NOISE, "DNS: snddq %d", dns->snddq.size ());
929 } 935 }
… …
1028 double latency = NOW - (*i)->sent; 1034 double latency = NOW - (*i)->sent;
1029 1035
1030 if (latency < dns->min_latency) 1036 if (latency < dns->min_latency)
1031 dns->min_latency = latency; 1037 dns->min_latency = latency;
1032 1038
1033 if (dns->send_interval > dns->min_latency * LATENCY_FACTOR) 1039 if (dns->send_interval > dns->min_latency * conf.dns_overlap_factor)
1034 dns->send_interval = dns->min_latency * LATENCY_FACTOR; 1040 dns->send_interval = dns->min_latency * conf.dns_overlap_factor;
1035 1041
1036 if (dns->send_interval < MIN_SEND_INTERVAL) 1042 if (dns->send_interval < conf.dns_send_interval)
1037 dns->send_interval = MIN_SEND_INTERVAL; 1043 dns->send_interval = conf.dns_send_interval;
1038 } 1044 }
1039 1045
1040 delete *i; 1046 delete *i;
1041 dns_sndpq.erase (i); 1047 dns_sndpq.erase (i);
1042 1048
… …
1175} 1181}
1176 1182
1177bool 1183bool
1178vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos) 1184vpn::send_dnsv4_packet (vpn_packet *pkt, const sockinfo &si, int tos)
1179{ 1185{
1180 int client = ntohs (si.port); 1186 int client = ntohl (si.host);
1181 1187
1182 assert (0 < client && client <= conns.size ()); 1188 assert (0 < client && client <= conns.size ());
1183 1189
1184 connection *c = conns [client - 1]; 1190 connection *c = conns [client - 1];
1185 1191
1186 if (!c->dns) 1192 if (!c->dns)
1187 c->dns = new dns_connection (c); 1193 c->dns = new dns_connection (c);
1188 1194
1189 if (!c->dns->snddq.put (pkt)) 1195 if (c->dns->snddq.put (pkt))
1190 return false;
1191
1192 c->dns->tw.trigger (); 1196 c->dns->tw.trigger ();
1193 1197
1198 // always return true even if the buffer overflows
1194 return true; 1199 return true;
1195} 1200}
1196 1201
1197void 1202void
1198connection::dnsv4_reset_connection () 1203connection::dnsv4_reset_connection ()
… …
1224 if (!send) 1229 if (!send)
1225 { 1230 {
1226 send = r; 1231 send = r;
1227 1232
1228 r->retry++; 1233 r->retry++;
1229 r->timeout = NOW + (r->retry * min_latency * 8.); 1234 r->timeout = NOW + (r->retry * min_latency * conf.dns_timeout_factor);
1230 1235
1231 // the following code changes the query section a bit, forcing 1236 // the following code changes the query section a bit, forcing
1232 // the forwarder to generate a new request 1237 // the forwarder to generate a new request
1233 if (r->stdhdr) 1238 if (r->stdhdr)
1234 { 1239 {
… …
1253 1258
1254 cfg.reset (THISNODE->id); 1259 cfg.reset (THISNODE->id);
1255 send->gen_syn_req (); 1260 send->gen_syn_req ();
1256 } 1261 }
1257 } 1262 }
1258 else if (vpn->dns_sndpq.size () < MAX_OUTSTANDING 1263 else if (vpn->dns_sndpq.size () < conf.dns_max_outstanding
1259 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1))) 1264 && !SEQNO_EQ (rcvseq, sndseq - (MAX_WINDOW - 1)))
1260 { 1265 {
1261 if (last_sent + send_interval <= NOW) 1266 if (last_sent + send_interval <= NOW)
1262 { 1267 {
1263 //printf ("sending data request etc.\n"); //D 1268 //printf ("sending data request etc.\n"); //D
… …
1267 NEXT (NOW + send_interval); 1272 NEXT (NOW + send_interval);
1268 } 1273 }
1269 1274
1270 send = new dns_snd (this); 1275 send = new dns_snd (this);
1271 send->gen_stream_req (sndseq, snddq); 1276 send->gen_stream_req (sndseq, snddq);
1272 send->timeout = NOW + min_latency * 8.; 1277 send->timeout = NOW + min_latency * conf.dns_timeout_factor;
1273 1278
1274 sndseq = (sndseq + 1) & SEQNO_MASK; 1279 sndseq = (sndseq + 1) & SEQNO_MASK;
1275 } 1280 }
1276 else 1281 else
1277 NEXT (last_sent + send_interval); 1282 NEXT (last_sent + send_interval);
… …
1293 poll_interval, send_interval, next - NOW, 1298 poll_interval, send_interval, next - NOW,
1294 vpn->dns_sndpq.size (), snddq.size (), 1299 vpn->dns_sndpq.size (), snddq.size (),
1295 rcvpq.size ()); 1300 rcvpq.size ());
1296 1301
1297 // TODO: no idea when this happens, but when next < NOW, we have a problem 1302 // TODO: no idea when this happens, but when next < NOW, we have a problem
1303 // doesn't seem to happen anymore
1298 if (next < NOW + 0.001) 1304 if (next < NOW + 0.001)
1299 next = NOW + 0.1; 1305 next = NOW + 0.1;
1300 1306
1301 w.start (next); 1307 w.start (next);
1302} 1308}

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