From 0e5b2871ca6456b01d4bf037a6e68badf1ff1a41 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Henryk=20Pl=C3=B6tz?= Date: Fri, 3 Oct 2014 19:58:52 +0200 Subject: Initial commit of djbdns-1.05.tar.gz Source was http://cr.yp.to/djbdns/djbdns-1.05.tar.gz, SHA1 2efdb3a039d0c548f40936aa9cb30829e0ce8c3d --- dns_transmit.c | 366 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 366 insertions(+) create mode 100644 dns_transmit.c (limited to 'dns_transmit.c') diff --git a/dns_transmit.c b/dns_transmit.c new file mode 100644 index 0000000..4d6e39f --- /dev/null +++ b/dns_transmit.c @@ -0,0 +1,366 @@ +#include +#include +#include +#include "socket.h" +#include "alloc.h" +#include "error.h" +#include "byte.h" +#include "uint16.h" +#include "dns.h" + +static int serverwantstcp(const char *buf,unsigned int len) +{ + char out[12]; + + if (!dns_packet_copy(buf,len,0,out,12)) return 1; + if (out[2] & 2) return 1; + return 0; +} + +static int serverfailed(const char *buf,unsigned int len) +{ + char out[12]; + unsigned int rcode; + + if (!dns_packet_copy(buf,len,0,out,12)) return 1; + rcode = out[3]; + rcode &= 15; + if (rcode && (rcode != 3)) { errno = error_again; return 1; } + return 0; +} + +static int irrelevant(const struct dns_transmit *d,const char *buf,unsigned int len) +{ + char out[12]; + char *dn; + unsigned int pos; + + pos = dns_packet_copy(buf,len,0,out,12); if (!pos) return 1; + if (byte_diff(out,2,d->query + 2)) return 1; + if (out[4] != 0) return 1; + if (out[5] != 1) return 1; + + dn = 0; + pos = dns_packet_getname(buf,len,pos,&dn); if (!pos) return 1; + if (!dns_domain_equal(dn,d->query + 14)) { alloc_free(dn); return 1; } + alloc_free(dn); + + pos = dns_packet_copy(buf,len,pos,out,4); if (!pos) return 1; + if (byte_diff(out,2,d->qtype)) return 1; + if (byte_diff(out + 2,2,DNS_C_IN)) return 1; + + return 0; +} + +static void packetfree(struct dns_transmit *d) +{ + if (!d->packet) return; + alloc_free(d->packet); + d->packet = 0; +} + +static void queryfree(struct dns_transmit *d) +{ + if (!d->query) return; + alloc_free(d->query); + d->query = 0; +} + +static void socketfree(struct dns_transmit *d) +{ + if (!d->s1) return; + close(d->s1 - 1); + d->s1 = 0; +} + +void dns_transmit_free(struct dns_transmit *d) +{ + queryfree(d); + socketfree(d); + packetfree(d); +} + +static int randombind(struct dns_transmit *d) +{ + int j; + + for (j = 0;j < 10;++j) + if (socket_bind4(d->s1 - 1,d->localip,1025 + dns_random(64510)) == 0) + return 0; + if (socket_bind4(d->s1 - 1,d->localip,0) == 0) + return 0; + return -1; +} + +static const int timeouts[4] = { 1, 3, 11, 45 }; + +static int thisudp(struct dns_transmit *d) +{ + const char *ip; + + socketfree(d); + + while (d->udploop < 4) { + for (;d->curserver < 16;++d->curserver) { + ip = d->servers + 4 * d->curserver; + if (byte_diff(ip,4,"\0\0\0\0")) { + d->query[2] = dns_random(256); + d->query[3] = dns_random(256); + + d->s1 = 1 + socket_udp(); + if (!d->s1) { dns_transmit_free(d); return -1; } + if (randombind(d) == -1) { dns_transmit_free(d); return -1; } + + if (socket_connect4(d->s1 - 1,ip,53) == 0) + if (send(d->s1 - 1,d->query + 2,d->querylen - 2,0) == d->querylen - 2) { + struct taia now; + taia_now(&now); + taia_uint(&d->deadline,timeouts[d->udploop]); + taia_add(&d->deadline,&d->deadline,&now); + d->tcpstate = 0; + return 0; + } + + socketfree(d); + } + } + + ++d->udploop; + d->curserver = 0; + } + + dns_transmit_free(d); return -1; +} + +static int firstudp(struct dns_transmit *d) +{ + d->curserver = 0; + return thisudp(d); +} + +static int nextudp(struct dns_transmit *d) +{ + ++d->curserver; + return thisudp(d); +} + +static int thistcp(struct dns_transmit *d) +{ + struct taia now; + const char *ip; + + socketfree(d); + packetfree(d); + + for (;d->curserver < 16;++d->curserver) { + ip = d->servers + 4 * d->curserver; + if (byte_diff(ip,4,"\0\0\0\0")) { + d->query[2] = dns_random(256); + d->query[3] = dns_random(256); + + d->s1 = 1 + socket_tcp(); + if (!d->s1) { dns_transmit_free(d); return -1; } + if (randombind(d) == -1) { dns_transmit_free(d); return -1; } + + taia_now(&now); + taia_uint(&d->deadline,10); + taia_add(&d->deadline,&d->deadline,&now); + if (socket_connect4(d->s1 - 1,ip,53) == 0) { + d->tcpstate = 2; + return 0; + } + if ((errno == error_inprogress) || (errno == error_wouldblock)) { + d->tcpstate = 1; + return 0; + } + + socketfree(d); + } + } + + dns_transmit_free(d); return -1; +} + +static int firsttcp(struct dns_transmit *d) +{ + d->curserver = 0; + return thistcp(d); +} + +static int nexttcp(struct dns_transmit *d) +{ + ++d->curserver; + return thistcp(d); +} + +int dns_transmit_start(struct dns_transmit *d,const char servers[64],int flagrecursive,const char *q,const char qtype[2],const char localip[4]) +{ + unsigned int len; + + dns_transmit_free(d); + errno = error_io; + + len = dns_domain_length(q); + d->querylen = len + 18; + d->query = alloc(d->querylen); + if (!d->query) return -1; + + uint16_pack_big(d->query,len + 16); + byte_copy(d->query + 2,12,flagrecursive ? "\0\0\1\0\0\1\0\0\0\0\0\0" : "\0\0\0\0\0\1\0\0\0\0\0\0gcc-bug-workaround"); + byte_copy(d->query + 14,len,q); + byte_copy(d->query + 14 + len,2,qtype); + byte_copy(d->query + 16 + len,2,DNS_C_IN); + + byte_copy(d->qtype,2,qtype); + d->servers = servers; + byte_copy(d->localip,4,localip); + + d->udploop = flagrecursive ? 1 : 0; + + if (len + 16 > 512) return firsttcp(d); + return firstudp(d); +} + +void dns_transmit_io(struct dns_transmit *d,iopause_fd *x,struct taia *deadline) +{ + x->fd = d->s1 - 1; + + switch(d->tcpstate) { + case 0: case 3: case 4: case 5: + x->events = IOPAUSE_READ; + break; + case 1: case 2: + x->events = IOPAUSE_WRITE; + break; + } + + if (taia_less(&d->deadline,deadline)) + *deadline = d->deadline; +} + +int dns_transmit_get(struct dns_transmit *d,const iopause_fd *x,const struct taia *when) +{ + char udpbuf[513]; + unsigned char ch; + int r; + int fd; + + errno = error_io; + fd = d->s1 - 1; + + if (!x->revents) { + if (taia_less(when,&d->deadline)) return 0; + errno = error_timeout; + if (d->tcpstate == 0) return nextudp(d); + return nexttcp(d); + } + + if (d->tcpstate == 0) { +/* +have attempted to send UDP query to each server udploop times +have sent query to curserver on UDP socket s +*/ + r = recv(fd,udpbuf,sizeof udpbuf,0); + if (r <= 0) { + if (errno == error_connrefused) if (d->udploop == 2) return 0; + return nextudp(d); + } + if (r + 1 > sizeof udpbuf) return 0; + + if (irrelevant(d,udpbuf,r)) return 0; + if (serverwantstcp(udpbuf,r)) return firsttcp(d); + if (serverfailed(udpbuf,r)) { + if (d->udploop == 2) return 0; + return nextudp(d); + } + socketfree(d); + + d->packetlen = r; + d->packet = alloc(d->packetlen); + if (!d->packet) { dns_transmit_free(d); return -1; } + byte_copy(d->packet,d->packetlen,udpbuf); + queryfree(d); + return 1; + } + + if (d->tcpstate == 1) { +/* +have sent connection attempt to curserver on TCP socket s +pos not defined +*/ + if (!socket_connected(fd)) return nexttcp(d); + d->pos = 0; + d->tcpstate = 2; + return 0; + } + + if (d->tcpstate == 2) { +/* +have connection to curserver on TCP socket s +have sent pos bytes of query +*/ + r = write(fd,d->query + d->pos,d->querylen - d->pos); + if (r <= 0) return nexttcp(d); + d->pos += r; + if (d->pos == d->querylen) { + struct taia now; + taia_now(&now); + taia_uint(&d->deadline,10); + taia_add(&d->deadline,&d->deadline,&now); + d->tcpstate = 3; + } + return 0; + } + + if (d->tcpstate == 3) { +/* +have sent entire query to curserver on TCP socket s +pos not defined +*/ + r = read(fd,&ch,1); + if (r <= 0) return nexttcp(d); + d->packetlen = ch; + d->tcpstate = 4; + return 0; + } + + if (d->tcpstate == 4) { +/* +have sent entire query to curserver on TCP socket s +pos not defined +have received one byte of packet length into packetlen +*/ + r = read(fd,&ch,1); + if (r <= 0) return nexttcp(d); + d->packetlen <<= 8; + d->packetlen += ch; + d->tcpstate = 5; + d->pos = 0; + d->packet = alloc(d->packetlen); + if (!d->packet) { dns_transmit_free(d); return -1; } + return 0; + } + + if (d->tcpstate == 5) { +/* +have sent entire query to curserver on TCP socket s +have received entire packet length into packetlen +packet is allocated +have received pos bytes of packet +*/ + r = read(fd,d->packet + d->pos,d->packetlen - d->pos); + if (r <= 0) return nexttcp(d); + d->pos += r; + if (d->pos < d->packetlen) return 0; + + socketfree(d); + if (irrelevant(d,d->packet,d->packetlen)) return nexttcp(d); + if (serverwantstcp(d->packet,d->packetlen)) return nexttcp(d); + if (serverfailed(d->packet,d->packetlen)) return nexttcp(d); + + queryfree(d); + return 1; + } + + return 0; +} -- cgit v1.2.3