Initial commit of djbdns-1.05.tar.gz

Source was http://cr.yp.to/djbdns/djbdns-1.05.tar.gz, SHA1 2efdb3a039d0c548f40936aa9cb30829e0ce8c3d

1 files changed, 366 insertions, 0 deletions

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 <sys/types.h>
+#include <sys/socket.h>
+#include <unistd.h>
+#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;
+}