#ifndef lint
static char copyright[] =
-"$Id: dns.c,v 1.2 1997/03/29 01:25:32 mellon Exp $ Copyright (c) 1997 The Internet Software Consortium. All rights reserved.\n";
+"$Id: dns.c,v 1.3 1997/05/09 08:02:33 mellon Exp $ Copyright (c) 1997 The Internet Software Consortium. All rights reserved.\n";
#endif /* not lint */
#include "dhcpd.h"
static int addlabel PROTO ((u_int8_t *, char *));
static int skipname PROTO ((u_int8_t *));
static int copy_out_name PROTO ((u_int8_t *, u_int8_t *, char *));
+static int nslookup PROTO ((u_int8_t, char *, int, u_int16_t, u_int16_t));
+static int zonelookup PROTO ((u_int8_t, char *, int, u_int16_t));
+u_int16_t dns_port;
/* Initialize the DNS protocol. */
void dns_startup ()
{
struct servent *srv;
- u_int16_t dns_port = htons (53);
struct sockaddr_in from;
/* Only initialize icmp once. */
dns_protocol_initialized = 1;
/* Get the protocol number (should be 1). */
- srv = getsrvbyname ("domain", "tcp");
+ srv = getservbyname ("domain", "tcp");
if (srv)
- port = srv -> s_port;
+ dns_port = srv -> s_port;
+ else
+ dns_port = htons (53);
- /* Get a raw socket for the ICMP protocol. */
+ /* Get a socket for the DNS protocol. */
dns_protocol_fd = socket (AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (!dns_protocol_fd)
error ("unable to create dns socket: %m");
+ pick_name_server ();
+
add_protocol ("dns", dns_protocol_fd, dns_packet, 0);
}
called with a null pointer. Otherwise, the callback is called with the
address of the string returned by the name server. */
-int ns_inaddr_lookup (server, id, inaddr)
- struct sockaddr_in *server;
+int ns_inaddr_lookup (id, inaddr)
u_int16_t id;
struct iaddr inaddr;
{
for (i = 3; i >= 0; --i) {
label = s++;
*label = 1;
- c = inaddr -> addr [i];
+ c = inaddr.iabuf [i];
if (c > 100) {
++*label;
*s++ = '0' + c / 100;
s += addlabel (s, "in-addr");
s += addlabel (s, "arpa");
*s++ = 0;
- return nslookup (server, id, namebuf, s - namebuf, T_PTR, C_IN);
+/* return nslookup (id, namebuf, s - namebuf, T_PTR, C_IN); */
+ return zonelookup (id, namebuf, s - namebuf, C_IN);
}
/* Construct and transmit a name server query. */
-int nslookup (server, id, qname, namelen, qtype, qclass)
- struct sockaddr_in *server;
+static int nslookup (id, qname, namelen, qtype, qclass)
u_int8_t id;
char *qname;
int namelen;
{
HEADER *hdr;
unsigned char query [512];
- unsigned char *s;
+ u_int8_t *s;
int len;
- int i;
+ int i, status;
+ struct sockaddr_in *server = pick_name_server ();
/* Construct a header... */
hdr = (HEADER *)query;
- memset (&hdr, 0, sizeof hdr);
+ memset (hdr, 0, sizeof *hdr);
hdr -> id = htons (id);
hdr -> rd = 1;
hdr -> opcode = QUERY;
hdr -> qdcount = htons (1);
/* Copy in the name we're looking up. */
- s = (u_int8_t)(hdr + 1);
+ s = (u_int8_t *)(hdr + 1);
memcpy (s, qname, namelen);
s += namelen;
return 1;
}
+/* Construct a query for the SOA for a specified name.
+ Try every possible SOA name starting from the name specified and going
+ to the root name - e.g., for
+
+ 215.5.5.192.in-addr.arpa, look for SOAs matching:
+
+ 215.5.5.5.192.in-addr.arpa
+ 5.5.192.in-addr.arpa
+ 5.192.in-addr.arpa
+ 192.in-addr.arpa
+ in-addr.arpa
+ arpa */
+
+static int zonelookup (id, qname, namelen, qclass)
+ u_int8_t id;
+ char *qname;
+ int namelen;
+ u_int16_t qclass;
+{
+ HEADER *hdr;
+ unsigned char query [512];
+ u_int8_t *s, *nptr;
+ int len;
+ int i, status, count;
+ struct sockaddr_in *server = pick_name_server ();
+
+ /* Construct a header... */
+ hdr = (HEADER *)query;
+ memset (hdr, 0, sizeof *hdr);
+ hdr -> id = htons (id);
+ hdr -> rd = 1;
+ hdr -> opcode = QUERY;
+
+ /* Copy in the name we're looking up. */
+ s = (u_int8_t *)(hdr + 1);
+ memcpy (s, qname, namelen);
+ s += namelen;
+
+ /* Set the query type. */
+ putUShort (s, T_SOA);
+ s += sizeof (u_int16_t);
+
+ /* Set the query class. */
+ putUShort (s, qclass);
+ s += sizeof (u_int16_t);
+ count = 1;
+
+ /* Now query up the hierarchy. */
+ nptr = (u_int8_t *)(hdr + 1);
+ while (*(nptr += *nptr + 1)) {
+ /* Store a compressed reference from the full name. */
+ putUShort (s, ntohs (htons (0xC000) |
+ htons (nptr - &query [0])));
+ s += sizeof (u_int16_t);
+
+ /* Store the query type. */
+ putUShort (s, T_SOA);
+ s += sizeof (u_int16_t);
+
+ putUShort (s, qclass);
+ s += sizeof (u_int16_t);
+
+ /* Increment the query count... */
+ ++count;
+break;
+ }
+ hdr -> qdcount = htons (count);
+
+dump_raw (query, s - query);
+ /* Send the query. */
+ status = sendto (dns_protocol_fd, query, s - query, 0,
+ (struct sockaddr *)server, sizeof *server);
+
+ /* If the send failed, report the failure. */
+ if (status < 0)
+ return 0;
+ return 1;
+}
+
/* Process a reply from a name server. */
-dns_packet (protocol)
+void dns_packet (protocol)
struct protocol *protocol;
{
HEADER *ns_header;
unsigned char nbuf [512];
unsigned char *base;
unsigned char *dptr;
- int type;
- int class;
- int ttl;
- int rdlength;
- char nbuf [MAXDNAME];
+ u_int16_t type;
+ u_int16_t class;
+ TIME ttl;
+ u_int16_t rdlength;
+ int len, status;
+ int i;
len = sizeof from;
- status = recvfrom (protocol -> fd, icbuf, sizeof icbuf, 0,
+ status = recvfrom (protocol -> fd, buf, sizeof buf, 0,
(struct sockaddr *)&from, &len);
if (status < 0) {
warn ("icmp_echoreply: %m");
ns_header = (HEADER *)buf;
base = (unsigned char *)(ns_header + 1);
+#if 0
/* Ignore invalid packets... */
if (ntohs (ns_header -> id) > ns_query_max) {
printf ("Out-of-range NS message; id = %d\n",
ntohs (ns_header -> id));
return;
}
+#endif
/* Parse the response... */
dptr = base;
- /* Skip over the query name... */
- dptr += skipname (dptr);
- /* Skip over the query type and the query class. */
- dptr += 2 * sizeof (short);
-
- /* Skip over the reply name... */
- dptr += skipname (dptr);
- /* Extract the numeric fields: */
- getUShort (dptr, (u_int8_t *)&type);
- dptr += sizeof type;
- getULong (dptr, (u_int8_t *)&class);
- dptr += sizeof class;
- getULong (dptr, (u_int8_t *)&ttl);
- dptr += sizeof ttl;
- getUShort (dptr, (u_int8_t *)&rdlength);
- dptr += sizeof rdlength;
-
- switch (type) {
- case T_A:
- printf ("A record; value is %d.%d.%d.%d",
- dptr [0], dptr [1], dptr [2], dptr [3]);
- break;
-
- case T_CNAME:
- case T_PTR:
- copy_out_name (base, dptr, nbuf);
- printf ("Domain name; value is %s\n", nbuf);
- return;
+ /* Skip over the queries... */
+ for (i = 0; i < ntohs (ns_header -> qdcount); i++) {
+ dptr += skipname (dptr);
+ /* Skip over the query type and query class. */
+ dptr += 2 * sizeof (u_int16_t);
+ }
- default:
- printf ("unhandled type: %x\n", type);
+ /* Process the answers... */
+ for (i = 0; i < ntohs (ns_header -> ancount); i++) {
+ /* Skip over the name we looked up. */
+ dptr += skipname (dptr);
+
+ /* Get the type. */
+ type = getUShort (dptr);
+ dptr += sizeof type;
+
+ /* Get the class. */
+ class = getUShort (dptr);
+ dptr += sizeof class;
+
+ /* Get the time-to-live. */
+ ttl = getULong (dptr);
+ dptr += sizeof ttl;
+
+ /* Get the length of the reply. */
+ rdlength = getUShort (dptr);
+ dptr += sizeof rdlength;
+
+ switch (type) {
+ case T_A:
+ note ("A record; value is %d.%d.%d.%d",
+ dptr [0], dptr [1], dptr [2], dptr [3]);
+ break;
+
+ case T_CNAME:
+ case T_PTR:
+ copy_out_name (base, dptr, nbuf);
+ note ("Domain name; value is %s\n", nbuf);
+ return;
+
+ default:
+ note ("unhandled type: %x", type);
+ }
}
}
projects / thirdparty / dhcp.git / commitdiff
