the DNS record type that is being sought
The output from the program is written to stdout. It is supposed to be in
-exactly the same format as a traditional namserver response (see RFC 1035) so
+exactly the same format as a traditional nameserver response (see RFC 1035) so
that Exim can process it as normal. At present, no compression is used.
Error messages are written to stderr.
HOST_NOT_FOUND.
Any DNS record line in a zone file can be prefixed with "DELAY=" and
-a number of milliseconds (followed by whitespace).
+a number of milliseconds (followed by one space).
-Any DNS record line in a zone file can be prefixed with "DNSSEC" and
-at least one space; if all the records found by a lookup are marked
-as such then the response will have the "AD" bit set. */
+Any DNS record line can be prefixed with "DNSSEC ";
+if all the records found by a lookup are marked
+as such then the response will have the "AD" bit set.
+
+Any DNS record line can be prefixed with "NXDOMAIN ";
+The record will be ignored (but the prefix set still applied);
+This lets us return a DNSSEC NXDOMAIN (=> HOST_NOT_FOUND).
+
+Any DNS record line can be prefixed with "AA "
+if all the records found by a lookup are marked
+as such then the response will have the "AA" bit set.
+
+Any DNS record line in a zone file can be prefixed with "TTL=" and
+a number of seconds (followed by one space).
+
+*/
#include <ctype.h>
#include <stdarg.h>
#include <errno.h>
#include <signal.h>
#include <arpa/nameser.h>
+#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/time.h>
#include <dirent.h>
+#include <unistd.h>
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
#define FALSE 0
#define TRUE 1
#define Ustrlen(s) (int)strlen(CCS(s))
#define Ustrncmp(s,t,n) strncmp(CCS(s),CCS(t),n)
#define Ustrncpy(s,t,n) strncpy(CS(s),CCS(t),n)
+#define Ustrtok(s,t) (uschar*)strtok(CS(s),CCS(t))
typedef struct zoneitem {
uschar *zone;
int value;
} tlist;
+#define DEFAULT_TTL 3600U
+
/* On some (older?) operating systems, the standard ns_t_xxx definitions are
not available, and only the older T_xxx ones exist in nameser.h. If ns_t_a is
not defined, assume we are in this state. A really old system might not even
qtypelen the length of qtype
pkptr points to the output buffer pointer; this is updated
countptr points to the record count; this is updated
+ dnssec_p points to the AD flag indicator; this is updated
+ aa_p points to the AA flag indicator; this is updated
Returns: 0 on success, else HOST_NOT_FOUND or NO_DATA or NO_RECOVERY or
PASS_ON - the latter if a "PASS ON NOT FOUND" line is seen
static int
find_records(FILE *f, uschar *zone, uschar *domain, uschar *qtype,
- int qtypelen, uschar **pkptr, int *countptr, BOOL * dnssec)
+ int qtypelen, uschar **pkptr, int *countptr, BOOL * dnssec_p, BOOL * aa_p)
{
int yield = HOST_NOT_FOUND;
int domainlen = Ustrlen(domain);
BOOL pass_on_not_found = FALSE;
tlist *typeptr;
uschar *pk = *pkptr;
-uschar buffer[256];
+uschar buffer[512];
uschar rrdomain[256];
uschar RRdomain[256];
-/* Decode the required type */
+/* Decode the required type */
for (typeptr = type_list; typeptr->name != NULL; typeptr++)
{ if (Ustrcmp(typeptr->name, qtype) == 0) break; }
if (typeptr->name == NULL)
rrdomain[0] = 0; /* No previous domain */
(void)fseek(f, 0, SEEK_SET); /* Start again at the beginning */
-*dnssec = TRUE; /* cancelled by first nonsecure rec found */
-
/* Scan for RRs */
while (fgets(CS buffer, sizeof(buffer), f) != NULL)
int tvalue = typeptr->value;
int qtlen = qtypelen;
BOOL rr_sec = FALSE;
+ BOOL rr_aa = FALSE;
+ BOOL rr_ignore = FALSE;
int delay = 0;
+ uint ttl = DEFAULT_TTL;
p = buffer;
while (isspace(*p)) p++;
p = buffer;
for (;;)
- {
- if (Ustrncmp(p, US"DNSSEC ", 7) == 0) /* tagged as secure */
- {
- rr_sec = TRUE;
- p += 7;
- }
- else if (Ustrncmp(p, US"DELAY=", 6) == 0) /* delay beforee response */
- {
- for (p += 6; *p >= '0' && *p <= '9'; p++)
- delay = delay*10 + *p - '0';
- while (isspace(*p)) p++;
- }
- else
- break;
- }
-
- if (!isspace(*p))
+ {
+ if (Ustrncmp(p, US"DNSSEC ", 7) == 0) /* tagged as secure */
+ {
+ rr_sec = TRUE;
+ p += 7;
+ }
+ if (Ustrncmp(p, US"NXDOMAIN ", 9) == 0) /* ignore record content */
+ {
+ rr_ignore = TRUE;
+ p += 9;
+ }
+ else if (Ustrncmp(p, US"AA ", 3) == 0) /* tagged as authoritative */
+ {
+ rr_aa = TRUE;
+ p += 3;
+ }
+ else if (Ustrncmp(p, US"DELAY=", 6) == 0) /* delay before response */
+ {
+ for (p += 6; *p >= '0' && *p <= '9'; p++) delay = delay*10 + *p - '0';
+ if (isspace(*p)) p++;
+ }
+ else if (Ustrncmp(p, US"TTL=", 4) == 0) /* TTL for record */
+ {
+ ttl = 0;
+ for (p += 4; *p >= '0' && *p <= '9'; p++) ttl = ttl*10 + *p - '0';
+ if (isspace(*p)) p++;
+ }
+ else
+ break;
+ }
+
+ if (!isspace(*p)) /* new domain name */
{
uschar *pp = rrdomain;
uschar *PP = RRdomain;
pp[-1] = 0;
PP[-1] = 0;
}
- }
+ } /* else use previous line's domain name */
/* Compare domain names; first check for a wildcard */
/* The domain matches */
- if (yield == HOST_NOT_FOUND) yield = NO_DATA;
+ if (yield == HOST_NOT_FOUND)
+ {
+ yield = NO_DATA;
+ if (dnssec_p) *dnssec_p = TRUE; /* cancelled by first nonsecure rec found */
+ if (aa_p) *aa_p = TRUE; /* cancelled by first non-aa rec found */
+ }
/* Compare RR types; a CNAME record is always returned */
else if (Ustrncmp(p, qtype, qtypelen) != 0 || !isspace(p[qtypelen])) continue;
/* Found a relevant record */
-
if (delay)
millisleep(delay);
- if (!rr_sec)
- *dnssec = FALSE; /* cancel AD return */
+ if (dnssec_p && !rr_sec)
+ *dnssec_p = FALSE; /* cancel AD return */
+
+ if (aa_p && !rr_aa)
+ *aa_p = FALSE; /* cancel AA return */
+
+ if (rr_ignore) continue;
yield = 0;
*countptr = *countptr + 1;
*pk++ = 0;
*pk++ = 1; /* class = IN */
- pk += 4; /* TTL field; don't care */
+ *pk++ = (ttl >>24) & 255;
+ *pk++ = (ttl >>16) & 255;
+ *pk++ = (ttl >> 8) & 255;
+ *pk++ = ttl & 255;
rdlptr = pk; /* remember rdlength field */
pk += 2;
switch (tvalue)
{
case ns_t_soa:
- p = strtok(p, " ");
- ep = p + strlen(p);
+ p = Ustrtok(p, " ");
+ ep = p + Ustrlen(p);
if (ep[-1] != '.') sprintf(CS ep, "%s.", zone);
- pk = packname(p, pk); /* primary ns */
- p = strtok(NULL, " ");
- pk = packname(p , pk); /* responsible mailbox */
- *(p += strlen(p)) = ' ';
+ pk = packname(p, pk); /* primary ns */
+ p = Ustrtok(NULL, " ");
+ pk = packname(p , pk); /* responsible mailbox */
+ *(p += Ustrlen(p)) = ' ';
while (isspace(*p)) p++;
- pk = longfield(&p, pk); /* serial */
- pk = longfield(&p, pk); /* refresh */
- pk = longfield(&p, pk); /* retry */
- pk = longfield(&p, pk); /* expire */
- pk = longfield(&p, pk); /* minimum */
+ pk = longfield(&p, pk); /* serial */
+ pk = longfield(&p, pk); /* refresh */
+ pk = longfield(&p, pk); /* retry */
+ pk = longfield(&p, pk); /* expire */
+ pk = longfield(&p, pk); /* minimum */
break;
case ns_t_a:
- for (i = 0; i < 4; i++)
- {
- value = 0;
- while (isdigit(*p)) value = value*10 + *p++ - '0';
- *pk++ = value;
- p++;
- }
+ inet_pton(AF_INET, CCS p, pk); /* FIXME: error checking */
+ pk += 4;
break;
- /* The only occurrence of a double colon is for ::1 */
case ns_t_aaaa:
- if (Ustrcmp(p, "::1") == 0)
- {
- memset(pk, 0, 15);
- pk += 15;
- *pk++ = 1;
- }
- else for (i = 0; i < 8; i++)
- {
- value = 0;
- while (isxdigit(*p))
- {
- value = value * 16 + toupper(*p) - (isdigit(*p)? '0' : '7');
- p++;
- }
- *pk++ = (value >> 8) & 255;
- *pk++ = value & 255;
- p++;
- }
+ inet_pton(AF_INET6, CCS p, pk); /* FIXME: error checking */
+ pk += 16;
break;
case ns_t_mx:
break;
case ns_t_txt:
- pp = pk++;
- if (*p == '"') p++; /* Should always be the case */
- while (*p != 0 && *p != '"') *pk++ = *p++;
- *pp = pk - pp - 1;
+ while (*p)
+ {
+ pp = pk++; /* Skip the size byte in output */
+ if (*p == '"') p++; /* Should always be the case */
+ while (*p && *p != '"') *pk++ = *p++;
+ *pp = pk - pp - 1; /* fill in the size */
+ p++; /* skip the closing doublequote */
+ while (isspace(*p)) p++; /* next chunk start */
+ }
break;
case ns_t_tlsa:
- pk = bytefield(&p, pk); /* usage */
- pk = bytefield(&p, pk); /* selector */
- pk = bytefield(&p, pk); /* match type */
+ pk = bytefield(&p, pk); /* usage */
+ pk = bytefield(&p, pk); /* selector */
+ pk = bytefield(&p, pk); /* match type */
while (isxdigit(*p))
{
value = toupper(*p) - (isdigit(*p) ? '0' : '7') << 4;
if (isxdigit(*++p))
- {
- value |= toupper(*p) - (isdigit(*p) ? '0' : '7');
- p++;
- }
+ {
+ value |= toupper(*p) - (isdigit(*p) ? '0' : '7');
+ p++;
+ }
*pk++ = value & 255;
}
case ns_t_srv:
for (i = 0; i < 3; i++)
- {
- value = 0;
- while (isdigit(*p)) value = value*10 + *p++ - '0';
- while (isspace(*p)) p++;
- *pk++ = (value >> 8) & 255;
- *pk++ = value & 255;
- }
+ {
+ value = 0;
+ while (isdigit(*p)) value = value*10 + *p++ - '0';
+ while (isspace(*p)) p++;
+ *pk++ = (value >> 8) & 255;
+ *pk++ = value & 255;
+ }
/* Fall through */
{
}
+
+/*************************************************
+* Special-purpose domains *
+*************************************************/
+
+static int
+special_manyhome(uschar * packet, uschar * domain)
+{
+uschar *pk = packet + 12;
+uschar *rdlptr;
+int i, j;
+
+memset(packet, 0, 12);
+
+for (i = 104; i <= 111; i++) for (j = 0; j <= 255; j++)
+ {
+ pk = packname(domain, pk);
+ *pk++ = (ns_t_a >> 8) & 255;
+ *pk++ = (ns_t_a) & 255;
+ *pk++ = 0;
+ *pk++ = 1; /* class = IN */
+ pk += 4; /* TTL field; don't care */
+ rdlptr = pk; /* remember rdlength field */
+ pk += 2;
+
+ *pk++ = 10; *pk++ = 250; *pk++ = i; *pk++ = j;
+
+ rdlptr[0] = ((pk - rdlptr - 2) >> 8) & 255;
+ rdlptr[1] = (pk - rdlptr - 2) & 255;
+ }
+
+packet[6] = (2048 >> 8) & 255;
+packet[7] = 2048 & 255;
+packet[10] = 0;
+packet[11] = 0;
+
+(void)fwrite(packet, 1, pk - packet, stdout);
+return 0;
+}
+
+static int
+special_again(uschar * packet, uschar * domain)
+{
+int delay = atoi(CCS domain); /* digits at the start of the name */
+if (delay > 0) sleep(delay);
+return TRY_AGAIN;
+}
+
+
/*************************************************
* Entry point and main program *
*************************************************/
uschar domain[256];
uschar buffer[256];
uschar qtype[12];
-uschar packet[512];
+uschar packet[2048 * 32 + 32];
+HEADER *header = (HEADER *)packet;
uschar *pk = packet;
-BOOL dnssec;
+BOOL dnssec = FALSE;
+BOOL aa = FALSE;
signal(SIGALRM, alarmfn);
(void)sprintf(CS buffer, "%s/dnszones", argv[1]);
-d = opendir(CCS buffer);
-if (d == NULL)
+if (!(d = opendir(CCS buffer)))
{
fprintf(stderr, "fakens: failed to opendir %s: %s\n", buffer,
strerror(errno));
return NO_RECOVERY;
}
-while ((de = readdir(d)) != NULL)
+while ((de = readdir(d)))
{
uschar *name = US de->d_name;
if (Ustrncmp(name, "qualify.", 8) == 0)
qtypelen = Ustrlen(qtype);
for (p = qtype; *p != 0; p++) *p = toupper(*p);
-/* Find the domain, lower case it, check that it is in a zone that we handle,
+/* Find the domain, lower case it, deal with any specials,
+check that it is in a zone that we handle,
and set up the zone file name. The zone names in the table all start with a
dot. */
domain[domlen] = 0;
for (i = 0; i < domlen; i++) domain[i] = tolower(domain[i]);
+if (Ustrcmp(domain, "manyhome.test.ex") == 0 && Ustrcmp(qtype, "A") == 0)
+ return special_manyhome(packet, domain);
+else if (domlen >= 14 && Ustrcmp(domain + domlen - 14, "test.again.dns") == 0)
+ return special_again(packet, domain);
+else if (domlen >= 13 && Ustrcmp(domain + domlen - 13, "test.fail.dns") == 0)
+ return NO_RECOVERY;
+
+
if (Ustrchr(domain, '.') == NULL && qualify != NULL &&
Ustrcmp(domain, "dontqualify") != 0)
{
(void)sprintf(CS buffer, "%s/dnszones/%s", argv[1], zonefile);
-/* Initialize the start of the response packet. We don't have to fake up
-everything, because we know that Exim will look only at the answer and
-additional section parts. */
+/* Initialize the start of the response packet. */
memset(packet, 0, 12);
pk += 12;
/* Open the zone file. */
-f = fopen(CS buffer, "r");
-if (f == NULL)
+if (!(f = fopen(CS buffer, "r")))
{
fprintf(stderr, "fakens: failed to open %s: %s\n", buffer, strerror(errno));
return NO_RECOVERY;
}
+header->qr = 1; /* query */
+header->opcode = QUERY; /* standard query */
+header->tc = 0; /* no truncation */
+
/* Find the records we want, and add them to the result. */
count = 0;
-yield = find_records(f, zone, domain, qtype, qtypelen, &pk, &count, &dnssec);
+yield = find_records(f, zone, domain, qtype, qtypelen, &pk, &count, &dnssec, &aa);
if (yield == NO_RECOVERY) goto END_OFF;
+header->ancount = htons(count);
-packet[6] = (count >> 8) & 255;
-packet[7] = count & 255;
+/* If the AA bit should be set (as indicated by the AA prefix in the zone file),
+we are expected to return some records in the authoritative section. Bind9: If
+there is data in the answer section, the authoritative section contains the NS
+records, otherwise it contains the SOA record. Mimic that.
+*/
+
+if (strcmp(qtype, "SOA") != 0 && strcmp(qtype, "NS") != 0)
+ if (count)
+ find_records(f, zone, zone[0] == '.' ? zone+1 : zone, US"NS", 2, &pk, &count, NULL, NULL);
+ else
+ find_records(f, zone, zone[0] == '.' ? zone+1 : zone, US"SOA", 3, &pk, &count, NULL, NULL);
+header->nscount = htons(count - ntohs(header->ancount));
/* There is no need to return any additional records because Exim no longer
(from release 4.61) makes any use of them. */
-
-packet[10] = 0;
-packet[11] = 0;
+header->arcount = 0;
if (dnssec)
- ((HEADER *)packet)->ad = 1;
+ header->ad = 1;
+
+if (aa)
+ header->aa = 1;
/* Close the zone file, write the result, and return. */
return yield;
}
-/* vi: aw ai sw=2
+/* vi: aw ai sw=2 sts=2 ts=8 et
*/
/* End of fakens.c */
git://git.exim.org / exim.git / blobdiff