-/* $Cambridge: exim/src/src/dns.c,v 1.9 2005/06/29 10:56:35 ph10 Exp $ */
+/* $Cambridge: exim/src/src/dns.c,v 1.10 2005/09/13 15:40:07 ph10 Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
#endif
+/*************************************************
+* Fake DNS resolver *
+*************************************************/
+
+/* This function is called instead of res_search() when Exim is running in its
+test harness. It recognizes some special domain names, and uses them to force
+failure and retry responses (optionally with a delay). It also recognises the
+zones test.ex and 10.in-addr.arpa, and for those it calls an external utility
+that mock-up a nameserver, if it can find the utility. Otherwise, it passes its
+arguments on to res_search().
+
+Background: the original test suite required a real nameserver to carry the
+test.ex and 10.in-addr.arpa zones, whereas the new test suit has the fake
+server for portability. This code supports both.
+
+Arguments:
+ name the domain name
+ type the DNS record type
+ answerptr where to put the answer
+ size size of the answer area
+
+Returns: length of returned data, or -1 on error (h_errno set)
+*/
+
+static int
+fakens_search(uschar *name, int type, uschar *answerptr, int size)
+{
+int len = Ustrlen(name);
+uschar *endname = name + len;
+
+if (len >= 14 && Ustrcmp(endname - 14, "test.again.dns") == 0)
+ {
+ int delay = Uatoi(name); /* digits at the start of the name */
+ DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n",
+ name, dns_text_type(type));
+ if (delay > 0)
+ {
+ DEBUG(D_dns) debug_printf("delaying %d seconds\n", delay);
+ sleep(delay);
+ }
+ h_errno = TRY_AGAIN;
+ return -1;
+ }
+
+if (len >= 13 && Ustrcmp(endname - 13, "test.fail.dns") == 0)
+ {
+ DEBUG(D_dns) debug_printf("Return from DNS lookup of %s (%s) faked for testing\n",
+ name, dns_text_type(type));
+ h_errno = NO_RECOVERY;
+ return -1;
+ }
+
+if (Ustrcmp(name, "test.ex") == 0 ||
+ (len > 8 && Ustrcmp(endname - 8, ".test.ex") == 0) ||
+ (len >= 16 && Ustrcmp(endname - 16, ".10.in-addr.arpa") == 0))
+ {
+ uschar utilname[256];
+ struct stat statbuf;
+
+ (void)string_format(utilname, sizeof(utilname), "%s/../bin/fakens",
+ spool_directory);
+
+ if (stat(CS utilname, &statbuf) >= 0)
+ {
+ pid_t pid;
+ int infd, outfd, rc;
+ uschar *argv[5];
+
+ DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens\n",
+ name, dns_text_type(type));
+
+ argv[0] = utilname;
+ argv[1] = spool_directory;
+ argv[2] = name;
+ argv[3] = dns_text_type(type);
+ argv[4] = NULL;
+
+ pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE);
+ if (pid < 0)
+ log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to run fakens: %s",
+ strerror(errno));
+
+ len = 0;
+ rc = -1;
+ while (size > 0 && (rc = read(outfd, answerptr, size)) > 0)
+ {
+ len += rc;
+ answerptr += rc;
+ size -= rc;
+ }
+
+ if (rc < 0)
+ log_write(0, LOG_MAIN|LOG_PANIC_DIE, "read from fakens failed: %s",
+ strerror(errno));
+
+ switch(child_close(pid, 0))
+ {
+ case 0: return len;
+ case 1: h_errno = HOST_NOT_FOUND; break;
+ case 2: h_errno = TRY_AGAIN; break;
+ default:
+ case 3: h_errno = NO_RECOVERY; break;
+ case 4: h_errno = NO_DATA; break;
+ }
+ return -1;
+ }
+ }
+
+/* Not test.ex or 10.in-addr.arpa, or fakens utility not found. */
+
+return res_search(CS name, C_IN, type, answerptr, size);
+}
+
+
/*************************************************
* Initialize and configure resolver *
int
dns_basic_lookup(dns_answer *dnsa, uschar *name, int type)
{
+int rc = -1;
#ifndef STAND_ALONE
-int rc;
uschar *save;
#endif
return previous->data.val;
}
-/* If we are running in the test harness, recognize a couple of special
-names that always give error returns. This makes it straightforward to
-test the handling of DNS errors. */
-
-if (running_in_test_harness)
- {
- uschar *endname = name + Ustrlen(name);
- if (Ustrcmp(endname - 14, "test.again.dns") == 0)
- {
- int delay = Uatoi(name); /* digits at the start of the name */
- DEBUG(D_dns) debug_printf("Real DNS lookup of %s (%s) bypassed for testing\n",
- name, dns_text_type(type));
- if (delay > 0)
- {
- DEBUG(D_dns) debug_printf("delaying %d seconds\n", delay);
- sleep(delay);
- }
- DEBUG(D_dns) debug_printf("returning DNS_AGAIN\n");
- return dns_return(name, type, DNS_AGAIN);
- }
- if (Ustrcmp(endname - 13, "test.fail.dns") == 0)
- {
- DEBUG(D_dns) debug_printf("Real DNS lookup of %s (%s) bypassed for testing\n",
- name, dns_text_type(type));
- DEBUG(D_dns) debug_printf("returning DNS_FAIL\n");
- return dns_return(name, type, DNS_FAIL);
- }
- }
-
/* If configured, check the hygene of the name passed to lookup. Otherwise,
although DNS lookups may give REFUSED at the lower level, some resolvers
turn this into TRY_AGAIN, which is silly. Give a NOMATCH return, since such
#endif /* STAND_ALONE */
/* Call the resolver; for an overlong response, res_search() will return the
-number of bytes the message would need, so we need to check for this case.
-The effect is to truncate overlong data. */
+number of bytes the message would need, so we need to check for this case. The
+effect is to truncate overlong data.
+
+If we are running in the test harness, instead of calling the normal resolver
+(res_search), we call fakens_search(), which recognizes certain special
+domains, and interfaces to a fake nameserver for certain special zones. */
+
+if (running_in_test_harness)
+ dnsa->answerlen = fakens_search(name, type, dnsa->answer, MAXPACKET);
+else
+ dnsa->answerlen = res_search(CS name, C_IN, type, dnsa->answer, MAXPACKET);
-dnsa->answerlen = res_search(CS name, C_IN, type, dnsa->answer, MAXPACKET);
if (dnsa->answerlen > MAXPACKET) dnsa->answerlen = MAXPACKET;
if (dnsa->answerlen < 0) switch (h_errno)
git://git.exim.org / users / jgh / exim.git / commitdiff