Refactor the res_search() fail hack

13 files changed, 62 insertions, 33 deletions

diff --git a/src/src/dns.c b/src/src/dns.c
index 8d9ec4708..28bc5958d 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -681,17 +681,6 @@ return rc;
 
 
 
-/* Return the TTL suitable for an NXDOMAIN result, which is given
-in the SOA.  We hope that one was returned in the lookup, and do not
-bother doing a separate lookup; if not found return a forever TTL.
-*/
-
-time_t
-dns_expire_from_soa(dns_answer * dnsa)
-{
-const HEADER * h = (const HEADER *)dnsa->answer;
-dns_scan dnss;
-
 /* This is really gross. The successful return value from res_search() is
 the packet length, which is stored in dnsa->answerlen. If we get a
 negative DNS reply then res_search() returns -1, which causes the bounds
@@ -703,12 +692,38 @@ re-implement res_search() and res_query() so that they don't muddle their
 success and packet length return values.) For added safety we only reset
 the packet length if the packet header looks plausible. */
 
-if (  h->qr == 1 && h->opcode == QUERY && h->tc == 0
+static void
+fake_dnsa_len_for_fail(dns_answer * dnsa)
+{
+const HEADER * h = (const HEADER *)dnsa->answer;
+
+if (  h->qr == 1				/* a response */
+   && h->opcode == QUERY
+   && h->tc == 0				/* nmessage not truncated */
    && (h->rcode == NOERROR || h->rcode == NXDOMAIN)
-   && (ntohs(h->qdcount) == 1 || f.running_in_test_harness)
-   && ntohs(h->ancount) == 0
-   && ntohs(h->nscount) >= 1)
-      dnsa->answerlen = sizeof(dnsa->answer);
+   && (  ntohs(h->qdcount) == 1			/* one question record */
+      || f.running_in_test_harness)
+   && ntohs(h->ancount) == 0			/* no answer records */
+   && ntohs(h->nscount) >= 1)			/* authority records */
+  {
+  DEBUG(D_dns) debug_printf("faking res_search() response length as %d\n",
+    (int)sizeof(dnsa->answer));
+  dnsa->answerlen = sizeof(dnsa->answer);
+  }
+}
+
+
+/* Return the TTL suitable for an NXDOMAIN result, which is given
+in the SOA.  We hope that one was returned in the lookup, and do not
+bother doing a separate lookup; if not found return a forever TTL.
+*/
+
+time_t
+dns_expire_from_soa(dns_answer * dnsa)
+{
+dns_scan dnss;
+
+fake_dnsa_len_for_fail(dnsa);
 
 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
      rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
@@ -1185,23 +1200,7 @@ switch (type)
 
     if (rc == DNS_NOMATCH)
       {
-      /* This is really gross. The successful return value from res_search() is
-      the packet length, which is stored in dnsa->answerlen. If we get a
-      negative DNS reply then res_search() returns -1, which causes the bounds
-      checks for name decompression to fail when it is treated as a packet
-      length, which in turn causes the authority search to fail. The correct
-      packet length has been lost inside libresolv, so we have to guess a
-      replacement value. (The only way to fix this properly would be to
-      re-implement res_search() and res_query() so that they don't muddle their
-      success and packet length return values.) For added safety we only reset
-      the packet length if the packet header looks plausible. */
-
-      const HEADER * h = (const HEADER *)dnsa->answer;
-      if (h->qr == 1 && h->opcode == QUERY && h->tc == 0
-	  && (h->rcode == NOERROR || h->rcode == NXDOMAIN)
-	  && ntohs(h->qdcount) == 1 && ntohs(h->ancount) == 0
-	  && ntohs(h->nscount) >= 1)
-	    dnsa->answerlen = sizeof(dnsa->answer);
+      fake_dnsa_len_for_fail(dnsa);
 
       for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
 	   rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
diff --git a/test/stderr/0002 b/test/stderr/0002
index 8f85e7146..3fbb40d2b 100644
--- a/test/stderr/0002
+++ b/test/stderr/0002
@@ -298,6 +298,7 @@ looking up host name for V4NET.0.0.1
 DNS lookup of 1.0.0.V4NET.in-addr.arpa (PTR) using fakens
 DNS lookup of 1.0.0.V4NET.in-addr.arpa (PTR) succeeded
 IP address lookup yielded "ten-1.test.ex"
+faking res_search() response length as 65535
 DNS lookup of ten-1.test.ex (A) using fakens
 DNS lookup of ten-1.test.ex (A) succeeded
 ten-1.test.ex V4NET.0.0.1 mx=-1 sort=xx 
diff --git a/test/stderr/0044 b/test/stderr/0044
index d2891b87a..1dcde9f8e 100644
--- a/test/stderr/0044
+++ b/test/stderr/0044
@@ -240,7 +240,9 @@ new DNS lookup for 99.99.99.V4NET.rbl.test.ex
 DNS lookup of 99.99.99.V4NET.rbl.test.ex (A) using fakens
 DNS lookup of 99.99.99.V4NET.rbl.test.ex (A) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for 99.99.99.V4NET.rbl.test.ex-A-xxxx, ttl 3000
+faking res_search() response length as 65535
 dnslists: wrote cache entry, ttl=3000
 DNS lookup for 99.99.99.V4NET.rbl.test.ex failed
 => that means V4NET.99.99.99 is not listed at rbl.test.ex
diff --git a/test/stderr/0094 b/test/stderr/0094
index 26cf91605..d464d0a50 100644
--- a/test/stderr/0094
+++ b/test/stderr/0094
@@ -83,12 +83,14 @@ DNS lookup of 90.99.99.V4NET.in-addr.arpa (PTR) using fakens
 DNS lookup of 90.99.99.V4NET.in-addr.arpa (PTR) succeeded
 IP address lookup yielded "oneback.test.ex"
   alias "host1.masq.test.ex"
+faking res_search() response length as 65535
 DNS lookup of oneback.test.ex (A) using fakens
 DNS lookup of oneback.test.ex (A) succeeded
 oneback.test.ex V4NET.99.99.90 mx=-1 sort=xx 
 checking addresses for oneback.test.ex
 Forward DNS security status: unverified
   V4NET.99.99.90 OK
+faking res_search() response length as 65535
 DNS lookup of host1.masq.test.ex (A) using fakens
 DNS lookup of host1.masq.test.ex (A) succeeded
 host1.masq.test.ex V4NET.90.90.90 mx=-1 sort=xx 
diff --git a/test/stderr/0183 b/test/stderr/0183
index 8b3450b78..46d536a11 100644
--- a/test/stderr/0183
+++ b/test/stderr/0183
@@ -92,6 +92,7 @@ ten-1.test.ex in "*"? yes (matched "*")
 DNS lookup of ten-1.test.ex (MX) using fakens
 DNS lookup of ten-1.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for ten-1.test.ex-MX-xxxx, ttl 3000
 ten-1.test.ex (MX resp) DNSSEC
 DNS lookup of ten-1.test.ex (A) using fakens
@@ -300,6 +301,7 @@ ten-1.test.ex in "*"? yes (matched "*")
 DNS lookup of ten-1.test.ex (MX) using fakens
 DNS lookup of ten-1.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for ten-1.test.ex-MX-xxxx, ttl 3000
 ten-1.test.ex (MX resp) DNSSEC
 DNS lookup of ten-1.test.ex (A) using fakens
@@ -450,6 +452,7 @@ nonexist.test.ex in "*"? yes (matched "*")
 DNS lookup of nonexist.test.ex (MX) using fakens
 DNS lookup of nonexist.test.ex (MX) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for nonexist.test.ex-MX-xxxx, ttl 3000
 lookuphost router declined for userx@nonexist.test.ex
 "more" is false: skipping remaining routers
@@ -509,6 +512,7 @@ ten-1.test.ex in "*"? yes (matched "*")
 DNS lookup of ten-1.test.ex (MX) using fakens
 DNS lookup of ten-1.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for ten-1.test.ex-MX-xxxx, ttl 3000
 ten-1.test.ex (MX resp) DNSSEC
 DNS lookup of ten-1.test.ex (A) using fakens
@@ -553,6 +557,7 @@ nonexist.test.ex in "*"? yes (matched "*")
 DNS lookup of nonexist.test.ex (A) using fakens
 DNS lookup of nonexist.test.ex (A) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for nonexist.test.ex-A-xxxx, ttl 3000
 useryz router: defer for usery@nonexist.test.ex
   message: lookup of host "nonexist.test.ex" failed in useryz router
@@ -724,6 +729,7 @@ nonexist.example.com in "*"? yes (matched "*")
 DNS lookup of nonexist.example.com (MX) using fakens
 DNS lookup of nonexist.example.com (MX) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for nonexist.example.com-MX-xxxx, ttl 2
 lookuphost router declined for userx@nonexist.example.com
 "more" is false: skipping remaining routers
@@ -767,6 +773,7 @@ DNS lookup of nonexist.example.com-MX: cached value DNS_NOMATCH past valid time
 DNS lookup of nonexist.example.com (MX) using fakens
 DNS lookup of nonexist.example.com (MX) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  update neg-cache entry for nonexist.example.com-MX-xxxx, ttl 2
 delay router declined for userd@nonexist.example.com
 "more" is false: skipping remaining routers
diff --git a/test/stderr/0361 b/test/stderr/0361
index 0e5ef679a..a8634a3f4 100644
--- a/test/stderr/0361
+++ b/test/stderr/0361
@@ -100,14 +100,17 @@ recurse.test.ex in "*"? yes (matched "*")
 DNS lookup of recurse.test.ex (MX) using fakens
 DNS lookup of recurse.test.ex (MX) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for recurse.test.ex-MX-xxxx, ttl 3000
 r1 router widened recurse.test.ex to recurse.test.ex.test.ex
 recurse.test.ex.test.ex in "*"? yes (matched "*")
 DNS lookup of recurse.test.ex.test.ex (MX) using fakens
 DNS lookup of recurse.test.ex.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for recurse.test.ex.test.ex-MX-xxxx, ttl 3000
 recurse.test.ex.test.ex (MX resp) DNSSEC
+faking res_search() response length as 65535
 DNS lookup of recurse.test.ex.test.ex (A) using fakens
 DNS lookup of recurse.test.ex.test.ex (A) succeeded
 fully qualified name = recurse.test.ex.test.ex
diff --git a/test/stderr/0381 b/test/stderr/0381
index 42b52d031..9cab0970b 100644
--- a/test/stderr/0381
+++ b/test/stderr/0381
@@ -41,12 +41,14 @@ DNS lookup of 97.99.99.V4NET.in-addr.arpa (PTR) using fakens
 DNS lookup of 97.99.99.V4NET.in-addr.arpa (PTR) succeeded
 IP address lookup yielded "x.gov.uk.test.ex"
   alias "x.co.uk.test.ex"
+faking res_search() response length as 65535
 DNS lookup of x.gov.uk.test.ex (A) using fakens
 DNS lookup of x.gov.uk.test.ex (A) succeeded
 x.gov.uk.test.ex V4NET.99.99.97 mx=-1 sort=xx 
 checking addresses for x.gov.uk.test.ex
 Forward DNS security status: unverified
   V4NET.99.99.97 OK
+faking res_search() response length as 65535
 DNS lookup of x.co.uk.test.ex (A) using fakens
 DNS lookup of x.co.uk.test.ex (A) succeeded
 x.co.uk.test.ex V4NET.99.99.97 mx=-1 sort=xx 
diff --git a/test/stderr/0419 b/test/stderr/0419
index 39c797009..0671390b9 100644
--- a/test/stderr/0419
+++ b/test/stderr/0419
@@ -25,8 +25,10 @@ dnslookup router called for k@mxt13.test.ex
 mxt13.test.ex in "*"? yes (matched "*")
 DNS lookup of mxt13.test.ex (MX) using fakens
 DNS lookup of mxt13.test.ex (MX) succeeded
+faking res_search() response length as 65535
 DNS lookup of other1.test.ex (A) using fakens
 DNS lookup of other1.test.ex (A) succeeded
+faking res_search() response length as 65535
 DNS lookup of other2.test.ex (A) using fakens
 DNS lookup of other2.test.ex (A) succeeded
 other1.test.ex in "!mxt13.test.ex : !other1.test.ex : *.test.ex"? no (matched "!other1.test.ex")
diff --git a/test/stderr/0545 b/test/stderr/0545
index 93cdfc62d..a17553ace 100644
--- a/test/stderr/0545
+++ b/test/stderr/0545
@@ -25,6 +25,7 @@ CNAME found: change to eximtesthost.test.ex
 DNS lookup of eximtesthost.test.ex (MX) using fakens
 DNS lookup of eximtesthost.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for eximtesthost.test.ex-MX-xxxx, ttl 3000
 alias-eximtesthost (MX resp) DNSSEC
 DNS lookup of alias-eximtesthost (A) using fakens
@@ -99,6 +100,7 @@ CNAME found: change to eximtesthost.test.ex
 DNS lookup of eximtesthost.test.ex (MX) using fakens
 DNS lookup of eximtesthost.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for eximtesthost.test.ex-MX-xxxx, ttl 3000
 alias-eximtesthost.test.ex (MX resp) DNSSEC
 DNS lookup of alias-eximtesthost.test.ex (A) using fakens
diff --git a/test/stderr/1006 b/test/stderr/1006
index d569343d0..c5dec1804 100644
--- a/test/stderr/1006
+++ b/test/stderr/1006
@@ -13,11 +13,13 @@ DNS lookup of 46.test.ex (A) succeeded
 DNS lookup of v6.test.ex (MX) using fakens
 DNS lookup of v6.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for v6.test.ex-MX-xxxx, ttl 3000
 DNS lookup of v6.test.ex (AAAA) succeeded
 DNS lookup of v6.test.ex (A) using fakens
 DNS lookup of v6.test.ex (A) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for v6.test.ex-A-xxxx, ttl 3000
 >>>>>>>>>>>>>>>> Exim pid=pppp (main) terminating with rc=0 >>>>>>>>>>>>>>>>
 Exim version x.yz ....
@@ -33,10 +35,12 @@ DNS lookup of 46.test.ex (A) succeeded
 DNS lookup of v6.test.ex (MX) using fakens
 DNS lookup of v6.test.ex (MX) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for v6.test.ex-MX-xxxx, ttl 3000
 DNS lookup of v6.test.ex (A) using fakens
 DNS lookup of v6.test.ex (A) gave NO_DATA
 returning DNS_NODATA
+faking res_search() response length as 65535
  writing neg-cache entry for v6.test.ex-A-xxxx, ttl 3000
 >>>>>>>>>>>>>>>> Exim pid=pppp (main) terminating with rc=2 >>>>>>>>>>>>>>>>
 
diff --git a/test/stderr/2201 b/test/stderr/2201
index 23ac93746..051836904 100644
--- a/test/stderr/2201
+++ b/test/stderr/2201
@@ -99,6 +99,7 @@ dnsdb key: unknown
 DNS lookup of unknown (TXT) using fakens
 DNS lookup of unknown (TXT) gave HOST_NOT_FOUND
 returning DNS_NOMATCH
+faking res_search() response length as 65535
  writing neg-cache entry for unknown-TXT-xxxx, ttl 3000
 lookup failed
 unknown in "dnsdb;unknown"? no (end of list)
diff --git a/test/stderr/4802 b/test/stderr/4802
index 9575f881f..a2510cc3a 100644
--- a/test/stderr/4802
+++ b/test/stderr/4802
@@ -4,6 +4,7 @@ admin user
 dropping to exim gid; retaining priv uid
 DNS lookup of mx-sec-a-aa.test.ex (MX) using fakens
 DNS lookup of mx-sec-a-aa.test.ex (MX) succeeded
+faking res_search() response length as 65535
 DNS lookup of a-aa.test.ex (A) using fakens
 DNS lookup of a-aa.test.ex (A) succeeded
 DNS lookup of a-aa.test.ex (A/AAAA) requested AD, but got AA
@@ -15,6 +16,7 @@ dropping to exim gid; retaining priv uid
 DNS lookup of mx-aa-a-sec.test.ex (MX) using fakens
 DNS lookup of mx-aa-a-sec.test.ex (MX) succeeded
 DNS lookup of mx-aa-a-sec.test.ex (MX) requested AD, but got AA
+faking res_search() response length as 65535
 DNS lookup of a-sec.test.ex (A) using fakens
 DNS lookup of a-sec.test.ex (A) succeeded
 >>>>>>>>>>>>>>>> Exim pid=pppp (main) terminating with rc=0 >>>>>>>>>>>>>>>>
diff --git a/test/stderr/4803 b/test/stderr/4803
index a7aa7bfa8..e86035acd 100644
--- a/test/stderr/4803
+++ b/test/stderr/4803
@@ -4,6 +4,7 @@ admin user
 dropping to exim gid; retaining priv uid
 DNS lookup of mx-sec-a-aa.test.ex (MX) using fakens
 DNS lookup of mx-sec-a-aa.test.ex (MX) succeeded
+faking res_search() response length as 65535
 DNS lookup of a-aa.test.ex (A) using fakens
 DNS lookup of a-aa.test.ex (A) succeeded
 DNS faked the AD bit (got AA and matched with dns_trust_aa (test.ex in *))
@@ -19,6 +20,7 @@ DNS lookup of mx-aa-a-sec.test.ex (MX) succeeded
 DNS faked the AD bit (got AA and matched with dns_trust_aa (test.ex in *))
 DNS faked the AD bit (got AA and matched with dns_trust_aa (test.ex in *))
 DNS faked the AD bit (got AA and matched with dns_trust_aa (test.ex in *))
+faking res_search() response length as 65535
 DNS lookup of a-sec.test.ex (A) using fakens
 DNS lookup of a-sec.test.ex (A) succeeded
 >>>>>>>>>>>>>>>> Exim pid=pppp (main) terminating with rc=0 >>>>>>>>>>>>>>>>