stop-gap: doc glibc 2.31 RES_TRUSTAD/trust-ad

[exim.git] / src / src / dns.c

diff --git a/src/src/dns.c b/src/src/dns.c
index 28bc5958d62ea162a7871941007a9b1074553fb3..e13aa74e24b17d880885bfd5e5cdad393df628d4 100644 (file)
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -60,7 +60,8 @@ if (stat(CS utilname, &statbuf) >= 0)
   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));
+  DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) using fakens\n",
+               name, dns_text_type(type));
 
   argv[0] = utilname;
   argv[1] = config_main_directory;
@@ -68,7 +69,7 @@ if (stat(CS utilname, &statbuf) >= 0)
   argv[3] = dns_text_type(type);
   argv[4] = NULL;
 
-  pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE);
+  pid = child_open(argv, NULL, 0000, &infd, &outfd, FALSE, US"fakens-search");
   if (pid < 0)
     log_write(0, LOG_MAIN|LOG_PANIC_DIE, "failed to run fakens: %s",
       strerror(errno));
@@ -221,16 +222,15 @@ a name that can be used to look up PTR records.
 
 Arguments:
   string     the IP address as a string
-  buffer     a suitable buffer, long enough to hold the result
 
-Returns:     nothing
+Returns:     an allocated string
 */
 
-void
-dns_build_reverse(const uschar *string, uschar *buffer)
+uschar *
+dns_build_reverse(const uschar * string)
 {
-const uschar *p = string + Ustrlen(string);
-uschar *pp = buffer;
+const uschar * p = string + Ustrlen(string);
+gstring * g = NULL;
 
 /* Handle IPv4 address */
 
@@ -240,14 +240,13 @@ if (Ustrchr(string, ':') == NULL)
   {
   for (int i = 0; i < 4; i++)
     {
-    const uschar *ppp = p;
+    const uschar * ppp = p;
     while (ppp > string && ppp[-1] != '.') ppp--;
-    Ustrncpy(pp, ppp, p - ppp);
-    pp += p - ppp;
-    *pp++ = '.';
+    g = string_catn(g, ppp, p - ppp);
+    g = string_catn(g, US".", 1);
     p = ppp - 1;
     }
-  Ustrcpy(pp, US"in-addr.arpa");
+  g = string_catn(g, US"in-addr.arpa", 12);
   }
 
 /* Handle IPv6 address; convert to binary so as to fill out any
@@ -257,6 +256,8 @@ abbreviation in the textual form. */
 else
   {
   int v6[4];
+
+  g = string_get_tainted(32, is_tainted(string));
   (void)host_aton(string, v6);
 
   /* The original specification for IPv6 reverse lookup was to invert each
@@ -265,8 +266,8 @@ else
 
   for (int i = 3; i >= 0; i--)
     for (int j = 0; j < 32; j += 4)
-      pp += sprintf(CS pp, "%x.", (v6[i] >> j) & 15);
-  Ustrcpy(pp, US"ip6.arpa.");
+      g = string_fmt_append(g, "%x.", (v6[i] >> j) & 15);
+  g = string_catn(g, US"ip6.arpa.", 9);
 
   /* Another way of doing IPv6 reverse lookups was proposed in conjunction
   with A6 records. However, it fell out of favour when they did. The
@@ -290,6 +291,7 @@ else
 
   }
 #endif
+return string_from_gstring(g);
 }
 
 
@@ -499,6 +501,8 @@ const uschar * auth_name;
 const uschar * trusted;
 
 if (dnsa->answerlen < 0) return FALSE;
+/* Beware that newer versions of glibc on Linux will filter out the ad bit
+unless their shiny new RES_TRUSTAD bit is set for the resolver.  */
 if (h->ad) return TRUE;
 
 /* If the resolver we ask is authoritative for the domain in question, it may
@@ -693,7 +697,7 @@ success and packet length return values.) For added safety we only reset
 the packet length if the packet header looks plausible. */
 
 static void
-fake_dnsa_len_for_fail(dns_answer * dnsa)
+fake_dnsa_len_for_fail(dns_answer * dnsa, int type)
 {
 const HEADER * h = (const HEADER *)dnsa->answer;
 
@@ -706,8 +710,8 @@ if (  h->qr == 1                            /* a response */
    && 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));
+  DEBUG(D_dns) debug_printf("faking res_search(%s) response length as %d\n",
+    dns_text_type(type), (int)sizeof(dnsa->answer));
   dnsa->answerlen = sizeof(dnsa->answer);
   }
 }
@@ -719,11 +723,11 @@ bother doing a separate lookup; if not found return a forever TTL.
 */
 
 time_t
-dns_expire_from_soa(dns_answer * dnsa)
+dns_expire_from_soa(dns_answer * dnsa, int type)
 {
 dns_scan dnss;
 
-fake_dnsa_len_for_fail(dnsa);
+fake_dnsa_len_for_fail(dnsa, type);
 
 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
      rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)
@@ -893,7 +897,7 @@ if (dnsa->answerlen < 0) switch (h_errno)
   case HOST_NOT_FOUND:
     DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave HOST_NOT_FOUND\n"
       "returning DNS_NOMATCH\n", name, dns_text_type(type));
-    return dns_fail_return(name, type, dns_expire_from_soa(dnsa), DNS_NOMATCH);
+    return dns_fail_return(name, type, dns_expire_from_soa(dnsa, type), DNS_NOMATCH);
 
   case TRY_AGAIN:
     DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave TRY_AGAIN\n",
@@ -913,7 +917,7 @@ if (dnsa->answerlen < 0) switch (h_errno)
       }
     DEBUG(D_dns) debug_printf("%s is in dns_again_means_nonexist: returning "
       "DNS_NOMATCH\n", name);
-    return dns_fail_return(name, type, dns_expire_from_soa(dnsa), DNS_NOMATCH);
+    return dns_fail_return(name, type, dns_expire_from_soa(dnsa, type), DNS_NOMATCH);
 
 #else   /* For stand-alone tests */
     return dns_fail_return(name, type, 0, DNS_AGAIN);
@@ -927,7 +931,7 @@ if (dnsa->answerlen < 0) switch (h_errno)
   case NO_DATA:
     DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave NO_DATA\n"
       "returning DNS_NODATA\n", name, dns_text_type(type));
-    return dns_fail_return(name, type, dns_expire_from_soa(dnsa), DNS_NODATA);
+    return dns_fail_return(name, type, dns_expire_from_soa(dnsa, type), DNS_NODATA);
 
   default:
     DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) gave unknown DNS error %d\n"
@@ -1200,7 +1204,7 @@ switch (type)
 
     if (rc == DNS_NOMATCH)
       {
-      fake_dnsa_len_for_fail(dnsa);
+      fake_dnsa_len_for_fail(dnsa, T_CSA);
 
       for (rr = dns_next_rr(dnsa, &dnss, RESET_AUTHORITY);
           rr; rr = dns_next_rr(dnsa, &dnss, RESET_NEXT)