BUG 5107: Fix handling of large DNS replies on AIX and Solaris.

On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
truncated replies never give back a resp_len > buflen
which ends up causing DNS resolve failures on large tcp DNS replies.

Also add more debug lines about processing the DNS reply.

(cherry-picked from 5ed9b92097460cd8180db806a08213e97cfb8daa
 with manually resolved conflicts)

diff --git a/source/libads/dns.c b/source/libads/dns.c
index bf51625797a556f3095ed13b667219fa90919f69..5ba6241a771c6cdd819baed4b28fe095c23d28ad 100644 (file)
--- a/source/libads/dns.c
+++ b/source/libads/dns.c
@@ -195,8 +195,15 @@ static BOOL ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
                DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
                return False;
        }
+
        srv->hostname = talloc_strdup( ctx, dcname );
 
+       DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n", 
+                 srv->hostname, 
+                 srv->priority,
+                 srv->weight,
+                 srv->port));
+
        return True;
 }
 
@@ -274,7 +281,7 @@ static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
                               uint8 **buf, int *resp_length )
 {
        uint8 *buffer = NULL;
-       size_t buf_len;
+       size_t buf_len = 0;
        int resp_len = NS_PACKETSZ;     
        
        do {
@@ -303,8 +310,25 @@ static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
                        }
                        return NT_STATUS_UNSUCCESSFUL;
                }
-       } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
-       
+
+               /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
+                  truncated replies never give back a resp_len > buflen
+                  which ends up causing DNS resolve failures on large tcp DNS replies */
+
+               if (buf_len == resp_len) {
+                       if (resp_len == MAX_DNS_PACKET_SIZE) {
+                               DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
+                                       name));
+                               TALLOC_FREE( buffer );
+                               return NT_STATUS_BUFFER_TOO_SMALL;
+                       }
+
+                       resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
+               }
+
+
+       } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
+
        *buf = buffer;
        *resp_length = resp_len;
 
@@ -374,8 +398,10 @@ static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dn
        for ( rrnum=0; rrnum<query_count; rrnum++ ) {
                struct dns_query q;
 
-               if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
-                       DEBUG(1,("ads_dns_lookup_srv: Failed to parse query record!\n"));
+               if (!ads_dns_parse_query(ctx, buffer,
+                                       buffer+resp_len, &p, &q)) {
+                       DEBUG(1,("ads_dns_lookup_srv: "
+                                "Failed to parse query record [%d]!\n", rrnum));
                        return NT_STATUS_UNSUCCESSFUL;
                }
        }
@@ -383,8 +409,10 @@ static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dn
        /* now we are at the answer section */
 
        for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
-               if ( !ads_dns_parse_rr_srv( ctx, buffer, buffer+resp_len, &p, &dcs[rrnum] ) ) {
-                       DEBUG(1,("ads_dns_lookup_srv: Failed to parse answer record!\n"));
+               if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
+                                       &p, &dcs[rrnum])) {
+                       DEBUG(1,("ads_dns_lookup_srv: "
+                                "Failed to parse answer recordi [%d]!\n", rrnum));
                        return NT_STATUS_UNSUCCESSFUL;
                }               
        }
@@ -396,8 +424,10 @@ static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dn
        for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
                struct dns_rr rr;
 
-               if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
-                       DEBUG(1,("ads_dns_lookup_srv: Failed to parse authority record!\n"));
+               if (!ads_dns_parse_rr( ctx, buffer,
+                                       buffer+resp_len, &p, &rr)) {
+                       DEBUG(1,("ads_dns_lookup_srv: "
+                                "Failed to parse authority record! [%d]\n", rrnum));
                        return NT_STATUS_UNSUCCESSFUL;
                }
        }
@@ -408,8 +438,10 @@ static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dn
                struct dns_rr rr;
                int i;
 
-               if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
-                       DEBUG(1,("ads_dns_lookup_srv: Failed to parse additional records section!\n"));
+               if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
+                                       &p, &rr)) {
+                       DEBUG(1,("ads_dns_lookup_srv: Failed "
+                                "to parse additional records section! [%d]\n", rrnum));
                        return NT_STATUS_UNSUCCESSFUL;
                }