diff options
| -rw-r--r-- | src/dns.cpp | 38 |
1 files changed, 30 insertions, 8 deletions
diff --git a/src/dns.cpp b/src/dns.cpp index 3beb6b7c5..d7f7b9697 100644 --- a/src/dns.cpp +++ b/src/dns.cpp @@ -367,47 +367,66 @@ int DNS::dns_getname(const insp_inaddr *ip) */ DNSResult DNS::dns_getresult() { - /* retrieve result of DNS query (buffered) */ + /* Fetch dns query response and decide where it belongs */ dns_header header; dns_connection *req; int length; unsigned char buffer[sizeof(dns_header)]; + /* Attempt to read a header */ length = recv(master_socket,buffer,sizeof(dns_header),0); + /* Did we get the whole header? */ if (length < 12) + /* Nope - something screwed up. */ return std::make_pair(-1,""); + /* Put the read header info into a header class */ dns_fill_header(&header,buffer,length - 12); - // Get the id of this request + /* Get the id of this request. + * Its a 16 bit value stored in two char's, + * so we use logic shifts to create the value. + */ unsigned long this_id = header.id[1] + (header.id[0] << 8); - // Do we have a pending request for it? - + /* Do we have a pending request matching this id? */ connlist_iter n_iter = connections.find(this_id); if (n_iter == connections.end()) { + /* Somehow we got a DNS response for a request we never made... */ log(DEBUG,"DNS: got a response for a query we didnt send with fd=%d queryid=%d",master_socket,this_id); return std::make_pair(-1,""); } else { - /* Remove the query from the list */ + /* Remove the query from the list of pending queries */ req = (dns_connection*)n_iter->second; - /* We don't delete c here, because its done later when needed */ connections.erase(n_iter); } + + /* Inform the dns_connection class that it has a result to be read. + * When its finished it will return a DNSInfo which is a pair of + * unsigned char* resource record data, and an error message. + */ DNSInfo data = req->result_ready(header, length); std::string resultstr; + /* Check if we got a result, if we didnt, its an error */ if (data.first == NULL) { + /* An error. + * Mask the ID with the value of ERROR_MASK, so that + * the dns_deal_with_classes() function knows that its + * an error response and needs to be treated uniquely. + * Put the error message in the second field. + */ delete req; return std::make_pair(this_id | ERROR_MASK, data.second); } else { + /* Forward lookups come back as binary data. We must format them into ascii */ if (req->type == DNS_QRY_A) { char formatted[16]; @@ -416,16 +435,17 @@ DNSResult DNS::dns_getresult() } else { + /* Reverse lookups just come back as char* */ resultstr = std::string((const char*)data.first); } + /* Build the reply with the id and hostname/ip in it */ delete req; return std::make_pair(this_id,resultstr); } } -/** A result is ready, process it - */ +/* A result is ready, process it */ DNSInfo dns_connection::result_ready(dns_header &header, int length) { int i = 0; @@ -446,7 +466,9 @@ DNSInfo dns_connection::result_ready(dns_header &header, int length) if (header.ancount < 1) return std::make_pair((unsigned char*)NULL,"No resource records returned"); + /* Subtract the length of the header from the length of the packet */ length -= 12; + while ((unsigned int)q < header.qdcount && i < length) { if (header.payload[i] > 63) |