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authorbrain <brain@e03df62e-2008-0410-955e-edbf42e46eb7>2006-08-02 18:55:10 +0000
committerbrain <brain@e03df62e-2008-0410-955e-edbf42e46eb7>2006-08-02 18:55:10 +0000
commit2280358b7bce6dcfb426a7e4f25ecff2cd3d95b8 (patch)
tree86a0f1e87f885432799a8f0bd5b570f9e75fe207
parente65b2c70e43882a8b4f31df78b5f9242140320f9 (diff)
More tidying. Add comments. More comments to do :p
git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@4647 e03df62e-2008-0410-955e-edbf42e46eb7
-rw-r--r--src/dns.cpp38
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)