Mirror/zeek
1
0
Fork 0
mirror of https://github.com/zeek/zeek.git synced 2025-10-05 08:08:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Merge remote branch 'origin/topic/seth/dns-updates'

Browse source 
* origin/topic/seth/dns-updates:
  Fixed some bugs with capturing data in the base DNS script.
  Some updates to the base DNS script.

Closes #702.
This commit is contained in:
Robin Sommer 2011-12-18 15:18:05 -08:00
commit 0a3e160a8d
4 changed files with 100 additions and 69 deletions
Download patch file Download diff file Expand all files Collapse all files

138
scripts/base/protocols/dns/main.bro
View file

@ -4,50 +4,50 @@ module DNS;
export {
redef enum Log::ID += { LOG };
type Info: record {
ts: time &log;
uid: string &log;
id: conn_id &log;
proto: transport_proto &log;
trans_id: count &log &optional;
query: string &log &optional;
qclass: count &log &optional;
qclass_name: string &log &optional;
qtype: count &log &optional;
qtype_name: string &log &optional;
rcode: count &log &optional;
rcode_name: string &log &optional;
QR: bool &log &default=F;
AA: bool &log &default=F;
TC: bool &log &default=F;
RD: bool &log &default=F;
RA: bool &log &default=F;
Z: count &log &default=0;
TTL: interval &log &optional;
answers: set[string] &log &optional;
ts: time &log;
uid: string &log;
id: conn_id &log;
proto: transport_proto &log;
trans_id: count &log &optional;
query: string &log &optional;
qclass: count &log &optional;
qclass_name: string &log &optional;
qtype: count &log &optional;
qtype_name: string &log &optional;
rcode: count &log &optional;
rcode_name: string &log &optional;
QR: bool &log &default=F;
AA: bool &log &default=F;
TC: bool &log &default=F;
RD: bool &log &default=F;
RA: bool &log &default=F;
Z: count &log &default=0;
answers: vector of string &log &optional;
TTLs: vector of interval &log &optional;
## This value indicates if this request/response pair is ready to be logged.
ready: bool &default=F;
total_answers: count &optional;
total_replies: count &optional;
};
type State: record {
## Indexed by query id, returns Info record corresponding to
## query/response which haven't completed yet.
pending: table[count] of Info &optional;
## This is the list of DNS responses that have completed based on the
## number of responses declared and the number received. The contents
## of the set are transaction IDs.
finished_answers: set[count] &optional;
};
global log_dns: event(rec: Info);
## This is called by the specific dns_*_reply events with a "reply" which
## may not represent the full data available from the resource record, but
## may not represent the full data available from the resource record, but
## it's generally considered a summarization of the response(s).
global do_reply: event(c: connection, msg: dns_msg, ans: dns_answer, reply: string);
}
@ -58,11 +58,11 @@ redef record connection += {
};
# DPD configuration.
redef capture_filters += {
redef capture_filters += {
["dns"] = "port 53",
["mdns"] = "udp and port 5353",
["llmns"] = "udp and port 5355",
["netbios-ns"] = "udp port 137",
["netbios-ns"] = "udp port 137",
};
const dns_ports = { 53/udp, 53/tcp, 137/udp, 5353/udp, 5355/udp };
@ -89,7 +89,7 @@ function new_session(c: connection, trans_id: count): Info
state$finished_answers=set();
c$dns_state = state;
}
local info: Info;
info$ts = network_time();
info$id = c$id;
@ -102,23 +102,29 @@ function new_session(c: connection, trans_id: count): Info
function set_session(c: connection, msg: dns_msg, is_query: bool)
{
if ( ! c?$dns_state || msg$id !in c$dns_state$pending )
{
c$dns_state$pending[msg$id] = new_session(c, msg$id);
# Try deleting this transaction id from the set of finished answers.
# Sometimes hosts will reuse ports and transaction ids and this should
# be considered to be a legit scenario (although bad practice).
delete c$dns_state$finished_answers[msg$id];
}
c$dns = c$dns_state$pending[msg$id];
c$dns$rcode = msg$rcode;
c$dns$rcode_name = base_errors[msg$rcode];
if ( ! is_query )
{
if ( ! c$dns?$total_answers )
c$dns$total_answers = msg$num_answers;
if ( c$dns?$total_replies &&
if ( c$dns?$total_replies &&
c$dns$total_replies != msg$num_answers + msg$num_addl + msg$num_auth )
{
event conn_weird("dns_changed_number_of_responses", c,
fmt("The declared number of responses changed from %d to %d",
event conn_weird("dns_changed_number_of_responses", c,
fmt("The declared number of responses changed from %d to %d",
c$dns$total_replies,
msg$num_answers + msg$num_addl + msg$num_auth));
}
@ -129,27 +135,30 @@ function set_session(c: connection, msg: dns_msg, is_query: bool)
}
}
}
event DNS::do_reply(c: connection, msg: dns_msg, ans: dns_answer, reply: string) &priority=5
{
set_session(c, msg, F);
c$dns$AA = msg$AA;
c$dns$RA = msg$RA;
c$dns$TTL = ans$TTL;
if ( ans$answer_type == DNS_ANS )
{
c$dns$AA = msg$AA;
c$dns$RA = msg$RA;
if ( msg$id in c$dns_state$finished_answers )
event conn_weird("dns_reply_seen_after_done", c, "");
if ( reply != "" )
{
if ( ! c$dns?$answers )
c$dns$answers = set();
add c$dns$answers[reply];
c$dns$answers = vector();
c$dns$answers[|c$dns$answers|] = reply;
if ( ! c$dns?$TTLs )
c$dns$TTLs = vector();
c$dns$TTLs[|c$dns$TTLs|] = ans$TTL;
}
if ( c$dns?$answers && |c$dns$answers| == c$dns$total_answers )
{
add c$dns_state$finished_answers[c$dns$trans_id];
@ -158,13 +167,12 @@ event DNS::do_reply(c: connection, msg: dns_msg, ans: dns_answer, reply: string)
}
}
}
event DNS::do_reply(c: connection, msg: dns_msg, ans: dns_answer, reply: string) &priority=-5
{
if ( c$dns$ready )
{
Log::write(DNS::LOG, c$dns);
add c$dns_state$finished_answers[c$dns$trans_id];
# This record is logged and no longer pending.
delete c$dns_state$pending[c$dns$trans_id];
}
@ -173,41 +181,41 @@ event DNS::do_reply(c: connection, msg: dns_msg, ans: dns_answer, reply: string)
event dns_request(c: connection, msg: dns_msg, query: string, qtype: count, qclass: count) &priority=5
{
set_session(c, msg, T);
c$dns$RD = msg$RD;
c$dns$TC = msg$TC;
c$dns$qclass = qclass;
c$dns$qclass_name = classes[qclass];
c$dns$qtype = qtype;
c$dns$qtype_name = query_types[qtype];
# Decode netbios name queries
# Note: I'm ignoring the name type for now. Not sure if this should be
# Note: I'm ignoring the name type for now. Not sure if this should be
# worked into the query/response in some fashion.
if ( c$id$resp_p == 137/udp )
query = decode_netbios_name(query);
c$dns$query = query;
c$dns$Z = msg$Z;
}
event dns_A_reply(c: connection, msg: dns_msg, ans: dns_answer, a: addr) &priority=5
{
event DNS::do_reply(c, msg, ans, fmt("%s", a));
}
event dns_TXT_reply(c: connection, msg: dns_msg, ans: dns_answer, str: string) &priority=5
{
event DNS::do_reply(c, msg, ans, str);
}
event dns_AAAA_reply(c: connection, msg: dns_msg, ans: dns_answer, a: addr,
event dns_AAAA_reply(c: connection, msg: dns_msg, ans: dns_answer, a: addr,
astr: string) &priority=5
{
# TODO: What should we do with astr?
event DNS::do_reply(c, msg, ans, fmt("%s", a));
}
event dns_NS_reply(c: connection, msg: dns_msg, ans: dns_answer, name: string) &priority=5
{
event DNS::do_reply(c, msg, ans, name);
@ -223,12 +231,12 @@ event dns_MX_reply(c: connection, msg: dns_msg, ans: dns_answer, name: string,
{
event DNS::do_reply(c, msg, ans, name);
}
event dns_PTR_reply(c: connection, msg: dns_msg, ans: dns_answer, name: string) &priority=5
{
event DNS::do_reply(c, msg, ans, name);
}
event dns_SOA_reply(c: connection, msg: dns_msg, ans: dns_answer, soa: dns_soa) &priority=5
{
event DNS::do_reply(c, msg, ans, soa$mname);
@ -238,7 +246,7 @@ event dns_WKS_reply(c: connection, msg: dns_msg, ans: dns_answer) &priority=5
{
event DNS::do_reply(c, msg, ans, "");
}
event dns_SRV_reply(c: connection, msg: dns_msg, ans: dns_answer) &priority=5
{
event DNS::do_reply(c, msg, ans, "");
@ -247,17 +255,17 @@ event dns_SRV_reply(c: connection, msg: dns_msg, ans: dns_answer) &priority=5
# TODO: figure out how to handle these
#event dns_EDNS(c: connection, msg: dns_msg, ans: dns_answer)
# {
#
#
# }
#
#event dns_EDNS_addl(c: connection, msg: dns_msg, ans: dns_edns_additional)
# {
#
#
# }
#
#event dns_TSIG_addl(c: connection, msg: dns_msg, ans: dns_tsig_additional)
# {
#
#
# }
@ -271,10 +279,10 @@ event connection_state_remove(c: connection) &priority=-5
{
if ( ! c?$dns_state )
return;
# If Bro is expiring state, we should go ahead and log all unlogged
# If Bro is expiring state, we should go ahead and log all unlogged
# request/response pairs now.
for ( trans_id in c$dns_state$pending )
Log::write(DNS::LOG, c$dns_state$pending[trans_id]);
}