Scriptable structures

module_qstate

class module_qstate

Module state, per query.

This class provides these data attributes:

qinfo

(query_info) Informations about query being answered. Name, RR type, RR class.

query_flags

(uint16) Flags for query. See QF_BIT_ predefined constants.

is_priming

If this is a (stub or root) priming query (with hints).

reply

comm_reply contains server replies.

return_msg

(dns_msg) The reply message, with message for client and calling module (read-only attribute). Note that if you want to create of modify return_msg you should use DNSMessage.

return_rcode

The rcode, in case of error, instead of a reply message. Determines whether the return_msg contains reply.

region

Region for this query. Cleared when query process finishes.

curmod

Which module is executing.

ext_state[]

Module states.

env

Environment for this query.

mesh_info

Mesh related information for this query.

edns_opts_front_in

Incoming EDNS options from the front end.

edns_opts_front_in_iter

Iterator for edns_opts_front_in.

edns_opts_back_out

Outgoing EDNS options to the back end.

edns_opts_back_out_iter

Iterator for edns_opts_back_out.

edns_opts_back_in

Incoming EDNS options from the back end.

edns_opts_back_in_iter

Iterator for ends_opts_back_in.

edns_opts_front_out

Outgoing EDNS options to the front end.

edns_opts_front_out_iter

Iterator for edns_opts_front_out.

no_cache_lookup

Flag to indicate whether modules should answer from the cache.

no_cache_store

Flag to indicate whether modules should store answer in the cache.

query_info

class query_info

This class provides these data attributes:

qname

The original question in the wireformat format (e.g. \x03www\x03nic\x02cz\x00 for www.nic.cz)

qname_len

Lenght of question name (number of bytes).

qname_list[]

The question qname converted into list of labels (e.g. [‘www’,’nic’,’cz’,’‘] for www.nic.cz)

qname_str

The question qname converted into string (e.g. www.nic.cz. for www.nic.cz)

qtype

The class type asked for. See RR_TYPE_ predefined constants.

qtype_str

The qtype in display presentation format (string) (e.g ‘A’ for RR_TYPE_A)

qclass

The question class. See RR_CLASS_ predefined constants.

qclass_str

The qclass in display presentation format (string).

edns_data

class edns_data

This class represents the EDNS information parsed/encoded from/to a packet. It provides these data attributes:

edns_present

If EDNS OPT record is present.

ext_rcode

Extended RCODE.

edns_version

The EDNS version number.

bits

The EDNS bits field from ttl (host order): Z.

udp_size

UDP reassembly size.

opt_list

The EDNS option list.

opt_list_iter

Iterator for opt_list.

edns_option

class edns_option

This class represents an EDNS option (code, data) found in EDNS option lists. It provides these data attributes:

code

The EDNS option code.

data

The EDNS option data.

reply_info

class reply_info

This class provides these data attributes:

flags

The flags for the answer, host byte order.

qdcount

Number of RRs in the query section. If qdcount is not 0, then it is 1, and the data that appears in the reply is the same as the query_info. Host byte order.

ttl

TTL of the entire reply (for negative caching). only for use when there are 0 RRsets in this message. if there are RRsets, check those instead.

security

The security status from DNSSEC validation of this message. See sec_status_ predefined constants.

an_numrrsets

Number of RRsets in each section. The answer section. Add up the RRs in every RRset to calculate the number of RRs, and the count for the dns packet. The number of RRs in RRsets can change due to RRset updates.

ns_numrrsets

Count of authority section RRsets

ar_numrrsets

Count of additional section RRsets

rrset_count

Number of RRsets: an_numrrsets + ns_numrrsets + ar_numrrsets

rrsets[]

(ub_packed_rrset_key) List of RR sets in the order in which they appear in the reply message. Number of elements is ancount + nscount + arcount RRsets.

ref[]

(rrset_ref) Packed array of ids (see counts) and pointers to packed_rrset_key. The number equals ancount + nscount + arcount RRsets. These are sorted in ascending pointer, the locking order. So this list can be locked (and id, ttl checked), to see if all the data is available and recent enough.

dns_msg

class dns_msg

Region allocated message reply

This class provides these data attributes:

qinfo

(query_info) Informations about query.

rep

(reply_info) This attribute points to the packed reply structure.

packed_rrset_key

class packed_rrset_key

The identifying information for an RRset.

This class provides these data attributes:

dname

The domain name. If not empty (for id = None) it is allocated, and contains the wireformat domain name. This dname is not canonicalized. E.g., the dname contains \x03www\x03nic\x02cz\x00 for www.nic.cz.

dname_len

Length of the domain name, including last 0 root octet.

dname_list[]

The domain name dname converted into list of labels (see query_info.qname_list).

dname_str

The domain name dname converted into string (see query_info.qname_str).

flags

Flags.

type

The rrset type in network format.

type_str

The rrset type in display presentation format.

rrset_class

The rrset class in network format.

rrset_class_str

The rrset class in display presentation format.

ub_packed_rrset_key

class ub_packed_rrset_key

This structure contains an RRset. A set of resource records that share the same domain name, type and class. Due to memory management and threading, the key structure cannot be deleted, although the data can be. The id can be set to 0 to store and the structure can be recycled with a new id.

The ub_packed_rrset_key provides these data attributes:

entry

(lruhash_entry) Entry into hashtable. Note the lock is never destroyed, even when this key is retired to the cache. the data pointer (if not None) points to a packed_rrset.

id

The ID of this rrset. unique, based on threadid + sequenceno. ids are not reused, except after flushing the cache. zero is an unused entry, and never a valid id. Check this value after getting entry.lock. The other values in this struct may only be altered after changing the id (which needs a writelock on entry.lock).

rk

(packed_rrset_key) RR set data.

lruhash_entry

class lruhash_entry

The ub_packed_rrset_key provides these data attributes:

lock

rwlock for access to the contents of the entry. Note that you cannot change hash and key, if so, you have to delete it to change hash or key.

data

(packed_rrset_data) entry data stored in wireformat (RRs and RRsigs).

packed_rrset_data

class packed_rrset_data

Rdata is stored in wireformat. The dname is stored in wireformat.

TTLs are stored as absolute values (and could be expired).

RRSIGs are stored in the arrays after the regular rrs.

You need the packed_rrset_key to know dname, type, class of the resource records in this RRset. (if signed the rrsig gives the type too).

The packed_rrset_data provides these data attributes:

ttl

TTL (in seconds like time()) of the RRset. Same for all RRs see rfc2181(5.2).

count

Number of RRs.

rrsig_count

Number of rrsigs, if 0 no rrsigs.

trust

The trustworthiness of the RRset data.

security

Security status of the RRset data. See sec_status_ predefined constants.

rr_len[]

Length of every RR’s rdata, rr_len[i] is size of rr_data[i].

rr_ttl[]

TTL of every rr. rr_ttl[i] ttl of rr i.

rr_data[]

Array of RR’s rdata (list of strings). The rdata is stored in uncompressed wireformat. The first 16B of rr_data[i] is rdlength in network format.

DNSMessage

class DNSMessage

Abstract representation of DNS message.

Usage

This example shows how to create an authoritative answer response

msg = DNSMessage(qstate.qinfo.qname_str, RR_TYPE_A, RR_CLASS_IN, PKT_AA)

#append RR
if (qstate.qinfo.qtype == RR_TYPE_A) or (qstate.qinfo.qtype == RR_TYPE_ANY):
    msg.answer.append("%s 10 IN A 127.0.0.1" % qstate.qinfo.qname_str)

#set qstate.return_msg
if not msg.set_return_msg(qstate):
    raise Exception("Can't create response")

The DNSMessage provides these methods and data attributes:

__init__(self, rr_name, rr_type, rr_class = RR_CLASS_IN, query_flags = 0, default_ttl = 0)

Prepares an answer (DNS packet) from given information. Query flags are combination of PKT_xx constants.

set_return_msg(self, qstate)
This method fills qstate return message according to the given informations.
It takes lists of RRs in each section of answer, created necessary RRsets in wire format and store the result in qstate.return_msg. Returns 1 if OK.
rr_name

RR name of question.

rr_type

RR type of question.

rr_class

RR class of question.

default_ttl

Default time-to-live.

query_flags

Query flags. See PKT_ predefined constants.

question[]

List of resource records that should appear (in the same order) in question section of answer.

answer[]

List of resource records that should appear (in the same order) in answer section of answer.

authority[]

List of resource records that should appear (in the same order) in authority section of answer.

additional[]

List of resource records that should appear (in the same order) in additional section of answer.

pythonmod_env

class pythonmod_env

Global state for the module.

This class provides these data attributes:

data

Here you can keep your own data shared across each thread.

fname

Python script filename.

qstate

Module query state.

pythonmod_qstate

class pythonmod_qstate

Per query state for the iterator module.

This class provides these data attributes:

data

Here you can keep your own private data (each thread has own data object).