dns :: renderer :: Renderer :: Class Renderer |
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# Class Renderer

source code

    object --+
             |
            Renderer

Helper class for building DNS wire-format messages.

Most applications can use the higher-level dns.message.Message class and its to_wire() method to generate wire-format messages. This class is for those applications which need finer control over the generation of messages.

Typical use:

       r = dns.renderer.Renderer(id=1, flags=0x80, max_size=512)
       r.add_question(qname, qtype, qclass)
       r.add_rrset(dns.renderer.ANSWER, rrset_1)
       r.add_rrset(dns.renderer.ANSWER, rrset_2)
       r.add_rrset(dns.renderer.AUTHORITY, ns_rrset)
       r.add_edns(0, 0, 4096)
       r.add_rrset(dns.renderer.ADDTIONAL, ad_rrset_1)
       r.add_rrset(dns.renderer.ADDTIONAL, ad_rrset_2)
       r.write_header()
       r.add_tsig(keyname, secret, 300, 1, 0, '', request_mac)
       wire = r.get_wire()

Instance Methods | [hide private]
__init__(self, id=None, flags=0, max_size=65535, origin=None) Initialize a new renderer. | source code
_rollback(self, where) Truncate the output buffer at offset where, and remove any compression table entries that pointed beyond the truncation point. | source code
_set_section(self, section) Set the renderer's current section. | source code
add_question(self, qname, rdtype, rdclass=1) Add a question to the message. | source code
add_rrset(self, section, rrset, **kw) Add the rrset to the specified section. | source code
add_rdataset(self, section, name, rdataset, **kw) Add the rdataset to the specified section, using the specified name as the owner name. | source code
add_edns(self, edns, ednsflags, payload, options=None) Add an EDNS OPT record to the message. | source code
add_tsig(self, keyname, secret, fudge, id, tsig_error, other_data, request_mac, algorithm=<DNS name HMAC-MD5.SIG-ALG.REG.INT.>) Add a TSIG signature to the message. | source code
write_header(self) Write the DNS message header. | source code
string |
get_wire(self) Return the wire format message. | source code
Inherited from `object`: `__delattr__`, `__format__`, `__getattribute__`, `__hash__`, `__new__`, `__reduce__`, `__reduce_ex__`, `__repr__`, `__setattr__`, `__sizeof__`, `__str__`, `__subclasshook__`

Instance Variables | [hide private]
dict | compress the compression table
int list of length 4 | counts list of the number of RRs in each section
int | flags the message flags
int | id the message id
string | mac the MAC of the rendered message (if TSIG was used)
int | max_size the maximum size of the message
dns.name.Name object | origin the origin to use when rendering relative names
cStringIO.StringIO object | output where rendering is written
int (dns.renderer.QUESTION, dns.renderer.ANSWER, dns.renderer.AUTHORITY, or dns.renderer.ADDITIONAL) | section the section currently being rendered

Properties | [hide private]
Inherited from `object`: `__class__`

Method Details | [hide private]

### __init__(self, id=None, flags=0, max_size=65535, origin=None) (Constructor) | source code
Initialize a new renderer. Parameters: `id` (int) - the message id `flags` (int) - the DNS message flags `max_size` (int) - the maximum message size; the default is 65535. If rendering results in a message greater than max_size, then dns.exception.TooBig will be raised. `origin` (dns.name.Namem or None.) - the origin to use when rendering relative names Overrides: object.__init__

### _rollback(self, where) | source code
Truncate the output buffer at offset where, and remove any compression table entries that pointed beyond the truncation point. Parameters: `where` (int) - the offset

### _set_section(self, section) | source code
Set the renderer's current section. Sections must be rendered order: QUESTION, ANSWER, AUTHORITY, ADDITIONAL. Sections may be empty. Parameters: `section` (int) - the section Raises: `dns.exception.FormError` - an attempt was made to set a section value less than the current section.

### add_question(self, qname, rdtype, rdclass=1) | source code
Add a question to the message. Parameters: `qname` (dns.name.Name) - the question name `rdtype` (int) - the question rdata type `rdclass` (int) - the question rdata class

### add_rrset(self, section, rrset, **kw) | source code
Add the rrset to the specified section. Any keyword arguments are passed on to the rdataset's to_wire() routine. Parameters: `section` (int) - the section `rrset` (dns.rrset.RRset object) - the rrset

### add_rdataset(self, section, name, rdataset, **kw) | source code
Add the rdataset to the specified section, using the specified name as the owner name. Any keyword arguments are passed on to the rdataset's to_wire() routine. Parameters: `section` (int) - the section `name` (dns.name.Name object) - the owner name `rdataset` (dns.rdataset.Rdataset object) - the rdataset

### add_edns(self, edns, ednsflags, payload, options=None) | source code
Add an EDNS OPT record to the message. Parameters: `edns` (int) - The EDNS level to use. `ednsflags` (int) - EDNS flag values. `payload` (int) - The EDNS sender's payload field, which is the maximum size of UDP datagram the sender can handle. `options` (list of dns.edns.Option instances) - The EDNS options list See Also: RFC 2671

### add_tsig(self, keyname, secret, fudge, id, tsig_error, other_data, request_mac, algorithm=<DNS name HMAC-MD5.SIG-ALG.REG.INT.>) | source code
Add a TSIG signature to the message. Parameters: `keyname` (dns.name.Name object) - the TSIG key name `secret` (string) - the secret to use `fudge` (int) - TSIG time fudge `id` (int) - the message id to encode in the tsig signature `tsig_error` (int) - TSIG error code; default is 0. `other_data` (string) - TSIG other data. `request_mac` (string) - This message is a response to the request which had the specified MAC. `algorithm` - the TSIG algorithm to use

### write_header(self) | source code
Write the DNS message header. Writing the DNS message header is done asfter all sections have been rendered, but before the optional TSIG signature is added.