3 [_]J*@shdZddlmZddlZddlZddlZddlZddlZddl m Z dZ dZ dZ dZGdd d eZdS) z*Help for building DNS wire format messages)BytesION)longc@seZdZdZdddZddZd d Zejj fd d Z d dZ ddZ dddZ ejjfddZejjfddZddZddZddZdS)RendereraHelper class for building DNS wire-format messages. Most applications can use the higher-level L{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() output, a BytesIO, where rendering is written id: the message id flags: the message flags max_size: the maximum size of the message origin: the origin to use when rendering relative names compress: the compression table section: an int, the section currently being rendered counts: list of the number of RRs in each section mac: the MAC of the rendered message (if TSIG was used) NrcCsht|_|dkr tjdd|_n||_||_||_||_i|_t |_ ddddg|_ |jj dd|_ dS)zInitialize a new renderer.Nri s )routputrandomrandintidflagsmax_sizeorigincompressQUESTIONsectioncountswritemac)selfrrrrr1/tmp/pip-build-yz_zf6az/dnspython/dns/renderer.py__init__Ms zRenderer.__init__cCs^|jj||jjg}x(|jjD]\}}||kr&|j|q&Wx|D] }|j|=qJWdS)zTruncate the output buffer at offset *where*, and remove any compression table entries that pointed beyond the truncation point. N)r seektruncateritemsappend)rwhereZkeys_to_deletekvrrr _rollback^s   zRenderer._rollbackcCs&|j|kr"|j|krtjj||_dS)aSet the renderer's current section. Sections must be rendered order: QUESTION, ANSWER, AUTHORITY, ADDITIONAL. Sections may be empty. Raises dns.exception.FormError if an attempt was made to set a section value less than the current section. N)rdns exceptionZ FormError)rrrrr _set_sectionms  zRenderer._set_sectioncCsz|jt|jj}|j|j|j|j|jjtj d|||jj}||j krd|j |t j j|jtd7<dS)zAdd a question to the message.z!HHrN)r'rr tellto_wirerrrstructpackrr$r%r&TooBigr)rqnameZrdtypeZrdclassbeforeafterrrr add_question|s     zRenderer.add_questioncKsh|j||jj}|j|j|j|jf|}|jj}||jkrR|j|tj j |j ||7<dS)zAdd the rrset to the specified section. Any keyword arguments are passed on to the rdataset's to_wire() routine. N) r'r r(r)rrrr$r%r&r,r)rrZrrsetkwr.nr/rrr add_rrsets     zRenderer.add_rrsetcKsj|j||jj}|j||j|j|jf|}|jj}||jkrT|j|tj j |j ||7<dS)zAdd 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. N) r'r r(r)rrrr$r%r&r,r)rrnameZrdatasetr1r.r2r/rrr add_rdatasets     zRenderer.add_rdatasetc Cs|tdM}||d>O}|jt|jj}|jjtjddtj j ||d|dk rJ|jj}x|D]}tjd|j d}|jj||jj} |j |j|jj} | | dkst |jj| dtjd | | }|jj||jjddqfW|jj} | |dkst |jj|dtjd | |}|jj||jjdd|jj} | |jkrr|j|tjj|jtd 7<dS) z&Add an EDNS OPT record to the message.l~z!BHHIHrNz!HHirz!Hr)rr' ADDITIONALr r(rr*r+r% rdatatypeOPTotyper)AssertionErrorrrr$r&r,r) rZednsZ ednsflagspayloadoptionsr.ZlstartoptstuffstartendZlendr/rrradd_ednss<                  zRenderer.add_ednsc CsJ|jj} tjj| ||ttj||||||d \} |_} |j| |dS)z$Add a TSIG signature to the message.) algorithmN) r getvaluer%tsigsigninttimer _write_tsig) rkeynamesecretfudger tsig_error other_data request_macrCs tsig_rdatactxrrradd_tsigs  zRenderer.add_tsigc CsT|jj} tjj| ||ttj|||||||dkd| d \} |_}|j| ||S)ayAdd a TSIG signature to the message. Unlike add_tsig(), this can be used for a series of consecutive DNS envelopes, e.g. for a zone transfer over TCP [RFC2845, 4.4]. For the first message in the sequence, give ctx=None. For each subsequent message, give the ctx that was returned from the add_multi_tsig() call for the previous message.NT)rRfirstZmultirC) r rDr%rErFrGrHrrI) rrRrJrKrLrrMrNrOrCrPrQrrradd_multi_tsigs   zRenderer.add_multi_tsigcCs|jt|jj}|j|j|j|j|jjtj dt j j t j jdd|jj}|jj||jj}||dkszt||jkr|j|t jj|jj|d|jjtj d|||jtd7<|jjd|jjtj d|jt|jjdddS)Nz!HHIHrirz!Hr )r'r7r r(r)rrrr*r+r%r8ZTSIG rdataclassANYr;rr$r&r,rr)rrQrJr.Z rdata_startr/rrrrIs$        zRenderer._write_tsigc CsX|jjd|jjtjd|j|j|jd|jd|jd|jd|jjdddS)zWrite the DNS message header. Writing the DNS message header is done after all sections have been rendered, but before the optional TSIG signature is added. rz!HHHHHHrrrN)r rrr*r+rrr)rrrr write_headers  zRenderer.write_headercCs |jjS)zReturn the wire format message.)r rD)rrrrget_wire szRenderer.get_wire)NrrN)N)__name__ __module__ __qualname____doc__rr$r'r%rWINr0r3r5rBrEZdefault_algorithmrSrUrIrYrZrrrrr$s'   $r)r^iorr*r rHZ dns.exceptionr%Zdns.tsig_compatrrZANSWERZ AUTHORITYr7objectrrrrrs