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  3. 扭曲名称如何构建查询的搜索结果？

扭曲名称如何构建查询的搜索结果？

2012-09-16 50 views

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0

以下是扭曲名称11.1的authority.py文件中的FileAuthority._lookup调用的注释版本。此方法负责同步搜索已从BIND区域文件，Python区域文件等索引的DNS信息。

def _lookup(self, name, cls, type, timeout = None): 
    """Return a list of results. 
    name: Queried host name. 
    cls: An enum of the query class. See dns.py: 

     IN, CS, CH, HS = range(1, 5) 

     QUERY_CLASSES = { 
      IN: 'IN', 
      CS: 'CS', 
      CH: 'CH', 
      HS: 'HS', 
      ANY: 'ANY' 
     } 

    type: The type of record to search for (or ANY/255 for any and all). 
      See dns.py: 

     (A, NS, MD, MF, CNAME, SOA, MB, MG, MR, NULL, WKS, PTR, HINFO, MINFO, MX, TXT, 
     RP, AFSDB) = range(1, 19) 
     AAAA = 28 
     SRV = 33 
     NAPTR = 35 
     A6 = 38 
     DNAME = 39 
     SPF = 99 

     QUERY_TYPES = { 
      A: 'A', 
      NS: 'NS', 
      MD: 'MD', 
      MF: 'MF', 
      CNAME: 'CNAME', 
      SOA: 'SOA', 
      MB: 'MB', 
      MG: 'MG', 
      MR: 'MR', 
      NULL: 'NULL', 
      WKS: 'WKS', 
      PTR: 'PTR', 
      HINFO: 'HINFO', 
      MINFO: 'MINFO', 
      MX: 'MX', 
      TXT: 'TXT', 
      RP: 'RP', 
      AFSDB: 'AFSDB', 

      # 19 through 27? Eh, I'll get to 'em. 

      AAAA: 'AAAA', 
      SRV: 'SRV', 
      NAPTR: 'NAPTR', 
      A6: 'A6', 
      DNAME: 'DNAME', 
      SPF: 'SPF' 
     } 

    timeout: The retention time for this record, in seconds. 
    """ 
    cnames = [] 
    results = [] 
    authority = [] 
    additional = [] 
    default_ttl = max(self.soa[1].minimum, self.soa[1].expire) 

    # Do records search. Get a list of classes like Record_A and Record_MX 
    # back. These are defined in dns.py . 
    domain_records = self.records.get(name.lower()) 

    # Structure the results so as to present them the way that DNS records 
    # usually come back. 

    if domain_records: 
     # Loop through all of the results. 
     for record in domain_records: 
      if record.ttl is not None: 
       ttl = record.ttl 
      else: 
       ttl = default_ttl 

      # If we're looking at a [subdomain?] NS record, note it. 
      if record.TYPE == dns.NS and name.lower() != self.soa[0].lower(): 
       # NS record belong to a child zone: this is a referral. As 
       # NS records are authoritative in the child zone, ours here 
       # are not. RFC 2181, section 6.1. 
       authority.append(
        dns.RRHeader(name, record.TYPE, dns.IN, ttl, record, auth=False) 
       ) 

      # Was the record what was requested, or did we want everything? 
      elif record.TYPE == type or type == dns.ALL_RECORDS: 
       results.append(
        dns.RRHeader(name, record.TYPE, dns.IN, ttl, record, auth=True) 
       ) 

      # If we're looking at a CNAME record, note it. 
      if record.TYPE == dns.CNAME: 
       cnames.append(
        dns.RRHeader(name, record.TYPE, dns.IN, ttl, record, auth=True) 
       ) 

     # If no requested records were found, use the CNAME records (if any). 
     if not results: 
      results = cnames 

     # Go through any NS, CNAME, or MX records found, and find the IPs 
     # for those hosts. 
     # 
     # NOTE: The "additional" list doesn't appear to be populated. 
     for record in results + authority: 
      section = {dns.NS: additional, dns.CNAME: results, dns.MX: additional}.get(record.type) 
      if section is not None: 
       n = str(record.payload.name) 
       for rec in self.records.get(n.lower(),()): 
        if rec.TYPE == dns.A: 
         section.append(
          dns.RRHeader(n, dns.A, dns.IN, rec.ttl or default_ttl, rec, auth=True) 
         ) 

     # Not found. Return an SOA record with the name that was requested 
     # (the normal response that you'll see at the console). 
     if not results and not authority: 
      # Empty response. Include SOA record to allow clients to cache 
      # this response. RFC 1034, sections 3.7 and 4.3.4, and RFC 2181 
      # section 7.1. 
      authority.append(
       dns.RRHeader(self.soa[0], dns.SOA, dns.IN, ttl, self.soa[1], auth=True) 
       ) 

     # We return a tuple of individual result lists. Each of the records 
     # is an instance of RRHeader, which wraps the Record_* classes in 
     # dns.py for returning as a result (Resource Record). 
     # 
     # The first item in the tuple refers to the "ANSWER SECTION" in the 
     # DiG output, and the third item refers to the "ADDITIONAL 
     # SECTION". As "authority" was an empty list in the example, no 
     # output relates to it. It will have NS records if any are present, 
     # or contain an SOA record for what was requested if nothing was 
     # found. 
     # 
     #;; QUESTION SECTION: 
     #;example-domain.com.   IN  ANY 
     # 
     #;; ANSWER SECTION: 
     #example-domain.com.  3600 IN  SOA  ns1.example-domain.com. root.example-domain.com. 2003010601 3600 3600 3600 3600 
     #example-domain.com.  3600 IN  A  127.9.9.9 
     #example-domain.com.  3600 IN  NS  ns1.example-domain.com. 
     #example-domain.com.  3600 IN  MX  0 mail.example-domain.com. 
     # 
     #;; ADDITIONAL SECTION: 
     #mail.example-domain.com. 3600 IN  A  123.0.16.43 

     return defer.succeed((results, authority, additional)) 
    else: 
     if name.lower().endswith(self.soa[0].lower()): 
      # We are the authority and we didn't find it. Goodbye. 
      return defer.fail(failure.Failure(dns.AuthoritativeDomainError(name))) 
     return defer.fail(failure.Failure(dns.DomainError(name)))

来源

2012-09-16 22:33:12

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