commit cb819ce76b011c4ee84fa15014c92166bca49577 Author: Damian Johnson <atagar@torproject.org> Date: Sat Mar 17 16:19:09 2012 -0700 Completely untested start for descriptor parsing Starting on server descriptor parsing. This is gonna need some other classes and helper functions (such as an ExitPolicy and is_valid_ip_address()) but otherwise should be pretty straight forward. --- stem/descriptor/server_descriptor.py | 132 ++++++++++++++++++++++++++++++++++ 1 files changed, 132 insertions(+), 0 deletions(-) diff --git a/stem/descriptor/server_descriptor.py b/stem/descriptor/server_descriptor.py new file mode 100644 index 0000000..e9782bc --- /dev/null +++ b/stem/descriptor/server_descriptor.py @@ -0,0 +1,132 @@ +""" +Parsing for Tor server descriptors, which contains the infrequently changing +information about a Tor relay (contact information, exit policy, public keys, +etc). This information is provided from a few sources... + +- control port via 'GETINFO desc/*' queries +- the 'cached-descriptors' file in tor's data directory +- tor metrics, at https://metrics.torproject.org/data.html +""" + +import re + +from stem.descriptor.descriptor import Descriptor + +ENTRY_START = "router" +ENTRY_END = "router-signature" + +KEYWORD_CHAR = "[a-zA-Z0-9-]" +WHITESPACE = "[ \t]" +KEYWORD_LINE = re.compile("^(%s+)%s*(%s*)$" % (KEYWORD_CHAR, WHITESPACE, KEYWORD_CHAR)) +SIGNATURE_START = re.compile("^-----BEGIN %s+ PUBLIC KEY-----$" % KEYWORD_CHAR) +SIGNATURE_END = re.compile("^-----END %s+ PUBLIC KEY-----$" % KEYWORD_CHAR) + +# entries must have exactly one of the following +REQUIRED_FIELDS = ( + "published", + "onion-key", + "signing-key", + "bandwidth", +) + +# optional entries that can appear at most once +SINGLE_FIELDS = ( + "contact", + "uptime", + "fingerprint", + "hibernating", + "read-history", + "write-history", + "eventdns", + "platform", + "family", +) + +def parse_server_descriptors_v2(path, descriptor_file): + """ + Iterates over the verion 2 server descriptors in a descriptor file. + """ + + pass + +class ServerDescriptorV2(Descriptor): + """ + Version 2 server descriptor, as specified in... + https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec-v2.txt + + Attributes: + nickname (str) - relay's nickname (*) + address (str) - IPv4 address of the relay (*) + or_port (int) - port used for relaying (*) + socks_port (int) - deprecated attribute, always zero (*) + dir_port (int) - deprecated port used for descriptor mirroring (*) + + * required fields + """ + + nickname = None + address = None + or_port = None + socks_port = None + dir_port = None + + def __init__(self, contents): + Descriptor.__init__(self, contents) + + # A descriptor contains a series of 'keyword lines' which are simply a + # keyword followed by an optional value. Lines can also be followed by a + # signature block. + # + # We care about the ordering of 'accept' and 'reject' entries because this + # influences the resulting exit policy, but for everything else the order + # does not matter so breaking it into key / value pairs. + + entries = {} + exit_policy_lines = [] + + for line in contents.split("\n"): + line_match = KEYWORD_LINE.match() + + if not line_match: + raise ValueError("Line contains invalid characters: %s" % line) + + keyword, value = line_match.groups() + + if keyword in ("accept", "reject"): + exit_policy_lines.append("%s %s" % (keyword, value)) + elif keyword in entries: + entries[keyword].append(value) + else: + entries[keyword] = [value] + + # validates restrictions about the entries + + for keyword in REQUIRED_FIELDS: + if not keyword in entries: + raise ValueError("Descriptor must have a '%s' entry" % keyword + + for keyword in SINGLE_FIELDS + REQUIRED_FIELDS: + if keyword in entries and len(entries[keyword]) > 1: + raise ValueError("The '%s' entry can only appear once in a descriptor" % keyword) + + # parse all the entries into our attributes + + for keyword, values in entres.items(): + if keyword == "router": + # "router" nickname address ORPort SocksPort DirPort + router_comp = values[0].split() + + if len(router_comp) != 5: + raise ValueError("Router line must have five values: router %s" % values[0] + + # TODO: also check validity of other fields + # Fingerprint = "$" 40*HEXDIG + # NicknameChar = "a"-"z" / "A"-"Z" / "0" - "9" + # Nickname = 1*19 NicknameChar + + self.nickname = router_comp[0] + self.address = router_comp[1] + self.or_port = router_comp[2] + self.socks_port = router_comp[3] + self.dir_port = router_comp[4] +