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Validating an XMPP jid with python?

What is the correct way to validate an xmpp jid? The syntax is described here:, but I don't really understand it. Also, it seems pretty complicated, so using a library to do it would seem like a good idea.

I'm currently using xmpppy, but I can't seem to find how to validate a jid with it. Any help appreciated!

like image 355
static_rtti Avatar asked Aug 18 '10 16:08

static_rtti


1 Answers

First off, the current best reference for JIDs is RFC 6122.

I was just going to give you the regex in here, but got a little carried away, and implemented all of the spec:

import re
import sys
import socket
import encodings.idna
import stringprep

# These characters aren't allowed in domain names that are used
# in XMPP
BAD_DOMAIN_ASCII = "".join([chr(c) for c in range(0,0x2d) +
                    [0x2e, 0x2f] +
                    range(0x3a,0x41) +
                    range(0x5b,0x61) +
                    range(0x7b, 0x80)])

# check bi-directional character validity
def bidi(chars):
    RandAL = map(stringprep.in_table_d1, chars)
    for c in RandAL:
        if c:
            # There is a RandAL char in the string. Must perform further
            # tests:
            # 1) The characters in section 5.8 MUST be prohibited.
            # This is table C.8, which was already checked
            # 2) If a string contains any RandALCat character, the string
            # MUST NOT contain any LCat character.
            if filter(stringprep.in_table_d2, chars):
                raise UnicodeError("Violation of BIDI requirement 2")

            # 3) If a string contains any RandALCat character, a
            # RandALCat character MUST be the first character of the
            # string, and a RandALCat character MUST be the last
            # character of the string.
            if not RandAL[0] or not RandAL[-1]:
                raise UnicodeError("Violation of BIDI requirement 3")

def nodeprep(u):
    chars = list(unicode(u))
    i = 0
    while i < len(chars):
        c = chars[i]
        # map to nothing
        if stringprep.in_table_b1(c):
            del chars[i]
        else:
            # case fold
            chars[i] = stringprep.map_table_b2(c)
            i += 1
    # NFKC
    chars = stringprep.unicodedata.normalize("NFKC", "".join(chars))
    for c in chars:
        if (stringprep.in_table_c11(c) or
            stringprep.in_table_c12(c) or
            stringprep.in_table_c21(c) or
            stringprep.in_table_c22(c) or
            stringprep.in_table_c3(c) or
            stringprep.in_table_c4(c) or
            stringprep.in_table_c5(c) or
            stringprep.in_table_c6(c) or
            stringprep.in_table_c7(c) or
            stringprep.in_table_c8(c) or
            stringprep.in_table_c9(c) or
            c in "\"&'/:<>@"):
            raise UnicodeError("Invalid node character")

    bidi(chars)

    return chars

def resourceprep(res):
    chars = list(unicode(res))
    i = 0
    while i < len(chars):
        c = chars[i]
        # map to nothing
        if stringprep.in_table_b1(c):
            del chars[i]
        else:
            i += 1
    # NFKC
    chars = stringprep.unicodedata.normalize("NFKC", "".join(chars))
    for c in chars:
        if (stringprep.in_table_c12(c) or
            stringprep.in_table_c21(c) or
            stringprep.in_table_c22(c) or
            stringprep.in_table_c3(c) or
            stringprep.in_table_c4(c) or
            stringprep.in_table_c5(c) or
            stringprep.in_table_c6(c) or
            stringprep.in_table_c7(c) or
            stringprep.in_table_c8(c) or
            stringprep.in_table_c9(c)):
            raise UnicodeError("Invalid node character")

    bidi(chars)
    
    return chars

def parse_jid(jid):
    # first pass
    m = re.match("^(?:([^\"&'/:<>@]{1,1023})@)?([^/@]{1,1023})(?:/(.{1,1023}))?$", jid)
    if not m:
        return False
    
    (node, domain, resource) = m.groups()
    try:
        # ipv4 address?
        socket.inet_pton(socket.AF_INET, domain)
    except socket.error:
        # ipv6 address?
        try:
            socket.inet_pton(socket.AF_INET6, domain)
        except socket.error:
            # domain name
            dom = []
            for label in domain.split("."):
                try:
                    label = encodings.idna.nameprep(unicode(label))
                    encodings.idna.ToASCII(label)
                except UnicodeError:
                    return False
                
                # UseSTD3ASCIIRules is set, but Python's nameprep doesn't enforce it.
                # a) Verify the absence of non-LDH ASCII code points; that is, the
                for c in label:
                    if c in BAD_DOMAIN_ASCII:
                        return False
                # Verify the absence of leading and trailing hyphen-minus
                if label[0] == '-' or label[-1] == "-":
                    return False
                dom.append(label)
            domain = ".".join(dom)
    try:
        if node is not None:
            node = nodeprep(node)
        if resource is not None:
            resource = resourceprep(resource)
    except UnicodeError:
        return False
    
    return node, domain, resource

if __name__ == "__main__":
    results = parse_jid(sys.argv[1])
    if not results:
        print "FAIL"
    else:   
        print results

Yes, this is a lot of work. There's good reasons for all of it, but we're hoping to simplify it in the future somewhat if the précis working group bears fruit.

like image 191
Joe Hildebrand Avatar answered Oct 08 '22 04:10

Joe Hildebrand