1 files changed, 163 insertions, 0 deletions
diff --git a/sleekxmpp/util/sasl/client.py b/sleekxmpp/util/sasl/client.py
new file mode 100644
index 00000000..bf05a617
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+++ b/sleekxmpp/util/sasl/client.py
@@ -0,0 +1,163 @@
+# -*- coding: utf-8 -*-
+"""
+    sleekxmpp.util.sasl.client
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    This module was originally based on Dave Cridland's Suelta library.
+
+    Part of SleekXMPP: The Sleek XMPP Library
+
+    :copyright: (c) 2012 Nathanael C. Fritz, Lance J.T. Stout
+    :license: MIT, see LICENSE for more details
+"""
+
+import stringprep
+
+from sleekxmpp.util import hashes, bytes, stringprep_profiles
+
+
+#: Global registry mapping mechanism names to implementation classes.
+MECHANISMS = {}
+
+
+#: Global registry mapping mechanism names to security scores.
+MECH_SEC_SCORES = {}
+
+
+#: The SASLprep profile of stringprep used to validate simple username
+#: and password credentials.
+saslprep = stringprep_profiles.create(
+    nfkc=True,
+    bidi=True,
+    mappings=[
+        stringprep_profiles.b1_mapping,
+        stringprep_profiles.c12_mapping],
+    prohibited=[
+        stringprep.in_table_c12,
+        stringprep.in_table_c21,
+        stringprep.in_table_c22,
+        stringprep.in_table_c3,
+        stringprep.in_table_c4,
+        stringprep.in_table_c5,
+        stringprep.in_table_c6,
+        stringprep.in_table_c7,
+        stringprep.in_table_c8,
+        stringprep.in_table_c9],
+    unassigned=[stringprep.in_table_a1])
+
+
+def sasl_mech(score):
+    sec_score = score
+    def register(mech):
+        n = 0
+        mech.score = sec_score
+        if mech.use_hashes:
+            for hashing_alg in hashes():
+                n += 1
+                score = mech.score + n
+                name = '%s-%s' % (mech.name, hashing_alg)
+                MECHANISMS[name] = mech
+                MECH_SEC_SCORES[name] = score
+
+                if mech.channel_binding:
+                    name += '-PLUS'
+                    score += 10
+                    MECHANISMS[name] = mech
+                    MECH_SEC_SCORES[name] = score
+        else:
+            MECHANISMS[mech.name] = mech
+            MECH_SEC_SCORES[mech.name] = mech.score
+            if mech.channel_binding:
+                MECHANISMS[mech.name + '-PLUS'] = mech
+                MECH_SEC_SCORES[name] = mech.score + 10
+        return mech
+    return register
+
+
+class SASLNoAppropriateMechanism(Exception):
+    pass
+
+
+class SASLCancelled(Exception):
+    pass
+
+
+class SASLFailed(Exception):
+    pass
+
+
+class SASLMutualAuthFailed(SASLFailed):
+    pass
+
+
+class Mech(object):
+
+    name = 'GENERIC'
+    score = -1
+    use_hashes = False
+    channel_binding = False
+    required_credentials = set()
+    optional_credentials = set()
+
+    def __init__(self, name, credentials, security_settings):
+        self.credentials = credentials
+        self.security_settings = security_settings
+        self.values = {}
+        self.base_name = self.name
+        self.name = name
+        self.setup(name)
+
+    def setup(self, name):
+        pass
+
+    def process(self, challenge=b''):
+        return b''
+
+
+def choose(mech_list, credentials, security_settings, limit=None, min_mech=None):
+    available_mechs = set(MECHANISMS.keys())
+    if limit is None:
+        limit = set(mech_list)
+    if not isinstance(limit, set):
+        limit = set(limit)
+    if not isinstance(mech_list, set):
+        mech_list = set(mech_list)
+
+    mech_list = mech_list.intersection(limit)
+    available_mechs = available_mechs.intersection(mech_list)
+
+    best_score = MECH_SEC_SCORES.get(min_mech, -1)
+    best_mech = None
+    for name in available_mechs:
+        if name in MECH_SEC_SCORES:
+            if MECH_SEC_SCORES[name] > best_score:
+                best_score = MECH_SEC_SCORES[name]
+                best_mech = name
+    if best_mech is None:
+        raise SASLNoAppropriateMechanism()
+
+    mech_class = MECHANISMS[best_mech]
+
+    try:
+        creds = credentials(mech_class.required_credentials,
+                            mech_class.optional_credentials)
+        for req in mech_class.required_credentials:
+            if req not in creds:
+                raise SASLCancelled('Missing credential: %s' % req)
+        for opt in mech_class.optional_credentials:
+            if opt not in creds:
+                creds[opt] = b''
+        for cred in creds:
+            if cred in ('username', 'password', 'authzid'):
+                creds[cred] = bytes(saslprep(creds[cred]))
+            else:
+                creds[cred] = bytes(creds[cred])
+        security_opts = security_settings(mech_class.security)
+
+        return mech_class(best_mech, creds, security_opts)
+    except SASLCancelled as e:
+        log.debug('SASL: %s: %s', (best_mech, e.message))
+        mech_list.remove(best_mech)
+        return choose(mech_list, credentials, security_settings,
+                limit=limit,
+                min_mech=min_mech)