implement attribute mapping functionality and do some refactoring

git-svn-id: http://arthurdejong.org/svn/nss-pam-ldapd/nss-pam-ldapd@1454 ef36b2f9-881f-0410-afb5-c4e39611909c

1 files changed, 194 insertions, 0 deletions

diff --git a/pynslcd/attmap.py b/pynslcd/attmap.py
new file mode 100644
index 0000000..f72fa62
--- /dev/null
+++ b/pynslcd/attmap.py
@@ -0,0 +1,194 @@
+
+# attributes.py - attribute mapping functions
+#
+# Copyright (C) 2011 Arthur de Jong
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""Module for handling attribute mappings used for LDAP searches.
+
+>>> attrs = Attributes(uid='uid',
+...                    userPassword='userPassword',
+...                    uidNumber='uidNumber',
+...                    gidNumber='gidNumber',
+...                    gecos='"${gecos:-$cn}"',
+...                    homeDirectory='homeDirectory',
+...                    loginShell='loginShell')
+>>> attrs.attributes()
+('uid', 'userPassword', 'uidNumber', 'gidNumber', 'gecos', 'cn', 'homeDirectory', 'loginShell')
+>>> attrs.value('gecos', {'cn': 'test'})
+['test']
+>>> attrs.search('uidNumber', 100)
+'(uidNumber=100)'
+>>> attrs['foo'] = '\"bar\"'
+>>> attrs.get('foo', {})
+['bar']
+"""
+
+# exported names
+__all__ = ( 'Attributes', )
+
+
+# FIXME: support multiple attribute values
+# TODO: support objectSid attributes
+# TODO: do more expression validity checking
+# TODO: handle userPassword specially to do filtering of results
+
+
+class MyIter(object):
+    """Custom iterator-like class with a back() method."""
+
+    def __init__(self, value):
+        self.value = value
+        self.pos = 0
+
+    def next(self):
+        self.pos += 1
+        return self.value[self.pos-1]
+
+    def back(self):
+        self.pos -= 1
+
+    def __iter__(self):
+        return self
+
+
+class DollarExpression(object):
+    """Class for handling a variable $xxx ${xxx}, ${xxx:-yyy} or ${xxx:+yyy}
+    expression."""
+
+    def _parse_varname(self, value):
+        """Read a variable name from the value iterator."""
+        name = ''
+        for c in value:
+            if not c.isalnum():
+                value.back()
+                return name
+            name += c
+
+    def __init__(self, value):
+        """Parse the expression as the start of a $-expression."""
+        self.op = None
+        self.expr = None
+        c = value.next()
+        if c == '{':
+            self.name = self._parse_varname(value)
+            c = value.next()
+            if c == '}':
+                return
+            self.op = c + value.next()
+            self.expr = Expression(value, endat='}')
+        else:
+            value.back()
+            self.name = self._parse_varname(value)
+
+    def value(self, variables):
+        """Expand the expression using the variables specified."""
+        value = variables.get(self.name, [''])[0]
+        # FIXME: expand list
+        if self.op == ':-':
+            return value if value else self.expr.value(variables)
+        elif self.op == ':+':
+            return self.expr.value(variables) if value else ''
+        return value
+
+    def variables(self, results):
+        """Add the variables used in the expression to results."""
+        results.add(self.name)
+        if self.expr:
+            self.expr.variables(results)
+
+
+class Expression(object):
+    """Class for parsing and expanding an expression."""
+
+    def __init__(self, value, endat=None):
+        """Parse the expression as a string."""
+        if not isinstance(value, MyIter):
+            value = MyIter(value)
+        if not endat:
+            endat = value.next() # skip opening quote
+        expr = []
+        literal = ''
+        c = value.next()
+        while c != endat:
+            if c == '$':
+                if literal:
+                    expr.append(literal)
+                expr.append(DollarExpression(value))
+                literal = ''
+            elif c == '\\':
+                literal += value.next()
+            else:
+                literal += c
+            c = value.next()
+        if literal:
+            expr.append(literal)
+        self.expr = expr
+
+    def value(self, variables):
+        """Expand the expression using the variables specified."""
+        res = ''
+        for x in self.expr:
+            if hasattr(x, 'value'):
+                res += x.value(variables)
+            else:
+                res += x
+        return res
+
+    def variables(self, results=None):
+        """Return the variables defined in the expression."""
+        if not results:
+            results = set()
+        for x in self.expr:
+            if hasattr(x, 'variables'):
+                x.variables(results)
+        return results
+
+
+class Attributes(dict):
+    """Dictionary-like class for handling a list of attributes."""
+
+    def _prepare(self):
+        """Go over all values to parse any expressions."""
+        updates = dict()
+        for k, v in self.iteritems():
+            if isinstance(v, basestring) and v[0] == '"':
+                updates[k] = Expression(v)
+        self.update(updates)
+
+    def attributes(self):
+        """Return a set of attributes that are referenced in this attribute
+        mapping."""
+        self._prepare()
+        results = set()
+        for value in self.itervalues():
+            if hasattr(value, 'variables'):
+                results.update(value.variables())
+            else:
+                results.add(value)
+        return list(results)
+
+    def mapped(self, variables):
+        """Return a dictionary with every attribute mapped to their value from
+        the specified variables."""
+        results = dict()
+        for k, v in self.iteritems():
+            if hasattr(v, 'value'):
+                results[k] = [v.value(variables)]
+            else:
+                results[k] = variables.get(v, [])
+        return results