terom@666: import logging; log = logging.getLogger('pvl.dhcp.config')
terom@666: import shlex
terom@673: import string
terom@673: 
terom@673: # simplified model of lexer chars
terom@679: TOKEN_START = string.ascii_letters + string.digits + '-'
terom@679: TOKEN = TOKEN_START + '_'
terom@679: 
terom@679: # be far more lenient when parsing
terom@679: TOKEN_EXTRA = TOKEN + ':.'
terom@679: 
terom@679: UNQUOTED_CONTEXT = set((
terom@679:     ('host', ),
terom@679:     ('fixed-address', ),
terom@679:     ('next-server', ),
terom@679:     ('hardware', 'ethernet'),
terom@679: ))
terom@255: 
terom@666: class DHCPConfigError(Exception):
terom@666:     def __init__ (self, parser, error, line=None):
terom@666:         self.parser = parser
terom@255: 
terom@666:         self.name = parser.name
terom@666:         self.line = line
terom@666:         self.error = error
terom@666: 
terom@666:     def __str__ (self):
terom@666:         return "{self.name}:{self.line}: {self.error}".format(self=self)
terom@666: 
terom@666: def split (line) :
terom@255:     """
terom@666:         Split given line-data into raw tokens.
terom@666:         
terom@666:         >>> list(split('foo'))
terom@666:         ['foo']
terom@666:         >>> list(split('foo bar'))
terom@666:         ['foo', 'bar']
terom@666:         >>> list(split('foo;'))
terom@666:         ['foo', ';']
terom@666:         >>> list(split('"foo"'))
terom@666:         ['foo']
terom@666:         >>> list(split('foo "asdf quux" bar'))
terom@666:         ['foo', 'asdf quux', 'bar']
terom@666:         >>> list(split('foo "asdf quux"'))
terom@666:         ['foo', 'asdf quux']
terom@666:         >>> list(split('# nevermind'))
terom@666:         []
terom@666:         >>> list(split(''))
terom@666:         []
terom@673:         >>> list(split('next-server foo'))
terom@673:         ['next-server', 'foo']
terom@673:         >>> list(split('include "foo/bar.conf";'))
terom@673:         ['include', 'foo/bar.conf', ';']
terom@666:     """
terom@666: 
terom@666:     if line is None:
terom@666:         raise TypeError(line)
terom@666: 
terom@666:     lexer = shlex.shlex(line, posix=True)
terom@666:     lexer.commenters = '#'
terom@679:     lexer.wordchars = TOKEN_EXTRA
terom@666: 
terom@666:     while True:
terom@666:         item = lexer.get_token()
terom@666: 
terom@666:         if item is None:
terom@666:             break
terom@666: 
terom@666:         yield item
terom@666: 
tero@695: class Field (object):
tero@695:     """
tero@695:         Pre-quoted fields for use in DHCP confs.
tero@695:     """
tero@695: 
tero@695:     def __init__(self, token):
tero@695:         self.token = token
tero@695: 
tero@695:     def __str__(self):
tero@695:         return self.token
tero@695: 
tero@699: class String (Field):
tero@699:     """
tero@699:         A quoted string
tero@699:     """
tero@699: 
tero@699:     def __init__(self, string):
tero@699:         self.string = string
tero@699: 
tero@699:     def __str__(self):
tero@699:         # TODO: escape
tero@699:         return '"{self.string}"'.format(self=self)
tero@699: 
terom@679: def quote (value, context=None):
terom@673:     """
terom@673:         Build a single field as part of a dhcp.conf line.
terom@673: 
terom@673:         >>> print quote('foo')
terom@673:         foo
terom@673:         >>> print quote('foo bar')
terom@673:         "foo bar"
terom@673:         >>> print quote('foo/bar.conf')
terom@673:         "foo/bar.conf"
terom@673:         >>> print quote(5)
terom@673:         5
terom@673:         >>> print quote('5')
terom@679:         5
terom@679:         >>> print quote('foo.bar')
terom@679:         "foo.bar"
terom@679:         >>> print quote('foo.bar', context=('host', ))
terom@679:         foo.bar
terom@679:         >>> print quote('192.0.2.1', context=('fixed-address', ))
terom@679:         192.0.2.1
terom@679:         >>> print quote('00:11:22:33:44:55', context=('hardware', 'ethernet'))
terom@679:         00:11:22:33:44:55
tero@695:         >>> print quote(Field('1:00:11:22:33:44:55'))
tero@695:         1:00:11:22:33:44:55
tero@699:         >>> print quote(String('foobar'))
tero@699:         "foobar"
terom@673:     """
terom@673: 
tero@695:     if isinstance(value, Field):
tero@695:         return str(value)
tero@695:     elif isinstance(value, int):
terom@673:         return str(value)
terom@679:     elif context in UNQUOTED_CONTEXT:
terom@679:         return str(value)
terom@679:     elif value[0] in TOKEN_START and all(c in TOKEN for c in value):
terom@673:         return str(value)
terom@673:     else:
terom@673:         # quoted
terom@673:         return '"{value}"'.format(value=value)
terom@673: 
terom@666: class Block (object):
terom@666:     """
terom@666:         A block in a dhcp conf includes parameters and sub-blocks.
terom@666:     """
terom@666: 
terom@668:     def __init__ (self, key, items=None, blocks=None, comment=None):
terom@666:         """
terom@666:             key: tuple      - name of block
terom@666:         """
terom@666: 
terom@666:         self.key = key
terom@666:         self.items = items or [ ]
terom@666:         self.blocks = blocks or [ ]
terom@668:         self.comment = comment
terom@666: 
terom@666:     def __str__ (self):
tero@707:         if self.key:
tero@707:             return ' '.join(self.key)
tero@707:         else:
tero@707:             # XXX: Item.__str__
tero@707:             return '; '.join(' '.join(str(x) for x in item) for item in self.items)
terom@666: 
terom@666:     def __repr__ (self):
terom@682:         return "Block({self.key!r}, items={self.items!r}, blocks={self.blocks!r})".format(self=self)
terom@666: 
terom@666: class DHCPConfigParser (object):
terom@666:     """
terom@666:         Simple parser for ISC dhcpd conf files.
terom@666: 
terom@666:         Supports iterative parsing as required for following a dhcpd.leases file.
terom@255: 
terom@255:         Doesn't implement the full spec, but a useful approximation.
terom@255:     """
terom@255: 
terom@256:     @classmethod
terom@666:     def load (cls, file, name=None):
terom@255:         """
terom@666:             Parse an complete file, returning the top-level Block.
terom@255: 
terom@673:             >>> DHCPConfigParser.load(['foo;', 'bar {', '\tasdf "quux";', '}'], name='test')
terom@682:             Block(None, items=[('foo',)], blocks=[Block(('bar',), items=[('asdf', 'quux')], blocks=[])])
terom@255:         """
terom@666:         
terom@666:         if name is None:
terom@666:             name = file.name
terom@255: 
terom@666:         parser = cls(name=name)
terom@255: 
terom@666:         for lineno, line in enumerate(file, 1):
terom@666:             try:
terom@666:                 for item in parser.parse_line(line):
terom@666:                     log.debug("%s", item)
terom@666:             except DHCPConfigError as error:
terom@666:                 error.line = lineno
terom@666:                 raise
terom@666: 
terom@666:         if parser.token:
terom@682:             raise DHCPConfError(parser, "Trailing data: {token}".format(token=parser.token), line=lineno)
terom@682:         
terom@682:         if parser.stack:
terom@682:             raise DHCPConfError(parser, "Unterminated block: {stack}".format(stack=parser.stack), line=lineno)
terom@666: 
terom@666:         return parser.block 
terom@666: 
terom@666:     def __init__ (self, name=None):
terom@666:         self.name = name
terom@666: 
terom@666:         # lexer state
terom@666:         self.token = []
terom@666:         
terom@666:         # parser state
terom@666:         self.stack = []
terom@666:         
terom@666:         # top-level block
terom@666:         self.block = Block(None)
terom@666: 
terom@666:     def lex (self, line):
terom@666:         """
terom@666:             Lex one line of input into basic expressions:
terom@666: 
terom@666:                 open:   [...] {
terom@666:                 item:       [..];
terom@666:                 close:  [] }
terom@666: 
terom@666:             Yields (event, (...)) tokens.
terom@666: 
terom@666:             Raises DHCPConfError.
terom@255:         """
terom@255: 
terom@255:         log.debug("%s", line)
terom@255: 
terom@666:         for word in split(line):
terom@666:             if word == '{':
terom@666:                 yield 'open', tuple(self.token)
terom@666:             
terom@666:             elif word == ';':
terom@666:                 yield 'item', tuple(self.token)
terom@255: 
terom@666:             elif word == '}':
terom@666:                 if self.token:
terom@666:                     raise DHCPConfError(self, "Leading data on close: {token}".format(token=self.token))
terom@255: 
terom@666:                 yield 'close', None
terom@255: 
terom@666:             else:
terom@666:                 self.token.append(word)
terom@666:                 continue
terom@666: 
terom@666:             self.token = [ ]
terom@255:        
terom@666:     def parse (self, tokens):
terom@666:         """
terom@666:             Parse given tokens, yielding any complete Blocks.
terom@255: 
terom@666:             Note that the Blocks yielded may be within some other Block which is still incomplete.
terom@255:         """
terom@256: 
terom@666:         for token, args in tokens:
terom@666:             if token == 'open':
terom@666:                 block = Block(args)
terom@256: 
terom@666:                 log.debug("open block: %s > %s", self.block, block)
terom@666:                 
terom@682:                 self.stack.append(self.block)
terom@666:                 self.block.blocks.append(block)
terom@666:                 self.block = block
terom@666:             
terom@666:             # must be within block!
terom@666:             elif token == 'item' :
terom@666:                 log.debug("block %s item: %s", self.block, args)
terom@255: 
terom@666:                 self.block.items.append(args)
terom@255: 
terom@255:             elif token == 'close' :
terom@255:                 log.debug("close block: %s", self.block)
terom@255: 
terom@666:                 block = self.block
terom@255: 
terom@666:                 if self.stack:
terom@666:                     self.block = self.stack.pop()
terom@666:                 else:
terom@666:                     raise DHCPConfigError(self, "Mismatched block close: {block}".format(block=block))
terom@255: 
terom@666:                 yield block
terom@666: 
terom@666:             else:
terom@666:                 raise ValueError(token, args)
terom@255:     
terom@666:     def parse_line (self, line):
terom@666:         """
terom@666:             Lex and parse line tokens.
terom@666:         """
terom@666: 
terom@666:         for block in self.parse(self.lex(line)):
terom@666:             yield block
terom@666: 
terom@255:     def parse_lines (self, lines) :
terom@255:         """
terom@255:             Trivial wrapper around parse to parse multiple lines.
terom@255:         """
terom@255: 
terom@666:         for line in lines:
terom@666:             for block in self.parse_line(line) :
terom@666:                 yield block
terom@666:     
terom@679: def build_line (item, end, indent=0, context=None):
tero@476:     """
tero@476:         Build a structured line.
tero@476: 
terom@679:         >>> print build_line(('foo', ), ';')
tero@476:         foo;
terom@679:         >>> print build_line(('host', 'foo'), ' {')
tero@476:         host foo {
terom@679:         >>> print build_line(('foo', 'bar quux'), ';', indent=1)
tero@476:             foo "bar quux";
tero@476:     """
tero@476: 
terom@679:     return '    '*indent + ' '.join(quote(field, context=context) for field in item) + end
tero@476: 
tero@476: def build_item (item, **opts):
tero@476:     """
tero@476:         Build a single parameter line.
tero@476: 
terom@679:         >>> print build_item(('foo', ))
tero@476:         foo;
tero@476:     """
tero@476: 
terom@679:     return build_line(item, end=';',
terom@679:         context     = item[:-1],
terom@679:         **opts
terom@679:     )
tero@476: 
terom@668: def build_block (block, indent=0):
tero@476:     """
terom@666:         Build a complete Block, recursively, yielding output lines.
tero@476: 
terom@681:         >>> for line in build_block(Block(('host', 'foo'), [('hardware', 'ethernet', '00:11:22:33:44:55')], comment="Testing")): print line
tero@476:         # Testing
tero@476:         host foo {
tero@476:             hardware ethernet 00:11:22:33:44:55;
tero@476:         }
terom@666:         >>> for line in build_block(Block(('group', ), [('next-server', 'booter')], [ \
terom@681:                     Block(('host', 'foo'), [('hardware', 'ethernet', '00:11:22:33:44:55')]) \
terom@666:                 ])): print line
tero@476:         group {
tero@476:             next-server booter;
tero@476:         <BLANKLINE>
tero@476:             host foo {
tero@476:                 hardware ethernet 00:11:22:33:44:55;
tero@476:             }
tero@476:         }
tero@476:     """
tero@476: 
terom@668:     if block.comment:
terom@668:         yield build_line((), end="# {comment}".format(comment=block.comment), indent=indent)
tero@685:     
tero@685:     if block.key:
tero@685:         yield build_line(block.key, end=' {', indent=indent, context=block.key[0:1])
tero@685:         indent += 1
tero@476:     
terom@666:     for item in block.items:
tero@685:         yield build_item(item, indent=indent)
tero@476: 
terom@666:     for subblock in block.blocks:
tero@685:         if block.items:
tero@685:             yield ''
tero@476: 
tero@685:         for line in build_block(subblock, indent=indent):
tero@476:             yield line
tero@685:     
tero@685:     if block.key:
tero@685:         indent -= 1
tero@685:         yield build_line((), end='}', indent=indent)