diff options
| -rw-r--r-- | viewstate/parse.py | 93 | ||||
| -rw-r--r-- | viewstate/viewstate.py | 4 |
2 files changed, 65 insertions, 32 deletions
diff --git a/viewstate/parse.py b/viewstate/parse.py index 99110f1..66573a2 100644 --- a/viewstate/parse.py +++ b/viewstate/parse.py @@ -3,6 +3,25 @@ from datetime import datetime from .exceptions import ViewStateException +class ViewStateParser(object): + def get_subparsers(self): + return {c.marker: c for c in self.__class__.__subclasses__()} + + def parse(self, b): + SUBPARSERS = self.get_subparsers() + marker, *remain = b + try: + return SUBPARSERS[marker]().parse(remain) + except KeyError: + raise ViewStateException('Unknown marker') + + +class Const(object): + def parse(self): + return self.const, self.remain + +class NoneConst(ViewStateParser) + CONSTS = { 100: None, 101: '', @@ -14,39 +33,53 @@ CONSTS = { def parse_const(b): return CONSTS.get(b, None) -def parse_int(b): - n = 0 - bits = 0 - i = 0 - while (bits < 32): - tmp = b[i] - i += 1 - n |= (tmp & 0x7f) << bits - if not (tmp & 0x80): - return n, b[i:] - bits += 7 - return n, b[i:] # overflow -def parse_string(b): - n = b[0] - n, remain = parse_int(b) - s = remain[:n] - return s.decode(), remain[n:] +class Integer(ViewStateParser): + marker = 0x02 -def parse_enum(b): - if b[0] in (0x29, 0x2a): - enum, remain = parse_string(b[1:]) - elif b[0] == 0x2b: - enum, remain = parse_int(b[1:]) - val, remain = parse_int(remain) # unsure about this part - final = 'Enum: {}, val: {}'.format(enum, val) - return final, remain + def parse(self, b): + n = 0 + bits = 0 + i = 0 + while (bits < 32): + tmp = b[i] + i += 1 + n |= (tmp & 0x7f) << bits + if not (tmp & 0x80): + return n, b[i:] + bits += 7 + return n, b[i:] # overflow + + +class String(ViewStateParser): + marker = (0x05, 0x1e) + + def parse(self, b): + n = b[0] + n, remain = Integer().parse(b) + s = remain[:n] + return s.decode(), remain[n:] + +class Enum(ViewStateParser): + marker = 0x0b + + def parse(self, b): + if b[0] in (0x29, 0x2a): + enum, remain = String().parse(b[1:]) + elif b[0] == 0x2b: + enum, remain = Integer().parse(b[1:]) + val, remain = Integer().parse(remain) # unsure about this part + final = 'Enum: {}, val: {}'.format(enum, val) + return final, remain + +class Color(ViewStateParser): + marker = 0x0a -def parse_color(b): - # No specification for color parsing, we're assuming it's just two bytes - # One example we have is that `\n\x91\x01` is parsed as `Color: Color [Salmon]` - # Originally reported in https://github.com/yuvadm/viewstate/issues/2 - return 'Color: unknown', b[2:] + def parse(self, b): + # No specification for color parsing, we're assuming it's just two bytes + # One example we have is that `\n\x91\x01` is parsed as `Color: Color [Salmon]` + # Originally reported in https://github.com/yuvadm/viewstate/issues/2 + return 'Color: unknown', b[2:] def parse_pair(b): first, remain = parse(b) diff --git a/viewstate/viewstate.py b/viewstate/viewstate.py index 994f1b1..c08e011 100644 --- a/viewstate/viewstate.py +++ b/viewstate/viewstate.py @@ -2,7 +2,7 @@ from base64 import b64decode, b64encode from binascii import Error as BinAsciiError from .exceptions import ViewStateException -from .parse import parse +from .parse import ViewStateParser class ViewState(object): @@ -42,7 +42,7 @@ class ViewState(object): if not self.is_valid(): raise ViewStateException('Cannot decode invalid viewstate, bad preamble') - self.decoded, self.remainder = parse(self.body) + self.decoded, self.remainder = ViewStateParser().parse(self.body) if self.remainder: if len(self.remainder) == 20: |