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........
  r65544 | guido.van.rossum | 2008-08-04 20:39:21 -0700 (Mon, 04 Aug 2008) | 28 lines

  Tracker issue 3487: sre "bytecode" verifier.

  This is a verifier for the binary code used by the _sre module (this
  is often called bytecode, though to distinguish it from Python bytecode
  I put it in quotes).

  I wrote this for Google App Engine, and am making the patch available as
  open source under the Apache 2 license.  Below are the copyright
  statement and license, for completeness.

  # Copyright 2008 Google Inc.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.

  It's not necessary to include these copyrights and bytecode in the
  source file.  Google has signed a contributor's agreement with the PSF
  already.
........
This commit is contained in:
Guido van Rossum 2008-08-06 19:29:14 +00:00
parent 11e18b0c2e
commit 10faf6a0a3
3 changed files with 541 additions and 76 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Lib/test/test_urllib.py
View File

@ -465,7 +465,7 @@ class UnquotingTests(unittest.TestCase):
def test_unquote_with_unicode(self):
r = urllib.parse.unquote('br%C3%BCckner_sapporo_20050930.doc')
self.assertEqual(r, 'br\xc3\xbcckner_sapporo_20050930.doc')
self.assertEqual(r, 'br\u00FCckner_sapporo_20050930.doc')
class urlencode_Tests(unittest.TestCase):
"""Tests for urlencode()"""

141
Lib/urllib/parse.py
View File

@ -261,84 +261,74 @@ def urldefrag(url):
return url, ''
_hextochr = dict(('%02x' % i, chr(i)) for i in range(256))
_hextochr.update(('%02X' % i, chr(i)) for i in range(256))
def unquote_as_string (s, plus=False, charset=None):
if charset is None:
charset = "UTF-8"
return str(unquote_as_bytes(s, plus=plus), charset, 'strict')
def unquote_as_bytes (s, plus=False):
"""unquote('abc%20def') -> 'abc def'."""
if plus:
s = s.replace('+', ' ')
res = s.split('%')
res[0] = res[0].encode('ASCII', 'strict')
for i in range(1, len(res)):
res[i] = (bytes.fromhex(res[i][:2]) +
res[i][2:].encode('ASCII', 'strict'))
return b''.join(res)
_always_safe = (b'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
b'abcdefghijklmnopqrstuvwxyz'
b'0123456789'
b'_.-')
_percent_code = ord('%')
_hextable = b'0123456789ABCDEF'
def quote_as_bytes(s, safe = '/', plus=False):
"""quote(b'abc@def') -> 'abc%40def'"""
if isinstance(s, str):
s = s.encode("UTF-8", "strict")
if not (isinstance(s, bytes) or isinstance(s, bytearray)):
raise ValueError("Argument to quote must be either bytes "
"or bytearray; string arguments will be "
"converted to UTF-8 bytes")
safeset = _always_safe + safe.encode('ASCII', 'strict')
if plus:
safeset += b' '
result = bytearray()
for i in s:
if i not in safeset:
result.append(_percent_code)
result.append(_hextable[(i >> 4) & 0xF])
result.append(_hextable[i & 0xF])
else:
result.append(i)
if plus:
result = result.replace(b' ', b'+')
return result
def quote_as_string(s, safe = '/', plus=False):
return str(quote_as_bytes(s, safe=safe, plus=plus), 'ASCII', 'strict')
# finally, define defaults for 'quote' and 'unquote'
def quote(s, safe='/'):
return quote_as_string(s, safe=safe)
def quote_plus(s, safe=''):
return quote_as_string(s, safe=safe, plus=True)
def unquote(s):
"""unquote('abc%20def') -> 'abc def'."""
res = s.split('%')
for i in range(1, len(res)):
item = res[i]
try:
res[i] = _hextochr[item[:2]] + item[2:]
except KeyError:
res[i] = '%' + item
except UnicodeDecodeError:
res[i] = chr(int(item[:2], 16)) + item[2:]
return "".join(res)
return unquote_as_string(s)
def unquote_plus(s):
"""unquote('%7e/abc+def') -> '~/abc def'"""
s = s.replace('+', ' ')
return unquote(s)
return unquote_as_string(s, plus=True)
always_safe = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'
'abcdefghijklmnopqrstuvwxyz'
'0123456789' '_.-')
_safe_quoters= {}
class Quoter:
def __init__(self, safe):
self.cache = {}
self.safe = safe + always_safe
def __call__(self, c):
try:
return self.cache[c]
except KeyError:
if ord(c) < 256:
res = (c in self.safe) and c or ('%%%02X' % ord(c))
self.cache[c] = res
return res
else:
return "".join(['%%%02X' % i for i in c.encode("utf-8")])
def quote(s, safe = '/'):
"""quote('abc def') -> 'abc%20def'
Each part of a URL, e.g. the path info, the query, etc., has a
different set of reserved characters that must be quoted.
RFC 2396 Uniform Resource Identifiers (URI): Generic Syntax lists
the following reserved characters.
reserved = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
"$" | ","
Each of these characters is reserved in some component of a URL,
but not necessarily in all of them.
By default, the quote function is intended for quoting the path
section of a URL. Thus, it will not encode '/'. This character
is reserved, but in typical usage the quote function is being
called on a path where the existing slash characters are used as
reserved characters.
"""
cachekey = (safe, always_safe)
try:
quoter = _safe_quoters[cachekey]
except KeyError:
quoter = Quoter(safe)
_safe_quoters[cachekey] = quoter
res = map(quoter, s)
return ''.join(res)
def quote_plus(s, safe = ''):
"""Quote the query fragment of a URL; replacing ' ' with '+'"""
if ' ' in s:
s = quote(s, safe + ' ')
return s.replace(' ', '+')
return quote(s, safe)
def urlencode(query,doseq=0):
"""Encode a sequence of two-element tuples or dictionary into a URL query string.
@ -387,7 +377,7 @@ def urlencode(query,doseq=0):
# is there a reasonable way to convert to ASCII?
# encode generates a string, but "replace" or "ignore"
# lose information and "strict" can raise UnicodeError
v = quote_plus(v.encode("ASCII","replace"))
v = quote_plus(v)
l.append(k + '=' + v)
else:
try:
@ -474,7 +464,8 @@ def splituser(host):
_userprog = re.compile('^(.*)@(.*)$')
match = _userprog.match(host)
if match: return map(unquote, match.group(1, 2))
if match:
return map(unquote, match.group(1, 2))
return None, host
_passwdprog = None

474
Modules/_sre.c
View File

@ -2637,6 +2637,8 @@ static PyTypeObject Pattern_Type = {
pattern_members, /* tp_members */
};
static int _validate(PatternObject *self); /* Forward */
static PyObject *
_compile(PyObject* self_, PyObject* args)
{
@ -2695,9 +2697,481 @@ _compile(PyObject* self_, PyObject* args)
self->weakreflist = NULL;
if (!_validate(self)) {
Py_DECREF(self);
return NULL;
}
return (PyObject*) self;
}
/* -------------------------------------------------------------------- */
/* Code validation */
/* To learn more about this code, have a look at the _compile() function in
Lib/sre_compile.py. The validation functions below checks the code array
for conformance with the code patterns generated there.
The nice thing about the generated code is that it is position-independent:
all jumps are relative jumps forward. Also, jumps don't cross each other:
the target of a later jump is always earlier than the target of an earlier
jump. IOW, this is okay:
J---------J-------T--------T
\ \_____/ /
\______________________/
but this is not:
J---------J-------T--------T
\_________\_____/ /
\____________/
It also helps that SRE_CODE is always an unsigned type, either 2 bytes or 4
bytes wide (the latter if Python is compiled for "wide" unicode support).
*/
/* Defining this one enables tracing of the validator */
#undef VVERBOSE
/* Trace macro for the validator */
#if defined(VVERBOSE)
#define VTRACE(v) printf v
#else
#define VTRACE(v)
#endif
/* Report failure */
#define FAIL do { VTRACE(("FAIL: %d\n", __LINE__)); return 0; } while (0)
/* Extract opcode, argument, or skip count from code array */
#define GET_OP \
do { \
VTRACE(("%p: ", code)); \
if (code >= end) FAIL; \
op = *code++; \
VTRACE(("%lu (op)\n", (unsigned long)op)); \
} while (0)
#define GET_ARG \
do { \
VTRACE(("%p= ", code)); \
if (code >= end) FAIL; \
arg = *code++; \
VTRACE(("%lu (arg)\n", (unsigned long)arg)); \
} while (0)
#define GET_SKIP \
do { \
VTRACE(("%p= ", code)); \
if (code >= end) FAIL; \
skip = *code; \
VTRACE(("%lu (skip to %p)\n", \
(unsigned long)skip, code+skip)); \
if (code+skip < code || code+skip > end) \
FAIL; \
code++; \
} while (0)
static int
_validate_charset(SRE_CODE *code, SRE_CODE *end)
{
/* Some variables are manipulated by the macros above */
SRE_CODE op;
SRE_CODE arg;
SRE_CODE offset;
int i;
while (code < end) {
GET_OP;
switch (op) {
case SRE_OP_NEGATE:
break;
case SRE_OP_LITERAL:
GET_ARG;
break;
case SRE_OP_RANGE:
GET_ARG;
GET_ARG;
break;
case SRE_OP_CHARSET:
offset = 32/sizeof(SRE_CODE); /* 32-byte bitmap */
if (code+offset < code || code+offset > end)
FAIL;
code += offset;
break;
case SRE_OP_BIGCHARSET:
GET_ARG; /* Number of blocks */
offset = 256/sizeof(SRE_CODE); /* 256-byte table */
if (code+offset < code || code+offset > end)
FAIL;
/* Make sure that each byte points to a valid block */
for (i = 0; i < 256; i++) {
if (((unsigned char *)code)[i] >= arg)
FAIL;
}
code += offset;
offset = arg * 32/sizeof(SRE_CODE); /* 32-byte bitmap times arg */
if (code+offset < code || code+offset > end)
FAIL;
code += offset;
break;
case SRE_OP_CATEGORY:
GET_ARG;
switch (arg) {
case SRE_CATEGORY_DIGIT:
case SRE_CATEGORY_NOT_DIGIT:
case SRE_CATEGORY_SPACE:
case SRE_CATEGORY_NOT_SPACE:
case SRE_CATEGORY_WORD:
case SRE_CATEGORY_NOT_WORD:
case SRE_CATEGORY_LINEBREAK:
case SRE_CATEGORY_NOT_LINEBREAK:
case SRE_CATEGORY_LOC_WORD:
case SRE_CATEGORY_LOC_NOT_WORD:
case SRE_CATEGORY_UNI_DIGIT:
case SRE_CATEGORY_UNI_NOT_DIGIT:
case SRE_CATEGORY_UNI_SPACE:
case SRE_CATEGORY_UNI_NOT_SPACE:
case SRE_CATEGORY_UNI_WORD:
case SRE_CATEGORY_UNI_NOT_WORD:
case SRE_CATEGORY_UNI_LINEBREAK:
case SRE_CATEGORY_UNI_NOT_LINEBREAK:
break;
default:
FAIL;
}
break;
default:
FAIL;
}
}
return 1;
}
static int
_validate_inner(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
{
/* Some variables are manipulated by the macros above */
SRE_CODE op;
SRE_CODE arg;
SRE_CODE skip;
VTRACE(("code=%p, end=%p\n", code, end));
if (code > end)
FAIL;
while (code < end) {
GET_OP;
switch (op) {
case SRE_OP_MARK:
/* We don't check whether marks are properly nested; the
sre_match() code is robust even if they don't, and the worst
you can get is nonsensical match results. */
GET_ARG;
if (arg > 2*groups+1) {
VTRACE(("arg=%d, groups=%d\n", (int)arg, (int)groups));
FAIL;
}
break;
case SRE_OP_LITERAL:
case SRE_OP_NOT_LITERAL:
case SRE_OP_LITERAL_IGNORE:
case SRE_OP_NOT_LITERAL_IGNORE:
GET_ARG;
/* The arg is just a character, nothing to check */
break;
case SRE_OP_SUCCESS:
case SRE_OP_FAILURE:
/* Nothing to check; these normally end the matching process */
break;
case SRE_OP_AT:
GET_ARG;
switch (arg) {
case SRE_AT_BEGINNING:
case SRE_AT_BEGINNING_STRING:
case SRE_AT_BEGINNING_LINE:
case SRE_AT_END:
case SRE_AT_END_LINE:
case SRE_AT_END_STRING:
case SRE_AT_BOUNDARY:
case SRE_AT_NON_BOUNDARY:
case SRE_AT_LOC_BOUNDARY:
case SRE_AT_LOC_NON_BOUNDARY:
case SRE_AT_UNI_BOUNDARY:
case SRE_AT_UNI_NON_BOUNDARY:
break;
default:
FAIL;
}
break;
case SRE_OP_ANY:
case SRE_OP_ANY_ALL:
/* These have no operands */
break;
case SRE_OP_IN:
case SRE_OP_IN_IGNORE:
GET_SKIP;
/* Stop 1 before the end; we check the FAILURE below */
if (!_validate_charset(code, code+skip-2))
FAIL;
if (code[skip-2] != SRE_OP_FAILURE)
FAIL;
code += skip-1;
break;
case SRE_OP_INFO:
{
/* A minimal info field is
<INFO> <1=skip> <2=flags> <3=min> <4=max>;
If SRE_INFO_PREFIX or SRE_INFO_CHARSET is in the flags,
more follows. */
SRE_CODE flags, min, max, i;
SRE_CODE *newcode;
GET_SKIP;
newcode = code+skip-1;
GET_ARG; flags = arg;
GET_ARG; min = arg;
GET_ARG; max = arg;
/* Check that only valid flags are present */
if ((flags & ~(SRE_INFO_PREFIX |
SRE_INFO_LITERAL |
SRE_INFO_CHARSET)) != 0)
FAIL;
/* PREFIX and CHARSET are mutually exclusive */
if ((flags & SRE_INFO_PREFIX) &&
(flags & SRE_INFO_CHARSET))
FAIL;
/* LITERAL implies PREFIX */
if ((flags & SRE_INFO_LITERAL) &&
!(flags & SRE_INFO_PREFIX))
FAIL;
/* Validate the prefix */
if (flags & SRE_INFO_PREFIX) {
SRE_CODE prefix_len, prefix_skip;
GET_ARG; prefix_len = arg;
GET_ARG; prefix_skip = arg;
/* Here comes the prefix string */
if (code+prefix_len < code || code+prefix_len > newcode)
FAIL;
code += prefix_len;
/* And here comes the overlap table */
if (code+prefix_len < code || code+prefix_len > newcode)
FAIL;
/* Each overlap value should be < prefix_len */
for (i = 0; i < prefix_len; i++) {
if (code[i] >= prefix_len)
FAIL;
}
code += prefix_len;
}
/* Validate the charset */
if (flags & SRE_INFO_CHARSET) {
if (!_validate_charset(code, newcode-1))
FAIL;
if (newcode[-1] != SRE_OP_FAILURE)
FAIL;
code = newcode;
}
else if (code != newcode) {
VTRACE(("code=%p, newcode=%p\n", code, newcode));
FAIL;
}
}
break;
case SRE_OP_BRANCH:
{
SRE_CODE *target = NULL;
for (;;) {
GET_SKIP;
if (skip == 0)
break;
/* Stop 2 before the end; we check the JUMP below */
if (!_validate_inner(code, code+skip-3, groups))
FAIL;
code += skip-3;
/* Check that it ends with a JUMP, and that each JUMP
has the same target */
GET_OP;
if (op != SRE_OP_JUMP)
FAIL;
GET_SKIP;
if (target == NULL)
target = code+skip-1;
else if (code+skip-1 != target)
FAIL;
}
}
break;
case SRE_OP_REPEAT_ONE:
case SRE_OP_MIN_REPEAT_ONE:
{
SRE_CODE min, max;
GET_SKIP;
GET_ARG; min = arg;
GET_ARG; max = arg;
if (min > max)
FAIL;
#ifdef Py_UNICODE_WIDE
if (max > 65535)
FAIL;
#endif
if (!_validate_inner(code, code+skip-4, groups))
FAIL;
code += skip-4;
GET_OP;
if (op != SRE_OP_SUCCESS)
FAIL;
}
break;
case SRE_OP_REPEAT:
{
SRE_CODE min, max;
GET_SKIP;
GET_ARG; min = arg;
GET_ARG; max = arg;
if (min > max)
FAIL;
#ifdef Py_UNICODE_WIDE
if (max > 65535)
FAIL;
#endif
if (!_validate_inner(code, code+skip-3, groups))
FAIL;
code += skip-3;
GET_OP;
if (op != SRE_OP_MAX_UNTIL && op != SRE_OP_MIN_UNTIL)
FAIL;
}
break;
case SRE_OP_GROUPREF:
case SRE_OP_GROUPREF_IGNORE:
GET_ARG;
if (arg >= groups)
FAIL;
break;
case SRE_OP_GROUPREF_EXISTS:
/* The regex syntax for this is: '(?(group)then|else)', where
'group' is either an integer group number or a group name,
'then' and 'else' are sub-regexes, and 'else' is optional. */
GET_ARG;
if (arg >= groups)
FAIL;
GET_SKIP;
code--; /* The skip is relative to the first arg! */
/* There are two possibilities here: if there is both a 'then'
part and an 'else' part, the generated code looks like:
GROUPREF_EXISTS
<group>
<skipyes>
...then part...
JUMP
<skipno>
(<skipyes> jumps here)
...else part...
(<skipno> jumps here)
If there is only a 'then' part, it looks like:
GROUPREF_EXISTS
<group>
<skip>
...then part...
(<skip> jumps here)
There is no direct way to decide which it is, and we don't want
to allow arbitrary jumps anywhere in the code; so we just look
for a JUMP opcode preceding our skip target.
*/
if (skip >= 3 && code+skip-3 >= code &&
code[skip-3] == SRE_OP_JUMP)
{
VTRACE(("both then and else parts present\n"));
if (!_validate_inner(code+1, code+skip-3, groups))
FAIL;
code += skip-2; /* Position after JUMP, at <skipno> */
GET_SKIP;
if (!_validate_inner(code, code+skip-1, groups))
FAIL;
code += skip-1;
}
else {
VTRACE(("only a then part present\n"));
if (!_validate_inner(code+1, code+skip-1, groups))
FAIL;
code += skip-1;
}
break;
case SRE_OP_ASSERT:
case SRE_OP_ASSERT_NOT:
GET_SKIP;
GET_ARG; /* 0 for lookahead, width for lookbehind */
code--; /* Back up over arg to simplify math below */
if (arg & 0x80000000)
FAIL; /* Width too large */
/* Stop 1 before the end; we check the SUCCESS below */
if (!_validate_inner(code+1, code+skip-2, groups))
FAIL;
code += skip-2;
GET_OP;
if (op != SRE_OP_SUCCESS)
FAIL;
break;
default:
FAIL;
}
}
VTRACE(("okay\n"));
return 1;
}
static int
_validate_outer(SRE_CODE *code, SRE_CODE *end, Py_ssize_t groups)
{
if (groups < 0 || groups > 100 || code >= end || end[-1] != SRE_OP_SUCCESS)
FAIL;
if (groups == 0) /* fix for simplejson */
groups = 100; /* 100 groups should always be safe */
return _validate_inner(code, end-1, groups);
}
static int
_validate(PatternObject *self)
{
if (!_validate_outer(self->code, self->code+self->codesize, self->groups))
{
PyErr_SetString(PyExc_RuntimeError, "invalid SRE code");
return 0;
}
else
VTRACE(("Success!\n"));
return 1;
}
/* -------------------------------------------------------------------- */
/* match methods */