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Chris McDonough's patch to defend against certain DoS attacks on FieldStorage.

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SF bug #1112549.
This commit is contained in:
Guido van Rossum 2006-08-10 17:41:07 +00:00
parent cd3d8bee02
commit 9568b738ec
3 changed files with 86 additions and 5 deletions
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20
Lib/cgi.py
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@ -251,6 +251,10 @@ def parse_multipart(fp, pdict):
XXX This should really be subsumed by FieldStorage altogether -- no
point in having two implementations of the same parsing algorithm.
Also, FieldStorage protects itself better against certain DoS attacks
by limiting the size of the data read in one chunk. The API here
does not support that kind of protection. This also affects parse()
since it can call parse_multipart().
"""
boundary = ""
@ -699,7 +703,7 @@ class FieldStorage:
def read_lines_to_eof(self):
"""Internal: read lines until EOF."""
while 1:
line = self.fp.readline()
line = self.fp.readline(1<<16)
if not line:
self.done = -1
break
@ -710,12 +714,13 @@ class FieldStorage:
next = "--" + self.outerboundary
last = next + "--"
delim = ""
last_line_lfend = True
while 1:
line = self.fp.readline()
line = self.fp.readline(1<<16)
if not line:
self.done = -1
break
if line[:2] == "--":
if line[:2] == "--" and last_line_lfend:
strippedline = line.strip()
if strippedline == next:
break
@ -726,11 +731,14 @@ class FieldStorage:
if line[-2:] == "\r\n":
delim = "\r\n"
line = line[:-2]
last_line_lfend = True
elif line[-1] == "\n":
delim = "\n"
line = line[:-1]
last_line_lfend = True
else:
delim = ""
last_line_lfend = False
self.__write(odelim + line)
def skip_lines(self):
@ -739,18 +747,20 @@ class FieldStorage:
return
next = "--" + self.outerboundary
last = next + "--"
last_line_lfend = True
while 1:
line = self.fp.readline()
line = self.fp.readline(1<<16)
if not line:
self.done = -1
break
if line[:2] == "--":
if line[:2] == "--" and last_line_lfend:
strippedline = line.strip()
if strippedline == next:
break
if strippedline == last:
self.done = 1
break
last_line_lfend = line.endswith('\n')
def make_file(self, binary=None):
"""Overridable: return a readable & writable file.