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Fix possible infinite growing of the SafeRe regexp cache by limiting the cache size

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This commit is contained in:
Vadim Ushakov 2021-10-20 17:25:47 +07:00
parent d2b65c550c
commit 769a2c08dd
2 changed files with 37 additions and 6 deletions
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1
ZNE-ChangeLog/ChangeLog-0.8.0.md
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@ -25,6 +25,7 @@
* Implemented the log level overriding for separate modules for easier debugging. * Implemented the log level overriding for separate modules for easier debugging.
* Make the site block check implemented in `ContentFilter` usable from plugins and core modules via `SiteManager.isAddressBlocked()`. * Make the site block check implemented in `ContentFilter` usable from plugins and core modules via `SiteManager.isAddressBlocked()`.
* Fixed possible infinite growing of the `SafeRe` regexp cache by limiting the cache size.
## Docker Image ## Docker Image

42
src/util/SafeRe.py
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@ -1,10 +1,16 @@
import re import re
import logging
log = logging.getLogger("SafeRe")
class UnsafePatternError(Exception): class UnsafePatternError(Exception):
pass pass
max_cache_size = 1000
cached_patterns = {} cached_patterns = {}
old_cached_patterns = {}
def isSafePattern(pattern): def isSafePattern(pattern):
@ -22,11 +28,35 @@ def isSafePattern(pattern):
return True return True
def match(pattern, *args, **kwargs): def compilePattern(pattern):
global cached_patterns
global old_cached_patterns
cached_pattern = cached_patterns.get(pattern) cached_pattern = cached_patterns.get(pattern)
if cached_pattern: if cached_pattern:
return cached_pattern.match(*args, **kwargs) return cached_pattern
else:
if isSafePattern(pattern): cached_pattern = old_cached_patterns.get(pattern)
cached_patterns[pattern] = re.compile(pattern) if cached_pattern:
return cached_patterns[pattern].match(*args, **kwargs) del old_cached_patterns[pattern]
cached_patterns[pattern] = cached_pattern
return cached_pattern
if isSafePattern(pattern):
cached_pattern = re.compile(pattern)
cached_patterns[pattern] = cached_pattern
log.debug("Compiled new pattern: %s" % pattern)
log.debug("Cache size: %d + %d" % (len(cached_patterns), len(old_cached_patterns)))
if len(cached_patterns) > max_cache_size:
old_cached_patterns = cached_patterns
cached_patterns = {}
log.debug("Size limit reached. Rotating cache.")
log.debug("Cache size: %d + %d" % (len(cached_patterns), len(old_cached_patterns)))
return cached_pattern
def match(pattern, *args, **kwargs):
cached_pattern = compilePattern(pattern)
return cached_pattern.match(*args, **kwargs)