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Decode headers before processing

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This commit is contained in:
Thomas Oettli
2020-02-27 16:37:50 +01:00
parent 13ca896a0f
commit c1ad068197
1 changed files with 32 additions and 27 deletions
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59
pyheadermilter/__init__.py
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@@ -25,6 +25,8 @@ import re
import sys
from Milter.utils import parse_addr
from email.message import EmailMessage
from email.policy import default as default_policy
from netaddr import IPAddress, IPNetwork, AddrFormatError
@@ -34,7 +36,7 @@ class HeaderRule:
def __init__(self, name, action, header, search="", value="", ignore_hosts=[], ignore_envfrom=None, only_hosts=[], log=True):
self.logger = logging.getLogger(__name__)
self.name = name
self._action = action
self.action = action
self.header = header
self.search = search
self.value = value
@@ -79,12 +81,6 @@ class HeaderRule:
except AddrFormatError as e:
raise RuntimeError("unable to parse option 'only_hosts' of rule '{}': {}".format(name, e))
def get_action(self):
return self._action
def log_modification(self):
return self.log
def ignore_host(self, host):
ip = IPAddress(host)
ignore = False
@@ -118,7 +114,7 @@ class HeaderRule:
def execute(self, headers):
"""Execute rule on given headers and return list with modified headers."""
if self._action == "add":
if self.action == "add":
return [(self.header, self.value, 0, 1)]
modified = []
@@ -126,7 +122,7 @@ class HeaderRule:
occurrences = {}
# iterate headers
for name, value in headers:
for name, hdr in headers:
# keep track of the occurrence of each header, needed by Milter.Base.chgheader
if name not in occurrences.keys():
occurrences[name] = 1
@@ -134,14 +130,18 @@ class HeaderRule:
occurrences[name] += 1
# check if header line matches regex
value = hdr[name]
if self.header.search("{}: {}".format(name, value)):
if self._action == "del":
if self.action == "del":
# set an empty value to delete the header
new_value = ""
else:
str(hdr).split(": ", 1)[1].strip()
new_value = self.search.sub(self.value, value)
if value != new_value:
modified.append((name, new_value, index, occurrences[name]))
hdr = EmailMessage(policy=default_policy)
hdr[name] = new_value
modified.append((name, hdr, index, occurrences[name]))
index += 1
return modified
@@ -194,7 +194,11 @@ class HeaderMilter(Milter.Base):
@Milter.noreply
def header(self, name, value):
self.headers.append((name, value.encode(errors="surrogateescape").decode(errors="replace")))
# remove surrogates from value
value = value.encode(errors="surrogateescape").decode(errors="replace")
hdr = EmailMessage(policy=default_policy)
hdr[name] = value
self.headers.append((name, hdr))
return Milter.CONTINUE
def eom(self):
@@ -202,36 +206,37 @@ class HeaderMilter(Milter.Base):
for rule in self.rules:
self.logger.debug("{}: executing rule '{}'".format(self.queueid, rule.name))
modified = rule.execute(self.headers)
action = rule.get_action()
log = rule.log_modification()
for name, value, index, occurrence in modified:
for name, hdr, index, occurrence in modified:
value = hdr[name]
encoded_value = bytes(header).decode().split(": ")[1].rstrip()
mod_header = "{}: {}".format(name, value)
if action == "add":
if log:
if rule.action == "add":
if rule.log:
self.logger.info("{}: add: header: {}".format(self.queueid, mod_header[0:70]))
else:
self.logger.debug("{}: add: header: {}".format(self.queueid, mod_header))
self.headers.insert(0, (name, value))
self.addheader(name, value, 1)
self.headers.insert(0, (name, hdr))
self.addheader(name, encoded_value, 1)
else:
if action == "mod":
old_header = "{}: {}".format(name, self.headers[index][1])
if log:
if rule.action == "mod":
old_value = self.headers[index][1][name]
old_header = "{}: {}".format(name, old_value)
if rule.log:
self.logger.info("{}: modify: header: {}: {}".format(
self.queueid, old_header[0:70], mod_header[0:70]))
else:
self.logger.debug("{}: modify: header (occ. {}): {}: {}".format(
self.queueid, occurrence, old_header, mod_header))
self.headers[index] = (name, value)
elif action == "del":
if log:
self.headers[index] = (name, hdr)
elif rule.action == "del":
if rule.log:
self.logger.info("{}: delete: header: {}".format(self.queueid, mod_header[0:70]))
else:
self.logger.debug("{}: delete: header (occ. {}): {}".format(self.queueid, occurrence, mod_header))
del self.headers[index]
self.chgheader(name, occurrence, value)
self.chgheader(name, occurrence, encoded_value)
return Milter.ACCEPT
except Exception as e:
self.logger.exception("an exception occured in eom function: {}".format(e))