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"""Logic to perform spam/ham classification"""
import sys
from typing import Any, List
from google.protobuf.json_format import MessageToDict
from vyper import v
from api.v1.spamcheck_pb2 import SpamVerdict
from app import event, logger, queue, data_store
from server.interceptors import SpamCheckContext
log = logger.logger
classifiers = v.get_string("ml_classifiers")
if classifiers:
sys.path.append(classifiers)
# pylint: disable=too-few-public-methods
class Spammable:
"""Base class for spammable types."""
allow_list = v.get("filter.allow_list")
deny_list = v.get("filter.deny_list")
allowed_domains = set(v.get("filter.allowed_domains"))
# Currently maximum allowed value is conditional allow to limit false positives.
max_verdict = SpamVerdict.CONDITIONAL_ALLOW
_inference_scores = {
0.9: SpamVerdict.BLOCK,
0.5: SpamVerdict.DISALLOW,
0.4: SpamVerdict.CONDITIONAL_ALLOW,
0.0: SpamVerdict.ALLOW,
}
_verdict_rankings = {
SpamVerdict.ALLOW: 1,
SpamVerdict.CONDITIONAL_ALLOW: 2,
SpamVerdict.DISALLOW: 3,
SpamVerdict.BLOCK: 4,
}
_verdict_mapping = {
"ALLOW": SpamVerdict.ALLOW,
"CONDITIONAL_ALLOW": SpamVerdict.CONDITIONAL_ALLOW,
"DISALLOW": SpamVerdict.DISALLOW,
"BLOCK": SpamVerdict.BLOCK,
}
def __init__(
self, spammable: Any, context: SpamCheckContext, classifier: None
) -> None:
self.context = context
self.spammable = spammable
self.classifier = classifier
@classmethod
def set_max_verdict(cls):
"""Set the maximum verdict for the spammable class."""
key = f"max_{cls.__name__}_verdict".lower()
verdict_value = v.get_string(key).upper()
try:
cls.max_verdict = cls._verdict_mapping[verdict_value]
except KeyError:
valid_args = ', '.join(cls._verdict_mapping.keys())
log.fatal(f"Max verdict must be in [{valid_args}]. Got: {verdict_value}")
@property
def spammable(self) -> Any:
"""spam.Spammable: The spammable to analyze for spam"""
return self._spammable
@spammable.setter
def spammable(self, spammable: Any):
self._spammable = spammable
self._email_allowed = self.email_allowed(spammable.user.emails)
if spammable.project:
self._project_allowed = self.project_allowed(spammable.project.project_id)
else:
self._project_allowed = True
def verdict(self) -> SpamVerdict:
"""Analyze the spammable and determine if spam.
Returns:
SpamVerdict
"""
# If the project is not allowed then this may be an indication that the model
# does not generalize well to the spammables in that project. In this case we will
# circumvent evaluating the spammable.
if not self._project_allowed:
return self._verdict(SpamVerdict.NOOP, 0.0, "project not allowed", False)
if not self.classifier:
return self._verdict(SpamVerdict.NOOP, 0.0, "classifier not loaded", False)
spammable_dict = self.to_dict()
confidence = self.classifier.score(spammable_dict)
data_store.save(self.type(), spammable_dict, confidence)
if self._email_allowed:
return self._verdict(SpamVerdict.ALLOW, confidence, "email allowed", True)
verdict = self.calculate_verdict(confidence)
return self._verdict(verdict, confidence, "ml inference score", True)
def calculate_verdict(self, confidence: float) -> SpamVerdict:
"""Convert an ML confidence value to a spam verdict.
Args:
confidence (float): The ML confidence value
Returns:
SpamVerdict
"""
for threshold, vdict in self._inference_scores.items():
if confidence >= threshold:
return self._maximum_verdict(vdict)
return SpamVerdict.NOOP
def _verdict(
self, verdict: int, confidence: float, reason: str, evaluated: bool
) -> SpamVerdict:
fields = {
"correlation_id": str(self.context.correlation_id),
"metric": "spamcheck_verdicts",
"spammable_type": self.type(),
"email_allowlisted": self._email_allowed,
"project_allowed": self._project_allowed,
"project_path": self._spammable.project.project_path,
"project_id": self._spammable.project.project_id,
"user_name": self._spammable.user.username,
"user_in_project": self._spammable.user_in_project,
"verdict": SpamVerdict.Verdict.Name(verdict),
"reason": reason,
"confidence": confidence,
"evaluated": evaluated,
}
log.info("Verdict calculated", extra=fields)
if verdict not in (SpamVerdict.ALLOW, SpamVerdict.NOOP):
evnt = event.Event(event.VERDICT, fields)
queue.publish(evnt)
return SpamVerdict(
verdict=verdict, score=confidence, reason=reason, evaluated=evaluated
)
def project_allowed(self, project_id: int) -> bool:
"""Determine if a project should be tested for spam.
Args:
project_id (int): The GitLab project ID
Returns:
bool
"""
if len(self.allow_list) != 0:
if self.allow_list.get(project_id) is not None:
return True
return False
if len(self.deny_list) != 0:
if self.deny_list.get(project_id) is not None:
return False
return True
return True
def email_allowed(self, emails: List) -> bool:
"""Determine if a user email should be exempt from spam checking.
Args:
emails (list): A list of Emails represented by protobuf objects
Returns:
bool
"""
for email in emails:
if not "@" in email.email:
continue
domain = email.email.split("@")[-1]
if email.verified and domain in self.allowed_domains:
return True
return False
def type(self) -> str:
"""Get the string representation of the spammable type."""
return type(self).__name__.lower()
def to_dict(self) -> dict:
"""Return the dictionary representation of the spammable."""
spammable_dict = MessageToDict(self._spammable)
spammable_dict["correlation_id"] = str(self.context.correlation_id)
return spammable_dict
def _maximum_verdict(self, verdict: SpamVerdict) -> SpamVerdict:
max_verdict = self._verdict_rankings[self.max_verdict]
current_verdict = self._verdict_rankings[verdict]
if max_verdict < current_verdict:
return self.max_verdict
return verdict
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