File size: 5,416 Bytes
27803aa | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 | """
Pre-filter: catches obvious spam BEFORE burning an AI API call.
Zero cost. Runs on every message. AI only sees what passes all filters.
"""
import re
import time
import logging
logger = logging.getLogger(__name__)
# Spam keyword patterns (multilingual)
SPAM_KEYWORDS = re.compile(
r'加[我微v]|私聊领|免费领|日[赚入]|月入[过百千万]|'
r'代[开做理]|招[代聘]|兼\s*职|刷\s*单|'
r'翻[几十百]倍|稳赚|保本|零风险|'
r'[\U0001F4B0\U0001F4B8\U0001F911]{2,}|' # money emoji spam
r'click here|earn money|work from home|make \$|'
r'free crypto|airdrop|whitelist spot|'
r'join (?:my|our|this) (?:channel|group)|'
r't\.me/(?:joinchat|[+])',
re.IGNORECASE
)
# URL patterns
URL_PATTERN = re.compile(
r'https?://|t\.me/|bit\.ly|tinyurl|wa\.me|'
r'@\w+bot\b',
re.IGNORECASE
)
# Contact info patterns
CONTACT_PATTERN = re.compile(
r'[\U0001F4DE\U0001F4F1]|' # phone emojis
r'(?:whatsapp|telegram|wechat|微信|qq)\s*[:：]?\s*\d|'
r'(?:加|add)\s*(?:我|me)',
re.IGNORECASE
)
class APIRateLimiter:
"""Token bucket rate limiter for AI API calls."""
def __init__(self, max_calls=50, window=60):
self.max_calls = max_calls # max calls per window
self.window = window # window in seconds
self.calls = [] # timestamps of recent calls
def can_call(self):
"""Check if we can make another API call."""
now = time.time()
self.calls = [t for t in self.calls if now - t < self.window]
return len(self.calls) < self.max_calls
def record_call(self):
"""Record an API call."""
self.calls.append(time.time())
def remaining(self):
"""How many calls left in current window."""
now = time.time()
self.calls = [t for t in self.calls if now - t < self.window]
return max(0, self.max_calls - len(self.calls))
def is_critical(self):
"""Below 20% budget — switch to sampling mode."""
return self.remaining() < self.max_calls * 0.2
# Global rate limiter: 50 AI calls per minute (adjustable)
api_limiter = APIRateLimiter(max_calls=50, window=60)
def keyword_spam(text):
"""Fast keyword check. Returns True if obvious spam."""
if not text:
return False
# Keyword match + has URL or contact = almost certainly spam
has_keywords = bool(SPAM_KEYWORDS.search(text))
has_url = bool(URL_PATTERN.search(text))
has_contact = bool(CONTACT_PATTERN.search(text))
if has_keywords and (has_url or has_contact):
return True
# Pure contact harvesting: just a contact method, no real conversation
if has_contact and len(text) < 100 and not any(c in text for c in '?？'):
return True
return False
def forward_spam(msg):
"""Forwarded message with link/contact = spam."""
if not msg.forward_date:
return False
text = msg.text or msg.caption or ""
if URL_PATTERN.search(text) or CONTACT_PATTERN.search(text):
return True
# Forwarded media with no caption from non-group member = suspicious
if not text and (msg.photo or msg.video or msg.document):
return True
return False
def new_account_spam(user, text):
"""New/suspicious accounts with links = spam."""
if not text or not URL_PATTERN.search(text):
return False
# No username + no profile photo + has link = high spam probability
suspicious = 0
if not user.username:
suspicious += 1
if not user.first_name or len(user.first_name) < 2:
suspicious += 1
# Name is just emojis or special chars
if user.first_name and not any(c.isalpha() for c in user.first_name):
suspicious += 1
return suspicious >= 2
def should_use_ai(msg):
"""Decide if this message needs AI analysis or if we should skip/sample."""
if not api_limiter.can_call():
logger.warning("API rate limit hit — falling back to rules only")
return False
if api_limiter.is_critical():
# Sampling mode: only check 1 in 3 messages
import random
if random.random() > 0.33:
logger.info("API budget critical — sampling mode, skipping this message")
return False
return True
def prefilter(msg, user, text):
"""
Run all pre-filters. Returns:
"spam" — definitely spam, skip AI, nuke immediately
"clean" — definitely clean, skip AI
"ai" — unclear, needs AI analysis
"""
# Layer 1: Forward spam (zero false positive)
if forward_spam(msg):
logger.info("PREFILTER forward_spam: user=" + str(user.id))
return "spam"
# Layer 2: Keyword + link/contact (very high accuracy)
if text and keyword_spam(text):
logger.info("PREFILTER keyword_spam: user=" + str(user.id) + " text=" + text[:50])
return "spam"
# Layer 3: Suspicious new account + link
if new_account_spam(user, text):
logger.info("PREFILTER new_account_spam: user=" + str(user.id))
return "spam"
# Layer 4: No text, no media = nothing to check
if not text and not msg.photo and not msg.video:
return "clean"
# Layer 5: Rate limiter — can we afford an AI call?
if not should_use_ai(msg):
return "clean" # let it through rather than false-positive
# Needs AI
api_limiter.record_call()
return "ai"
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