From 6eea3e7c1c3727f464e9bbe0e6f7f1af84372f1e Mon Sep 17 00:00:00 2001
From: Marc Abonce Seguin <marc-abonce@mailbox.org>
Date: Sun, 27 Mar 2022 20:21:37 -0600
Subject: [PATCH] allow many rate limiters per engine

---
 docs/admin/engines/settings.rst      |  4 ++--
 searx/engines/__init__.py            | 10 +++++-----
 searx/plugins/engine_rate_limiter.py | 27 +++++++++++----------------
 3 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/docs/admin/engines/settings.rst b/docs/admin/engines/settings.rst
index 6a5e6b4db..ea03b9fbe 100644
--- a/docs/admin/engines/settings.rst
+++ b/docs/admin/engines/settings.rst
@@ -423,8 +423,8 @@ engine is shown.  Most of the options have a default value or even are optional.
      max_keepalive_connections: 10
      keepalive_expiry: 5.0
      rate_limit:
-        max_requests: 200
-        interval: 60
+        - max_requests: 200
+          interval: 60
      proxies:
        http:
          - http://proxy1:8080
diff --git a/searx/engines/__init__.py b/searx/engines/__init__.py
index 24f9087f0..2249f1d71 100644
--- a/searx/engines/__init__.py
+++ b/searx/engines/__init__.py
@@ -44,7 +44,7 @@ ENGINE_DEFAULT_ARGS = {
     "enable_http": False,
     "using_tor_proxy": False,
     "display_error_messages": True,
-    "rate_limit": { "max_requests": float('inf'), "interval": 1 },
+    "rate_limit": [{ "max_requests": float('inf'), "interval": 1 }],
     "tokens": [],
     "about": {},
 }
@@ -170,10 +170,10 @@ def update_engine_attributes(engine: Engine, engine_data):
         elif hasattr(engine, 'about') and param_name == 'about':
             engine.about = {**engine.about, **engine_data['about']}
         elif hasattr(engine, 'rate_limit') and param_name == 'rate_limit':
-            engine.rate_limit = {
-                'max_requests': int(param_value.get('max_requests')),
-                'interval': int(param_value.get('interval', 1))
-            }
+            engine.rate_limit = [{
+                'max_requests': int(rate_limit.get('max_requests')),
+                'interval': int(rate_limit.get('interval', 1))
+            } for rate_limit in param_value]
         else:
             setattr(engine, param_name, param_value)
 
diff --git a/searx/plugins/engine_rate_limiter.py b/searx/plugins/engine_rate_limiter.py
index cff1f688a..f46a62ca0 100644
--- a/searx/plugins/engine_rate_limiter.py
+++ b/searx/plugins/engine_rate_limiter.py
@@ -11,9 +11,6 @@ Enable ``settings.yml``:
 - ``interval: ...`` number of seconds before rate limiting resets (optional, by default 1 second)
 """
 
-import hmac
-
-from searx import settings
 from searx.engines import engines
 from searx.shared import redisdb
 
@@ -43,26 +40,24 @@ def check_rate_limiter(engine_name, limit, interval):
     """
     script_sha = redis_client.script_load(lua_script)
 
-    secret_key_bytes = bytes(settings['server']['secret_key'], encoding='utf-8')
-    m = hmac.new(secret_key_bytes, digestmod='sha256')
-    m.update(bytes(engine_name, encoding='utf-8'))
-    key = m.digest()
-
+    key = f'rate_limiter_{engine_name}_{limit}r/{interval}s'.encode()
     requestsCounter = redis_client.evalsha(script_sha, 1, key, limit, interval)
     return int(requestsCounter)
 
 
 def below_rate_limit(engine_name):
     engine = engines[engine_name]
-    max_requests = engine.rate_limit['max_requests']
-    interval = engine.rate_limit['interval']
+    is_below_rate_limit = True
+    for rate_limit in engine.rate_limit:
+        max_requests = rate_limit['max_requests']
+        interval = rate_limit['interval']
+        if max_requests == float('inf'):
+            continue
+        if max_requests < check_rate_limiter(engine_name, max_requests, interval):
+            is_below_rate_limit = False
+            logger.debug(f"{engine_name} exceeded rate limit of {max_requests} requests per {interval} seconds")  # pylint: disable=undefined-variable
 
-    if max_requests == float('inf'):
-        return True
-    if max_requests >= check_rate_limiter(engine_name, max_requests, interval):
-        return True
-    logger.debug(f"{engine_name} exceeded rate limit of {max_requests} requests per {interval} seconds")  # pylint: disable=undefined-variable
-    return False
+    return is_below_rate_limit
 
 
 def pre_search(_, search):