[httpx] replace searx.poolrequests by searx.network

settings.yml:

* outgoing.networks:
   * can contains network definition
   * propertiers: enable_http, verify, http2, max_connections, max_keepalive_connections,
     keepalive_expiry, local_addresses, support_ipv4, support_ipv6, proxies, max_redirects, retries
   * retries: 0 by default, number of times searx retries to send the HTTP request (using different IP & proxy each time)
   * local_addresses can be "192.168.0.1/24" (it supports IPv6)
   * support_ipv4 & support_ipv6: both True by default
     see https://github.com/searx/searx/pull/1034
* each engine can define a "network" section:
   * either a full network description
   * either reference an existing network

* all HTTP requests of engine use the same HTTP configuration (it was not the case before, see proxy configuration in master)

1 files changed, 214 insertions, 0 deletions

diff --git a/searx/network/client.py b/searx/network/client.py
new file mode 100644
index 00000000..631e36f8
--- /dev/null
+++ b/searx/network/client.py
@@ -0,0 +1,214 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+
+import asyncio
+import logging
+import threading
+
+import httpcore
+import httpx
+from httpx_socks import AsyncProxyTransport
+from python_socks import parse_proxy_url
+import python_socks._errors
+
+from searx import logger
+
+# Optional uvloop (support Python 3.6)
+try:
+    import uvloop
+except ImportError:
+    pass
+else:
+    uvloop.install()
+
+
+logger = logger.getChild('searx.http.client')
+LOOP = None
+TRANSPORT_KWARGS = {
+    'backend': 'asyncio',
+    'trust_env': False,
+}
+
+
+async def close_connections_for_url(connection_pool: httpcore.AsyncConnectionPool, url: httpcore._utils.URL):
+    origin = httpcore._utils.url_to_origin(url)
+    logger.debug('Drop connections for %r', origin)
+    connections_to_close = connection_pool._connections_for_origin(origin)
+    for connection in connections_to_close:
+        await connection_pool._remove_from_pool(connection)
+        try:
+            await connection.aclose()
+        except httpcore.NetworkError as e:
+            logger.warning('Error closing an existing connection', exc_info=e)
+
+
+class AsyncHTTPTransportNoHttp(httpcore.AsyncHTTPTransport):
+    """Block HTTP request"""
+
+    async def arequest(self, method, url, headers=None, stream=None, ext=None):
+        raise httpcore.UnsupportedProtocol("HTTP protocol is disabled")
+
+
+class AsyncProxyTransportFixed(AsyncProxyTransport):
+    """Fix httpx_socks.AsyncProxyTransport
+
+    Map python_socks exceptions to httpcore.ProxyError
+
+    Map socket.gaierror to httpcore.ConnectError
+
+    Note: keepalive_expiry is ignored, AsyncProxyTransport should call:
+    * self._keepalive_sweep()
+    * self._response_closed(self, connection)
+
+    Note: AsyncProxyTransport inherit from AsyncConnectionPool
+
+    Note: the API is going to change on httpx 0.18.0
+    see https://github.com/encode/httpx/pull/1522
+    """
+
+    async def arequest(self, method, url, headers=None, stream=None, ext=None):
+        retry = 2
+        while retry > 0:
+            retry -= 1
+            try:
+                return await super().arequest(method, url, headers, stream, ext)
+            except (python_socks._errors.ProxyConnectionError,
+                    python_socks._errors.ProxyTimeoutError,
+                    python_socks._errors.ProxyError) as e:
+                raise httpcore.ProxyError(e)
+            except OSError as e:
+                # socket.gaierror when DNS resolution fails
+                raise httpcore.NetworkError(e)
+            except httpcore.RemoteProtocolError as e:
+                # in case of httpcore.RemoteProtocolError: Server disconnected
+                await close_connections_for_url(self, url)
+                logger.warning('httpcore.RemoteProtocolError: retry', exc_info=e)
+                # retry
+            except (httpcore.NetworkError, httpcore.ProtocolError) as e:
+                # httpcore.WriteError on HTTP/2 connection leaves a new opened stream
+                # then each new request creates a new stream and raise the same WriteError
+                await close_connections_for_url(self, url)
+                raise e
+
+
+class AsyncHTTPTransportFixed(httpx.AsyncHTTPTransport):
+    """Fix httpx.AsyncHTTPTransport"""
+
+    async def arequest(self, method, url, headers=None, stream=None, ext=None):
+        retry = 2
+        while retry > 0:
+            retry -= 1
+            try:
+                return await super().arequest(method, url, headers, stream, ext)
+            except OSError as e:
+                # socket.gaierror when DNS resolution fails
+                raise httpcore.ConnectError(e)
+            except httpcore.CloseError as e:
+                # httpcore.CloseError: [Errno 104] Connection reset by peer
+                # raised by _keepalive_sweep()
+                #   from https://github.com/encode/httpcore/blob/4b662b5c42378a61e54d673b4c949420102379f5/httpcore/_backends/asyncio.py#L198  # noqa
+                await close_connections_for_url(self._pool, url)
+                logger.warning('httpcore.CloseError: retry', exc_info=e)
+                # retry
+            except httpcore.RemoteProtocolError as e:
+                # in case of httpcore.RemoteProtocolError: Server disconnected
+                await close_connections_for_url(self._pool, url)
+                logger.warning('httpcore.RemoteProtocolError: retry', exc_info=e)
+                # retry
+            except (httpcore.ProtocolError, httpcore.NetworkError) as e:
+                await close_connections_for_url(self._pool, url)
+                raise e
+
+
+def get_transport_for_socks_proxy(verify, http2, local_address, proxy_url, limit, retries):
+    global LOOP, TRANSPORT_KWARGS
+    # support socks5h (requests compatibility):
+    # https://requests.readthedocs.io/en/master/user/advanced/#socks
+    # socks5://   hostname is resolved on client side
+    # socks5h://  hostname is resolved on proxy side
+    rdns = False
+    socks5h = 'socks5h://'
+    if proxy_url.startswith(socks5h):
+        proxy_url = 'socks5://' + proxy_url[len(socks5h):]
+        rdns = True
+
+    proxy_type, proxy_host, proxy_port, proxy_username, proxy_password = parse_proxy_url(proxy_url)
+
+    return AsyncProxyTransportFixed(proxy_type=proxy_type, proxy_host=proxy_host, proxy_port=proxy_port,
+                                    username=proxy_username, password=proxy_password,
+                                    rdns=rdns,
+                                    loop=LOOP,
+                                    verify=verify,
+                                    http2=http2,
+                                    local_address=local_address,
+                                    max_connections=limit.max_connections,
+                                    max_keepalive_connections=limit.max_keepalive_connections,
+                                    keepalive_expiry=limit.keepalive_expiry,
+                                    retries=retries,
+                                    **TRANSPORT_KWARGS)
+
+
+def get_transport(verify, http2, local_address, proxy_url, limit, retries):
+    return AsyncHTTPTransportFixed(verify=verify,
+                                   http2=http2,
+                                   local_address=local_address,
+                                   proxy=httpx._config.Proxy(proxy_url) if proxy_url else None,
+                                   limits=limit,
+                                   retries=retries,
+                                   **TRANSPORT_KWARGS)
+
+
+def iter_proxies(proxies):
+    # https://www.python-httpx.org/compatibility/#proxy-keys
+    if isinstance(proxies, str):
+        yield 'all://', proxies
+    elif isinstance(proxies, dict):
+        for pattern, proxy_url in proxies.items():
+            yield pattern, proxy_url
+
+
+def new_client(enable_http, verify, enable_http2,
+               max_connections, max_keepalive_connections, keepalive_expiry,
+               proxies, local_address, retries, max_redirects):
+    limit = httpx.Limits(max_connections=max_connections,
+                         max_keepalive_connections=max_keepalive_connections,
+                         keepalive_expiry=keepalive_expiry)
+    # See https://www.python-httpx.org/advanced/#routing
+    mounts = {}
+    for pattern, proxy_url in iter_proxies(proxies):
+        if not enable_http and (pattern == 'http' or pattern.startswith('http://')):
+            continue
+        if proxy_url.startswith('socks4://') \
+           or proxy_url.startswith('socks5://') \
+           or proxy_url.startswith('socks5h://'):
+            mounts[pattern] = get_transport_for_socks_proxy(verify, enable_http2, local_address, proxy_url, limit,
+                                                            retries)
+        else:
+            mounts[pattern] = get_transport(verify, enable_http2, local_address, proxy_url, limit, retries)
+
+    if not enable_http:
+        mounts['http://'] = AsyncHTTPTransportNoHttp()
+
+    transport = get_transport(verify, enable_http2, local_address, None, limit, retries)
+    return httpx.AsyncClient(transport=transport, mounts=mounts, max_redirects=max_redirects)
+
+
+def init():
+    # log
+    for logger_name in ('hpack.hpack', 'hpack.table'):
+        logging.getLogger(logger_name).setLevel(logging.WARNING)
+
+    # loop
+    def loop_thread():
+        global LOOP
+        LOOP = asyncio.new_event_loop()
+        LOOP.run_forever()
+
+    th = threading.Thread(
+        target=loop_thread,
+        name='asyncio_loop',
+        daemon=True,
+    )
+    th.start()
+
+
+init()