make connection_strategy=eager the default

mitmproxy/addons/proxyserver.py

@@ -83,8 +83,11 @@ class Proxyserver:
 
     def load(self, loader):
         loader.add_option(
-            "connection_strategy", str, "lazy",
-            "Determine when server connections should be established.",
+            "connection_strategy", str, "eager",
+            "Determine when server connections should be established. When set to lazy, mitmproxy "
+            "tries to defer establishing an upstream connection as long as possible. This makes it possible to "
+            "use server replay while being offline. When set to eager, mitmproxy can detect protocols with "
+            "server-side greetings, as well as accurately mirror TLS ALPN negotiation.",
             choices=("eager", "lazy")
         )
         loader.add_option(

mitmproxy/proxy/layers/modes.py

@@ -23,7 +23,7 @@ class DestinationKnown(layer.Layer, metaclass=ABCMeta):
     child_layer: layer.Layer
 
     def finish_start(self) -> layer.CommandGenerator[Optional[str]]:
-        if self.context.options.connection_strategy == "eager":
+        if self.context.options.connection_strategy == "eager" and self.context.server.address:
             err = yield commands.OpenConnection(self.context.server)
             if err:
                 self._handle_event = self.done  # type: ignore

test/mitmproxy/proxy/layers/http/test_http.py

@@ -546,6 +546,7 @@ def test_http_proxy_tcp(tctx, mode, close_first):
     """Test TCP over HTTP CONNECT."""
     server = Placeholder(Server)
     f = Placeholder(TCPFlow)
+    tctx.options.connection_strategy = "lazy"
 
     if mode == "upstream":
         tctx.options.mode = "upstream:http://proxy:8080"
@@ -813,6 +814,7 @@ def test_http_server_aborts(tctx, stream):
                                   "response", "error"])
 def test_kill_flow(tctx, when):
     """Test that we properly kill flows if instructed to do so"""
+    tctx.options.connection_strategy = "lazy"
     server = Placeholder(Server)
     connect_flow = Placeholder(HTTPFlow)
     flow = Placeholder(HTTPFlow)

test/mitmproxy/proxy/layers/test_modes.py

@@ -119,6 +119,7 @@ def test_reverse_proxy(tctx, keep_host_header):
     """
     server = Placeholder(Server)
     tctx.options.mode = "reverse:http://localhost:8000"
+    tctx.options.connection_strategy = "lazy"
     tctx.options.keep_host_header = keep_host_header
     assert (
         Playbook(modes.ReverseProxy(tctx), hooks=False)
@@ -321,6 +322,7 @@ def test_socks5_success(address: str, packed: bytes, tctx: Context):
 
 
 def test_socks5_trickle(tctx: Context):
+    tctx.options.connection_strategy = "lazy"
     playbook = Playbook(modes.Socks5Proxy(tctx))
     for x in CLIENT_HELLO:
         playbook >> DataReceived(tctx.client, bytes([x]))