Implement MTU command

README.md

@@ -2,7 +2,7 @@
     =====================================
     generator=datazen
     version=3.1.4
-    hash=75472a985efe131b3312ecf46e006599
+    hash=3b287fdc5e1b1691d94597b8f170f111
     =====================================
 -->
 
@@ -102,10 +102,19 @@ options:
 ```
 $ ./venv3.12/bin/runtimepy mtu -h
 
-usage: runtimepy mtu [-h]
+usage: runtimepy mtu [-h] [--probe-size PROBE_SIZE] [--fallback FALLBACK] [-t]
+                     destination [destination ...]
+
+positional arguments:
+  destination           endpoint parameters (host, port[, flowinfo, scope_id])
 
 options:
-  -h, --help  show this help message and exit
+  -h, --help            show this help message and exit
+  --probe-size PROBE_SIZE
+                        data payload size to use for probe (default: 1432)
+  --fallback FALLBACK   fallback MTU value if probing doesn't succeed (i.e.
+                        not on Linux, default: 1432)
+  -t, --tcp             use TCP instead of UDP
 
 ```
 

runtimepy/commands/mtu.py

@@ -4,6 +4,7 @@
 
 # built-in
 import argparse
+import socket
 
 # third-party
 from vcorelib.args import CommandFunction
@@ -15,18 +16,13 @@
 def mtu_cmd(args: argparse.Namespace) -> int:
     """Execute the mtu command."""
 
-    print(args.probe_size)
-    print(args.fallback)
-
-    print(discover_mtu)
-
-    # def discover_mtu(
-    #     *destination: IpHostlike,
-    #     local: IpHost = None,
-    #     probe_size=args.probe_size,
-    #     fallback=args.fallback,
-    #     kind: int = socket.SOCK_DGRAM,
-    # ) -> int:
+    discover_mtu(
+        args.destination[0],
+        *(int(x) for x in args.destination[1:]),
+        probe_size=args.probe_size,
+        fallback=args.fallback,
+        kind=socket.SOCK_STREAM if args.tcp else socket.SOCK_DGRAM,
+    )
 
     return 0
 
@@ -48,10 +44,14 @@ def add_mtu_cmd(parser: argparse.ArgumentParser) -> CommandFunction:
         "(i.e. not on Linux, default: %(default)d)",
     )
 
-    # udp vs tcp
-    # ip6 flag?
+    parser.add_argument(
+        "-t", "--tcp", action="store_true", help="use TCP instead of UDP"
+    )
 
-    # dest
-    # local params?
+    parser.add_argument(
+        "destination",
+        nargs="+",
+        help="endpoint parameters (host, port[, flowinfo, scope_id])",
+    )
 
     return mtu_cmd

runtimepy/net/mtu.py

@@ -116,8 +116,8 @@ def discover_mtu(
     host.
     """
 
-    local = normalize_host(local)
     dest = normalize_host(*destination)
+    local = normalize_host(local, default=type(dest))
     result = host_discover_mtu(local, dest, probe_size, fallback, kind=kind)
 
     LOG.info(

tests/commands/test_mtu.py

@@ -13,4 +13,5 @@ def test_mtu_command_basic():
     """Test basic usages of the 'mtu' command."""
 
     base = base_args("mtu")
-    assert runtimepy_main(base) == 0
+    assert runtimepy_main(base + ["localhost", "8000"]) == 0
+    assert runtimepy_main(base + ["::1", "8000", "0", "0"]) == 0

tests/net/test_mtu.py

@@ -4,15 +4,13 @@
 
 # module under test
 from runtimepy.net.mtu import discover_mtu
-from runtimepy.net.util import IPv6Host, normalize_host
+
+# from runtimepy.net.util import IPv6Host, normalize_host
 
 
 def test_ipv4_mtu_discovery() -> None:
     """Test that we can discover maximum transmission units."""
 
     assert discover_mtu("localhost", 80) > 0
-    assert (
-        discover_mtu("::1", 80, 0, 0, local=normalize_host(default=IPv6Host))
-        > 0
-    )
+    assert discover_mtu("::1", 80, 0, 0) > 0
     assert discover_mtu("localhost", 80, probe_size=2**16) > 0