Reland of "[telemetry] Wire TsProxy through telemetry's network stack."

telemetry/telemetry/internal/forwarders/__init__.py

Index: telemetry/telemetry/internal/forwarders/__init__.py
diff --git a/telemetry/telemetry/internal/forwarders/__init__.py b/telemetry/telemetry/internal/forwarders/__init__.py
index b11fbfeee761c930fa2016820168ed742546d1d3..45f92392028306132e4c369c1dfad9b604b18442 100644
--- a/telemetry/telemetry/internal/forwarders/__init__.py
+++ b/telemetry/telemetry/internal/forwarders/__init__.py
@@ -8,15 +8,36 @@
 PortPair = collections.namedtuple('PortPair', ['local_port', 'remote_port'])
 PortSet = collections.namedtuple('PortSet', ['http', 'https', 'dns'])
 
+class PortPairs(collections.namedtuple('PortPairs', ['http', 'https', 'dns'])):
+  __slots__ = ()
+
+  @classmethod
+  def Zip(cls, local_ports, remote_ports):
+    """Zip a pair of PortSet's into a single PortPairs object."""
+    with_dns = local_ports.dns is not None and remote_ports.dns is not None
+    return cls(
+      PortPair(local_ports.http, remote_ports.http),
+      PortPair(local_ports.https, remote_ports.https),
+      PortPair(local_ports.dns, remote_ports.dns) if with_dns else None)
+
+  @property
+  def local_ports(self):
+    """Return a tuple of local ports only."""
+    return PortSet(*[p.local_port if p is not None else None for p in self])
+
+  @property
+  def remote_ports(self):
+    """Return a tuple of remote ports only."""
+    return PortSet(*[p.remote_port if p is not None else None for p in self])
 
 
 class ForwarderFactory(object):
 
-  def Create(self, port_pair):
+  def Create(self, port_pairs):
     """Creates a forwarder that maps remote (device) <-> local (host) ports.
 
     Args:
-      port_pair: A PortPairs instance that consists of a PortPair mapping
+      port_pairs: A PortPairs instance that consists of a PortPair mapping
           for each protocol. http is required. https and dns may be None.
     """
     raise NotImplementedError()
@@ -28,22 +49,22 @@
 
 class Forwarder(object):
 
-  def __init__(self, port_pair):
-    assert port_pair, 'Port mapping is required.'
-    self._port_pair = port_pair
+  def __init__(self, port_pairs):
+    assert port_pairs.http, 'HTTP port mapping is required.'
+    self._port_pairs = port_pairs
     self._forwarding = True
 
   @property
   def host_port(self):
-    return self._port_pair.remote_port
+    return self._port_pairs.http.remote_port
 
   @property
   def host_ip(self):
     return '127.0.0.1'
 
   @property
-  def port_pair(self):
-    return self._port_pair
+  def port_pairs(self):
+    return self._port_pairs
 
   @property
   def url(self):
@@ -51,5 +72,5 @@
     return 'http://%s:%i' % (self.host_ip, self.host_port)
 
   def Close(self):
-    self._port_pair = None
+    self._port_pairs = None
     self._forwarding = False