Allow the adb server to bind on ::1

Currently the adb server can only bind on 127.0.0.1 or * if -a is
provided. This diff adds the ability for adb to bind on ::1 as
well for use cases where you might want to force adb to be IPv6
only.

To bind the adb server on ::1
```
$ ./adb -L tcp:[::1]:1234 server
$ lsof -nPi :1234
COMMAND ... NODE NAME
adb     ...  TCP [::1]:1234 (LISTEN)
```
The original behaviour is also retained, so this would only affect
users explicitly specifying ::1 in the socket spec
```
$ export ANDROID_ADB_SERVER_PORT=1234
$ ./adb server
$ lsof -nPi :1234
COMMAND ... NODE NAME
adb     ...  TCP 127.0.0.1:1234 (LISTEN)
```

Note: I've only implemented this behaviour for posix base systems,
due to my limited understanding of networking on windows. If
needed I can do some research to implement it there as well, but
there is currently no IPv6 support at all on the windows side.

Test: New unit test and the commands in the summary

Change-Id: I23e4531e8dfda4de9348124ad7491d728aecdbf7

1 files changed, 31 insertions, 0 deletions

diff --git a/test_adb.py b/test_adb.py
index 8272722e..3d6de266 100755
--- a/test_adb.py
+++ b/test_adb.py
@@ -281,6 +281,37 @@ class ServerTest(unittest.TestCase):
             subprocess.check_output(["adb", "-P", str(port), "kill-server"],
                                     stderr=subprocess.STDOUT)
 
+    @unittest.skipUnless(
+        os.name == "posix",
+        "adb doesn't yet support IPv6 on Windows",
+    )
+    def test_starts_on_ipv6_localhost(self):
+        """
+        Tests that the server can start up on ::1 and that it's accessible
+        """
+        server_port = 5037
+        # Kill any existing server on this non-default port.
+        subprocess.check_output(
+            ["adb", "-P", str(server_port), "kill-server"],
+            stderr=subprocess.STDOUT,
+        )
+        try:
+            subprocess.check_output(
+                ["adb", "-L", "tcp:[::1]:{}".format(server_port), "server"],
+                stderr=subprocess.STDOUT,
+            )
+            with fake_adbd() as (port, _):
+                with adb_connect(self, serial="localhost:{}".format(port)):
+                    pass
+        finally:
+            # If we started a server, kill it.
+            subprocess.check_output(
+                ["adb", "-P", str(server_port), "kill-server"],
+                stderr=subprocess.STDOUT,
+            )
+
+
+
 
 class EmulatorTest(unittest.TestCase):
     """Tests for the emulator connection."""