Adds a new view for protocol buffers

The view uses protoc from the Google protocol buffer
tools. If the tool isn't installed, the view isn't
shown.

Google protobuf repo:
https://code.google.com/p/protobuf/

libmproxy/console/contentview.py

@@ -12,7 +12,7 @@ import netlib.utils
 import common
 from .. import utils, encoding, flow
 from ..contrib import jsbeautifier, html2text
-
+import subprocess
 try:
     import pyamf
     from pyamf import remoting, flex
@@ -364,6 +364,38 @@ class ViewImage:
             )
         return "%s image"%img.format, fmt
 
+class ViewProtobuf:
+    """Human friendly view of protocol buffers
+    The view uses the protoc compiler to decode the binary
+    """
+
+    name = "Protocol Buffer"
+    prompt = ("protobuf", "p")
+    content_types = ["application/x-protobuf"]
+
+    @staticmethod
+    def is_available():
+        try:
+            p = subprocess.Popen(["protoc", "--version"], stdout=subprocess.PIPE)
+            out, _ = p.communicate()
+            return out.startswith("libprotoc")
+        except:
+            return False
+
+    def decode_protobuf(self, content):
+        # if Popen raises OSError, it will be caught in
+        # get_content_view and fall back to Raw
+        p = subprocess.Popen(['protoc', '--decode_raw'],
+                             stdin=subprocess.PIPE,
+                             stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE)
+        out, _ = p.communicate(input=content)
+        return out
+
+    def __call__(self, hdrs, content, limit):
+        decoded = self.decode_protobuf(content)
+        txt = _view_text(decoded[:limit], len(decoded), limit)
+        return "Protobuf", txt
 
 views = [
     ViewAuto(),
@@ -381,6 +413,9 @@ views = [
 if pyamf:
     views.append(ViewAMF())
 
+if ViewProtobuf.is_available():
+    views.append(ViewProtobuf())
+
 content_types_map = {}
 for i in views:
     for ct in i.content_types:

test/data/protobuf01

@@ -0,0 +1,2 @@
+
+$3bbc333c-e61c-433b-819a-0b9a8cc103b8

test/test_console_contentview.py

@@ -234,6 +234,14 @@ if pyamf:
         p = tutils.test_data.path("data/amf03")
         assert v([], file(p).read(), sys.maxint)
 
+if cv.ViewProtobuf.is_available():
+    def test_view_protobuf_request():
+        v = cv.ViewProtobuf()
+
+        p = tutils.test_data.path("data/protobuf01")
+        content_type, output = v([], file(p).read(), sys.maxint)
+        assert content_type == "Protobuf"
+        assert output[0].text == '1: "3bbc333c-e61c-433b-819a-0b9a8cc103b8"'
 
 def test_get_by_shortcut():
     assert cv.get_by_shortcut("h")