From f4b9930b05488f6674ad8bed33b0b2634f9f699c Mon Sep 17 00:00:00 2001
From: Shiva <shiva@exotel.in>
Date: Thu, 15 Oct 2020 13:48:39 +0530
Subject: [PATCH] Added support to echo http trailers in dumper addon

---
 mitmproxy/addons/dumper.py           |  3 +++
 mitmproxy/contentviews/__init__.py   |  8 +++++---
 mitmproxy/test/tutils.py             |  2 +-
 test/mitmproxy/addons/test_dumper.py | 13 +++++++++++++
 4 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/mitmproxy/addons/dumper.py b/mitmproxy/addons/dumper.py
index 3832e5ef5..b04506597 100644
--- a/mitmproxy/addons/dumper.py
+++ b/mitmproxy/addons/dumper.py
@@ -12,6 +12,7 @@ from mitmproxy import exceptions
 from mitmproxy import flowfilter
 from mitmproxy.utils import human
 from mitmproxy.utils import strutils
+from mitmproxy.net import http
 
 
 def indent(n: int, text: str) -> str:
@@ -225,6 +226,8 @@ class Dumper:
             self._echo_response_line(f)
             if ctx.options.flow_detail >= 2:
                 self._echo_headers(f.response.headers)
+                if f.response.trailers is not None and isinstance(f.response.trailers, http.Headers):
+                    self._echo_headers(f.response.trailers)
             if ctx.options.flow_detail >= 3:
                 self._echo_message(f.response, f)
 
diff --git a/mitmproxy/contentviews/__init__.py b/mitmproxy/contentviews/__init__.py
index 49c41f2ff..7778c8165 100644
--- a/mitmproxy/contentviews/__init__.py
+++ b/mitmproxy/contentviews/__init__.py
@@ -9,9 +9,10 @@ protobuf messages sent as WebSocket frames.
 
 Thus, the View API is very minimalistic. The only arguments are `data` and
 `**metadata`, where `data` is the actual content (as bytes). The contents on
-metadata depend on the protocol in use. For HTTP, the message headers are
-passed as the ``headers`` keyword argument. For HTTP requests, the query
-parameters are passed as the ``query`` keyword argument.
+metadata depend on the protocol in use. For HTTP, the message headers and
+message trailers are passed as the ``headers`` and ``trailers`` keyword
+argument. For HTTP requests, the query parameters are passed as the ``query``
+keyword argument.
 """
 import traceback
 from typing import Dict, Optional  # noqa
@@ -103,6 +104,7 @@ def get_message_content_view(viewname, message, flow):
         metadata["query"] = message.query
     if isinstance(message, http.Message):
         metadata["headers"] = message.headers
+        metadata["trailers"] = message.trailers
     metadata["message"] = message
     metadata["flow"] = flow
 
diff --git a/mitmproxy/test/tutils.py b/mitmproxy/test/tutils.py
index 79751060e..5b2bfe353 100644
--- a/mitmproxy/test/tutils.py
+++ b/mitmproxy/test/tutils.py
@@ -46,7 +46,7 @@ def tresp(**kwargs) -> http.Response:
         reason=b"OK",
         headers=http.Headers(((b"header-response", b"svalue"), (b"content-length", b"7"))),
         content=b"message",
-        trailers=None,
+        trailers=http.Headers(((b"trailer-response", b"svalue"), (b"trailer", b"this trailer-1"))),
         timestamp_start=946681202,
         timestamp_end=946681203,
     )
diff --git a/test/mitmproxy/addons/test_dumper.py b/test/mitmproxy/addons/test_dumper.py
index 7359229b3..d0d9d4e9b 100644
--- a/test/mitmproxy/addons/test_dumper.py
+++ b/test/mitmproxy/addons/test_dumper.py
@@ -124,6 +124,19 @@ def test_echo_body():
         d._echo_message(f.response, f)
         t = sio.getvalue()
         assert "cut off" in t
+        sio.truncate(0)
+
+        f = tflow.tflow(client_conn=True, server_conn=True, resp=True)
+        f.response.headers["content-type"] = "text/html"
+        f.response.content = b"foo bar voing\n" * 100
+        f.response.trailers["trailer-2"] = "this is trailer 2"
+        d._echo_headers(f.response.headers)
+        d._echo_message(f.response, f)
+        d._echo_headers(f.response.trailers)
+        t = sio.getvalue()
+        assert "content-type" in t
+        assert "cut off" in t
+        assert "trailer-2" in t
 
 
 def test_echo_request_line():