several fixes on command exports has several problems: #3676

* authority can usually rely on actual URL. as `:authority` headers will
break curl command. (advise if it's better to change them to Host, or if
it should be reported on curl side)
* `content-length`: 0 is added for each request. if it's found in the
curl argument list, it'll try to fetch an empty body (and crash).
also trying to guess on accept-encoding header to add the
`--compress` option when fetching potentially compressed content.
* ditto for httpie

mitmproxy/addons/export.py

@@ -11,6 +11,15 @@ import mitmproxy.types
 import pyperclip
 
 
+def cleanup_for_commands(request):
+    if ('content-length' in request.headers.keys() and
+            request.headers['content-length'] == '0' and
+            request.method == 'GET'):
+        request.headers.pop('content-length')
+    request.headers.pop(':authority', None)
+    return request
+
+
 def raise_if_missing_request(f: flow.Flow) -> None:
     if not hasattr(f, "request"):
         raise exceptions.CommandError("Can't export flow with no request.")
@@ -21,10 +30,15 @@ def curl_command(f: flow.Flow) -> str:
     data = "curl "
     request = f.request.copy()  # type: ignore
     request.decode(strict=False)
+    request = cleanup_for_commands(request)
     for k, v in request.headers.items(multi=True):
         data += "-H '%s:%s' " % (k, v)
     if request.method != "GET":
         data += "-X %s " % request.method
+    for header in request.headers.keys():
+        if ('accept-encoding' == header.lower() and
+                any(comp in request.headers[header] for comp in ['gzip', 'deflate'])):
+            data += "--compressed "
     data += "'%s'" % request.url
     if request.content:
         data += " --data-binary '%s'" % strutils.bytes_to_escaped_str(
@@ -39,6 +53,7 @@ def httpie_command(f: flow.Flow) -> str:
     request = f.request.copy()  # type: ignore
     data = "http %s " % request.method
     request.decode(strict=False)
+    request = cleanup_for_commands(request)
     data += "%s" % request.url
     for k, v in request.headers.items(multi=True):
         data += " '%s:%s'" % (k, v)

test/mitmproxy/addons/test_export.py

@@ -14,29 +14,23 @@ from unittest import mock
 @pytest.fixture
 def get_request():
     return tflow.tflow(
-        req=tutils.treq(
-            method=b'GET',
-            content=b'',
-            path=b"/path?a=foo&a=bar&b=baz"
-        )
-    )
+        req=tutils.treq(method=b'GET', content=b'', path=b"/path?a=foo&a=bar&b=baz"))
 
 
 @pytest.fixture
 def post_request():
     return tflow.tflow(
-        req=tutils.treq(
-            method=b'POST',
-            headers=(),
-            content=bytes(range(256))
-        )
-    )
+        req=tutils.treq(method=b'POST', headers=(), content=bytes(range(256))))
 
 
 @pytest.fixture
 def patch_request():
     return tflow.tflow(
-        req=tutils.treq(method=b'PATCH', path=b"/path?query=param")
+        req=tutils.treq(
+            method=b'PATCH',
+            content=b'content',
+            path=b"/path?query=param"
+        )
     )
 
 
@@ -47,7 +41,7 @@ def tcp_flow():
 
 class TestExportCurlCommand:
     def test_get(self, get_request):
-        result = """curl -H 'header:qvalue' -H 'content-length:0' 'http://address:22/path?a=foo&a=bar&b=baz'"""
+        result = """curl -H 'header:qvalue' 'http://address:22/path?a=foo&a=bar&b=baz'"""
         assert export.curl_command(get_request) == result
 
     def test_post(self, post_request):
@@ -67,7 +61,7 @@ class TestExportCurlCommand:
 
 class TestExportHttpieCommand:
     def test_get(self, get_request):
-        result = """http GET http://address:22/path?a=foo&a=bar&b=baz 'header:qvalue' 'content-length:0'"""
+        result = """http GET http://address:22/path?a=foo&a=bar&b=baz 'header:qvalue'"""
         assert export.httpie_command(get_request) == result
 
     def test_post(self, post_request):