Don't send `Content-Length` for `OPTIONS` requests when there is no data. (#1319)

5 files changed, 71 insertions, 5 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 764c1738..509e7ee2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 This document records all notable changes to [HTTPie](https://httpie.io).
 This project adheres to [Semantic Versioning](https://semver.org/).
 
+## [3.1.1.dev0](https://github.com/httpie/httpie/compare/3.1.0...HEAD) (Unreleased)
+
+- Fixed redundant creation of `Content-Length` header on `OPTIONS` requests. ([#1310](https://github.com/httpie/httpie/issues/1310))
+
 ## [3.1.0](https://github.com/httpie/httpie/compare/3.0.2...3.1.0) (2022-03-08)
 
 - **SECURITY** Fixed the [vulnerability](https://github.com/httpie/httpie/security/advisories/GHSA-9w4w-cpc8-h2fq) that caused exposure of cookies on redirects to third party hosts. ([#1312](https://github.com/httpie/httpie/pull/1312))
diff --git a/httpie/__init__.py b/httpie/__init__.py
index 90aa2789..c8b2eb5e 100644
--- a/httpie/__init__.py
+++ b/httpie/__init__.py
@@ -3,6 +3,6 @@ HTTPie: modern, user-friendly command-line HTTP client for the API era.
 
 """
 
-__version__ = '3.1.0'
+__version__ = '3.1.1.dev0'
 __author__ = 'Jakub Roztocil'
 __licence__ = 'BSD'
diff --git a/httpie/cli/constants.py b/httpie/cli/constants.py
index e8188938..61e61f40 100644
--- a/httpie/cli/constants.py
+++ b/httpie/cli/constants.py
@@ -9,6 +9,7 @@ URL_SCHEME_RE = re.compile(r'^[a-z][a-z0-9.+-]*://', re.IGNORECASE)
 
 HTTP_POST = 'POST'
 HTTP_GET = 'GET'
+HTTP_OPTIONS = 'OPTIONS'
 
 # Various separators used in args
 SEPARATOR_HEADER = ':'
diff --git a/httpie/client.py b/httpie/client.py
index 530d589c..047b7856 100644
--- a/httpie/client.py
+++ b/httpie/client.py
@@ -13,7 +13,7 @@ import urllib3
 from . import __version__
 from .adapters import HTTPieHTTPAdapter
 from .context import Environment
-from .cli.constants import EMPTY_STRING
+from .cli.constants import EMPTY_STRING, HTTP_OPTIONS
 from .cli.dicts import HTTPHeadersDict, NestedJSONArray
 from .encoding import UTF8
 from .models import RequestsMessage
@@ -34,6 +34,8 @@ JSON_CONTENT_TYPE = 'application/json'
 JSON_ACCEPT = f'{JSON_CONTENT_TYPE}, */*;q=0.5'
 DEFAULT_UA = f'HTTPie/{__version__}'
 
+IGNORE_CONTENT_LENGTH_METHODS = frozenset([HTTP_OPTIONS])
+
 
 def collect_messages(
     env: Environment,
@@ -85,7 +87,7 @@ def collect_messages(
 
     request = requests.Request(**request_kwargs)
     prepared_request = requests_session.prepare_request(request)
-    apply_missing_repeated_headers(prepared_request, request.headers)
+    transform_headers(request, prepared_request)
     if args.path_as_is:
         prepared_request.url = ensure_path_as_is(
             orig_url=args.url,
@@ -200,9 +202,30 @@ def finalize_headers(headers: HTTPHeadersDict) -> HTTPHeadersDict:
     return final_headers
 
 
+def transform_headers(
+    request: requests.Request,
+    prepared_request: requests.PreparedRequest
+) -> None:
+    """Apply various transformations on top of the `prepared_requests`'s
+    headers to change the request prepreation behavior."""
+
+    # Remove 'Content-Length' when it is misplaced by requests.
+    if (
+        prepared_request.method in IGNORE_CONTENT_LENGTH_METHODS
+        and prepared_request.headers.get('Content-Length') == '0'
+        and request.headers.get('Content-Length') != '0'
+    ):
+        prepared_request.headers.pop('Content-Length')
+
+    apply_missing_repeated_headers(
+        request.headers,
+        prepared_request
+    )
+
+
 def apply_missing_repeated_headers(
-    prepared_request: requests.PreparedRequest,
-    original_headers: HTTPHeadersDict
+    original_headers: HTTPHeadersDict,
+    prepared_request: requests.PreparedRequest
 ) -> None:
     """Update the given `prepared_request`'s headers with the original
     ones. This allows the requests to be prepared as usual, and then later
diff --git a/tests/test_httpie.py b/tests/test_httpie.py
index f646d4e0..f07f34b9 100644
--- a/tests/test_httpie.py
+++ b/tests/test_httpie.py
@@ -324,3 +324,41 @@ def test_json_input_preserve_order(httpbin_both):
     assert HTTP_OK in r
     assert r.json['data'] == \
         '{"order": {"map": {"1": "first", "2": "second"}}}'
+
+
+@pytest.mark.parametrize('extra_args, expected_content_length', [
+    (
+        ['Content-Length:0'],
+        '0'
+    ),
+    (
+        ['Content-Length:xxx'],
+        'xxx',
+    ),
+    (
+        ['--raw=data'],
+        '4'
+    ),
+    (
+        ['query[param]=something'],
+        '33'
+    )
+])
+def test_options_content_length_preservation(httpbin, extra_args, expected_content_length):
+    r = http(
+        '--offline',
+        'OPTIONS',
+        httpbin + '/anything',
+        *extra_args
+    )
+    assert f'Content-Length: {expected_content_length}' in r
+
+
+@pytest.mark.parametrize('method', ['options', 'Options', 'OPTIONS'])
+def test_options_dropping_redundant_content_length(httpbin, method):
+    r = http(
+        '--offline',
+        method,
+        httpbin + '/anything'
+    )
+    assert 'Content-Length' not in r