From 31b35ab838dfab92ea199a2688fefb74215aa7e9 Mon Sep 17 00:00:00 2001
From: Nate Prewitt <Nate.Prewitt@gmail.com>
Date: Wed, 21 Sep 2016 10:19:44 -0600
Subject: [PATCH] removing redundant logic from prepare_content_length

---
 requests/models.py     | 22 ++++++++++------------
 tests/test_requests.py | 10 ++++++++++
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/requests/models.py b/requests/models.py
index b9a9d360..ea25e356 100644
--- a/requests/models.py
+++ b/requests/models.py
@@ -424,7 +424,6 @@ class PreparedRequest(RequestEncodingMixin, RequestHooksMixin):
         # Nottin' on you.
         body = None
         content_type = None
-        length = None
 
         if not data and json is not None:
             # urllib3 requires a bytes-like body. Python 2's json.dumps
@@ -475,17 +474,16 @@ class PreparedRequest(RequestEncodingMixin, RequestHooksMixin):
         self.body = body
 
     def prepare_content_length(self, body):
-        if hasattr(body, 'seek') and hasattr(body, 'tell'):
-            curr_pos = body.tell()
-            body.seek(0, 2)
-            end_pos = body.tell()
-            self.headers['Content-Length'] = builtin_str(max(0, end_pos - curr_pos))
-            body.seek(curr_pos, 0)
-        elif body is not None:
-            l = super_len(body)
-            if l:
-                self.headers['Content-Length'] = builtin_str(l)
-        elif (self.method not in ('GET', 'HEAD')) and (self.headers.get('Content-Length') is None):
+        """Prepare Content-Length header based on request method and body"""
+        if body is not None:
+            length = super_len(body)
+            if length:
+                # If length exists, set it. Otherwise, we fallback
+                # to Transfer-Encoding: chunked.
+                self.headers['Content-Length'] = builtin_str(length)
+        elif self.method not in ('GET', 'HEAD') and self.headers.get('Content-Length') is None:
+            # Set Content-Length to 0 for methods that can have a body
+            # but don't provide one. (i.e. not GET or HEAD)
             self.headers['Content-Length'] = '0'
 
     def prepare_auth(self, auth, url=''):
diff --git a/tests/test_requests.py b/tests/test_requests.py
index 24f296f0..3ea30db0 100755
--- a/tests/test_requests.py
+++ b/tests/test_requests.py
@@ -90,6 +90,16 @@ class TestRequests:
         req = requests.Request(method, httpbin(method.lower())).prepare()
         assert 'Content-Length' not in req.headers
 
+    @pytest.mark.parametrize('method', ('POST', 'PUT', 'PATCH', 'OPTIONS'))
+    def test_no_body_content_length(self, httpbin, method):
+        req = requests.Request(method, httpbin(method.lower())).prepare()
+        assert req.headers['Content-Length'] == '0'
+
+    @pytest.mark.parametrize('method', ('POST', 'PUT', 'PATCH', 'OPTIONS'))
+    def test_empty_content_length(self, httpbin, method):
+        req = requests.Request(method, httpbin(method.lower()), data='').prepare()
+        assert req.headers['Content-Length'] == '0'
+
     def test_override_content_length(self, httpbin):
         headers = {
             'Content-Length': 'not zero'