Issue #16037: HTTPMessage.readheaders() raises an HTTPException when more than

100 headers are read.  Adapted from patch by Jyrki Pulliainen.

2 files changed, 13 insertions, 0 deletions

diff --git a/Lib/http/client.py b/Lib/http/client.py
index b72cf08..cc452e2 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -214,6 +214,8 @@ MAXAMOUNT = 1048576
 
 # maximal line length when calling readline().
 _MAXLINE = 65536
+_MAXHEADERS = 100
+
 
 class HTTPMessage(email.message.Message):
     # XXX The only usage of this method is in
@@ -261,6 +263,8 @@ def parse_headers(fp, _class=HTTPMessage):
         if len(line) > _MAXLINE:
             raise LineTooLong("header line")
         headers.append(line)
+        if len(headers) > _MAXHEADERS:
+            raise HTTPException("got more than %d headers" % _MAXHEADERS)
         if line in (b'\r\n', b'\n', b''):
             break
     hstring = b''.join(headers).decode('iso-8859-1')
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index 769ab13..f3c27c2 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -345,6 +345,15 @@ class BasicTest(TestCase):
             self.fail("Did not expect response from HEAD request")
         self.assertEqual(bytes(b), b'\x00'*5)
 
+    def test_too_many_headers(self):
+        headers = '\r\n'.join('Header%d: foo' % i
+                              for i in range(client._MAXHEADERS + 1)) + '\r\n'
+        text = ('HTTP/1.1 200 OK\r\n' + headers)
+        s = FakeSocket(text)
+        r = client.HTTPResponse(s)
+        self.assertRaisesRegex(client.HTTPException,
+                               r"got more than \d+ headers", r.begin)
+
     def test_send_file(self):
         expected = (b'GET /foo HTTP/1.1\r\nHost: example.com\r\n'
                     b'Accept-Encoding: identity\r\nContent-Length:')