Add server_tokens configuration option

Fixes benoitc#825

docs/source/settings.rst

@@ -1095,6 +1095,23 @@ The variables are passed to the the PasteDeploy entrypoint. Example::
 
 .. versionadded:: 19.7
 
+.. _server-tokens:
+
+server_tokens
+~~~~~~~~~~~~~
+
+* ``--server-tokens``
+* ``true``
+
+Enable or disable emitting gunicorn version in the ``Server`` http response header.
+
+This setting may also be used to emit a custom ``Server`` header value
+or disable the header entirely.
+
+A value of ``true`` will result in the default behavior. ``false`` will disable
+emittance of gunicorn version. A string value will emit itself as a custom ``Server``
+header value, and an empty string will disable the ``Server`` response header.
+
 Server Socket
 -------------
 

gunicorn/config.py

@@ -17,7 +17,7 @@
 import sys
 import textwrap
 
-from gunicorn import __version__, util
+from gunicorn import __version__, util, SERVER_SOFTWARE
 from gunicorn.errors import ConfigError
 from gunicorn.reloader import reloader_engines
 
@@ -221,6 +221,17 @@ def paste_global_conf(self):
 
         return global_conf
 
+    @property
+    def server_tokens(self):
+        s = self.settings['server_tokens'].get()
+        if s == 'true':
+            return SERVER_SOFTWARE
+
+        if s == 'false':
+            return 'gunicorn'
+
+        return s
+
 
 class SettingMeta(type):
     def __new__(cls, name, bases, attrs):
@@ -1988,3 +1999,21 @@ class PasteGlobalConf(Setting):
 
         .. versionadded:: 19.7
         """
+
+class ServerTokens(Setting):
+    name = "server_tokens"
+    section = "Server Mechanics"
+    cli = ["--server-tokens"]
+    validator = validate_string
+    default = 'true'
+    desc = """\
+        Enable or disable emitting gunicorn version in the ``Server`` http response header.
+        
+        This setting may also be used to emit a custom ``Server`` header value
+        or disable the header entirely.
+        
+        A value of ``true`` will result in the default behavior. ``false`` will disable
+        emittance of gunicorn version. A string value will emit itself as a custom ``Server``
+        header value, and an empty string will disable the ``Server`` response header.
+    """
+

gunicorn/http/wsgi.py

@@ -194,7 +194,6 @@ class Response(object):
     def __init__(self, req, sock, cfg):
         self.req = req
         self.sock = sock
-        self.version = SERVER_SOFTWARE
         self.status = None
         self.chunked = False
         self.must_close = False
@@ -300,10 +299,11 @@ def default_headers(self):
         headers = [
             "HTTP/%s.%s %s\r\n" % (self.req.version[0],
                 self.req.version[1], self.status),
-            "Server: %s\r\n" % self.version,
             "Date: %s\r\n" % util.http_date(),
             "Connection: %s\r\n" % connection
         ]
+        if self.cfg and self.cfg.server_tokens:
+            headers.append("Server: %s\r\n" % self.cfg.server_tokens)
         if self.chunked:
             headers.append("Transfer-Encoding: chunked\r\n")
         return headers

tests/test_config.py

@@ -8,7 +8,7 @@
 
 import pytest
 
-from gunicorn import config
+from gunicorn import config, SERVER_SOFTWARE
 from gunicorn.app.base import Application
 from gunicorn.errors import ConfigError
 from gunicorn.workers.sync import SyncWorker
@@ -435,3 +435,14 @@ def test_bind_fd():
     with AltArgs(["prog_name", "-b", "fd://42"]):
         app = NoConfigApp()
     assert app.cfg.bind == ["fd://42"]
+
+
+def test_server_tokens():
+    c = config.Config()
+    assert c.server_tokens == SERVER_SOFTWARE
+    c.set('server_tokens', 'false')
+    assert c.server_tokens == 'gunicorn'
+    c.set('server_tokens', 'server software')
+    assert c.server_tokens == 'server software'
+    c.set('server_tokens', '')
+    assert c.server_tokens == ''

tests/test_http.py

@@ -4,7 +4,7 @@
 import t
 import pytest
 
-from gunicorn import util
+from gunicorn import util, config, SERVER_SOFTWARE
 from gunicorn.http.body import Body, LengthReader, EOFReader
 from gunicorn.http.wsgi import Response
 from gunicorn.http.unreader import Unreader, IterUnreader, SocketUnreader
@@ -226,3 +226,42 @@ def test_eof_reader_read_invalid_size():
         reader.read([100])
     with pytest.raises(ValueError):
         reader.read(-100)
+
+
+def test_http_server_header():
+    """ tests whether the http server header is set correctly """
+
+    def get_server_header(headers):
+        for header in headers:
+            if header[:8] == 'Server: ':
+                return header[8:].strip()
+        return None
+
+    mocked_socket = mock.MagicMock()
+    mocked_socket.sendall = mock.MagicMock()
+
+    mocked_request = mock.MagicMock()
+    c = config.Config()
+
+    # default server header
+    response = Response(mocked_request, mocked_socket, c)
+    headers = response.default_headers()
+    assert get_server_header(headers) == SERVER_SOFTWARE
+
+    # server header w/o version number
+    c.set('server_tokens', 'false')
+    response = Response(mocked_request, mocked_socket, c)
+    headers = response.default_headers()
+    assert get_server_header(headers) == 'gunicorn'
+
+    # custom server header
+    c.set('server_tokens', 'server software')
+    response = Response(mocked_request, mocked_socket, c)
+    headers = response.default_headers()
+    assert get_server_header(headers) == 'server software'
+
+    # disabled server header
+    c.set('server_tokens', '')
+    response = Response(mocked_request, mocked_socket, c)
+    headers = response.default_headers()
+    assert get_server_header(headers) is None