bpo-42527: Use ignore mode instead strict for headers enconding in order to encode headers with special chars like emojis

Lib/http/server.py

@@ -506,15 +506,15 @@ def send_response_only(self, code, message=None):
                 self._headers_buffer = []
             self._headers_buffer.append(("%s %d %s\r\n" %
                     (self.protocol_version, code, message)).encode(
-                        'latin-1', 'strict'))
+                        'latin-1', 'ignore'))
 
     def send_header(self, keyword, value):
         """Send a MIME header to the headers buffer."""
         if self.request_version != 'HTTP/0.9':
             if not hasattr(self, '_headers_buffer'):
                 self._headers_buffer = []
             self._headers_buffer.append(
-                ("%s: %s\r\n" % (keyword, value)).encode('latin-1', 'strict'))
+                ("%s: %s\r\n" % (keyword, value)).encode('latin-1', 'ignore'))
 
         if keyword.lower() == 'connection':
             if value.lower() == 'close':

Lib/test/test_httpservers.py

@@ -126,6 +126,14 @@ def do_LATINONEHEADER(self):
             body = self.headers['x-special-incoming'].encode('utf-8')
             self.wfile.write(body)
 
+        def do_LATINONEEMOJIHEADER(self):
+            self.send_response(999)
+            self.send_header('X-Special', 'Emoji Dängerous Mind🛒')
+            self.send_header('Connection', 'close')
+            self.end_headers()
+            body = self.headers['x-special-incoming'].encode('utf-8')
+            self.wfile.write(body)
+
         def do_SEND_ERROR(self):
             self.send_error(int(self.path[1:]))
 
@@ -244,6 +252,14 @@ def test_latin1_header(self):
         self.assertEqual(res.getheader('X-Special'), 'Dängerous Mind')
         self.assertEqual(res.read(), 'Ärger mit Unicode'.encode('utf-8'))
 
+    def test_latin1_header_with_emoji(self):
+        self.con.request('LATINONEEMOJIHEADER', '/', headers={
+            'X-Special-Incoming':       'Ärger mit Unicode'
+        })
+        res = self.con.getresponse()
+        self.assertEqual(res.getheader('X-Special'), 'Emoji Dängerous Mind')
+        self.assertEqual(res.read(), 'Ärger mit Unicode'.encode('utf-8'))
+
     def test_error_content_length(self):
         # Issue #16088: standard error responses should have a content-length
         self.con.request('NOTFOUND', '/')

Misc/NEWS.d/next/Library/2021-08-25-15-33-23.bpo-42527.M7RMp5.rst

@@ -0,0 +1 @@
+Use utf-8 instead of latin-1

Misc/NEWS.d/next/Library/2021-08-25-16-15-39.bpo-42527.M7RMp5.rst

@@ -0,0 +1 @@
+Use utf-8 instead of latin-1

Misc/NEWS.d/next/Library/2021-08-25-16-16-34.bpo-42527.DrXbr7.rst

@@ -0,0 +1 @@
+Use ignore mode instead strict for headers enconding in order to encode headers with special chars like emojis