gh-100985: Consistently wrap IPv6 IP address during CONNECT (GH-100986)

Update _get_hostport to always remove square brackets
from IPv6 addresses. Then add them if needed
in "CONNECT .." and "Host: ".

1 files changed, 10 insertions, 5 deletions

diff --git a/Lib/http/client.py b/Lib/http/client.py
index 5eebfccafbc..a353716a850 100644
--- a/Lib/http/client.py
+++ b/Lib/http/client.py
@@ -936,17 +936,23 @@ class HTTPConnection:
                 host = host[:i]
             else:
                 port = self.default_port
-            if host and host[0] == '[' and host[-1] == ']':
-                host = host[1:-1]
+        if host and host[0] == '[' and host[-1] == ']':
+            host = host[1:-1]
 
         return (host, port)
 
     def set_debuglevel(self, level):
         self.debuglevel = level
 
+    def _wrap_ipv6(self, ip):
+        if b':' in ip and ip[0] != b'['[0]:
+            return b"[" + ip + b"]"
+        return ip
+
     def _tunnel(self):
         connect = b"CONNECT %s:%d %s\r\n" % (
-            self._tunnel_host.encode("idna"), self._tunnel_port,
+            self._wrap_ipv6(self._tunnel_host.encode("idna")),
+            self._tunnel_port,
             self._http_vsn_str.encode("ascii"))
         headers = [connect]
         for header, value in self._tunnel_headers.items():
@@ -1221,9 +1227,8 @@ class HTTPConnection:
 
                     # As per RFC 273, IPv6 address should be wrapped with []
                     # when used as Host header
-
+                    host_enc = self._wrap_ipv6(host_enc)
                     if ":" in host:
-                        host_enc = b'[' + host_enc + b']'
                         host_enc = _strip_ipv6_iface(host_enc)
 
                     if port == self.default_port: