From 9993d349a8abcb7ba07bebcc8cc71ecec291ca68 Mon Sep 17 00:00:00 2001
From: Ross Schlaikjer <ross@schlaikjer.net>
Date: Mon, 2 Jul 2018 10:26:15 -0400
Subject: Do not assert that new URI port is same as old port

When handling 301 redirects from http -> https on Erlang 21.0.1, the
following error is encountered:

```
8> Options = [].
9> httpc:request(head, {"http://rhye.org", []}, Options, []).
{error,{shutdown,{{error,{badmatch,443}},
                  [{httpc_response,resolve_uri,7,
                                   [{file,"/usr/local/lib/erlang/lib/inets-7.0/src/http_client/httpc_response.erl"},
                                    {line,431}]},
                   {httpc_response,redirect,2,
                                   [{file,"/usr/local/lib/erlang/lib/inets-7.0/src/http_client/httpc_response.erl"},
                                    {line,396}]},
                   {httpc_handler,handle_response,1,
                                  [{file,"httpc_handler.erl"},{line,1052}]},
                   {httpc_handler,handle_info,2,
                                  [{file,"httpc_handler.erl"},{line,283}]},
                   {gen_server,try_dispatch,4,
                               [{file,"gen_server.erl"},{line,637}]},
                   {gen_server,handle_msg,6,
                               [{file,"gen_server.erl"},{line,711}]},
                   {proc_lib,init_p_do_apply,3,
                             [{file,"proc_lib.erl"},{line,249}]}]}}}
```

This seems to be caused by the following code in `resolve_uri`:
```
resolve_uri(Scheme, Host, Port, Path, Query, URI, Map0) ->
    case maps:is_key(scheme, URI) of
        true ->
            Port = get_port(URI)
```

The value of `Port` passed in to `resolve_uri` here is 80, since the
original URL is http. However, since the redirected URL is https, the
`get_port` call returns 443, which is not equal to 80, and crashes.

Assigning to a new variable seems to fix redirects.
---
 lib/inets/src/http_client/httpc_response.erl | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/inets/src/http_client/httpc_response.erl b/lib/inets/src/http_client/httpc_response.erl
index 0f3bd0a06d..0931f0b4d3 100644
--- a/lib/inets/src/http_client/httpc_response.erl
+++ b/lib/inets/src/http_client/httpc_response.erl
@@ -425,11 +425,11 @@ resolve_uri(Scheme, Host, Port, Path, Query, URI) ->
 resolve_uri(Scheme, Host, Port, Path, Query, URI, Map0) ->
     case maps:is_key(scheme, URI) of
         true ->
-            Port = get_port(URI),
+            Port0 = get_port(URI),
             maybe_add_query(
               Map0#{scheme => maps:get(scheme, URI),
                    host => maps:get(host, URI),
-                   port => Port,
+                   port => Port0,
                    path => maps:get(path, URI)},
               URI);
         false ->
-- 
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