bug#35969: 26.2, Excorporate

[Thomas Fitzsimmons <fitzsim@fitzsim.org>]

Hi,

I found a proxy server to test against.  I've now replicated Collin's
findings.

Andreas Schwab <schwab@linux-m68k.org> writes:

> On Jun 14 2019, Thomas Fitzsimmons <fitzsim@fitzsim.org> wrote:
>
>> diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el
>> index 00803a103a..723d111d58 100644
>> --- a/lisp/url/url-http.el
>> +++ b/lisp/url/url-http.el
>> @@ -329,7 +329,10 @@ url-http-create-request
>>               ;; The request
>>               (or url-http-method "GET") " "
>>               (url-http--encode-string
>> -              (if using-proxy (url-recreate-url url-http-target-url) real-fname))
>> +              (if (and using-proxy
>> +                       (not (equal "https" (url-type url-http-target-url))))
>> +                  (url-recreate-url url-http-target-url)
>> +                real-fname))

For discussion purposes, let's call the above "patch T"...

> That should already be handled by commit 84613dae5c.

... and this commit "patch A", which is:

diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el
index 53798f77c3..817c5ce3b3 100644
--- a/lisp/url/url-http.el
+++ b/lisp/url/url-http.el
@@ -1412,7 +1412,9 @@ url-https-proxy-after-change-function
                         'url-http-wait-for-headers-change-function)
                   (set-process-filter tls-connection 'url-http-generic-filter)
                   (process-send-string tls-connection
-                                       (url-http-create-request)))
+                                       ;; Use the non-proxy form of the request
+                                       (let (url-http-proxy)
+                                         (url-http-create-request))))
               (gnutls-error
                (url-http-activate-callback)
                (error "gnutls-error: %s" e))

I tried on Emacs 26.2 and master tip, and in both cases, Excorporate
worked with patch T applied and patch A not present (26.2) or reverted
(master); it failed with any other combination of the patches (A and T,
A only, neither A nor T).

One difference I noticed is that with A applied, the Connection header
is set to keep-alive and the connection is reused, whereas with just T,
Connection is set to close and the connection is re-established.  The
attached patch fixes it.  Andreas, do you have a test case that patch A
fixed, and if so, can you retest with the proposed fix?

Thanks,
Thomas

diff --git a/lisp/url/url-http.el b/lisp/url/url-http.el
index 838f0a30c1..eb054cd65a 100644
--- a/lisp/url/url-http.el
+++ b/lisp/url/url-http.el
@@ -1436,7 +1436,8 @@ url-https-proxy-after-change-function
                   (set-process-filter tls-connection 'url-http-generic-filter)
                   (process-send-string tls-connection
                                        ;; Use the non-proxy form of the request
-                                       (let (url-http-proxy)
+                                       (let (url-http-proxy
+                                             url-http-attempt-keepalives)
                                          (url-http-create-request))))
               (gnutls-error
                (url-http-activate-callback)