Issue 3403 - Add web redirect for the uninstallation page

modules/web/templates/adblockplus.org.conf.erb

 # XSS and clickjacking prevention headers
 
 set $csp_frame "";
 if ($uri ~ ^/(:?\w\w(_\w\w)?/)?(?:index|firefox|chrome|opera|android|internet-explorer|safari|yandex-browser|maxthon)?$)
 {
   set $csp_frame "; frame-src www.youtube-nocookie.com;";
 }
 add_header Content-Security-Policy "default-src 'self'; img-src * data:; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline' 'unsafe-eval' $csp_frame";
 add_header X-Frame-Options "sameorigin";
 
@@ skipping 153 matching lines @@
 
   set $lang "en";
   set $link "";
   set $anchor "";
 
   if ($arg_link ~ "^share-")
   {
     set $link "share";
     set $anchor "?a=minimal";
   }
+  if ($arg_link = "uninstalled")
+  {
+    set $link "uninstalled";
+  }
   if ($arg_link = "gettingStarted")
   {
     set $link "getting_started";
   }
   if ($arg_link = "faq")
   {
     set $link "faq";
   }
   if ($arg_link = "filterdoc")
   {
@@ skipping 49 matching lines @@
     set $lang "$1_$2";
   }
   if (!-f "$document_root/$lang/$link")
   {
     set $lang "en";
   }
   if ($link = "share")
   {
     rewrite ^ https://share.adblockplus.org/$lang/? redirect;
   }
+  if ($link = "uninstalled")
+  {
+    # For the uninstallation page we need to preserve the query parameters

[Sebastian Noack, 2015/12/14 12:38:37]

We probably should strip the "link" parameter. Any way to do that?

[kzar, 2015/12/14 12:44:11]

Sure it's redundant but it doesn't harm. I couldn't see an easy way to strip it
but if you have a suggestion I'll give it a go.

[Felix Dahlke, 2015/12/14 12:49:10]

I thought about this as well, but AFAIK there's no really simple way to do it. I
see two options:

1. We capture all args after "link" in the rewrite, then add `?` to the target
again and append the captured args after that. It's not gonna work if link is
not the first parameter, but that should be fine.

2. We add the `?` back and list all the args we want explicitly using the
`$arg_` variables.

I'm not sure it's worth the trouble though.

[kzar, 2015/12/14 12:59:12]

My vote is to leave it as-is, it's simple and it works. It would be a shame to
miss getting the uninstall page launched this quater because of a single
redundant parameter.

[Sebastian Noack, 2015/12/14 13:17:25]

Well, this certainly isn't something that would delay the launch. We wouldn't
have a release before Jan 5 anyway, there are still some issues with the
uninstallation page itself that needs to be fixed first, and the possible
solutions here aren't to complicated after all. But yeah, they aren't too great
either, but IMO also not worse than not stripping the link parameter.

+    rewrite ^ /$lang/$link redirect;
+  }
   rewrite ^ /$lang/$link$anchor? redirect;
 }
 
 location /devbuilds
 {
   rewrite ^(.*) https://downloads.adblockplus.org$1;
 }
 
 # Locations still served by the legacy server
 
@@ skipping 44 matching lines @@
 location /403.html
 {
   try_files $uri @proxied;
 }
 location @proxied
 {
   proxy_pass https://server16.adblockplus.org;
   proxy_set_header Host adblockplus.org;
   proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
 }