http: clear the proxy credentials as well on port or scheme change

Add tests 2009-2011 to verify switching between proxies with credentials
when the switch is driven by a redirect

Reported-by: Dwij Mehta

Closes #21304

lib/http.c

@@ -1278,12 +1278,24 @@ CURLcode Curl_http_follow(struct Curl_easy *data, const char *newurl,
         curlx_free(scheme);
       }
       if(clear) {
+        CURLcode result = Curl_reset_userpwd(data);
+        if(result) {
+          curlx_free(follow_url);
+          return result;
+        }
         curlx_safefree(data->state.aptr.user);
         curlx_safefree(data->state.aptr.passwd);
       }
     }
   }
   DEBUGASSERT(follow_url);
+  {
+    CURLcode result = Curl_reset_proxypwd(data);
+    if(result) {
+      curlx_free(follow_url);
+      return result;
+    }
+  }
 
   if(type == FOLLOW_FAKE) {
     /* we are only figuring out the new URL if we would have followed locations

lib/transfer.c

@@ -438,6 +438,40 @@ void Curl_init_CONNECT(struct Curl_easy *data)
   data->state.upload = (data->state.httpreq == HTTPREQ_PUT);
 }
 
+/*
+ * Restore the user credentials to those set in options.
+ */
+CURLcode Curl_reset_userpwd(struct Curl_easy *data)
+{
+  CURLcode result;
+  if(data->set.str[STRING_USERNAME] || data->set.str[STRING_PASSWORD])
+    data->state.creds_from = CREDS_OPTION;
+  result = Curl_setstropt(&data->state.aptr.user,
+                          data->set.str[STRING_USERNAME]);
+  if(!result)
+    result = Curl_setstropt(&data->state.aptr.passwd,
+                            data->set.str[STRING_PASSWORD]);
+  return result;
+}
+
+/*
+ * Restore the proxy credentials to those set in options.
+ */
+CURLcode Curl_reset_proxypwd(struct Curl_easy *data)
+{
+#ifndef CURL_DISABLE_PROXY
+  CURLcode result = Curl_setstropt(&data->state.aptr.proxyuser,
+                                   data->set.str[STRING_PROXYUSERNAME]);
+  if(!result)
+    result = Curl_setstropt(&data->state.aptr.proxypasswd,
+                            data->set.str[STRING_PROXYPASSWORD]);
+  return result;
+#else
+  (void)data;
+  return CURLE_OK;
+#endif
+}
+
 /*
  * Curl_pretransfer() is called immediately before a transfer starts, and only
  * once for one transfer no matter if it has redirects or do multi-pass
@@ -586,23 +620,10 @@ CURLcode Curl_pretransfer(struct Curl_easy *data)
       return CURLE_OUT_OF_MEMORY;
   }
 
-  if(data->set.str[STRING_USERNAME] ||
-     data->set.str[STRING_PASSWORD])
-    data->state.creds_from = CREDS_OPTION;
   if(!result)
-    result = Curl_setstropt(&data->state.aptr.user,
-                            data->set.str[STRING_USERNAME]);
+    result = Curl_reset_userpwd(data);
   if(!result)
-    result = Curl_setstropt(&data->state.aptr.passwd,
-                            data->set.str[STRING_PASSWORD]);
-#ifndef CURL_DISABLE_PROXY
-  if(!result)
-    result = Curl_setstropt(&data->state.aptr.proxyuser,
-                            data->set.str[STRING_PROXYUSERNAME]);
-  if(!result)
-    result = Curl_setstropt(&data->state.aptr.proxypasswd,
-                            data->set.str[STRING_PROXYPASSWORD]);
-#endif
+    result = Curl_reset_proxypwd(data);
 
   data->req.headerbytecount = 0;
   Curl_headers_cleanup(data);

lib/transfer.h

@@ -31,6 +31,8 @@ char *Curl_checkheaders(const struct Curl_easy *data,
 
 void Curl_init_CONNECT(struct Curl_easy *data);
 
+CURLcode Curl_reset_userpwd(struct Curl_easy *data);
+CURLcode Curl_reset_proxypwd(struct Curl_easy *data);
 CURLcode Curl_pretransfer(struct Curl_easy *data);
 
 CURLcode Curl_sendrecv(struct Curl_easy *data);