Update networking layer w/ CURL and emscripten impl

External/curl-8.17.0/docs/libcurl/opts/CURLINFO_USED_PROXY.md

@@ -0,0 +1,71 @@
+---
+c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Title: CURLINFO_USED_PROXY
+Section: 3
+Source: libcurl
+See-also:
+  - CURLOPT_NOPROXY (3)
+  - CURLOPT_PROXY (3)
+  - curl_easy_getinfo (3)
+  - curl_easy_setopt (3)
+Protocol:
+  - All
+Added-in: 8.7.0
+---
+
+# NAME
+
+CURLINFO_USED_PROXY - whether the transfer used a proxy
+
+# SYNOPSIS
+
+~~~c
+#include <curl/curl.h>
+
+CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_USED_PROXY,
+                           long *authp);
+~~~
+
+# DESCRIPTION
+
+Pass a pointer to a long. It gets set to zero set if no proxy was used in the
+previous transfer or a non-zero value if a proxy was used.
+
+# %PROTOCOLS%
+
+# EXAMPLE
+
+~~~c
+int main(int argc, char *argv[])
+{
+  CURL *curl = curl_easy_init();
+  if(curl) {
+    CURLcode res;
+    curl_easy_setopt(curl, CURLOPT_URL, argv[1]);
+    curl_easy_setopt(curl, CURLOPT_PROXY, "http://127.0.0.1:80");
+    curl_easy_setopt(curl, CURLOPT_NOPROXY, "example.com");
+
+    res = curl_easy_perform(curl);
+
+    if(!res) {
+      /* extract the available proxy authentication types */
+      long used;
+      res = curl_easy_getinfo(curl, CURLINFO_USED_PROXY, &used);
+      if(!res) {
+        printf("The proxy was %sused\n", used ? "": "NOT ");
+      }
+    }
+    curl_easy_cleanup(curl);
+  }
+}
+~~~
+
+# %AVAILABILITY%
+
+# RETURN VALUE
+
+curl_easy_getinfo(3) returns a CURLcode indicating success or error.
+
+CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
+libcurl-errors(3).