Update networking layer w/ CURL and emscripten impl

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

@@ -0,0 +1,80 @@
+---
+c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
+SPDX-License-Identifier: curl
+Title: CURLOPT_SSH_HOSTKEYDATA
+Section: 3
+Source: libcurl
+See-also:
+  - CURLOPT_SSH_HOSTKEYFUNCTION (3)
+Protocol:
+  - SFTP
+  - SCP
+Added-in: 7.84.0
+---
+
+# NAME
+
+CURLOPT_SSH_HOSTKEYDATA - pointer to pass to the SSH host key callback
+
+# SYNOPSIS
+
+~~~c
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSH_HOSTKEYDATA, void *pointer);
+~~~
+
+# DESCRIPTION
+
+Pass a void * as parameter. This *pointer* is passed along untouched to
+the callback set with CURLOPT_SSH_HOSTKEYFUNCTION(3).
+
+# DEFAULT
+
+NULL
+
+# %PROTOCOLS%
+
+# EXAMPLE
+
+~~~c
+struct mine {
+  void *custom;
+};
+
+static int hostkeycb(void *clientp,   /* CURLOPT_SSH_HOSTKEYDATA */
+                     int keytype,     /* CURLKHTYPE */
+                     const char *key, /* host key to check */
+                     size_t keylen)   /* length of the key */
+{
+  /* 'clientp' points to the callback_data struct */
+  /* investigate the situation and return the correct value */
+  return CURLKHMATCH_OK;
+}
+
+int main(void)
+{
+  CURL *curl = curl_easy_init();
+  if(curl) {
+    struct mine callback_data;
+    curl_easy_setopt(curl, CURLOPT_URL, "sftp://example.com/thisfile.txt");
+    curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYFUNCTION, hostkeycb);
+    curl_easy_setopt(curl, CURLOPT_SSH_HOSTKEYDATA, &callback_data);
+
+    curl_easy_perform(curl);
+  }
+}
+~~~
+
+# NOTES
+
+Works only with the libssh2 backend.
+
+# %AVAILABILITY%
+
+# RETURN VALUE
+
+curl_easy_setopt(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).