Update http server example to showcase SSL

examples/http-restful-server/main.c

@@ -1,9 +1,14 @@
 // Copyright (c) 2020 Cesanta Software Limited
 // All rights reserved
+//
+// To enable SSL/TLS,
+//    1. Change s_listen_on from http:// to https://
+//    2. make MBEDTLS_DIR=/path/to/your/mbedtls/installation
+//    3. curl -k https://127.0.0.1:8000
 
 #include "mongoose.h"
 
-static const char *s_listen_on = "http://localhost:8000";
+static const char *s_listen_on = "https://localhost:8000";
 static const char *s_web_directory = ".";
 
 // This RESTful server implements the following endpoints:
@@ -11,7 +16,15 @@ static const char *s_web_directory = ".";
 //   /api/f2/:id - wildcard example, respond with JSON string {"result": "URI"}
 //   any other URI serves static files from s_web_directory
 static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
-  if (ev == MG_EV_HTTP_MSG) {
+  if (ev == MG_EV_ACCEPT && mg_url_is_ssl(s_listen_on)) {
+    // If s_listen_on URL is https://, tell listening connection to use TLS
+    struct mg_tls_opts opts = {
+        //.ca = "ca.pem",         // Uncomment to enable two-way SSL
+        .cert = "server.pem",     // Certificate PEM file
+        .certkey = "server.pem",  // This pem conains both cert and key
+    };
+    mg_tls_init(c, &opts);
+  } else if (ev == MG_EV_HTTP_MSG) {
     struct mg_http_message *hm = (struct mg_http_message *) ev_data;
     if (mg_http_match_uri(hm, "/api/f1")) {
       mg_http_reply(c, 200, "", "{\"result\": %d}\n", 123);  // Serve REST
@@ -27,6 +40,7 @@ static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
 
 int main(void) {
   struct mg_mgr mgr;                            // Event manager
+  mg_log_set("2");                              // Set to 3 to enable debug
   mg_mgr_init(&mgr);                            // Initialise event manager
   mg_http_listen(&mgr, s_listen_on, fn, NULL);  // Create HTTP listener
   for (;;) mg_mgr_poll(&mgr, 1000);             // Infinite event loop