Added proxy example, with SSE html page

examples/proxy.c

+// Copyright (c) 2014 Cesanta Software Limited
+// All rights reserved
+//
+// To build and run this example:
+//    git clone https://github.com/cesanta/net_skeleton.git
+//    git clone https://github.com/cesanta/mongoose.git
+//    cd mongoose/examples
+//    make proxy
+//    ./proxy   # (then point your browser at http://localhost:2014)
+
+#include "net_skeleton.h"
+#include "mongoose.h"
+
+static int s_received_signal = 0;
+static const char *s_ca_cert = NULL;
+static const char *s_cert = NULL;
+static const char *s_sse_port = "2014";
+static const char *s_proxy_port = "2015";
+static struct mg_server *s_sse_server = NULL;
+static struct mg_server *s_proxy_server = NULL;
+
+static void elog(int do_exit, const char *fmt, ...) {
+  va_list ap;
+  va_start(ap, fmt);
+  vfprintf(stderr, fmt, ap);
+  va_end(ap);
+  fputc('\n', stderr);
+  if (do_exit) exit(EXIT_FAILURE);
+}
+
+static void signal_handler(int sig_num) {
+  signal(sig_num, signal_handler);
+  s_received_signal = sig_num;
+}
+
+static int sse_push(struct mg_connection *conn, enum mg_event ev) {
+  const char *str = (const char *) conn->connection_param;
+  if (ev == MG_POLL && str != NULL && strcmp(str, "sse") == 0) {
+    mg_printf(conn, "data: %s\r\n\r\n", (const char *) conn->callback_param);
+  }
+  return MG_TRUE;
+}
+
+static void *sse_pusher_thread_func(void *param) {
+  while (s_received_signal == 0) {
+    mg_wakeup_server_ex(s_sse_server, sse_push, "%lu %s",
+                        (unsigned long) time(NULL), (const char *) param);
+    sleep(1);
+  }
+  return NULL;
+}
+
+static int sse_handler(struct mg_connection *conn, enum mg_event ev) {
+  switch (ev) {
+    case MG_REQUEST:
+      if (strcmp(conn->uri, "/") == 0) {
+        mg_printf(conn, "%s", "HTTP/1.1 302 Moved\r\n"
+                  "Location: /sse.html\r\n\r\n");
+        return MG_TRUE;
+      }
+      if (strcmp(conn->uri, "/api/sse") == 0) {
+        conn->connection_param = (void *) "sse";
+        mg_printf(conn, "%s",
+                  "HTTP/1.0 200 OK\r\n"
+                  "Content-Type: text/event-stream\r\n"
+                  "Cache-Control: no-cache\r\n"
+                  "\r\n");
+        return MG_MORE;
+      }
+      return MG_FALSE;
+    case MG_AUTH:
+      return MG_TRUE;
+    case MG_POLL:
+      return MG_FALSE;
+    default:
+      return MG_FALSE;
+  }
+}
+
+static void *serve_thread_func(void *param) {
+  struct mg_server *server = (struct mg_server *) param;
+  printf("Starting on port %s\n", mg_get_option(server, "listening_port"));
+
+  while (s_received_signal == 0) {
+    mg_poll_server(server, 1000);
+  }
+
+  return NULL;
+}
+
+static void show_usage_and_exit(const char *prog) {
+  elog(1, "Usage: %s [-ca_cert FILE] [-sse_port PORT] [-proxy_port PORT]",
+       prog);
+  exit(EXIT_FAILURE);
+}
+
+int main(int argc, char *argv[]) {
+  int i;
+
+  // Parse command line options
+  for (i = 1; i < argc; i++) {
+    if (strcmp(argv[i], "-ca_cert") == 0 && i + 1 < argc) {
+      s_ca_cert = argv[++i];
+    } else if (strcmp(argv[i], "-cert") == 0 && i + 1 < argc) {
+      s_cert = argv[++i];
+    } else if (strcmp(argv[i], "-sse_port") == 0 && i + 1 < argc) {
+      s_sse_port = argv[++i];
+    } else if (strcmp(argv[i], "-proxy_port") == 0 && i + 1 < argc) {
+      s_proxy_port = argv[++i];
+    } else {
+      show_usage_and_exit(argv[0]);
+    }
+  }
+
+  signal(SIGTERM, signal_handler);
+  signal(SIGINT, signal_handler);
+  
+  // Create, configure and start proxy server in a separate thread
+  s_proxy_server = mg_create_server(NULL, &sse_handler);
+  mg_set_option(s_proxy_server, "listening_port", s_proxy_port);
+  mg_set_option(s_proxy_server, "ssl_certificate", s_cert);
+  mg_set_option(s_proxy_server, "ssl_ca_certificate", s_ca_cert);
+  mg_start_thread(serve_thread_func, s_proxy_server);
+
+  // Create, configure and start SSE server and SSE pusher threads
+  // Start two SSE pushing threads
+  // Serve SSE server in the main thread
+  s_sse_server = mg_create_server(NULL, &sse_handler);
+  mg_set_option(s_sse_server, "listening_port", s_sse_port);
+  mg_set_option(s_sse_server, "document_root", ".");
+  mg_start_thread(sse_pusher_thread_func, (void *) "sse_pusher_thread_1");
+  mg_start_thread(sse_pusher_thread_func, (void *) "sse_pusher_thread_2");
+  serve_thread_func(s_sse_server);
+
+  printf("Existing on signal %d\n", s_received_signal);
+  mg_destroy_server(&s_sse_server);
+  mg_destroy_server(&s_proxy_server);
+
+  return EXIT_SUCCESS;
+}
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examples/sse.html

+<html>
+  <head>
+    <script type="text/javascript">
+    window.onload = function() {
+      var es = new EventSource("/api/sse");
+      var div = document.getElementById('events');
+      es.onmessage = function(ev) {
+        var el = document.createElement('div');
+        el.innerHTML = 'sse message: ' + ev.data;
+        div.appendChild(el);
+        // Keep only last 5 messages in the list
+        while (div.childNodes.length > 5) div.removeChild(div.firstChild);
+      };
+    };
+    </script>
+  </head>
+  <body>
+    <h1>SSE pushes, done by separate threads at random times:</h1>
+    <div id="events"></div>
+  </body>
+</html>
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