move to new skeleton

tutorials/http/http-reverse-proxy/main.c

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+// Copyright (c) 2020 Cesanta Software Limited
+// All rights reserved
+//
+// Example HTTP reverse proxy
+//    1. Run `make`. This builds and starts a proxy on port 8000
+//    2. Start your browser, go to https://localhost:8000
+//
+// To enable SSL/TLS, see https://mongoose.ws/tutorials/tls/#how-to-build
+
+#include "mongoose.h"
+
+static const char *s_backend_url =
+#if MG_TLS
+    "https://cesanta.com";
+#else
+    "http://info.cern.ch";
+#endif
+static const char *s_listen_url = "http://localhost:8000";
+
+// Forward client request to the backend connection, rewriting the Host header
+static void forward_request(struct mg_http_message *hm,
+                            struct mg_connection *c) {
+  size_t i, max = sizeof(hm->headers) / sizeof(hm->headers[0]);
+  struct mg_str host = mg_url_host(s_backend_url);
+  mg_printf(c, "%.*s\r\n",
+            (int) (hm->proto.buf + hm->proto.len - hm->message.buf),
+            hm->message.buf);
+  for (i = 0; i < max && hm->headers[i].name.len > 0; i++) {
+    struct mg_str *k = &hm->headers[i].name, *v = &hm->headers[i].value;
+    if (mg_strcmp(*k, mg_str("Host")) == 0) v = &host;
+    mg_printf(c, "%.*s: %.*s\r\n", (int) k->len, k->buf, (int) v->len, v->buf);
+  }
+  mg_send(c, "\r\n", 2);
+  mg_send(c, hm->body.buf, hm->body.len);
+  MG_DEBUG(("FORWARDING: %.*s %.*s", (int) hm->method.len, hm->method.buf,
+            (int) hm->uri.len, hm->uri.buf));
+}
+
+static void fn2(struct mg_connection *c, int ev, void *ev_data) {
+  struct mg_connection *c2 = (struct mg_connection *) c->fn_data;
+  if (ev == MG_EV_READ) {
+    // All incoming data from the backend, forward to the client
+    if (c2 != NULL) mg_send(c2, c->recv.buf, c->recv.len);
+    mg_iobuf_del(&c->recv, 0, c->recv.len);
+  } else if (ev == MG_EV_CLOSE) {
+    if (c2 != NULL) c2->fn_data = NULL;
+  }
+  (void) ev_data;
+}
+
+static void fn(struct mg_connection *c, int ev, void *ev_data) {
+  struct mg_connection *c2 = c->fn_data;
+  if (ev == MG_EV_HTTP_MSG) {
+    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
+    // Client request, create backend connection Note that we're passing
+    // client connection `c` as fn_data for the created backend connection.
+    c2 = mg_connect(c->mgr, s_backend_url, fn2, c);
+    if (c2 == NULL) {
+      mg_error(c, "Cannot create backend connection");
+    } else {
+      if (mg_url_is_ssl(s_backend_url)) {
+        struct mg_tls_opts opts = {.ca = mg_unpacked("/certs/ca.pem"),
+                                   .name = mg_url_host(s_backend_url)};
+        mg_tls_init(c2, &opts);
+      }
+      c->fn_data = c2;
+      forward_request(hm, c2);
+      c->is_resp = 0;  // process further msgs in keep-alive connection
+      c2->is_hexdumping = 1;
+    }
+  } else if (ev == MG_EV_CLOSE) {
+    if (c2 != NULL) c2->is_closing = 1;
+    if (c2 != NULL) c2->fn_data = NULL;
+  }
+}
+
+int main(void) {
+  struct mg_mgr mgr;
+
+  mg_log_set(MG_LL_DEBUG);                       // Set log level
+  mg_mgr_init(&mgr);                             // Initialise event manager
+  mg_http_listen(&mgr, s_listen_url, fn, NULL);  // Start proxy
+  for (;;) mg_mgr_poll(&mgr, 1000);              // Event loop
+  mg_mgr_free(&mgr);
+
+  return 0;
+}