mongoose/examples/http-reverse-proxy/main.c

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2020-12-25 12:32:56 +08:00
// 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, build it like this:
// make MBEDTLS_DIR=/path/to/your/mbedtls/installation
static const char *s_backend_url = "https://cesanta.com";
static const char *s_listen_url = "http://localhost:8000";
#include "mongoose.h"
// 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.ptr + hm->proto.len - hm->message.ptr),
hm->message.ptr);
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->ptr, (int) v->len, v->ptr);
}
mg_send(c, "\r\n", 2);
mg_send(c, hm->body.ptr, hm->body.len);
LOG(LL_DEBUG, ("FORWARDING: %.*s %.*s", (int) hm->method.len, hm->method.ptr,
(int) hm->uri.len, hm->uri.ptr));
}
static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
struct mg_connection *c2 = fn_data;
if (ev == MG_EV_HTTP_MSG) {
struct mg_http_message *hm = (struct mg_http_message *) ev_data;
if (c->label[0] != 'B' && c2 == NULL) {
// Client request, create backend connection Note that we're passing
// client connection `c` as fn_data for the created backend connection.
// This way, we tie together these two connections via `fn_data` pointer:
// client's c->fn_data points to the backend connection, and backend's
// c->fn_data points to the client connection
c2 = mg_connect(c->mgr, s_backend_url, fn, c);
c->fn_data = c2;
if (c2 != NULL) {
c2->is_hexdumping = 1;
c2->label[0] = 'B'; // Mark this connection as backend
} else {
c->is_closing = 1;
}
}
if (c2 != NULL && c2->label[0] == 'B') forward_request(hm, c2);
} else if (ev == MG_EV_READ) {
if (c->label[0] == 'B' && c2 != NULL) {
// All incoming data from the backend, forward to the client
mg_send(c2, c->recv.buf, c->recv.len);
mg_iobuf_delete(&c->recv, c->recv.len);
}
} else if (ev == MG_EV_CONNECT) {
if (mg_url_is_ssl(s_backend_url)) {
struct mg_tls_opts opts = {.ca = "ca.pem"};
mg_tls_init(c, &opts);
}
} else if (ev == MG_EV_CLOSE) {
if (c->label[0] != 'B' && c2 != NULL) c2->is_closing = 1;
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c->fn_data = NULL;
}
}
int main(void) {
struct mg_mgr mgr;
mg_log_set("3"); // 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;
}