Add streaming client support, MG_EV_HTTP_CHUNK

examples/http-streaming-client/main.c

@@ -0,0 +1,65 @@
+// Copyright (c) 2021 Cesanta Software Limited
+// All rights reserved
+//
+// Example HTTP client.
+// Instead of buffering the whole HTTP response in memory and wait for the
+// MG_EV_HTTP_MSG event, this client catches MG_EV_HTTP_CHUNK events and
+// prints them. This is useful to download large content without spooling
+// everything to memory, or catch chunked content.
+//
+// You can change `s_url` from the command line by executing: ./example YOUR_URL
+//
+// To enable SSL/TLS for this client, build it like this:
+//    make MBEDTLS=/path/to/your/mbedtls/installation
+//    make OPENSSL=/path/to/your/openssl/installation
+
+#include "mongoose.h"
+
+// The very first web page in history. You can replace it from command line
+static const char *s_url = "http://info.cern.ch";
+
+// Print HTTP response and signal that we're done
+static void fn(struct mg_connection *c, int ev, void *ev_data, void *fn_data) {
+  if (ev == MG_EV_CONNECT) {
+    // Connected to server. Extract host name from URL
+    struct mg_str host = mg_url_host(s_url);
+
+    // If s_url is https://, tell client connection to use TLS
+    if (mg_url_is_ssl(s_url)) {
+      struct mg_tls_opts opts = {.ca = "ca.pem", .srvname = host};
+      mg_tls_init(c, &opts);
+    }
+
+    // Send request
+    mg_printf(c,
+              "GET %s HTTP/1.0\r\n"
+              "Host: %.*s\r\n"
+              "\r\n",
+              mg_url_uri(s_url), (int) host.len, host.ptr);
+  } else if (ev == MG_EV_HTTP_CHUNK) {
+    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
+    LOG(LL_INFO, ("%.*s", (int) hm->chunk.len, hm->chunk.ptr));
+    mg_http_delete_chunk(c, hm);
+    if (hm->chunk.len == 0) *(bool *) fn_data = true;  // Last chunk
+  } else if (ev == MG_EV_HTTP_MSG) {
+    // Response is received. Print it
+    struct mg_http_message *hm = (struct mg_http_message *) ev_data;
+    LOG(LL_INFO, ("%.*s", (int) hm->body.len, hm->body.ptr));
+    c->is_closing = 1;         // Tell mongoose to close this connection
+    *(bool *) fn_data = true;  // Tell event loop to stop
+  } else if (ev == MG_EV_ERROR) {
+    *(bool *) fn_data = true;  // Error, tell event loop to stop
+  }
+}
+
+int main(int argc, char *argv[]) {
+  struct mg_mgr mgr;                        // Event manager
+  bool done = false;                        // Event handler flips it to true
+  if (argc > 1) s_url = argv[1];            // Use URL from command line
+  mg_log_set("3");                          // Set to 0 to disable debug
+  mg_mgr_init(&mgr);                        // Initialise event manager
+  mg_http_connect(&mgr, s_url, fn, &done);  // Create client connection
+  while (!done) mg_mgr_poll(&mgr, 1000);    // Infinite event loop
+  mg_mgr_free(&mgr);                        // Free resources
+  return 0;
+}