mongoose/examples/http-streaming-client/main.c
2023-09-26 20:45:24 +01:00

80 lines
3.2 KiB
C

// Copyright (c) 2021 Cesanta Software Limited
// All rights reserved
//
// Example streaming HTTP client.
// The default HTTP handler waits until the whole HTTP message is buffered in
// c->recv IO buffer. It can be large. This example shows how to receive
// a potentially large response in chunks by handling the MG_EV_READ events.
//
// You can change `s_url` from the command line by executing: ./example YOUR_URL
// To enable SSL/TLS, see https://mongoose.ws/tutorials/tls/#how-to-build
#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 (mg_url_is_ssl(s_url)) {
struct mg_tls_opts opts = {.ca = mg_unpacked("/certs/ca.pem"),
.name = host};
mg_tls_init(c, &opts);
}
// Send request
mg_printf(c,
"GET %s HTTP/1.1\r\n"
"Connection: keep-alive\r\n"
"Keep-Alive: timeout=60\r\n"
"Host: %.*s\r\n"
"\r\n",
mg_url_uri(s_url), (int) host.len, host.ptr);
} else if (ev == MG_EV_READ) {
// Parse the incoming data ourselves. If we can parse the request,
// store two size_t variables in the c->data: expected len and recv len.
size_t *data = (size_t *) c->data;
if (data[0]) { // Already parsed, simply print received data
data[1] += c->recv.len;
fwrite(c->recv.buf, 1, c->recv.len, stdout);
c->recv.len = 0; // And cleanup the receive buffer. Streming!
if (data[1] >= data[0]) * (bool *) fn_data = true;
} else {
struct mg_http_message hm;
int n = mg_http_parse((char *) c->recv.buf, c->recv.len, &hm);
if (n < 0) mg_error(c, "Bad response");
if (n > 0) {
fwrite(c->recv.buf + n, 1, c->recv.len - n, stdout); // Print body
data[0] = n + hm.body.len;
data[1] = c->recv.len;
c->recv.len = 0; // Cleanup receive buffer
if (data[1] >= data[0]) * (bool *) fn_data = true;
}
}
} else if (ev == MG_EV_CLOSE) {
*(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
}
(void) ev_data;
}
int main(int argc, char *argv[]) {
struct mg_mgr mgr; // Event manager
bool done = false; // Event handler flips it to true
const char *log_level = getenv("V"); // Log level
mg_mgr_init(&mgr); // Initialise event manager
if (log_level == NULL) log_level = "2"; // If not set, set to DEBUG
mg_log_set(atoi(log_level)); // Set to 0 to disable debug log
if (argc > 1) s_url = argv[1]; // Use URL from command line
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;
}