/* * lws-minimal-http-client-post * * Copyright (C) 2018 Andy Green * * This file is made available under the Creative Commons CC0 1.0 * Universal Public Domain Dedication. * * This demonstrates the a minimal http client using lws and POST. * * It POSTs both form data and a file to the form at * https://libwebsockets.org/testserver/formtest and dumps * the html page received generated by the POST handler. */ #include #include #include static int interrupted; static struct lws *client_wsi; struct pss { char boundary[32]; char body_part; }; static int callback_http(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len) { struct pss *pss = (struct pss *)user; char buf[LWS_PRE + 1024], *start = &buf[LWS_PRE], *p = start, *end = &buf[sizeof(buf) - 1]; uint8_t **up, *uend; uint32_t r; int n; switch (reason) { /* because we are protocols[0] ... */ case LWS_CALLBACK_CLIENT_CONNECTION_ERROR: lwsl_err("CLIENT_CONNECTION_ERROR: %s\n", in ? (char *)in : "(null)"); client_wsi = NULL; break; /* ...callbacks related to receiving the result... */ case LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP: lwsl_user("LWS_CALLBACK_ESTABLISHED_CLIENT_HTTP: response %d\n", lws_http_client_http_response(wsi)); break; case LWS_CALLBACK_RECEIVE_CLIENT_HTTP_READ: lwsl_user("RECEIVE_CLIENT_HTTP_READ: read %d\n", (int)len); lwsl_hexdump_notice(in, len); return 0; /* don't passthru */ case LWS_CALLBACK_RECEIVE_CLIENT_HTTP: n = sizeof(buf) - LWS_PRE; if (lws_http_client_read(wsi, &p, &n) < 0) return -1; return 0; /* don't passthru */ case LWS_CALLBACK_COMPLETED_CLIENT_HTTP: lwsl_user("LWS_CALLBACK_COMPLETED_CLIENT_HTTP\n"); client_wsi = NULL; break; /* ...callbacks related to generating the POST... */ case LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER: lwsl_user("LWS_CALLBACK_CLIENT_APPEND_HANDSHAKE_HEADER\n"); up = (uint8_t **)in; uend = *up + len - 1; /* generate a random boundary string */ lws_get_random(lws_get_context(wsi), &r, sizeof(r)); lws_snprintf(pss->boundary, sizeof(pss->boundary) - 1, "---boundary-%08x", r); n = lws_snprintf(buf, sizeof(buf) - 1, "multipart/form-data; boundary=%s", pss->boundary); if (lws_add_http_header_by_token(wsi, WSI_TOKEN_HTTP_CONTENT_TYPE, (uint8_t *)buf, n, up, uend)) return 1; /* * Notice because we are sending multipart/form-data we can * usually rely on the server to understand where the form * payload ends without having to give it an overall * content-length (which can be troublesome to compute ahead * of generating the data to send). * * Tell lws we are going to send the body next... */ lws_client_http_body_pending(wsi, 1); lws_callback_on_writable(wsi); break; case LWS_CALLBACK_CLIENT_HTTP_WRITEABLE: lwsl_user("LWS_CALLBACK_CLIENT_HTTP_WRITEABLE\n"); n = LWS_WRITE_HTTP; /* * For a small body like this, we could prepare it in memory and * send it all at once. But to show how to handle, eg, * arbitrary-sized file payloads, or huge form-data fields, the * sending is done in multiple passes through the event loop. */ switch (pss->body_part++) { case 0: /* notice every usage of the boundary starts with -- */ p += lws_snprintf(p, end - p, "--%s\xd\xa" "content-disposition: " "form-data; name=\"text\"\xd\xa" "\xd\xa" "my text field" "\xd\xa", pss->boundary); break; case 1: p += lws_snprintf(p, end - p, "--%s\xd\xa" "content-disposition: form-data; name=\"file\";" "filename=\"myfile.txt\"\xd\xa" "content-type: text/plain\xd\xa" "\xd\xa" "This is the contents of the " "uploaded file.\xd\xa" "\xd\xa", pss->boundary); break; case 2: p += lws_snprintf(p, end - p, "--%s--\xd\xa", pss->boundary); lws_client_http_body_pending(wsi, 0); /* necessary to support H2, it means we will write no * more on this stream */ n = LWS_WRITE_HTTP_FINAL; break; default: /* * We can get extra callbacks here, if nothing to do, * then do nothing. */ return 0; } if (lws_write(wsi, (uint8_t *)start, lws_ptr_diff(p, start), n) != lws_ptr_diff(p, start)) return 1; if (n != LWS_WRITE_HTTP_FINAL) lws_callback_on_writable(wsi); return 0; default: break; } return lws_callback_http_dummy(wsi, reason, user, in, len); } static const struct lws_protocols protocols[] = { { "http", callback_http, sizeof(struct pss), 0, }, { NULL, NULL, 0, 0 } }; static void sigint_handler(int sig) { interrupted = 1; } int main(int argc, char **argv) { struct lws_context_creation_info info; struct lws_client_connect_info i; struct lws_context *context; int n = 0; signal(SIGINT, sigint_handler); lws_set_log_level(LLL_USER | LLL_ERR | LLL_WARN | LLL_NOTICE /* for LLL_ verbosity above NOTICE to be built into lws, * lws must have been configured and built with * -DCMAKE_BUILD_TYPE=DEBUG instead of =RELEASE */ /* | LLL_INFO */ /* | LLL_PARSER */ /* | LLL_HEADER */ /* | LLL_EXT */ /* | LLL_CLIENT */ /* | LLL_LATENCY */ /* | LLL_DEBUG */, NULL); lwsl_user("LWS minimal http client - POST\n"); memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */ info.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT; info.port = CONTEXT_PORT_NO_LISTEN; /* we do not run any server */ info.protocols = protocols; #if defined(LWS_WITH_MBEDTLS) /* * OpenSSL uses the system trust store. mbedTLS has to be told which * CA to trust explicitly. */ info.client_ssl_ca_filepath = "./libwebsockets.org.cer"; #endif context = lws_create_context(&info); if (!context) { lwsl_err("lws init failed\n"); return 1; } memset(&i, 0, sizeof i); /* otherwise uninitialized garbage */ i.context = context; i.port = 443; i.address = "libwebsockets.org"; i.path = "/testserver/formtest"; i.ssl_connection = /* LCCSCF_NOT_H2 | */ LCCSCF_USE_SSL; i.host = i.address; i.origin = i.address; i.method = "POST"; i.protocol = protocols[0].name; i.pwsi = &client_wsi; lws_client_connect_via_info(&i); while (n >= 0 && client_wsi && !interrupted) n = lws_service(context, 1000); lws_context_destroy(context); lwsl_user("Completed\n"); return 0; }