/**********************************************************************************
* libwebsockets libwebsockets-webserver.c hacking
* 说明：
* 找点libwesockets的资料看看，主要是为后续使用做准备。
*
* 2017-6-9 深圳 龙华樟坑村 曾剑锋
*********************************************************************************/ 一、参考文档：
. libwebsockets如何使用？
https://www.zhihu.com/question/57474416
. libwebsockets: Simple HTTP server
https://medium.com/@martin.sikora/libwebsockets-simple-http-server-2b34c13ab540
. martinsik/libwebsockets-webserver.c
https://gist.github.com/martinsik/3216369
. martinsik/index.html
https://gist.github.com/martinsik/3654228 二、代码解读：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <libwebsockets.h> // 浏览器websocket访问的回调函数
static int callback_http(struct libwebsocket_context *context,
struct libwebsocket *wsi,
enum libwebsocket_callback_reasons reason, void *user,
void *in, size_t len)
{ switch (reason) {
// 头文件链接描述，出了作为Server会喷出一行连接建立以外，这里不进行任何处理
// http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/libwebsockets.h#n260
case LWS_CALLBACK_CLIENT_WRITEABLE:
printf("connection established\n"); // 头文件链接描述
// http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/libwebsockets.h#n281
case LWS_CALLBACK_HTTP: {
char *requested_uri = (char *) in;
printf("requested URI: %s\n", requested_uri); // 喷出访问的URL // uri为"/"访问，直接给出hello world
if (strcmp(requested_uri, "/") == ) {
void *universal_response = "Hello, World!";
// http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/libwebsockets.h#n597
libwebsocket_write(wsi, universal_response,
strlen(universal_response), LWS_WRITE_HTTP);
break; } else {
// try to get current working directory
char cwd[];
char *resource_path; if (getcwd(cwd, sizeof(cwd)) != NULL) {
// allocate enough memory for the resource path
// 动态分配路径存储空间
resource_path = malloc(strlen(cwd) + strlen(requested_uri)); // join current working direcotry to the resource path
// 合成资源路径
sprintf(resource_path, "%s%s", cwd, requested_uri);
printf("resource path: %s\n", resource_path); // 获取文件扩展名
char *extension = strrchr(resource_path, '.');
char *mime; // choose mime type based on the file extension
// 设置扩展类型
if (extension == NULL) {
mime = "text/plain";
} else if (strcmp(extension, ".png") == ) {
mime = "image/png";
} else if (strcmp(extension, ".jpg") == ) {
mime = "image/jpg";
} else if (strcmp(extension, ".gif") == ) {
mime = "image/gif";
} else if (strcmp(extension, ".html") == ) {
mime = "text/html";
} else if (strcmp(extension, ".css") == ) {
mime = "text/css";
} else {
mime = "text/plain";
} // by default non existing resources return code 400
// for more information how this function handles headers
// see it's source code
// http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/parsers.c#n1896
libwebsockets_serve_http_file(wsi, resource_path, mime); }
} // close connection
// 关闭连接
libwebsocket_close_and_free_session(context, wsi,
LWS_CLOSE_STATUS_NORMAL);
break;
}
default:
printf("unhandled callback\n");
break;
} return ;
} /* list of supported protocols and callbacks */
// 配置协议以及其回调函数
static struct libwebsocket_protocols protocols[] = {
/* first protocol must always be HTTP handler */ {
"http-only", /* name */
callback_http, /* callback */
/* per_session_data_size */
},
{
NULL, NULL, /* End of list */
} }; int main(void) {
// server url will be http://localhost:7681
int port = ;
const char *interface = NULL;
struct libwebsocket_context *context;
// we're not using ssl
const char *cert_path = NULL;
const char *key_path = NULL;
// no special options
int opts = ; // create libwebsocket context representing this server
// 创建上下文
context = libwebsocket_create_context(port, interface, protocols,
libwebsocket_internal_extensions,
cert_path, key_path, -, -, opts); if (context == NULL) {
fprintf(stderr, "libwebsocket init failed\n");
return -;
} printf("starting server...\n"); // infinite loop, the only option to end this serer is
// by sending SIGTERM. (CTRL+C)
while () {
libwebsocket_service(context, );
// libwebsocket_service will process all waiting events with their
// callback functions and then wait 50 ms.
// (this is single threaded webserver and this will keep
// our server from generating load while there are not
// requests to process)
} libwebsocket_context_destroy(context); return ;
}