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更新时间：2022-09-16 20:35:06
采用libevent2将输入的字符变成大写，然后在返回去，代码如下
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/* For sockaddr_in */#include <netinet/in.h>/* For socket functions */#include <sys/socket.h>/* For fcntl */#include <fcntl.h>#include <event2/event.h>#include <event2/buffer.h>#include <event2/bufferevent.h>#include <assert.h>#include <unistd.h>#include <string.h>#include <stdlib.h>#include <stdio.h>#include <errno.h>#define MAX_LINE 16384static const int MY_PORT = 40713;static const int LISTEN_QUENE = 16;/** * 将字符变成大写
*/
char DoUpper(char c){ if ('a' <= c && c <= 'z')
{
c = c - ('a' - 'A');
}
return c;
}/** * 处理输入数据的回调函数
*/
void ReadCallBack(struct bufferevent *pBuffEnt, void *pContext){ struct evbuffer* pInstream = bufferevent_get_input(pBuffEnt);
struct evbuffer* pOutstream = bufferevent_get_output(pBuffEnt);
char *szLine;
size_t n;
// 注意，返回的line是在堆上分配的内存，用完后马上需要清理，否则产生内存泄漏
while ((szLine = evbuffer_readln(pInstream, &n, EVBUFFER_EOL_LF)))
{
// 将当前行的字符串转换
for (int i = 0; i < n; ++i)
{
szLine[i] = DoUpper(szLine[i]);
}
// 将当前数据输出给客户端
evbuffer_add(pOutstream, szLine, n);
evbuffer_add(pOutstream, "\n", 1);
free(szLine);
}
if (evbuffer_get_length(pInstream) >= MAX_LINE) {
/* Too long; just process what there is and go on so that the buffer
* doesn't grow infinitely long. */
char buf[1024];
while (evbuffer_get_length(pInstream)) {
int n = evbuffer_remove(pInstream, buf, sizeof(buf));
for (int i = 0; i < n; ++i)
{
buf[i] = DoUpper(buf[i]);
}
evbuffer_add(pOutstream, buf, n);
}
evbuffer_add(pOutstream, "\n", 1);
}
}void ErrorCallBack(struct bufferevent *bev, short error, void *ctx){ if (error & BEV_EVENT_EOF) {
/* connection has been closed, do any clean up here */
printf("ErrorCallBack, connection closed\n");
} else if (error & BEV_EVENT_ERROR) {
perror("ErrorCallBack");
} else if (error & BEV_EVENT_TIMEOUT) {
/* must be a timeout event handle, handle it */
/* ... */
}
bufferevent_free(bev);
}/** * 回调函数会接受三个参数
* listener 注册的fd
* event 注册的事件
* arg 注册时的参数
*/
void DoAccept(evutil_socket_t nListenSock, short event, void *pArg){ // 获取链接的fd
struct sockaddr_storage oAddr;
socklen_t nAddrLen = sizeof(oAddr);
int nConnSock = accept(nListenSock, (struct sockaddr*)&oAddr, &nAddrLen);
if (nConnSock < 0) {
perror("accept");
} else if (nConnSock > FD_SETSIZE) {
close(nConnSock);
} else {
evutil_make_socket_nonblocking(nConnSock); // 设置为非堵塞的socket
// 获取传入的参数——event base,自对象在DoAccpet中穿件，用于存放所有的fd
struct event_base *pEventBase = (struct event_base*)pArg;
// 创建一个缓冲事件，缓冲事件，顾名思义，就是当数据缓冲到一定程度，才触发，而不是只要有数据就触发
struct bufferevent* pBuffEnt = bufferevent_socket_new(pEventBase, nConnSock, BEV_OPT_CLOSE_ON_FREE);
bufferevent_setcb(pBuffEnt, ReadCallBack, NULL, ErrorCallBack, NULL);
// “程度”通过高/低水位来设定
bufferevent_setwatermark(pBuffEnt, EV_READ, 0, MAX_LINE);
// 必须调用这句，否则enabled == false
bufferevent_enable(pBuffEnt, EV_READ|EV_WRITE);
}
}void Run(void){ // 设置地址，此服务器监听在40713上
struct sockaddr_in oAddr;
oAddr.sin_family = AF_INET;
oAddr.sin_addr.s_addr = htonl(INADDR_ANY);
oAddr.sin_port = htons(MY_PORT);
// 创建监听socket
evutil_socket_t nListenSock = socket(AF_INET, SOCK_STREAM, 0);
evutil_make_socket_nonblocking(nListenSock);
// 将监听socket设置为地址重用
int nOne = 1;
setsockopt(nListenSock, SOL_SOCKET, SO_REUSEADDR, &nOne, sizeof(nOne));
// 绑定端口
if (bind(nListenSock, (struct sockaddr*)&oAddr, sizeof(oAddr)) < 0)
{
perror("bind");
return;
}
// 开始监听
if (listen(nListenSock, LISTEN_QUENE)<0)
{
perror("listen");
return;
}
// 创建事件的集合对象
struct event_base *pEventBase = event_base_new();
if (NULL == pEventBase)
{
perror("event_base creating failed");
return; /*XXXerr*/
}
// 将listen socket fd的read事件添加到事件集合中
// EV_PERSIST设置监听socket的读取事件（新的连接）持续发生
struct event* pListenEvent = event_new(pEventBase, nListenSock, EV_READ|EV_PERSIST, DoAccept, (void*)pEventBase);
// 注册监听事件
event_add(pListenEvent, NULL);
// 开始主程序的循环
event_base_dispatch(pEventBase);
}int main(int c, char **v)
{ // 设置标准输出stdout没有缓冲，直接输出任何异常
setvbuf(stdout, NULL, _IONBF, 0);
Run();
return 0;
}
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