17.3 习题

ch17/echo_epollserv.c

@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+#include <sys/epoll.h>
+
+#define BUF_SIZE 100
+#define EPOLL_SIZE 50
+void error_handling(char *message);
+
+int main(int argc, char *argv[])
+{
+    int serv_sock, clnt_sock;
+    struct sockaddr_in serv_adr, clnt_adr;
+    socklen_t adr_sz;
+    int str_len, i;
+    char buf[BUF_SIZE];
+
+    struct epoll_event *ep_events;
+    struct epoll_event event;
+    int epfd, event_cnt;
+
+    if (argc != 2)
+    {
+        printf("Usage : %s <port> \n", argv[0]);
+        exit(1);
+    }
+    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
+    memset(&serv_adr, 0, sizeof(serv_adr));
+    serv_adr.sin_family = AF_INET;
+    serv_adr.sin_addr.s_addr = htonl(INADDR_ANY);
+    serv_adr.sin_port = htons(atoi(argv[1]));
+
+    if (bind(serv_sock, (struct sockaddr *)&serv_adr, sizeof(serv_adr)) == -1)
+        error_handling("bind() error");
+    if (listen(serv_sock, 5) == -1)
+        error_handling("listen() error");
+
+    epfd = epoll_create(EPOLL_SIZE); //可以忽略这个参数，填入的参数为操作系统参考
+    ep_events = malloc(sizeof(struct epoll_event) * EPOLL_SIZE);
+
+    event.events = EPOLLIN; //需要读取数据的情况
+    event.data.fd = serv_sock;
+    epoll_ctl(epfd, EPOLL_CTL_ADD, serv_sock, &event); //例程epfd 中添加文件描述符 serv_sock，目的是监听 enevt 中的事件
+
+    while (1)
+    {
+        event_cnt = epoll_wait(epfd, ep_events, EPOLL_SIZE, -1); //获取改变了的文件描述符，返回数量
+        if (event_cnt == -1)
+        {
+            puts("epoll_wait() error");
+            break;
+        }
+
+        for (i = 0; i < event_cnt; i++)
+        {
+            if (ep_events[i].data.fd == serv_sock) //客户端请求连接时
+            {
+                adr_sz = sizeof(clnt_adr);
+                clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_adr, &adr_sz);
+                event.events = EPOLLIN;
+                event.data.fd = clnt_sock; //把客户端套接字添加进去
+                epoll_ctl(epfd, EPOLL_CTL_ADD, clnt_sock, &event);
+                printf("connected client : %d \n", clnt_sock);
+            }
+            else //是客户端套接字时
+            {
+                str_len = read(ep_events[i].data.fd, buf, BUF_SIZE);
+                if (str_len == 0)
+                {
+                    epoll_ctl(epfd, EPOLL_CTL_DEL, ep_events[i].data.fd, NULL); //从epoll中删除套接字
+                    close(ep_events[i].data.fd);
+                    printf("closed client : %d \n", ep_events[i].data.fd);
+                }
+                else
+                {
+                    write(ep_events[i].data.fd, buf, str_len);
+                }
+            }
+        }
+    }
+    close(serv_sock);
+    close(epfd);
+
+    return 0;
+}
+
+void error_handling(char *message)
+{
+    fputs(message, stderr);
+    fputc('\n', stderr);
+    exit(1);
+}