int iSocketFd = socket(AF_INET, SOCK_STREAM, 0);
checkError(iSocketFd);
int re = 1;
checkError(setsockopt(iSocketFd, SOL_SOCKET, SO_REUSEADDR, &re, sizeof(re)));
struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY); /*receive any address*/
server_addr.sin_port = htons(7878);
checkError(bind(iSocketFd, (struct sockaddr*)&server_addr, sizeof(server_addr)));
checkError(listen(iSocketFd, 5));
int iSockClient;
struct sockaddr_in client_addr;
memset(&client_addr, 0, sizeof(client_addr));
socklen_t client_len = sizeof(client_addr);
while(1);
iSocketFd = socket(AF_INET, SOCK_STREAM, 0);
checkError(iSocketFd);
int re = 1;
checkError(setsockopt(iSocketFd, SOL_SOCKET, SO_REUSEADDR, &re, sizeof(re)));
struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY); /*receive any address*/
//server_addr.sin_addr.s_addr = inet_addr("10.128.118.43");
server_addr.sin_port = htons(7878);
while(1){
printf("conncet to server...\n");
if(-1 != connect(iSocketFd, (struct sockaddr *)&server_addr, sizeof(server_addr))){
break;
}
sleep(1);
}
printf("connect success\n");
char aRecv[2048] = {0};
const char *aSend = "This is tcp client";
while(1)
{
checkError(send(iSocketFd, aSend, strlen(aSend), 0));
printf("wait server data...\n");
int irecv = recv(iSocketFd, aRecv, sizeof(aRecv), 0);
panchangtao@1003:~/WorkSpace$ netstat | grep "7878"
tcp 0 0 localhost:39709 localhost:7878 ESTABLISHED
tcp 18 0 localhost:7878 localhost:39709 ESTABLISHED
可以看到,server在调用了listen后就可以让客户端连上了,那么accept是做什么的呢? 另外,7878是服务器端口,但是客户端连接上后用的却是39709作为通信端口。
这是一段关于listen函数的解释,也就是说listen后,客户端就可以连接到服务器了,只是这时候连接的客户端都放到了一个队列中,当调用accept时从队列中取数据,如果队列为空,就阻塞。 所以客户端和服务端的三路握手是内核的TCP/IP协议驱动自己完成的,listen和accept都没有做这个工作。