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最初参考网上资料完成如下：/* * tcpserver.c *Author:coder_xia * Description:a simple tcp server */#include#include //sockaddr_in#include //inet_addr#include //close#include #include #include #define BUFFERSIZE 128#define TCPPORT 8001#define BACKLOG 5 //max connection numberint main(void) { int server_sockfd, client_sockfd; int addr_len, result, recv_len, on = 1; struct sockaddr_in server_address; struct sockaddr_in client_address; char recvbuf[BUFFERSIZE]; //init address server_address.sin_family = AF_INET; server_address.sin_addr.s_addr = htonl(INADDR_ANY); server_address.sin_port = htons(TCPPORT); addr_len = sizeof(struct sockaddr_in); //new server socket server_sockfd = socket(AF_INET, SOCK_STREAM, 0); if (-1 == server_sockfd) { perror("socket"); exit(EXIT_FAILURE); } //Enable address reuse result = setsockopt(server_sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on)); //bind and listen result = bind(server_sockfd, (struct sockaddr*)&server_address, addr_len); if (-1 == result) { perror("bind"); close(server_sockfd); exit(EXIT_FAILURE); } result = listen(server_sockfd, BACKLOG); if (-1 == result) { perror("listen"); close(server_sockfd); exit(EXIT_FAILURE); } while (1) { memset(recvbuf, 0, BUFFERSIZE); printf("server is waiting\n"); //Accept a connection, accept will block here, //so ,there's no need to sleep in this loop like in udp client_sockfd = accept(server_sockfd, (struct sockaddr*)&client_address, &addr_len); //recv message from client recv_len = recv(client_sockfd, recvbuf, BUFFERSIZE, 0); if (-1 == recv_len) { //error while recv perror("recv"); close(client_sockfd); close(server_sockfd); exit(EXIT_FAILURE); } else if (0 == recv_len) { //peer closed the socket close(client_sockfd); close(server_sockfd); exit(EXIT_FAILURE); } printf("server receieve : %s\n", recvbuf); printf("server port : %d\n", ntohs(server_address.sin_port)); printf("client port : %d\n", ntohs(client_address.sin_port)); printf("client addr : %s\n", inet_ntoa(client_address.sin_addr)); //send to client via client_sockfd result = send(client_sockfd, recvbuf, recv_len, 0); if (-1 == result) { perror("send"); close(client_sockfd); close(server_sockfd); exit(EXIT_FAILURE); } } close(server_sockfd); return 0;}
不过这个程序是存在一些问题的，虽然情况下都能运行，不过对异常情况没有任何抵抗力
1、client_sockfd未关闭
2、%s输出方式，如果收到的字符串不包含\0等特殊情况？（关于%s，更多参考）
3、server为所有client服务，如果一个client端出错或者关闭，则关闭server，逻辑处理失当
修改while部分如下：
while (1) { memset(recvbuf, 0, BUFFERSIZE); printf("server is waiting\n"); //Accept a connection, accept will block here, //so ,there's no need to sleep in this loop like in udp client_sockfd = accept(server_sockfd, (struct sockaddr*)&client_address, &addr_len); //recv message from client recv_len = recv(client_sockfd, recvbuf, BUFFERSIZE-1, 0); if (-1 == recv_len) { //error while recv perror("recv"); close(client_sockfd); continue; } else if (0 == recv_len) { //peer closed the socket close(client_sockfd); continue; } recvbuf[recv_len] = '\0'; printf("server receieve : %s\n", recvbuf); printf("server port : %d\n", ntohs(server_address.sin_port)); printf("client port : %d\n", ntohs(client_address.sin_port)); printf("client addr : %s\n", inet_ntoa(client_address.sin_addr)); sleep(3); //send to client via client_sockfd result = send(client_sockfd, recvbuf, recv_len, 0); if (result != result) { perror("send"); close(client_sockfd); continue; } close(client_sockfd); } client部分如下： /* * tcpclient.c * Author : coder_xia * Description:a simple tcp client */#include存在隐患如下：#include //sockaddr_in#include //inet_addr#include //close#include #include #include #define TCPPORT 8001#define LOCALHOST "127.0.0.1"#define BUFFERSIZE 128int main(void) { int sockfd, addr_len; struct sockaddr_in address; int result; char strsend[] = "hello server,I am client \n"; char recvbuf[BUFFERSIZE]; //Init address. address.sin_family = AF_INET; address.sin_addr.s_addr = inet_addr(LOCALHOST); address.sin_port = htons(TCPPORT); //zero the left part of struct bzero(&(address.sin_zero), sizeof(address.sin_zero)); addr_len = sizeof(address); //Create socket for the client. //After this, we need not to call bind() sockfd = socket(AF_INET, SOCK_STREAM, 0); if (-1 == sockfd) { perror("socket"); exit(EXIT_FAILURE); } //Connect to the server's socket via sockfd //connect will autoly find an unused port and call bind() to bind socket on that port result = connect(sockfd, (struct sockaddr*)&address, addr_len); if (result == -1) { perror("connect"); exit(1); } //Now we can read/write via sockfd. memset(recvbuf, 0, BUFFERSIZE); result = send(sockfd, strsend, strlen(strsend) + 1, 0); if (-1 == result) { //send error perror("write"); close(sockfd); exit(EXIT_FAILURE); } result = recv(sockfd, recvbuf, BUFFERSIZE, 0); if (-1 == result) { //error while recv perror("recv"); close(sockfd); exit(EXIT_FAILURE); } else if (0 == result) { //server has been closed close(sockfd); exit(EXIT_FAILURE); } printf("recieve from server : %s\n", recvbuf); close(sockfd); return EXIT_SUCCESS;}
1、发送时采用strlen(数组)+1方法，如果发送缓冲区包含\0,则无法发送所有数据
2、接收输出%s显示，如接收字符串不包含\0？（实际上，由于是接收保存到数组，所以会查找到数组结束位置，如果为char*，则可能带来越界访问的危害）
解决办法为：修改send一行如下：
result = send(sockfd, strsend, sizeof(strsend), 0);说点个人的看法吧：
网上的很多参考的东东，在功能实现上，的确是不会出太大问题的，正常情况下，一般不会出bug，不过健壮性欠佳，当然，也是对我们思考的一个好锻炼。不能只是拿来用啊。
关于linux套接字，更多可以参考，和（其中用到了这里面的地址复用）
就这样吧，have a good day
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