c/c++实现TCP服务器和客户端
TCP客户端代码
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#define MAXLINE 80
#define SERV_PORT 6666
int main(int argc, char *argv[])
{
struct sockaddr_in servaddr;
char buf[MAXLINE];
int sockfd, n;
char *str;
if (argc != 2) {
fputs("usage: ./client message\n", stderr);
exit(1);
}
str = argv[1];
sockfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
servaddr.sin_port = htons(SERV_PORT);
connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
write(sockfd, str, strlen(str));
n = read(sockfd, buf, MAXLINE);
printf("Response from server:\n");
write(STDOUT_FILENO, buf, n);
close(sockfd);
return 0;
}
由于客户端不需要固定的端口号,因此不必调用bind(),客户端的端口号由内核自动分配。注意,客户端不是不允许调用bind(),只是没有必要调用bind()固定一个端口号,服务器也不是必须调用bind(),但如果服务器不调用bind(),内核会自动给服务器分配监听端口,每次启动服务器时端口号都不一样,客户端要连接服务器就会遇到麻烦。
客户端和服务器启动后可以使用netstat命令查看链接情况:
TCP服务器代码
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define MAXLINE 80
#define SERV_PORT 6666
int main(void)
{
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
int listenfd, connfd;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i, n;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
listen(listenfd, 20);
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
n = read(connfd, buf, MAXLINE);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (i = 0; i < n; i++)
buf[i] = toupper(buf[i]);
write(connfd, buf, n);
close(connfd);
}
return 0;
}
版权声明:拷贝、转载请附上本文连接