1.TCP通信
1）TCP进程服务器
/* server */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
//socket 所需的头文件
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
//进程需要使用的头文件
#include <sys/types.h>
#include <unistd.h>
//waitpid函数需要的头文件
#include <sys/types.h>
#include <sys/wait.h>
#define MAXLINE 80
#define SERV_PORT 8000
int main(void)
{
struct sockaddr_in servaddr, cliaddr; //socket 地址结构体 服务端和客户端地址
socklen_t cliaddr_len;
int listenfd, connfd;//文件描述符
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i,n;
int status;
pid_t pid;
struct sigaction act_new;
//创建流式套接字，即TCP socket
listenfd = socket(AF_INET, SOCK_STREAM, 0);
if (listenfd == -1) {
fprintf(stderr, "create socket\n");
exit(1);
}
//初始化socket地址
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;//地址类型
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);//可监听任意ip地址
servaddr.sin_port = htons(SERV_PORT);//可监听的网络端口
//绑定地址与端口到套接字
status = bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr) );
if (status == -1) {
fprintf(stderr, "bind\n");
exit(1);
}
//设置socket为监听模式，最多允许有20个客户端处于连接待状态
listen(listenfd, 20);
if (status == -1) {
fprintf(stderr, "listen\n");
exit(1);
}
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);
//服务端阻塞等待客户端连接
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
//当有新的客户端连接时，fork出一个新进程来管理接收
pid = fork();
if (pid == -1) {
perror("call to fork");
exit(1);
} else if (pid == 0) {
//child
close(listenfd);
printf("connect to %s at PORT %d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port));
while (1) {
//通过文件描述符读取数据 阻塞等待
n = read(connfd, buf, MAXLINE);
if (n == 0) {
printf("disconnect to %s at PORT %d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)), ntohs(cliaddr.sin_port));
exit(0);
}
//客户端的端口是随机分配的
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]);//将小写变大写
}
//通过文件描述符写入数据
write(connfd, buf, n);
}
close(connfd);
} else {
//parent
close(connfd);
}
}
close(listenfd);
}
2）TCP客户端
/* client */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
//socket 所需的头文件
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#define MAXLINE 80
#define SERV_PORT 8000
//将client改为交互式输入
int main(int argc, char *argv[])
{
struct sockaddr_in servaddr;
char buf[MAXLINE];
int sockfd; //文件描述符
int n;
//创建流式套接字，即TCP socket
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
fprintf(stderr, "create socket\n");
exit(1);
}
//初始化socket地址
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);
//客户端请求连接服务器
connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
while (1) {
if (fgets(buf, MAXLINE, stdin) != NULL) {
//通过文件描述符写入数据
write(sockfd, buf, strlen(buf));
//通过文件描述符读取数据 阻塞等待
n = read(sockfd, buf, MAXLINE);
if (n == 0) {
printf("the other side has been closed.\n");
} else {
printf("Response from server:\n");
write(STDOUT_FILENO, buf, n);
}
}
}
close(sockfd);
return 0;
}
2.UDP通信
1）UDP服务器
/* server */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
//socket 所需的头文件
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#define MAXLINE 80
#define SERV_PORT 8000
int main(void)
{
struct sockaddr_in servaddr, cliaddr; //socket 地址结构体 服务端和客户端地址
socklen_t cliaddr_len;
int sockfd;//文件描述符
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i,n;
int status;
//创建块式套接字，即UDP socket
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1) {
fprintf(stderr, "create socket\n");
exit(1);
}
//初始化socket地址
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;//地址类型
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);//可监听任意ip地址
servaddr.sin_port = htons(SERV_PORT);//可监听的网络端口
//绑定地址与端口到套接字
status = bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr) );
if (status == -1) {
fprintf(stderr, "bind\n");
exit(1);
}
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);
//阻塞等待客户端数据到来
n = recvfrom(sockfd, buf, MAXLINE, 0, (struct sockaddr *)&cliaddr, &cliaddr_len);
if (n == -1) {
fprintf(stderr, "recvfrom error\n");
exit(1);
}
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]);//小写字母转大写
}
n = sendto(sockfd, buf, n, 0, (struct sockaddr *)&cliaddr, sizeof(cliaddr));
if (n == -1) {
fprintf(stderr, "sendto error\n");
exit(1);
}
}
}
2）UDP客户端
/* client */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
//socket 所需的头文件
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <ctype.h>
#define MAXLINE 80
#define SERV_PORT 8000
int main(int argc, char *argv[])
{
struct sockaddr_in servaddr;
int sockfd, n;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
socklen_t servaddr_len;
//创建UDP socket
sockfd = socket(AF_INET, SOCK_DGRAM, 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);
while (1) {
if (fgets(buf, MAXLINE, stdin) != NULL) {
//通过文件描述符发送数据
n = sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
if (n == -1) {
fprintf(stderr, "sendto error\n");
exit(1);
}
//通过文件描述符接收数据
n = recvfrom(sockfd, buf, MAXLINE, 0, NULL, 0);
if (n == -1) {
fprintf(stderr, "recvfrom error\n");
exit(1);
}
write(STDOUT_FILENO, buf, n);
}
}
close(sockfd);
return 0;
}
