一、通信流程

       TCP:

 

 

   UDP:

 

   部分函数知识可以参考之前写的 Linux 网络编程——TCP

  TCP通信：

 

  客户端：

#include<stdio.h>

include<sys/socket.h>

include<netinet/in.h>

include<stdlib.h>

include<memory.h>

include<string.h>

define PORT 8888

int main(int argc,char **argv){
int sock;
struct sockaddr_in my_addr;
int len;
char buf[100];
if(argc <3){
printf(“Usage: %s <ip> <port> <message>”,argv[0]);
exit(1);
}

if((sock=socket(AF_INET,SOCK_STREAM,0))<0){
    printf("socket create error!\n");
    exit(1);
}
my_addr.sin_family=AF_INET;
my_addr.sin_port=htons(8888);
if(inet_aton(argv[1],(struct in_addr *)&my_addr.sin_addr.s_addr) == 0){
    printf("%s chage error!\n",argv[1]);
    exit(1);
}
if(connect(sock,(struct sockaddr*)&my_addr,sizeof(struct sockaddr))<0){
    printf("connect error!\n");
    exit(1);
}
printf("connected!\n");

while(1){
    memset(buf,0,100);
    len=recv(sock,buf,100,0);
    if(len<0){
        printf("recv error!\n");
        exit(1);
    }else if(len == 0){
        printf("the client quit!\n");
        exit(1);
    }else{
        printf("receive message: %s \n",buf);
    }
    printf("-------------------------\n");
    memset(buf,0,100);
    printf("Input message to send: ");
    fgets(buf,100,stdin);
    len=send(sock,buf,strlen(buf)-1,0);
    if(len<0){
        printf("send error!\n");
        exit(1);
    }else{
        printf("send succeed! send : %s\n",buf);
    }
}
close(sock);

}

  服务端：

#include<stdio.h>

include<sys/socket.h>

include<netinet/in.h>

include<stdlib.h>

include<memory.h>

include<string.h>

include<sys/socket.h>

define PORT 8888

int main(){
int sock,new_sock;
struct sockaddr_in my_addr,client_addr;
int len;
char buf[100];

if((sock=socket(AF_INET,SOCK_STREAM,0))<0){
    printf("socket create error!\n");
    exit(1);
}
memset(&my_addr,0,sizeof(my_addr));
my_addr.sin_family=AF_INET;
my_addr.sin_port=htons(PORT);
my_addr.sin_addr.s_addr=INADDR_ANY;

if(bind(sock,(struct sockaddr*)&my_addr,sizeof(my_addr))==-1){
    printf("bind error!\n");
    exit(1);
}
if(listen(sock,5)<0){
    printf("listen error!\n");
    exit(1);
}
len=sizeof(struct sockaddr);
if((new_sock=accept(sock,(struct sockaddr*)&client_addr,&len))<0){
    printf("accept error!\n");
    exit(1);
}else{
    printf("server: get connection from %s,port %d socket %d \n",inet_ntoa(client_addr.sin_addr),ntohs(client_addr.sin_port),new_sock);

}
while(1){
    memset(buf,0,100);
    printf("Input message to send: ");
    fgets(buf,100,stdin);
    if(!strncasecmp(buf,"quit",4)){
        printf("server is closing...\n");
        break;
    }
    len=send(new_sock,buf,strlen(buf)-1,0);
    if(len<0){
        printf("send error!\n");
        exit(1);
    }else{
        printf("send succeed! send : %s\n",buf);
    }
    printf("------------------------------\n");
    memset(buf,0,100);
    len=recv(new_sock,buf,100,0);
    if(len<0){
        printf("recv error!\n");
        exit(1);
    }else if(len == 0){
        printf("the client quit!\n");
        break;
    }else{
        printf("receive message: %s \n",buf);
    }
}
close(sock);
close(new_sock);

}

 

         相对于TCP来说UDP就要简单写，毕竟步骤少嘛：

 

     服务端 ：

#include <stdio.h>

include <string.h>

include <sys/types.h>

include <netinet/in.h>

include <sys/socket.h>

include <errno.h>

include <stdlib.h>

include <arpa/inet.h>

int main(int argc, char **argv){ struct sockaddr_in s_addr,c_addr; int sock; socklen_t addr_len; int len; char buff[128];

if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    perror("socket");
    exit(errno);
} else
    printf("create socket.\n\r");

memset(&s_addr, 0, sizeof(struct sockaddr_in));

s_addr.sin_family = AF_INET;
s_addr.sin_port = htons(7838);
s_addr.sin_addr.s_addr = INADDR_ANY;

if ((bind(sock, (struct sockaddr *) &s_addr, sizeof(s_addr))) == -1) {
    perror("bind");
    exit(errno);
} else
    printf("bind address to socket.\n\r");

addr_len = sizeof(c_addr);
while (1) {
              memset(buff,0,sizeof(buff));
              //第三个参数标识为0，第四个参数为信息来源主机地址信息
    len = recvfrom(sock, buff, sizeof(buff) - 1, 0, (struct sockaddr *) &c_addr, &addr_len);
    if (len < 0) {
        perror("recvfrom");
        exit(errno);
    }

    buff[len] = '\0';
    printf("recive come from %s:%d message:%s\n\r",inet_ntoa(c_addr.sin_addr), ntohs(c_addr.sin_port), buff);
}
return 0;

}

 

     客户端：

#include <stdio.h>

include <string.h>

include <sys/types.h>

include <netinet/in.h>

include <sys/socket.h>

include <errno.h>

include <stdlib.h>

include <arpa/inet.h>

int main(int argc, char **argv){
struct sockaddr_in s_addr;
int sock;
int addr_len;
int len;
char buff[128];

if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    perror("socket");
    exit(errno);
} else
    printf("create socket.\n\r");

s_addr.sin_family = AF_INET;
s_addr.sin_port = htons(7838);
if (argc>2){
    s_addr.sin_addr.s_addr = inet_addr(argv[1]);
    strcpy(buff,argv[2]);
}
else {
    printf("input sever ip!\n");
    exit(0);
}

addr_len = sizeof(s_addr);
len = sendto(sock, buff, strlen(buff), 0, (struct sockaddr *) &s_addr, addr_len);
if (len < 0) {
    printf("\n\rsend error.\n\r");
    return 3;
}

printf("send success.\n\r");
return 0;

}

 

 

    本篇博客出自  阿修罗道，转载出处：http://blog.csdn.net/fansongy/article/details/6896851