1. 流程
服務(wù)器：
創(chuàng)建套接字 socket( )
填充服務(wù)器網(wǎng)絡(luò)信息結(jié)構(gòu)體 sockaddr_in
將套接字與服務(wù)器網(wǎng)絡(luò)信息結(jié)構(gòu)體綁定 bind( )
進(jìn)行通信 recvfrom( )/sendto( )
客戶端：
創(chuàng)建套接字 socket( )
填充服務(wù)器網(wǎng)絡(luò)信息結(jié)構(gòu)體 sockaddr_in
進(jìn)行通信 sendto( )/recvfrom( )
2. sendto
#include <sys/socket.h>
ssize_t sendto(int socket, const void *message, size_t length,
int flags, const struct sockaddr *dest_addr, socklen_t dest_len);
功能:發(fā)送數(shù)據(jù)
參數(shù)：
socket：文件描述符
message：發(fā)送的數(shù)據(jù)
length：數(shù)據(jù)的長(zhǎng)度
flags：標(biāo)志位国拇，一般為0
dest_addr：目的地址（發(fā)送給誰）
dest_len：addr的大小
返回值：
成功：發(fā)送數(shù)據(jù)的長(zhǎng)度
失斅冈獭：-1
3.recvfrom
#include <sys/types.h>
#include <sys/socket.h>
ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
struct sockaddr *src_addr, socklen_t *addrlen);
功能:接收數(shù)據(jù)
參數(shù)：
sockfd：文件描述符
buf：接收的數(shù)據(jù)
len：部分的長(zhǎng)度
flags：標(biāo)志位，一般為0
src_addr：源的地址（接收誰的數(shù)據(jù)溅蛉，自動(dòng)填充）
addrlen：addr的大小
返回值：
成功：接收的數(shù)據(jù)的長(zhǎng)度
失敗：-1
服務(wù)器端
#include <stdio.h> //printf
#include <arpa/inet.h> //inet_addr htons
#include <sys/types.h>
#include <sys/socket.h> //scoket bind listen accept connect
#include <netinet/in.h> //sockaddr_in
#include <stdlib.h> //exit
#include <unistd.h> //close
#include <string.h> //strcat
#include <strings.h>
#define N 128
#define errlog(errmsg) do{perror(errmsg);\
printf("%s-->%s-->%d\n", __FILE__, __func__, __LINE__);\
exit(1);\
}while(0)
int main(int argc, const char *argv[])
{
int sockfd;
struct sockaddr_in serveraddr, clientaddr;
socklen_t addrlen = sizeof(serveraddr);
char buf[N] = {};
//初始化結(jié)構(gòu)體
//bzero memset
bzero(&serveraddr, addrlen);
bzero(&clientaddr, addrlen);
if(argc < 3)
{
printf("the argument is too less\n");
exit(1);
}
//第一步：創(chuàng)建套接字
if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
errlog("fail to socket");
}
//第二步：填充服務(wù)器網(wǎng)絡(luò)信息結(jié)構(gòu)體
//inet_addr:將點(diǎn)分十進(jìn)制IP地址轉(zhuǎn)化為網(wǎng)絡(luò)字節(jié)序的整型數(shù)據(jù)
//htons：將主機(jī)字節(jié)序轉(zhuǎn)化為網(wǎng)絡(luò)字節(jié)序
//atoi：將數(shù)字型字符串轉(zhuǎn)化為整型數(shù)據(jù)
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
serveraddr.sin_port = htons(atoi(argv[2]));
//第三步：將套接字域網(wǎng)絡(luò)信息結(jié)構(gòu)體綁定
if(bind(sockfd, (struct sockaddr *)&serveraddr, sizeof(serveraddr)) < 0)
{
errlog("fail to bind");
}
ssize_t ret;
while(1)
{
if((ret = recvfrom(sockfd, buf, N, 0, (struct sockaddr *)&clientaddr, &addrlen)) < 0)
{
errlog("fail to recvfrom");
}
else
{
if(strncmp(buf, "quit", 4) == 0)
{
break;
}
else
{
printf("%s --> %d\n", inet_ntoa(clientaddr.sin_addr), ntohs(clientaddr.sin_port));
printf("client:%s\n", buf);
strcat(buf, " *_*");
if(sendto(sockfd, buf, N, 0, (struct sockaddr *)&clientaddr, addrlen) < 0)
{
errlog("fail to sendto");
}
}
}
}
close(sockfd);
return 0;
}
客戶端
#include <stdio.h> //printf
#include <arpa/inet.h> //inet_addr htons
#include <sys/types.h>
#include <sys/socket.h> //scoket bind listen accept connect
#include <netinet/in.h> //sockaddr_in
#include <stdlib.h> //exit
#include <unistd.h> //close
#include <string.h>
#define N 128
#define errlog(errmsg) do{perror(errmsg);\
printf("%s-->%s-->%d\n", __FILE__, __func__, __LINE__);\
exit(1);\
}while(0)
int main(int argc, const char *argv[])
{
int sockfd;
struct sockaddr_in serveraddr, clientaddr;
socklen_t addrlen = sizeof(serveraddr);
char buf[N] = {};
if(argc < 3)
{
printf("the argument is too less\n");
exit(1);
}
//第一步：創(chuàng)建套接字
if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
{
errlog("fail to socket");
}
//第二步：填充服務(wù)器網(wǎng)絡(luò)信息結(jié)構(gòu)體
//inet_addr:將點(diǎn)分十進(jìn)制IP地址轉(zhuǎn)化為網(wǎng)絡(luò)字節(jié)序的整型數(shù)據(jù)
//htons：將主機(jī)字節(jié)序轉(zhuǎn)化為網(wǎng)絡(luò)字節(jié)序
//atoi：將數(shù)字型字符串轉(zhuǎn)化為整型數(shù)據(jù)
serveraddr.sin_family = AF_INET;
serveraddr.sin_addr.s_addr = inet_addr(argv[1]);
serveraddr.sin_port = htons(atoi(argv[2]));
while(1)
{
fgets(buf, N, stdin);
buf[strlen(buf) - 1] = '\0';
if(sendto(sockfd, buf, N, 0, (struct sockaddr *)&serveraddr, addrlen) < 0)
{
errlog("fail to sendto");
}
if(strncmp(buf, "quit", 4) == 0)
{
break;
}
else
{
if(recvfrom(sockfd, buf, N, 0, NULL, NULL) < 0)
{
errlog("fail to recvfrom");
}
printf("server:%s\n", buf);
}
}
close(sockfd);
return 0;
}
