Linux系统下UDP发送和接收广播消息

//?发送端??
#include?<iostream>??
#include?<stdio.h>??
#include?<sys/socket.h>??
#include?<unistd.h>??
#include?<sys/types.h>??
#include?<netdb.h>??
#include?<netinet/in.h>??
#include?<arpa/inet.h>??
#include?<string.h>??


using?namespace?std;??

int?main()??
{??
????setvbuf(stdout,?NULL,?_IONBF,?0);???
????fflush(stdout);???

????int?sock?=?-1;??
????if?((sock?=?socket(AF_INET,?SOCK_DGRAM,?0))?==?-1)???
????{?????
????????cout<<"socket?error"<<endl;???
????????return?false;??
????}?????

????const?int?opt?=?1;??
????//设置该套接字为广播类型，??
????int?nb?=?0;??
????nb?=?setsockopt(sock,?SOL_SOCKET,?SO_BROADCAST,?(char?*)&opt,?sizeof(opt));??
????if(nb?==?-1)??
????{??
????????cout<<"set?socket?error..."<<endl;??
????????return?false;??
????}??

????struct?sockaddr_in?addrto;??
????bzero(&addrto,?sizeof(struct?sockaddr_in));??
????addrto.sin_family=AF_INET;??
????addrto.sin_addr.s_addr=htonl(INADDR_BROADCAST);??
????addrto.sin_port=htons(6000);??
????int?nlen=sizeof(addrto);??

????while(1)??
????{??
????????sleep(1);??
????????//从广播地址发送消息??
????????char?smsg[]?=?{"abcdef"};??
????????int?ret=sendto(sock,?smsg,?strlen(smsg),?0,?(sockaddr*)&addrto,?nlen);??
????????if(ret<0)??
????????{??
????????????cout<<"send?error...."<<ret<<endl;??
????????}??
????????else??
????????{?????????
????????????printf("ok?");????
????????}??
????}??

????return?0;??
}

//?接收端

#include?<iostream>??
#include?<stdio.h>??
#include?<sys/socket.h>??
#include?<unistd.h>??
#include?<sys/types.h>??
#include?<netdb.h>??
#include?<netinet/in.h>??
#include?<arpa/inet.h>??
#include?<string.h>??


using?namespace?std;??

int?main()??
{??
????setvbuf(stdout,?0);???
????fflush(stdout);???

????//?绑定地址??
????struct?sockaddr_in?addrto;??
????bzero(&addrto,?sizeof(struct?sockaddr_in));??
????addrto.sin_family?=?AF_INET;??
????addrto.sin_addr.s_addr?=?htonl(INADDR_ANY);??
????addrto.sin_port?=?htons(6000);??

????//?广播地址??
????struct?sockaddr_in?from;??
????bzero(&from,?sizeof(struct?sockaddr_in));??
????from.sin_family?=?AF_INET;??
????from.sin_addr.s_addr?=?htonl(INADDR_ANY);??
????from.sin_port?=?htons(6000);??

????int?sock?=?-1;??
????if?((sock?=?socket(AF_INET,?sizeof(opt));??
????if(nb?==?-1)??
????{??
????????cout<<"set?socket?error..."<<endl;??
????????return?false;??
????}??

????if(bind(sock,(struct?sockaddr?*)&(addrto),?sizeof(struct?sockaddr_in))?==?-1)???
????{?????
????????cout<<"bind?error..."<<endl;??
????????return?false;??
????}??

????int?len?=?sizeof(sockaddr_in);??
????char?smsg[100]?=?{0};??

????while(1)??
????{??
????????//从广播地址接受消息??
????????int?ret=recvfrom(sock,?100,?(struct?sockaddr*)&from,(socklen_t*)&len);??
????????if(ret<=0)??
????????{??
????????????cout<<"read?error...."<<sock<<endl;??
????????}??
????????else??
????????{?????????
????????????printf("%st",?smsg);?????
????????}??

????????sleep(1);??
????}??

????return?0;??
}