如何在本地使用UDP套接字广播消息？

我想在本地广播消息到许多应用程序。 为此，我认为UDP套接字是最好的IPC，纠正我，如果我worng。

为此，我使用以下代码：

对于广播：

/* ** broadcaster.c -- a datagram "client" that can broadcast */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define SERVERPORT 4950 // the port users will be connecting to int main(int argc,char *argv[]) { int sockfd; struct sockaddr_in their_addr; // connector's address @R_303_4045@ion struct hostent *he; int numbytes; int broadcast = 1; //char broadcast = '1'; // if that doesn't work,try this if (argc != 3) { fprintf(stderr,"usage: broadcaster hostname messagen"); exit(1); } if ((he=gethostbyname(argv[1])) == NULL) { // get the host info perror("gethostbyname"); exit(1); } if ((sockfd = socket(AF_UNIX,SOCK_DGRAM,0)) == -1) { perror("socket"); exit(1); } // this call is what allows broadcast packets to be sent: if (setsockopt(sockfd,SOL_SOCKET,SO_broADCAST,&broadcast,sizeof broadcast) == -1) { perror("setsockopt (SO_broADCAST)"); exit(1); } their_addr.sin_family = AF_UNIX; // host byte order their_addr.sin_port = htons(SERVERPORT); // short,network byte order their_addr.sin_addr = *((struct in_addr *)he->h_addr); memset(their_addr.sin_zero,'',sizeof their_addr.sin_zero); if ((numbytes=sendto(sockfd,argv[2],strlen(argv[2]),(struct sockaddr *)&their_addr,sizeof their_addr)) == -1) { perror("sendto"); exit(1); } printf("sent %d bytes to %sn",numbytes,inet_ntoa(their_addr.sin_addr)); close(sockfd); return 0; }

并听取：

即使有更多的cmsghdr对象，CMSG_NXTHDR（）也会返回NULL

通过域套接字传输的单个数据包大小的实际限制是什么？

处理socket描述符如文件描述符（fstream）？ C ++ / Linux的

Python 3.4多处理队列比pipe道更快，意外

Python的UDP套接字半随机无法接收

/* ** listener.c -- a datagram sockets "server" demo */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <netdb.h> #define MYPORT "4950" // the port users will be connecting to #define MAXBUFLEN 100 // get sockaddr,IPv4 or IPv6: void *get_in_addr(struct sockaddr *sa) { if (sa->sa_family == AF_INET) { return &(((struct sockaddr_in*)sa)->sin_addr); } return &(((struct sockaddr_in6*)sa)->sin6_addr); } int main(void) { int sockfd; struct addrinfo hints,*servinfo,*p; int rv; int numbytes; struct sockaddr_storage their_addr; char buf[MAXBUFLEN]; socklen_t addr_len; char s[INET6_ADDRSTRLEN]; int optval = 1; memset(&hints,sizeof hints); hints.ai_family = AF_UNSPEC; // set to AF_INET to force IPv4 hints.ai_socktype = SOCK_DGRAM; hints.ai_flags = AI_PASSIVE; // use my IP if ((rv = getaddrinfo(NULL,MYPORT,&hints,&servinfo)) != 0) { fprintf(stderr,"getaddrinfo: %sn",gai_strerror(rv)); return 1; } // loop through all the results and bind to the first we can for(p = servinfo; p != NULL; p = p->ai_next) { if ((sockfd = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == -1) { perror("listener: socket"); continue; } if(setsockopt(sockfd,SO_REUSEADDR,&optval,sizeof optval) != 0) { perror("listener: setsockopt"); continue; } if (bind(sockfd,p->ai_addr,p->ai_addrlen) == -1) { close(sockfd); perror("listener: bind"); continue; } break; } if (p == NULL) { fprintf(stderr,"listener: Failed to bind socketn"); return 2; } freeaddrinfo(servinfo); printf("listener: waiting to recvfrom...n"); addr_len = sizeof their_addr; if ((numbytes = recvfrom(sockfd,buf,MAXBUFLEN-1,&addr_len)) == -1) { perror("recvfrom"); exit(1); } printf("listener: got packet from %sn",inet_ntop(their_addr.ss_family,get_in_addr((struct sockaddr *)&their_addr),s,sizeof s)); printf("listener: packet is %d bytes longn",numbytes); buf[numbytes] = ''; printf("listener: packet contains "%s"n",buf); close(sockfd); return 0; }

问题是我必须通过这样的192.168.1.255的IP，但在真实情况下可能没有eth0接口，只会有环回。 那我怎么能做到这一点？

什么本地接口连接或数据包接收？

使用node.js连接到已经build立的UNIX套接字？

C- Unix套接字 – 非阻塞读取

在Windows上发送数据报时发生EACCES错误

closures第一个连接尝试的c ++套接字

服务器不应绑定到从getaddrinfo获得的地址，而应该绑定到127.255.255.255 （用于回送接口）。

有关广播服务器/客户端的现成示例，请参阅http://www.ccplusplus.com/2011/09/udp-broadcast-client-server-example.html

Unix域套接字不支持多/广播。

您可以在本地接口127.0.0.1上进行广播。