组播数据发送与接收示例代码

# include # include # include # include # include # include # include # include # include static int log_debug;# define MSGBUFSIZE 256static void usage(void){    printf("Usage: mcast [option] [argv]\n");    printf("    -v : verbose\n");    printf("    -h : help\n");    printf("    -c : client say hello to group\n");    printf("    -s : listener recveive from group\n");    printf("    -g [group]: ip group for client and server\n");    printf("    -p [port] : ip port for client and server\n");}static int add_multigroup(int fd, char *group){    struct ip_mreq mreq;    memset((void*)&mreq, 0, sizeof(mreq));    mreq.imr_multiaddr.s_addr = inet_addr(group);    mreq.imr_interface.s_addr = htonl(INADDR_ANY);    if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,                   &mreq, sizeof(mreq)) < 0) {        perror("setsockopt:IP_ADD_MEMBERSHIP");        return -1;    }    return 0;}static int start_client(char *group, int port){    int fd, ret;    struct sockaddr_in addr;    char *message = "Hello, World!";    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {        perror("socket");        return -1;    }    memset(&addr, 0, sizeof(addr));    addr.sin_family = AF_INET;    addr.sin_addr.s_addr = inet_addr(group);    addr.sin_port = htons(port);    while (1) {        if (sendto(fd, message, strlen(message), 0,                   (struct sockaddr *) &addr, sizeof(addr)) < 0) {            perror("sendto");            ret = -1;            break;        }        sleep(1);    }    close(fd);    return ret;}static int start_server(char *group, int port){    int fd = -1;    struct sockaddr_in addr;    int nbytes = 0;    socklen_t addrlen = sizeof(struct sockaddr_in);    char msgbuf[MSGBUFSIZE];    u_int reuseflag = 1;    int ret = 0;    if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {        perror("socket");        return -1;    }    ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuseflag, sizeof(reuseflag));    if (ret < 0) {        perror("SO_REUSEADDR");        close(fd);        return -1;    }    memset(&addr, 0, sizeof(addr));    addr.sin_family = AF_INET;    addr.sin_addr.s_addr = htonl(INADDR_ANY);    addr.sin_port = htons(port);    if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {        perror("bind");        close(fd);        return -1;    }    ret = add_multigroup(fd, group);    if (ret) {        printf("join a multicast group %s failed!\n", group);        close(fd);        return ret;    }    while (1) {        nbytes = recvfrom(fd, msgbuf, MSGBUFSIZE, 0,                          (struct sockaddr *)&addr, (socklen_t *)&addrlen);        if (nbytes < 0) {            perror("recvfrom");            ret = -1;            break;        }        msgbuf[nbytes] = '\0';        printf("recv: %s\n", msgbuf);    }    close(fd);    return ret;}int main(int argc, char *argv[]){    int ret = 0;    int c;    int mode = 0;    int port = -1;    char *group = NULL;    while (1) {        int option_index = 0;        static struct option long_options[] = {            {"help",  no_argument,          0, 'h' },            {"verbose", no_argument,        0, 'v' },            {"client",  no_argument,        0, 'c' },            {"server",  no_argument,        0, 's' },            {"group",   required_argument,  0, 'g' },            {"port",    required_argument,  0, 'p' },            {    0,             0,          0,  0  }        };        c = getopt_long(argc, argv, "hvcsg:p:",                        long_options, &option_index);        if (c == -1)            break;        switch (c) {            case 'v':                log_debug = 1;                break;            case 'c':                mode = 0;                break;            case 's':                mode = 1;                break;            case 'g':                group = optarg;                break;            case 'p':                port = atoi(optarg);                break;            case 'h':                usage();                return 0;            default:                break;        }    }    if (port < 0 || !group) {        usage();        return -1;    }    switch (mode) {        case 0:            printf("multicast test:client..\n");            ret = start_client(group, port);            break;        case 1:            printf("multicast test:server..\n");            ret = start_server(group, port);            break;        default:            break;    }    return ret;}

关键字：组播

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