广播数据扫描和发送

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <netinet/ip.h>
#include <arpa/inet.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>

#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <pthread.h>
#include <sys/select.h>

 
#define ERRLOG(errmsg) do{\
                perror(errmsg);\
                printf("%s--%s(%d)\n", __FILE__, __func__, __LINE__);\
                exit(-1);\
            }while(0)
 
int scanMsg(const char* ip, const char* port, const char* groupNamePack, const char* masterIP)
{
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(-1 == sockfd){
        ERRLOG("socket error");
		close(sockfd);
		return -1;
    }
 
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));

    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(atoi(port));
    server_addr.sin_addr.s_addr = inet_addr(ip);
    socklen_t addrlen = sizeof(server_addr);
 
    if(-1 == bind(sockfd, (struct sockaddr *)&server_addr, addrlen)){
        ERRLOG("bind error");
		close(sockfd);
		return -1;
    }
 
    struct sockaddr_in client_addr;
    memset(&server_addr, 0, sizeof(client_addr));
    socklen_t clientaddrlen = sizeof(client_addr);
 
    char buff[128] = {0};
	fd_set rset;
	FD_ZERO(&rset);
	FD_SET(sockfd, &rset);

	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = 100*1000;

	int retsta = select(sockfd + 1, &rset, NULL, NULL, &tv);
	if(retsta < 0){
		ERRLOG("select error");
		close(sockfd);
		return -1;
	}else if (retsta > 0 && FD_ISSET(sockfd, &rset)){
		if(-1 == recvfrom(sockfd, buff, 128, 0, (struct sockaddr *)&client_addr, &clientaddrlen)){
			ERRLOG("recvfrom error");
			close(sockfd);
    		return -1;
		}		
		printf("%s(%d):%s\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port), buff);
		if(strcmp(buff, groupNamePack) == 0){
			//发送应答信息
			if(-1 == sendto(sockfd, masterIP, strlen(masterIP), 0, (struct sockaddr *)&client_addr, clientaddrlen)){
				ERRLOG("sendto error");
				close(sockfd);
				return -1;
			}
		}

	}else{
		printf("scanMsg don't receive mess\n");
	}
	close(sockfd);
    return 0;
}
 
int sendMsg(const char* ip, const char* port, const char* groupNamePack, char* masterIP, size_t len)
{
    int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if(-1 == sockfd){
        ERRLOG("socket error");
		close(sockfd);
		return -1;
    }
 
    //设置套接字允许发送广播
    int on = 1;
    if(-1 == setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on))){
        ERRLOG("setsockopt error");
		close(sockfd);
		return -1;
    }
 
    struct sockaddr_in server_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(atoi(port));
    server_addr.sin_addr.s_addr = inet_addr(ip);
    socklen_t addrlen = sizeof(server_addr);
 
	if(-1 == sendto(sockfd, groupNamePack, strlen(groupNamePack), 0, (struct sockaddr *)&server_addr, addrlen)){
		ERRLOG("sendto error");
		close(sockfd);
		return -1;
	}

	struct timeval tv;
	tv.tv_sec = 0;
	tv.tv_usec = 1000*100;
	
	fd_set rset;
	FD_ZERO(&rset);
	FD_SET(sockfd, &rset);

	int retsta = select(sockfd + 1, &rset, NULL, NULL, &tv);
	if(retsta < 0){
		ERRLOG("select error");
		close(sockfd);
		return -1;
	}else if (retsta > 0 && FD_ISSET(sockfd, &rset)){
		if(-1 == recvfrom(sockfd, masterIP, len, 0, NULL, NULL)){
			ERRLOG("recvfrom error");
			close(sockfd);
    		return -1;
		}	
	}else{
		printf("sendMsg don't receive\n");
	}
    
    close(sockfd);
    return 0;
}
void* run(void* arg)
{
	while(true){
		scanMsg("192.168.1.255", "4000", "sjhdhasdhjshj", "this is my ip");
		usleep(1000);
	}
	return NULL;
}
int main(int argc, char const *argv[])
{
	pthread_t tid;
	pthread_create(&tid, NULL, run, NULL);
	// pthread_join(tid, NULL);

	char msIP[128] = {0};
	sendMsg("192.168.1.255", "4000", "sjhdhasdhjshj", msIP, 128);
	
	if(strlen(msIP)){
		printf("msIP:%s\n", msIP);
	}
	usleep(1000);
	return 0;
}