C ++通过UDP发送数据包但未接收到它

Question

I'm currently working on a project need to broadcast the data packet to a common port D88 for every second, but the client can not receive the data packet. I'm not sure I'm using the right way to send the packet.

int sockfdBroad;
struct sockaddr_in addrBroad;
swStat.packetBroadSent=0;

sockfdBroad=socket(AF_INET,SOCK_DGRAM,0);


bzero(&addrBroad,sizeof(addrBroad));
addrBroad.sin_family = AF_INET;
addrBroad.sin_addr.s_addr=inet_addr("192.168.1.255");
addrBroad.sin_port=htons(3464);   


if ((cycles%1000)==0)
    {

        currenttime = getMicrosTimeStamp();
        createTimePacket(bufferTime,currenttime,Odroid_Trigger);
        sendto(sockfdBroad,bufferTime,PACKET_LENGTH_TIME,0,(struct sockaddr *)&addrBroad,sizeof(addrBroad));
        swStat.packetBroadSent++;
    }

Answer 1

Assuming that the netmask for 192.168.1.255 is 255.255.255.0, 192.168.1.255 is a broadcast address. From man ip(7) :

Datagrams to broadcast addresses can be only sent or received when the SO_BROADCAST socket flag is set.

In other words, both the sender and the receiver must do:

int value = 1;
if(-1 == setsockopt(socket, SOL_SOCKET, SO_BROADCAST, &value, sizeof value))
    // Handle error.

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If you check the return value of sendto it must be -1 and errno == EACCESS . Always check the return values.