提升时间戳 UDP 数据包

Question

I would like to retrieve the reception timestamp for UDP packets received using boost asio.

I found out that the kernel provides the socket option SO_TIMESTAMP which should allow the generation of a timestamp when the packets is received by the NIC. I also found this old ticket which was proposing a patch to add support for SO_TIMESTAMP.

I'm using boost 1.60.0 and I couldn't enable this option:

ip::udp::socket sock; 
... 
sock.set_option(ip::unicast::timestamp(true));

How can I retrieve a UDP packet reception time with boost and compute the elapsed time since reception when I receive the packet with a synchronous or an asynchronous read?

Answer 1

It seems boost has not implement this option yet, you can do it with native socket if your platform supports ancillary data:

int socket = sock.native(); 
int opt = 1;
setsockopt( sock, SOL_SOCKET, SO_TIMESTAMP, &opt, sizeof(opt));

then access control messages from the native socket:

int received = recvmsg(socket, &msgh, 0);
struct msghdr msgh;
struct cmsghdr *cmsg;
for (cmsg = CMSG_FIRSTHDR(msgh); cmsg != NULL; cmsg = CMSG_NXTHDR(msgh, cmsg)) {
    if ((cmsg->cmsg_level == SOL_SOCKET ) &&(cmsg->cmsg_type == SO_TIMESTAMP ))
        // read the timestamp
}