[英]TOS Field fetch from received packet on TCP socket in linux?
I have a C++ network application running on linux using TCP sockets.我有一个使用 TCP 套接字在 linux 上运行的 C++ 网络应用程序。 I have been trying to fetch the DSCP marking from a received packet for TCP.
我一直在尝试从接收到的 TCP 数据包中获取 DSCP 标记。 We have IP_RECVTOS socket option for UDP.
我们有用于 UDP 的 IP_RECVTOS 套接字选项。 But I have tested in code that it is not working for TCP.
但是我在代码中测试过它不适用于 TCP。
What options do I have except raw sockets to address the issue ?除了原始套接字之外,我还有哪些选项可以解决这个问题?
Example code : The following is for UDP. I am looking for something similar for TCP.
//Set the socket option to receive IP_TOS:
unsigned char set = 0x03;
if(setsockopt(udpSocket, IPPROTO_IP, IP_RECVTOS, &set,sizeof(set))<0)
{
printf("cannot set recvtos\n");
}
else
{
printf("socket set to recvtos\n");
}
// and Retrieve the IP_TOS value from every packet header by:
struct PC_Pkt pkt;
int *ecnptr;
unsigned char received_ecn;
struct msghdr msg;
struct iovec iov[1];
memset(&msg, '\0', sizeof(msg));
msg.msg_iov = iov;
msg.msg_iovlen = 1;
iov[0].iov_base = (char *) &pkt;
iov[0].iov_len = sizeof(pkt);
int cmsg_size = sizeof(struct cmsghdr)+sizeof(received_ecn);
char buf[CMSG_SPACE(sizeof(received_ecn))];
msg.msg_control = buf;
msg.msg_controllen = sizeof(buf);
nRet = recvmsg(udpSocket, &msg, 0);
if (nRet > 0) {
struct cmsghdr *cmsg;
for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
cmsg = CMSG_NXTHDR(&msg,cmsg)) {
if ((cmsg->cmsg_level == IPPROTO_IP) &&
(cmsg->cmsg_type == IP_TOS) && (cmsg->cmsg_len) ){
ecnptr = (int *) CMSG_DATA(cmsg);
received_ecn = *ecnptr;
int isecn = ((received_ecn & INET_ECN_MASK) == INET_ECN_CE);
printf("received_ecn = %i and %d, is ECN CE marked = %d \n", ecnptr, received_ecn, isecn);
break;
}
}
}
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