getsockopt 返回与 setsockopt 中设置的不同的 IP_TOS 值

我正在尝试使用setsockopt to set IPTOS价值IPTOS_THROUGHPUT. The setsockopt回电0。但是，那getsockopt显示了IP_TOS值设置为1，这不同于IPTOS_THROUGHPUT (0x8）。有谁知道什么可能导致不匹配IPTOS值在setsockopt and getsockopt?

这是日志输出：

在套接字 26 上设置 DSCP 标记

套接字 26 到 8 上的 setsockopt 返回 0

套接字 26 上的 DSCP 标记为 1，与预期的 8 不同

下面是代码：

int iptos = IPTOS_THROUGHPUT;

log(debug, 10, "Set DSCP Marking on socket %d\n", sockfd);

retval = setsockopt(sockfd, IPPROTO_TCP, IP_TOS,  &iptos, sizeof(iptos));
if (retval<0) {
   log(error, 99, "Failed to set DSCP marking on socket %d with error %d\n",
      sockfd, retval);
} else {
   log(debug, 10, "setsockopt on socket %d to %d returns %d\n", sockfd, iptos,
      retval);
   int tos=0;
   socklen_t toslen=sizeof(tos);

   retval = getsockopt(sockfd, IPPROTO_TCP, IP_TOS,  &tos, &toslen);
   if(retval<0) {
      log(warning, 99, "Failed to get DSCP marking on socket %d with error %d\n",
         sockfd, retval);
   }else {
      if( tos != iptos ) {
         log(warning, 99, "DSCP marking on socket %d is %d, different from expected %d\n",
            sockfd, tos, iptos);
         retval = 9999;
      }
      else {
         log(debug, 10, "Success: Set DSCP Marking on socket %d to %d\n",
            sockfd, iptos);
         retval = 0;
      }
   }
}

您应该使用 level 选项IPPROTO_IP代替IPPROTO_TCP