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

Question

我正在尝试使用 setsockopt 将 IPTOS 值设置为 IPTOS_THROUGHPUT。 setsockopt 调用返回了 0。但是 getsockopt 显示 IP_TOS 值设置为 1，这不同于 IPTOS_THROUGHPUT (0x8 )。有谁知道是什么导致了 setsockopt 和 getsockopt 中的 IPTOS 值不匹配？

这是日志输出:

Set DSCP Marking on socket 26

setsockopt on socket 26 to 8 returns 0

DSCP marking on socket 26 is 1, different from expected 8

代码如下:

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;
      }
   }
}

Answer 1

您应该使用级别选项 IPPROTO_IP 而不是 IPPROTO_TCP