我正在进行一个项目,旨在从NIC获取TCP套接字的接收和传输时间戳,如Linux时间戳文档中所述。但是所有文档和测试代码都是针对UDP套接字完成的。但我能够获得NIC的传输时间戳,却无法获取接收TCP数据包的时间戳。
我的接口支持以下时间戳:
Time stamping parameters for enp4s0:
Capabilities:
hardware-transmit (SOF_TIMESTAMPING_TX_HARDWARE)
software-transmit (SOF_TIMESTAMPING_TX_SOFTWARE)
hardware-receive (SOF_TIMESTAMPING_RX_HARDWARE)
software-receive (SOF_TIMESTAMPING_RX_SOFTWARE)
software-system-clock (SOF_TIMESTAMPING_SOFTWARE)
hardware-raw-clock (SOF_TIMESTAMPING_RAW_HARDWARE)
PTP Hardware Clock: 3
Hardware Transmit Timestamp Modes:
off (HWTSTAMP_TX_OFF)
on (HWTSTAMP_TX_ON)
Hardware Receive Filter Modes:
none (HWTSTAMP_FILTER_NONE)
all (HWTSTAMP_FILTER_ALL)
我使用ioctl(sockfd, SIOCSHWTSTAMP, & net_device);
在 bind()
之后为NIC启用时间戳,
memset(&net_device, 0, sizeof(net_device));
strncpy(net_device.ifr_name, interface_name, sizeof(net_device.ifr_name));
net_device.ifr_data = (void *)&tstconfig;
memset(&tstconfig, 0, sizeof(tstconfig));
tstconfig.tx_type = HWTSTAMP_TX_OFF;
tstconfig.rx_filter = HWTSTAMP_FILTER_ALL;
然后通过setsockopt()
在网络接口卡中启用时间戳
int opt= 0;
opt |= SOF_TIMESTAMPING_RX_HARDWARE;
opt |= SOF_TIMESTAMPING_RAW_HARDWARE;
if (setsockopt(sockfd, SOL_SOCKET, SO_TIMESTAMPING,
(char *)&opt, sizeof(opt))) {
error(1, 0, "setsockopt timestamping");
bail("setsockopt SO_TIMESTAMPING");
}
在执行 listen()
和 accept()
后,我使用 select()
,检查是否 fd
在 rfds
中,然后使用以下选项调用 recvmsg()
。
int rc;
struct iovec vec[1];
struct msghdr msg;
char data[8192];
struct cmsghdr *cmsg;
union {
struct cmsghdr cm;
char control[256];
} cmsg_un;
vec[0].iov_base = data;
vec[0].iov_len = sizeof(data);
memset(&msg, 0, sizeof(msg));
memset(&from_addr, 0, sizeof(from_addr));
memset(&cmsg_un, 0, sizeof(cmsg_un));
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = vec;
msg.msg_iovlen = 1;
msg.msg_control = cmsg_un.control;
msg.msg_controllen = sizeof(cmsg_un.control);
rc = recvmsg(flow->fd, &msg, 0);
printf("tried reading %d bytes, got %d", bytes, rc);
if (msg.msg_flags & MSG_TRUNC) {
printf("received truncated message\n");
return 0;
}
if (msg.msg_flags & MSG_CTRUNC) {
printf("received truncated ancillary data\n");
return 0;
}
if (msg.msg_controllen <= 0) {
printf("`received short ancillary data (%ld/%ld)`\n",
(long)msg.msg_controllen, (long)sizeof(cmsg_un.control));
return 0;
}
但我始终收到以下消息:
received short ancillary data (0/256)
我从recvmsg()
中没有获取到附属数据,想知道Linux是否支持NIC的TCP接收硬件时间戳。