731 lines
21 KiB
Go
731 lines
21 KiB
Go
//go:build linux
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package transport
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"io"
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"syscall"
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"time"
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"omnisocketgo/cmd/internal/latencylog"
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"omnisocketgo/cmd/internal/protocol"
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)
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const (
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linuxTimestampControlBufferSize = 256 // 控制消息缓冲区。
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linuxTXTimestampWaitTimeout = 250 * time.Millisecond // 等待 TX 时间戳的上限。
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linuxTXTimestampPollInterval = time.Millisecond // 轮询 errqueue 的间隔。
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linuxDataPollInterval = time.Millisecond // 轮询普通收发的间隔。
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linuxSOTimestampingNew = 0x41
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linuxSCMTimestampingNew = linuxSOTimestampingNew
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linuxSOEEOriginTimestamping = 4 // timestamping errqueue 事件。
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linuxSCMTstampSnd = 0 // 对应 A_TX_SOFTWARE。
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linuxSCMTstampSched = 1 // 对应 A_TX_SCHED。
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linuxSOFTimestampingTXSoftware = 1 << 1 // 打开 TX software timestamp。
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linuxSOFTimestampingRXSoftware = 1 << 3 // 打开 RX software timestamp。
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linuxSOFTimestampingSoftware = 1 << 4 // software timestamp 总开关。
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linuxSOFTimestampingOptID = 1 << 7 // 给时间戳关联 ID。
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linuxSOFTimestampingTXSched = 1 << 8 // 打开 TX sched timestamp。
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linuxSOFTimestampingOptTSONLY = 1 << 11 // 只回时间戳。
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linuxSOFTimestampingOptIDTCP = 1 << 16 // 让 TCP 也带 timestamp ID。
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linuxTXTimestampPhasePreSendDrain = "pre_send_drain"
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linuxTXTimestampPhasePostSendCollect = "post_send_collect"
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linuxTXTimestampPhasePostSelectDrain = "post_select_drain"
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)
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type txSendChunk struct {
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SendCallIndex int
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FrameOffsetStart int
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FrameOffsetEnd int // 包含当前 sendmsg 成功写出的最后一个 frame 字节偏移。
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BytesWritten int
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ExpectedTXID uint32
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}
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type txTimestampEvent struct {
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EventName string
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TSUnixNano int64
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EEInfo uint32
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EEData uint32
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}
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type observedTXTimestampEvent struct {
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Phase string
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ReadIndex int
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Event txTimestampEvent
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}
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type txTimestampSelection struct {
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SelectedID uint32
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Timestamps map[string]int64
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HasEvent bool
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}
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type socketExtendedErrInfo struct {
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Info uint32
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Data uint32
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}
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// 拿到底层 fd，并打开 Linux timestamping。
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func (c *TCPConn) initLinuxTimestamping() error {
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sysConn, ok := c.conn.(interface {
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SyscallConn() (syscall.RawConn, error)
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})
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if !ok {
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return fmt.Errorf("transport: connection does not support SyscallConn")
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}
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rawConn, err := sysConn.SyscallConn()
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if err != nil || rawConn == nil {
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if err != nil {
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return fmt.Errorf("transport: get syscall conn: %w", err)
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}
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return fmt.Errorf("transport: missing syscall conn")
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}
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//socket是否可以成功打开 timestamping 取决于内核版本和配置，尝试多个 flag 组合直到成功或遇到非 EINVAL 错误。
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if err := enableLinuxTimestamping(rawConn); err != nil {
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return fmt.Errorf("transport: enable linux timestamping: %w", err)
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}
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//成功打开 timestamping 后，rawConn 就可以用来收 TX/RX 时间戳了。
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c.raw = rawConn
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return nil
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}
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// 给 socket开权限打开TX software timestamping。
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func enableLinuxTimestamping(rawConn syscall.RawConn) error {
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flagCandidates := []int{ //不同linux版本可能支持不同的 flag 组合，尝试多个组合直到成功。
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linuxSOFTimestampingTXSched |
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linuxSOFTimestampingTXSoftware |
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linuxSOFTimestampingRXSoftware |
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linuxSOFTimestampingSoftware |
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linuxSOFTimestampingOptID | //TCP 协议栈给每个时间戳生成一个序列号
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linuxSOFTimestampingOptIDTCP |
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linuxSOFTimestampingOptTSONLY,
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linuxSOFTimestampingTXSched |
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linuxSOFTimestampingTXSoftware |
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linuxSOFTimestampingRXSoftware |
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linuxSOFTimestampingSoftware |
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linuxSOFTimestampingOptID |
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linuxSOFTimestampingOptTSONLY,
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linuxSOFTimestampingTXSched |
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linuxSOFTimestampingTXSoftware |
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linuxSOFTimestampingRXSoftware |
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linuxSOFTimestampingSoftware |
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linuxSOFTimestampingOptTSONLY,
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}
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var lastErr error
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for _, flags := range flagCandidates { //尝试不同的 flag 组合，直到成功或遇到非 EINVAL 错误。
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// 内核根据 fd 找到对应的内存结构体（Socket 缓冲区）
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err := rawConn.Control(func(fd uintptr) { //Control 方法保证在回调里 fd 是有效的，可以安全地调用 syscall.SetsockoptInt。
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lastErr = syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, linuxSOTimestampingNew, flags)
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})
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||
if err != nil {
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||
return err
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||
}
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||
if lastErr == nil {
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||
return nil
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||
}
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||
if !errors.Is(lastErr, syscall.EINVAL) {
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||
return lastErr
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||
}
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||
}
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||
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return lastErr
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||
}
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// sendMessageLinux 编码消息、写完整帧，再记录 TX 时间戳。
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func (c *TCPConn) sendMessageLinux(msg protocol.Message) error {
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payload, err := protocol.EncodeMessage(msg)
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if err != nil {
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return fmt.Errorf("protocol: encode message: %w", err)
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}
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//编码后的消息 payload 前面加 4 字节长度，构成完整帧。
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frame := make([]byte, 4+len(payload))
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binary.BigEndian.PutUint32(frame[:4], uint32(len(payload)))
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copy(frame[4:], payload)
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readIndex := 0
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c.drainPendingTXTimestampEvents(msg, nil, linuxTXTimestampPhasePreSendDrain, &readIndex)
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chunks, err := c.writeFrameLinux(frame, msg)
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if err != nil {
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return fmt.Errorf("protocol: write frame: %w", err)
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}
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//记录发送延时日志
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c.logTXTimestampEvents(msg, chunks, &readIndex)
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return nil
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||
}
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// writeFrameLinux 用 sendmsg 写完整帧。
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func (c *TCPConn) writeFrameLinux(frame []byte, msg protocol.Message) ([]txSendChunk, error) {
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written := 0
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sendCallIndex := 0
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chunks := make([]txSendChunk, 0, 1)
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for written < len(frame) {
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n, err := c.sendmsgDataOnce(frame[written:])
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switch {
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case err == nil:
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if n <= 0 {
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return nil, io.ErrShortWrite
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||
}
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chunk := txSendChunk{
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SendCallIndex: sendCallIndex,
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FrameOffsetStart: written,
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FrameOffsetEnd: written + n - 1,
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BytesWritten: n,
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ExpectedTXID: c.txWriteSeq + uint32(n) - 1,
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}
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c.txWriteSeq += uint32(n)
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chunks = append(chunks, chunk)
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c.logTXSendChunkDebugRecord(msg, chunk)
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sendCallIndex++
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written += n
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case isWouldBlock(err):
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time.Sleep(linuxDataPollInterval)
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default:
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return nil, err
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}
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}
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return chunks, nil
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}
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// 把 A_TX_SCHED / A_TX_SOFTWARE 写入日志。(发送过程中）
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func (c *TCPConn) logTXTimestampEvents(msg protocol.Message, chunks []txSendChunk, readIndex *int) {
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timestamps := c.collectTXTimestampEvents(msg, chunks, readIndex)
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if ts, ok := timestamps[latencylog.EventATXSched]; ok {
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latencylog.LogMessageEventAt(c.logger, c.nodeRole, c.nodeID, latencylog.EventATXSched, ts, msg)
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}
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if ts, ok := timestamps[latencylog.EventATXSoftware]; ok {
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latencylog.LogMessageEventAt(c.logger, c.nodeRole, c.nodeID, latencylog.EventATXSoftware, ts, msg)
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}
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}
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// 在 errqueue 里等两类 TX 时间戳。
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func (c *TCPConn) collectTXTimestampEvents(msg protocol.Message, chunks []txSendChunk, readIndex *int) map[string]int64 {
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deadline := time.Now().Add(linuxTXTimestampWaitTimeout)
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observed := make([]observedTXTimestampEvent, 0, 4)
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finalChunk, hasFinalChunk := finalTXSendChunk(chunks)
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// 轮询 errqueue，优先等待本次消息最后一个 sendmsg chunk 的 sched/software 两类时间戳。
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for time.Now().Before(deadline) {
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event, err := c.recvTXTimestampOnce()
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if err != nil {
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if isWouldBlock(err) {
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time.Sleep(linuxTXTimestampPollInterval)
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||
continue
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}
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break
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}
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if event.EventName == "" || event.TSUnixNano <= 0 {
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continue
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}
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observed = append(observed, observedTXTimestampEvent{
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Phase: linuxTXTimestampPhasePostSendCollect,
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ReadIndex: *readIndex,
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Event: event,
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})
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*readIndex = *readIndex + 1
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selection := selectTXTimestampEvents(observed, finalChunk.ExpectedTXID, hasFinalChunk)
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if hasFinalChunk && selection.HasEvent && selection.SelectedID == finalChunk.ExpectedTXID && hasCompleteTXTimestampPair(selection.Timestamps) {
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break
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}
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}
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selection := selectTXTimestampEvents(observed, finalChunk.ExpectedTXID, hasFinalChunk)
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c.logObservedTXTimestampEvents(msg, chunks, observed, selection)
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c.drainPendingTXTimestampEvents(msg, chunks, linuxTXTimestampPhasePostSelectDrain, readIndex)
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return selection.Timestamps
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}
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// recvTXTimestampOnce 从 errqueue 读一次时间戳事件。
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||
func (c *TCPConn) recvTXTimestampOnce() (txTimestampEvent, error) {
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||
var (
|
||
event txTimestampEvent
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||
opErr error
|
||
)
|
||
|
||
err := c.raw.Control(func(fd uintptr) {
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||
//设置足够大的 oob buffer 来接收控制消息，调用 recvmsg 从 errqueue 读一条消息。
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oob := make([]byte, linuxTimestampControlBufferSize)
|
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//recvmsg 的 flags 里必须带 MSG_ERRQUEUE，才能从 errqueue 里读消息，非阻塞模式下如果没有消息可读会返回 EAGAIN。
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_, oobn, _, _, recvErr := syscall.Recvmsg(int(fd), nil, oob, syscall.MSG_ERRQUEUE|syscall.MSG_DONTWAIT)
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if recvErr != nil {
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opErr = recvErr
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return
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}
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//解析控制消息，看看是不是我们关心的 TX 时间戳事件，如果是就拿到事件名和时间戳。
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event, _ = parseTXTimestampControlMessages(oob[:oobn])
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})
|
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if err != nil {
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return txTimestampEvent{}, err
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}
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if opErr != nil {
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return txTimestampEvent{}, opErr
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}
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|
||
return event, nil
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||
}
|
||
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||
// 把底层时间戳映射成日志事件名。
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func parseTXTimestampControlMessages(oob []byte) (txTimestampEvent, bool) {
|
||
if len(oob) == 0 {
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return txTimestampEvent{}, false
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||
}
|
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//解析控制消息，看看是不是我们关心的 TX 时间戳事件，如果是就拿到事件名和时间戳。
|
||
controlMessages, err := syscall.ParseSocketControlMessage(oob)
|
||
if err != nil {
|
||
return txTimestampEvent{}, false
|
||
}
|
||
|
||
return parseTXTimestampSocketControlMessages(controlMessages)
|
||
}
|
||
|
||
func parseTXTimestampSocketControlMessages(controlMessages []syscall.SocketControlMessage) (txTimestampEvent, bool) {
|
||
var (
|
||
event txTimestampEvent
|
||
hasTS bool
|
||
hasKind bool
|
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)
|
||
|
||
for _, controlMessage := range controlMessages {
|
||
switch {
|
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case controlMessage.Header.Level == syscall.SOL_SOCKET && controlMessage.Header.Type == linuxSCMTimestampingNew:
|
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if ts := parseSCMTimestampingData(controlMessage.Data); ts > 0 {
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event.TSUnixNano = ts
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hasTS = true
|
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}
|
||
case isSocketExtendedErr(controlMessage): //判断时间戳是否进入了errqueue，
|
||
if info, ok := parseSocketExtendedErrInfo(controlMessage.Data); ok {
|
||
event.EEInfo = info.Info
|
||
event.EEData = info.Data
|
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event.EventName = mapLinuxTXTimestampEventName(info.Info)
|
||
hasKind = true
|
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}
|
||
}
|
||
}
|
||
|
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if !hasTS || !hasKind || event.EventName == "" {
|
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return txTimestampEvent{}, false
|
||
}
|
||
|
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return event, true
|
||
}
|
||
|
||
// 判断控制消息是否来自 socket extended err。
|
||
// 内核产生的时间戳并不会混合在普通的数据流里，而是被包装成一种特殊的“错误消息”丢进 Error Queue。
|
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func isSocketExtendedErr(controlMessage syscall.SocketControlMessage) bool {
|
||
switch {
|
||
case controlMessage.Header.Level == syscall.SOL_IP && controlMessage.Header.Type == syscall.IP_RECVERR:
|
||
return true
|
||
case controlMessage.Header.Level == syscall.SOL_IPV6 && controlMessage.Header.Type == syscall.IPV6_RECVERR:
|
||
return true
|
||
default:
|
||
return false
|
||
}
|
||
}
|
||
|
||
// 从 socket extended err 的数据里取 origin timestamping 信息。
|
||
func parseSocketExtendedErrInfo(data []byte) (socketExtendedErrInfo, bool) {
|
||
if len(data) < 16 {
|
||
return socketExtendedErrInfo{}, false
|
||
}
|
||
if data[4] != linuxSOEEOriginTimestamping {
|
||
return socketExtendedErrInfo{}, false
|
||
}
|
||
|
||
return socketExtendedErrInfo{
|
||
Info: binary.NativeEndian.Uint32(data[8:12]),
|
||
Data: binary.NativeEndian.Uint32(data[12:16]),
|
||
}, true
|
||
}
|
||
|
||
func mapLinuxTXTimestampEventName(tsKind uint32) string {
|
||
switch tsKind {
|
||
case linuxSCMTstampSched:
|
||
return latencylog.EventATXSched
|
||
case linuxSCMTstampSnd:
|
||
return latencylog.EventATXSoftware
|
||
default:
|
||
return fmt.Sprintf("TX_TIMESTAMP_KIND_%d", tsKind)
|
||
}
|
||
}
|
||
|
||
func finalTXSendChunk(chunks []txSendChunk) (txSendChunk, bool) {
|
||
if len(chunks) == 0 {
|
||
return txSendChunk{}, false
|
||
}
|
||
|
||
return chunks[len(chunks)-1], true
|
||
}
|
||
|
||
func isBusinessTXTimestampEventName(eventName string) bool {
|
||
return eventName == latencylog.EventATXSched || eventName == latencylog.EventATXSoftware
|
||
}
|
||
|
||
func hasCompleteTXTimestampPair(timestamps map[string]int64) bool {
|
||
if len(timestamps) == 0 {
|
||
return false
|
||
}
|
||
|
||
return timestamps[latencylog.EventATXSched] > 0 && timestamps[latencylog.EventATXSoftware] > 0
|
||
}
|
||
|
||
func selectTXTimestampEvents(events []observedTXTimestampEvent, expectedFinalTXID uint32, hasExpectedFinalTXID bool) txTimestampSelection {
|
||
byID := make(map[uint32]map[string]int64)
|
||
selection := txTimestampSelection{
|
||
Timestamps: make(map[string]int64, 2),
|
||
}
|
||
|
||
var (
|
||
highestID uint32
|
||
haveHighest bool
|
||
)
|
||
for _, observed := range events {
|
||
event := observed.Event
|
||
selection.HasEvent = true
|
||
if !haveHighest || event.EEData > highestID {
|
||
highestID = event.EEData
|
||
haveHighest = true
|
||
}
|
||
|
||
if !isBusinessTXTimestampEventName(event.EventName) {
|
||
continue
|
||
}
|
||
if _, ok := byID[event.EEData]; !ok {
|
||
byID[event.EEData] = make(map[string]int64, 2)
|
||
}
|
||
if existing, exists := byID[event.EEData][event.EventName]; !exists || event.TSUnixNano < existing {
|
||
byID[event.EEData][event.EventName] = event.TSUnixNano
|
||
}
|
||
}
|
||
|
||
if !selection.HasEvent {
|
||
return selection
|
||
}
|
||
|
||
switch {
|
||
case hasExpectedFinalTXID && len(byID[expectedFinalTXID]) > 0:
|
||
selection.SelectedID = expectedFinalTXID
|
||
selection.Timestamps = copyTXTimestampMap(byID[expectedFinalTXID])
|
||
case len(byID[highestID]) > 0:
|
||
selection.SelectedID = highestID
|
||
selection.Timestamps = copyTXTimestampMap(byID[highestID])
|
||
default:
|
||
selection.SelectedID = highestID
|
||
}
|
||
|
||
return selection
|
||
}
|
||
|
||
func copyTXTimestampMap(src map[string]int64) map[string]int64 {
|
||
dst := make(map[string]int64, len(src))
|
||
for key, value := range src {
|
||
dst[key] = value
|
||
}
|
||
return dst
|
||
}
|
||
|
||
func (c *TCPConn) drainPendingTXTimestampEvents(msg protocol.Message, chunks []txSendChunk, phase string, readIndex *int) {
|
||
for {
|
||
event, err := c.recvTXTimestampOnce()
|
||
if err != nil {
|
||
if isWouldBlock(err) {
|
||
return
|
||
}
|
||
return
|
||
}
|
||
if event.EventName == "" || event.TSUnixNano <= 0 {
|
||
continue
|
||
}
|
||
c.logTXErrqueueDebugRecord(msg, chunks, observedTXTimestampEvent{
|
||
Phase: phase,
|
||
ReadIndex: *readIndex,
|
||
Event: event,
|
||
}, false)
|
||
*readIndex = *readIndex + 1
|
||
}
|
||
}
|
||
|
||
func (c *TCPConn) logObservedTXTimestampEvents(msg protocol.Message, chunks []txSendChunk, observed []observedTXTimestampEvent, selection txTimestampSelection) {
|
||
if len(observed) == 0 {
|
||
return
|
||
}
|
||
|
||
for _, entry := range observed {
|
||
selected := selection.HasEvent &&
|
||
entry.Event.EEData == selection.SelectedID &&
|
||
isBusinessTXTimestampEventName(entry.Event.EventName) &&
|
||
selection.Timestamps[entry.Event.EventName] == entry.Event.TSUnixNano
|
||
c.logTXErrqueueDebugRecord(msg, chunks, entry, selected)
|
||
}
|
||
}
|
||
|
||
func (c *TCPConn) logTXSendChunkDebugRecord(msg protocol.Message, chunk txSendChunk) {
|
||
if c.txTimestampDebugLogger == nil {
|
||
return
|
||
}
|
||
|
||
sendCallIndex := chunk.SendCallIndex
|
||
frameOffsetStart := chunk.FrameOffsetStart
|
||
frameOffsetEnd := chunk.FrameOffsetEnd
|
||
bytesWritten := chunk.BytesWritten
|
||
expectedTXID := chunk.ExpectedTXID
|
||
|
||
record := c.newTXTimestampDebugRecord(msg)
|
||
record.RecordType = txTimestampDebugRecordTypeSendChunk
|
||
record.SendCallIndex = &sendCallIndex
|
||
record.FrameOffsetStart = &frameOffsetStart
|
||
record.FrameOffsetEnd = &frameOffsetEnd
|
||
record.BytesWritten = &bytesWritten
|
||
record.ExpectedTXID = &expectedTXID
|
||
c.logTXTimestampDebugRecord(record)
|
||
}
|
||
|
||
func (c *TCPConn) logTXErrqueueDebugRecord(msg protocol.Message, chunks []txSendChunk, observed observedTXTimestampEvent, selected bool) {
|
||
if c.txTimestampDebugLogger == nil {
|
||
return
|
||
}
|
||
|
||
readIndex := observed.ReadIndex
|
||
tsUnixNano := observed.Event.TSUnixNano
|
||
eeInfo := observed.Event.EEInfo
|
||
eeData := observed.Event.EEData
|
||
selectedForLatency := selected
|
||
|
||
record := c.newTXTimestampDebugRecord(msg)
|
||
record.RecordType = txTimestampDebugRecordTypeErrqueueEvent
|
||
record.Phase = observed.Phase
|
||
record.ReadIndex = &readIndex
|
||
record.EventName = observed.Event.EventName
|
||
record.TSUnixNano = &tsUnixNano
|
||
record.EEInfo = &eeInfo
|
||
record.EEData = &eeData
|
||
record.SelectedForLatency = &selectedForLatency
|
||
if matchedSendCallIndex, ok := matchTXTimestampEventToSendChunk(observed.Event.EEData, chunks); ok {
|
||
record.MatchedSendCallIndex = &matchedSendCallIndex
|
||
}
|
||
c.logTXTimestampDebugRecord(record)
|
||
}
|
||
|
||
func matchTXTimestampEventToSendChunk(txID uint32, chunks []txSendChunk) (int, bool) {
|
||
for _, chunk := range chunks {
|
||
if chunk.ExpectedTXID == txID {
|
||
return chunk.SendCallIndex, true
|
||
}
|
||
}
|
||
|
||
return 0, false
|
||
}
|
||
|
||
func (c *TCPConn) newTXTimestampDebugRecord(msg protocol.Message) TXTimestampDebugRecord {
|
||
return TXTimestampDebugRecord{
|
||
NodeRole: c.nodeRole,
|
||
NodeID: c.nodeID,
|
||
MessageType: msg.Type,
|
||
MessageID: msg.ID,
|
||
From: msg.From,
|
||
To: msg.To,
|
||
FileName: msg.FileName,
|
||
BodySize: len(msg.Body),
|
||
}
|
||
}
|
||
|
||
func (c *TCPConn) logTXTimestampDebugRecord(record TXTimestampDebugRecord) {
|
||
if c.txTimestampDebugLogger == nil {
|
||
return
|
||
}
|
||
|
||
_ = c.txTimestampDebugLogger.LogTXTimestampDebugRecord(record)
|
||
}
|
||
|
||
// 读一条完整消息，并记录 B_RX_SOFTWARE。
|
||
func (c *TCPConn) receiveMessageLinux() (protocol.Message, error) {
|
||
payload, rxTimestamp, err := c.readFrameLinux()
|
||
if err != nil {
|
||
return protocol.Message{}, fmt.Errorf("protocol: read frame: %w", err)
|
||
}
|
||
|
||
msg, err := protocol.DecodeMessage(payload)
|
||
if err != nil {
|
||
return protocol.Message{}, fmt.Errorf("protocol: decode message: %w", err)
|
||
}
|
||
|
||
if rxTimestamp > 0 {
|
||
latencylog.LogMessageEventAt(c.logger, c.nodeRole, c.nodeID, latencylog.EventBRXSoftware, rxTimestamp, msg)
|
||
}
|
||
|
||
return msg, nil
|
||
}
|
||
|
||
// readFrameLinux 先读 4 字节长度，再读整条 payload。
|
||
func (c *TCPConn) readFrameLinux() ([]byte, int64, error) {
|
||
var frameHeader [4]byte
|
||
rxTimestamp, err := c.readFullLinux(frameHeader[:])
|
||
if err != nil {
|
||
return nil, rxTimestamp, err
|
||
}
|
||
|
||
size := binary.BigEndian.Uint32(frameHeader[:])
|
||
switch {
|
||
case size == 0:
|
||
return nil, rxTimestamp, protocol.ErrInvalidFrameLength
|
||
case size > protocol.MaxFrameSize:
|
||
return nil, rxTimestamp, protocol.ErrFrameTooLarge
|
||
}
|
||
|
||
payload := make([]byte, int(size))
|
||
bodyTimestamp, err := c.readFullLinux(payload)
|
||
if rxTimestamp == 0 {
|
||
rxTimestamp = bodyTimestamp
|
||
}
|
||
if err != nil {
|
||
return nil, rxTimestamp, err
|
||
}
|
||
|
||
return payload, rxTimestamp, nil
|
||
}
|
||
|
||
// 读满 buf，并保留首个 RX_SOFTWARE（返回进入tcp协议栈的时间戳）。
|
||
func (c *TCPConn) readFullLinux(buf []byte) (int64, error) {
|
||
if len(buf) == 0 {
|
||
return 0, nil
|
||
}
|
||
|
||
var (
|
||
offset int
|
||
firstRXTime int64
|
||
)
|
||
|
||
for offset < len(buf) {
|
||
n, rxTimestamp, err := c.recvmsgLinux(buf[offset:])
|
||
if firstRXTime == 0 && rxTimestamp > 0 {
|
||
firstRXTime = rxTimestamp
|
||
}
|
||
if err != nil {
|
||
if errors.Is(err, io.EOF) && offset > 0 {
|
||
return firstRXTime, io.ErrUnexpectedEOF
|
||
}
|
||
return firstRXTime, err
|
||
}
|
||
|
||
offset += n
|
||
}
|
||
|
||
return firstRXTime, nil
|
||
}
|
||
|
||
// recvmsgLinux 用 recvmsg 同时读取数据和控制消息。
|
||
func (c *TCPConn) recvmsgLinux(buf []byte) (int, int64, error) {
|
||
for {
|
||
n, rxTimeNS, err := c.recvmsgDataOnce(buf)
|
||
switch {
|
||
case err == nil:
|
||
if n == 0 {
|
||
return 0, 0, io.EOF
|
||
}
|
||
return n, rxTimeNS, nil
|
||
case isWouldBlock(err):
|
||
time.Sleep(linuxDataPollInterval)
|
||
default:
|
||
return 0, 0, err
|
||
}
|
||
}
|
||
}
|
||
|
||
// 从控制消息里取 RX_SOFTWARE。
|
||
func parseRXTimestampControlMessages(oob []byte) int64 {
|
||
if len(oob) == 0 {
|
||
return 0
|
||
}
|
||
|
||
controlMessages, err := syscall.ParseSocketControlMessage(oob)
|
||
if err != nil {
|
||
return 0
|
||
}
|
||
|
||
for _, controlMessage := range controlMessages {
|
||
if controlMessage.Header.Level != syscall.SOL_SOCKET || controlMessage.Header.Type != linuxSCMTimestampingNew {
|
||
continue
|
||
}
|
||
|
||
if ts := parseSCMTimestampingData(controlMessage.Data); ts > 0 {
|
||
return ts
|
||
}
|
||
}
|
||
|
||
return 0
|
||
}
|
||
|
||
// 取第一个非零 timespec。
|
||
func parseSCMTimestampingData(data []byte) int64 {
|
||
const timespec64Size = 16
|
||
|
||
for offset := 0; offset+timespec64Size <= len(data); offset += timespec64Size {
|
||
sec := int64(binary.NativeEndian.Uint64(data[offset : offset+8]))
|
||
nsec := int64(binary.NativeEndian.Uint64(data[offset+8 : offset+16]))
|
||
if sec == 0 && nsec == 0 {
|
||
continue
|
||
}
|
||
return sec*int64(time.Second) + nsec
|
||
}
|
||
|
||
return 0
|
||
}
|
||
|
||
// 判断错误是否是 EAGAIN 或 EWOULDBLOCK。
|
||
func isWouldBlock(err error) bool {
|
||
return errors.Is(err, syscall.EAGAIN) || errors.Is(err, syscall.EWOULDBLOCK)
|
||
}
|
||
|
||
func (c *TCPConn) sendmsgDataOnce(buf []byte) (int, error) {
|
||
var (
|
||
n int
|
||
opErr error
|
||
)
|
||
|
||
err := c.raw.Control(func(fd uintptr) {
|
||
n, opErr = syscall.SendmsgN(int(fd), buf, nil, nil, 0)
|
||
})
|
||
if err != nil {
|
||
return 0, err
|
||
}
|
||
|
||
return n, opErr
|
||
}
|
||
|
||
func (c *TCPConn) recvmsgDataOnce(buf []byte) (int, int64, error) {
|
||
var (
|
||
n int
|
||
rxTimeNS int64
|
||
opErr error
|
||
)
|
||
|
||
err := c.raw.Control(func(fd uintptr) {
|
||
oob := make([]byte, linuxTimestampControlBufferSize)
|
||
readN, oobN, _, _, recvErr := syscall.Recvmsg(int(fd), buf, oob, 0)
|
||
if recvErr != nil {
|
||
opErr = recvErr
|
||
return
|
||
}
|
||
n = readN
|
||
rxTimeNS = parseRXTimestampControlMessages(oob[:oobN])
|
||
})
|
||
if err != nil {
|
||
return 0, 0, err
|
||
}
|
||
|
||
return n, rxTimeNS, opErr
|
||
}
|