You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: syscall.go
    path of file: ./repos/sharingan/replayer/fastmock
    
    the code of the file until where you have to start completion: package fastmock

import (
	"bytes"
	"fmt"
	"net"
	"reflect"
	"regexp"
	"strconv"
	"syscall"
	"time"

	"github.com/didi/sharingan/replayer/internal"
	"github.com/didi/sharingan/replayer/monkey"
)

const (
	HTTP_SERVER = "HTTP_SERVER"
	GRPC_SERVER = "GRPC_SERVER"
)

var (
	// inbound header feature, include traceID、replay Time
	traceRegex  = regexp.MustCompile(`Sharingan-Replayer-Trace(?:id|ID)\s?: (\w{32})\r\n`)
	timeRegex   = regexp.MustCompile(`Sharingan-Replayer-Time\s?: (\d{19})\r\n`)
	serverRegex = regexp.MustCompile(`Sharingan-Replayer-Server\s?: (\w{11})\r\n`)

	// outbound traffic prefix, include traceID、origin connect addr
	trafficPrefix = `/*{"rid":"%s","addr":"%s"}*/`

	// mysqlGreetingTrace, val === md5("MYSQL_GREETING")
	mysqlGreetingTrace = "ca4bc2ca79c2f79729b322fbfbd91ef3"
)

// MockSyscall mock conn
func MockSyscall() 
    
func mockTCPConnRead() {
	var c *net.TCPConn

	monkey.MockMemberFunc(reflect.TypeOf(c), "Read", func(conn *net.TCPConn, b []byte) (int, error) {
		threadID := internal.GetCurrentGoRoutineID()
		fd := internal.GetConnFD(conn)

		// accsess
		ReplayerGlobalThreads.Access(threadID)
		// globalSockets.Access(fd)  // ignore Read Access

		// origin Read
		n, err := internal.ConnRead(conn, b)

		// only process inbound Request
		if err != nil || n <= 0 || !isInboundFD(fd) {
			return n, err
		}

		// Inbound Hook
		newb, newn := b, n
		traceID, replayTime, serverType := "", int64(0), ""

		// get and remove server-type header
		if ss := serverRegex.FindAllSubmatch(newb, -1); len(ss) >= 1 {
			serverType = string(ss[0][1])
			newb = bytes.Replace(newb, ss[0][0], []byte(""), -1)
			newn -= len(ss[0][0])
		}

		// get and remove traceID header
		if ss := traceRegex.FindAllSubmatch(newb, -1); GRPC_SERVER != serverType && len(ss) >= 1 {
			traceID = string(ss[0][1])
			newb = bytes.Replace(newb, ss[0][0], []byte(""), -1)
			newn -= len(ss[0][0])
		}

		// get and remove time header
		if ss := timeRegex.FindAllSubmatch(newb, -1); GRPC_SERVER != serverType && len(ss) >= 1 {
			replayTime, _ = strconv.ParseInt(string(ss[0][1]), 10, 64)
			newb = bytes.Replace(newb, ss[0][0], []byte(""), -1)
			newn -= len(ss[0][0])
		}

		if traceID != "" || replayTime != 0 {
			ReplayerGlobalThreads.Set(threadID, traceID, replayTime)
		}

		// remove header
		if len(b) > len(newb) && n > newn {
			copy(b, newb)
			n = newn
		}

		return n, err
	})
}