First Commmit

experimental/libbox/internal/procfs/procfs.go

@@ -0,0 +1,148 @@
+package procfs
+
+import (
+	"bufio"
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+	"net"
+	"net/netip"
+	"os"
+	"strconv"
+	"strings"
+	"unsafe"
+
+	N "github.com/sagernet/sing/common/network"
+)
+
+var (
+	netIndexOfLocal = -1
+	netIndexOfUid   = -1
+	nativeEndian    binary.ByteOrder
+)
+
+func init() {
+	var x uint32 = 0x01020304
+	if *(*byte)(unsafe.Pointer(&x)) == 0x01 {
+		nativeEndian = binary.BigEndian
+	} else {
+		nativeEndian = binary.LittleEndian
+	}
+}
+
+func ResolveSocketByProcSearch(network string, source, _ netip.AddrPort) int32 {
+	if netIndexOfLocal < 0 || netIndexOfUid < 0 {
+		return -1
+	}
+
+	path := "/proc/net/"
+
+	if network == N.NetworkTCP {
+		path += "tcp"
+	} else {
+		path += "udp"
+	}
+
+	if source.Addr().Is6() {
+		path += "6"
+	}
+
+	sIP := source.Addr().AsSlice()
+	if len(sIP) == 0 {
+		return -1
+	}
+
+	var bytes [2]byte
+	binary.BigEndian.PutUint16(bytes[:], source.Port())
+	local := fmt.Sprintf("%s:%s", hex.EncodeToString(nativeEndianIP(sIP)), hex.EncodeToString(bytes[:]))
+
+	file, err := os.Open(path)
+	if err != nil {
+		return -1
+	}
+
+	defer file.Close()
+
+	reader := bufio.NewReader(file)
+
+	for {
+		row, _, err := reader.ReadLine()
+		if err != nil {
+			return -1
+		}
+
+		fields := strings.Fields(string(row))
+
+		if len(fields) <= netIndexOfLocal || len(fields) <= netIndexOfUid {
+			continue
+		}
+
+		if strings.EqualFold(local, fields[netIndexOfLocal]) {
+			uid, err := strconv.Atoi(fields[netIndexOfUid])
+			if err != nil {
+				return -1
+			}
+
+			return int32(uid)
+		}
+	}
+}
+
+func nativeEndianIP(ip net.IP) []byte {
+	result := make([]byte, len(ip))
+
+	for i := 0; i < len(ip); i += 4 {
+		value := binary.BigEndian.Uint32(ip[i:])
+
+		nativeEndian.PutUint32(result[i:], value)
+	}
+
+	return result
+}
+
+func init() {
+	file, err := os.Open("/proc/net/tcp")
+	if err != nil {
+		return
+	}
+
+	defer file.Close()
+
+	reader := bufio.NewReader(file)
+
+	header, _, err := reader.ReadLine()
+	if err != nil {
+		return
+	}
+
+	columns := strings.Fields(string(header))
+
+	var txQueue, rxQueue, tr, tmWhen bool
+
+	for idx, col := range columns {
+		offset := 0
+
+		if txQueue && rxQueue {
+			offset--
+		}
+
+		if tr && tmWhen {
+			offset--
+		}
+
+		switch col {
+		case "tx_queue":
+			txQueue = true
+		case "rx_queue":
+			rxQueue = true
+		case "tr":
+			tr = true
+		case "tm->when":
+			tmWhen = true
+		case "local_address":
+			netIndexOfLocal = idx + offset
+		case "uid":
+			netIndexOfUid = idx + offset
+		}
+	}
+}