Routing config: Add processName (#5489)

common/net/find_process_linux.go

@@ -0,0 +1,178 @@
+//go:build linux
+
+package net
+
+import (
+	"bufio"
+	"encoding/hex"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	"github.com/xtls/xray-core/common/errors"
+)
+
+func FindProcess(dest Destination) (int, string, error) {
+	isLocal, err := IsLocal(dest.Address.IP())
+	if err != nil {
+		return 0, "", errors.New("failed to determine if address is local: ", err)
+	}
+	if !isLocal {
+		return 0, "", ErrNotLocal
+	}
+	if dest.Network != Network_TCP && dest.Network != Network_UDP {
+		panic("Unsupported network type for process lookup.")
+	}
+	// the core should never has a domain as source(?
+	if dest.Address.Family() == AddressFamilyDomain {
+		panic("Domain addresses are not supported for process lookup.")
+	}
+	var procFile string
+
+	switch dest.Network {
+	case Network_TCP:
+		if dest.Address.Family() == AddressFamilyIPv4 {
+			procFile = "/proc/net/tcp"
+		}
+		if dest.Address.Family() == AddressFamilyIPv6 {
+			procFile = "/proc/net/tcp6"
+		}
+	case Network_UDP:
+		if dest.Address.Family() == AddressFamilyIPv4 {
+			procFile = "/proc/net/udp"
+		}
+		if dest.Address.Family() == AddressFamilyIPv6 {
+			procFile = "/proc/net/udp6"
+		}
+	default:
+		panic("Unsupported network type for process lookup.")
+	}
+
+	targetHexAddr, err := formatLittleEndianString(dest.Address, dest.Port)
+	if err != nil {
+		return 0, "", errors.New("failed to format address: ", err)
+	}
+
+	inode, err := findInodeInFile(procFile, targetHexAddr)
+	if err != nil {
+		return 0, "", errors.New("could not search in ", procFile).Base(err)
+	}
+	if inode == "" {
+		return 0, "", errors.New("connection for ", dest.Address, ":", dest.Port, " not found in ", procFile)
+	}
+
+	pidStr, err := findPidByInode(inode)
+	if err != nil {
+		return 0, "", errors.New("could not find PID for inode ", inode, ": ", err)
+	}
+	if pidStr == "" {
+		return 0, "", errors.New("no process found for inode ", inode)
+	}
+
+	procName, err := getProcessName(pidStr)
+	if err != nil {
+		return 0, "", fmt.Errorf("could not get process name for PID %s: %w", pidStr, err)
+	}
+
+	pid, err := strconv.Atoi(pidStr)
+	if err != nil {
+		return 0, "", errors.New("failed to parse PID: ", err)
+	}
+
+	return pid, procName, nil
+}
+
+func formatLittleEndianString(addr Address, port Port) (string, error) {
+	ip := addr.IP()
+	var ipBytes []byte
+	if addr.Family() == AddressFamilyIPv4 {
+		ipBytes = ip.To4()
+	} else {
+		ipBytes = ip.To16()
+	}
+	if ipBytes == nil {
+		return "", errors.New("invalid IP format for ", addr.Family(), ": ", ip)
+	}
+
+	for i, j := 0, len(ipBytes)-1; i < j; i, j = i+1, j-1 {
+		ipBytes[i], ipBytes[j] = ipBytes[j], ipBytes[i]
+	}
+	portHex := fmt.Sprintf("%04X", uint16(port))
+	ipHex := strings.ToUpper(hex.EncodeToString(ipBytes))
+	return fmt.Sprintf("%s:%s", ipHex, portHex), nil
+}
+
+func findInodeInFile(filePath, targetHexAddr string) (string, error) {
+	file, err := os.Open(filePath)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		line := scanner.Text()
+		fields := strings.Fields(line)
+
+		if len(fields) < 10 {
+			continue
+		}
+
+		localAddress := fields[1]
+		if localAddress == targetHexAddr {
+			inode := fields[9]
+			return inode, nil
+		}
+	}
+
+	return "", scanner.Err()
+}
+
+func findPidByInode(inode string) (string, error) {
+	procDir, err := os.ReadDir("/proc")
+	if err != nil {
+		return "", err
+	}
+
+	targetLink := "socket:[" + inode + "]"
+
+	for _, entry := range procDir {
+		if !entry.IsDir() {
+			continue
+		}
+		pid := entry.Name()
+		if _, err := strconv.Atoi(pid); err != nil {
+			continue
+		}
+
+		fdPath := fmt.Sprintf("/proc/%s/fd", pid)
+		fdDir, err := os.ReadDir(fdPath)
+		if err != nil {
+			continue
+		}
+
+		for _, fdEntry := range fdDir {
+			linkPath := fmt.Sprintf("%s/%s", fdPath, fdEntry.Name())
+			linkTarget, err := os.Readlink(linkPath)
+			if err != nil {
+				continue
+			}
+			if linkTarget == targetLink {
+				return pid, nil
+			}
+		}
+	}
+	return "", nil
+}
+
+func getProcessName(pid string) (string, error) {
+	path := fmt.Sprintf("/proc/%s/comm", pid)
+	content, err := os.ReadFile(path)
+	if err != nil {
+		return "", err
+	}
+	// remove trailing \n
+	return strings.TrimSpace(string(content)), nil
+}