XTLS/Xray-core · error

failed to determine if address is local:

Error message

failed to determine if address is local: 

What it means

The Linux FindProcess first checks whether srcIP belongs to a local interface via IsLocal; that check enumerates network interfaces and failed. The wrapped error after the colon is from net.Interfaces() (e.g. error reading /sys/class/net or netlink). Without knowing the address is local, the /proc-based lookup cannot proceed.

Source

Thrown at common/net/find_process_linux.go:20

package net

import (
	"bufio"
	"encoding/hex"
	"fmt"
	"net"
	"os"
	"strconv"
	"strings"

	"github.com/xtls/xray-core/common/errors"
)

func FindProcess(network, srcIP string, srcPort uint16, destIP string, destPort uint16) (PID int, Name string, AbsolutePath string, err error) {
	isLocal, err := IsLocal(net.ParseIP(srcIP))
	if err != nil {
		return 0, "", "", errors.New("failed to determine if address is local: ", err)
	}
	if !isLocal {
		return 0, "", "", ErrNotLocal
	}
	if network != "tcp" && network != "udp" {
		panic("Unsupported network type for process lookup.")
	}

	var procFile string

	switch network {
	case "tcp":
		if net.ParseIP(srcIP).To4() != nil {
			procFile = "/proc/net/tcp"
		} else {
			procFile = "/proc/net/tcp6"
		}
	case "udp":

View on GitHub (pinned to 7d214f8b09)

Solutions

1. Validate srcIP parses (net.ParseIP(srcIP) != nil) before calling FindProcess
2. In containers, ensure /sys/class/net and /proc are properly mounted (not masked)
3. Check the wrapped error: if it mentions a specific interface, that interface is in a bad state (dangling link)
4. Fall back to non-process routing when the check fails

Example fix

// before
pid, name, path, err := net.FindProcess(network, srcIP, srcPort, dstIP, dstPort)

// after
if ip := net.ParseIP(srcIP); ip == nil {
    return fmt.Errorf("invalid srcIP %q", srcIP)
}
pid, name, path, err := net.FindProcess(network, srcIP, srcPort, dstIP, dstPort)

if ip := net.ParseIP(srcIP); ip == nil {
    return fmt.Errorf("invalid srcIP %q", srcIP) // IsLocal receives nil otherwise
}
if _, err := net.Interfaces(); err != nil {
    // interface enumeration broken; lookup will fail
}

if _, _, _, err := net.FindProcess(netw, srcIP, srcPort, dstIP, dstPort); err != nil {
    if strings.Contains(err.Error(), "failed to determine if address is local") {
        // environment problem (interfaces unreadable), not a routing miss
    }
}

When it happens

Trigger: Calling FindProcess on Linux when interface enumeration fails: /sys/class/net unreadable inside a broken container, netlink socket failure in a restricted namespace, or srcIP being nil because net.ParseIP(srcIP) was given a malformed string.

Common situations: Containers with read-only or masked /proc//sys, network namespaces created without interfaces, or callers passing unparsable srcIP so ParseIP returns nil and IsLocal errors on nil input.

Related errors

• could not search in
• failed to format address:
• connection for :: not found in
• could not find PID for inode :
• no process found for inode

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/2a000b667c5a0874. Report an issue: GitHub.