github.com/vishvananda/netlink v1.1.0: AddrList, LinkByName, LinkList

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify pkg:golang/github.com/vishvananda/netlink@v1.1.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/github.com/vishvananda/netlink@v1.1.0
Demonstrate these symbols/APIs:
  - netlink.AddrList
  - netlink.LinkByName
  - netlink.LinkList
  - netlink.ParseAddr

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:05d67f3b81262927a637bdc445e057277b616c053e1f21ff4673b3d5bce25581","contract":["netlink.LinkByName(\"lo\") returns loopback Link with Name=\"lo\"","netlink.LinkByName returns non-nil error when link does not exist","netlink.ParseAddr parses IPv4 CIDR string into Addr with correct IP and mask size","netlink.ParseAddr parses IPv6 CIDR string into Addr with correct IP and mask size","netlink.ParseAddr returns non-nil error for invalid CIDR string","netlink.AddrList on loopback Link returns IPv4 address 127.0.0.1","netlink.AddrList with FAMILY_ALL returns all configured loopback addresses","netlink.LinkList returns non-empty slice of network Links including loopback"],"goal":"verify pkg:golang/github.com/vishvananda/netlink@v1.1.0","kind":"HOW","packages":["pkg:golang/github.com/vishvananda/netlink@v1.1.0"],"schemaVersion":1,"symbols":["netlink.AddrList","netlink.LinkByName","netlink.LinkList","netlink.ParseAddr"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/github.com/vishvananda/netlink@v1.1.0"],"schemaVersion":1,"subject":"pkg:golang/github.com/vishvananda/netlink@v1.1.0","symbols":["netlink.AddrList","netlink.LinkByName","netlink.LinkList","netlink.ParseAddr"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require github.com/vishvananda/netlink v1.1.0

require (
	github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df // indirect
	golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444 // indirect
)

github.com/vishvananda/netlink v1.1.0 h1:1iyaYNBLmP6L0220aDnYQpo1QEV4t4hJ+xEEhhJH8j0=
github.com/vishvananda/netlink v1.1.0/go.mod h1:cTgwzPIzzgDAYoQrMm0EdrjRUBkTqKYppBueQtXaqoE=
github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df h1:OviZH7qLw/7ZovXvuNyL3XQl8UFofeikI1NW1Gypu7k=
github.com/vishvananda/netns v0.0.0-20191106174202-0a2b9b5464df/go.mod h1:JP3t17pCcGlemwknint6hfoeCVQrEMVwxRLRjXpq+BU=
golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444 h1:/d2cWp6PSamH4jDPFLyO150psQdqvtoNX8Zjg3AQ31g=
golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

{
  "schemaVersion": 1,
  "goal": "verify pkg:golang/github.com/vishvananda/netlink@v1.1.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/github.com/vishvananda/netlink@v1.1.0"
  ],
  "symbols": [
    "netlink.AddrList",
    "netlink.LinkByName",
    "netlink.LinkList",
    "netlink.ParseAddr"
  ]
}

package test

import (
	"net"
	"testing"

	"github.com/vishvananda/netlink"
)

func TestNetlinkContract(t *testing.T) {
	// 1. netlink.LinkByName - retrieve loopback interface
	lo, err := netlink.LinkByName("lo")
	if err != nil {
		t.Fatalf("netlink.LinkByName('lo') failed: %v", err)
	}
	attrs := lo.Attrs()
	if attrs.Name != "lo" {
		t.Fatalf("expected link name 'lo', got '%s'", attrs.Name)
	}

	// Verify netlink.LinkByName returns error for non-existent link
	_, err = netlink.LinkByName("nonexistent_dev_99")
	if err == nil {
		t.Fatalf("expected error for non-existent link, got nil")
	}

	// 2. netlink.ParseAddr - valid IPv4 CIDR
	addrV4, err := netlink.ParseAddr("192.168.10.1/24")
	if err != nil {
		t.Fatalf("netlink.ParseAddr('192.168.10.1/24') failed: %v", err)
	}
	if addrV4.IP.String() != "192.168.10.1" {
		t.Errorf("expected IP 192.168.10.1, got %s", addrV4.IP.String())
	}
	ones, bits := addrV4.Mask.Size()
	if ones != 24 || bits != 32 {
		t.Errorf("expected /24 mask (ones=24, bits=32), got ones=%d, bits=%d", ones, bits)
	}

	// netlink.ParseAddr - valid IPv6 CIDR
	addrV6, err := netlink.ParseAddr("2001:db8::1/64")
	if err != nil {
		t.Fatalf("netlink.ParseAddr('2001:db8::1/64') failed: %v", err)
	}
	if addrV6.IP.String() != "2001:db8::1" {
		t.Errorf("expected IP 2001:db8::1, got %s", addrV6.IP.String())
	}
	ones6, bits6 := addrV6.Mask.Size()
	if ones6 != 64 || bits6 != 128 {
		t.Errorf("expected /64 mask (ones=64, bits=128), got ones=%d, bits=%d", ones6, bits6)
	}

	// netlink.ParseAddr - invalid CIDR returns error
	_, err = netlink.ParseAddr("invalid-cidr-string")
	if err == nil {
		t.Fatalf("expected error parsing invalid cidr string, got nil")
	}

	// 3. netlink.AddrList - list addresses on loopback interface
	v4Addrs, err := netlink.AddrList(lo, netlink.FAMILY_V4)
	if err != nil {
		t.Fatalf("netlink.AddrList(lo, FAMILY_V4) failed: %v", err)
	}
	foundLoopbackIPv4 := false
	for _, a := range v4Addrs {
		if a.IP.Equal(net.IPv4(127, 0, 0, 1)) {
			foundLoopbackIPv4 = true
			break
		}
	}
	if !foundLoopbackIPv4 {
		t.Errorf("expected 127.0.0.1 address in AddrList(lo, FAMILY_V4), got %v", v4Addrs)
	}

	allAddrs, err := netlink.AddrList(lo, netlink.FAMILY_ALL)
	if err != nil {
		t.Fatalf("netlink.AddrList(lo, FAMILY_ALL) failed: %v", err)
	}
	if len(allAddrs) == 0 {
		t.Errorf("expected at least 1 address in AddrList(lo, FAMILY_ALL), got 0")
	}

	// 4. netlink.LinkList - list all network links
	links, err := netlink.LinkList()
	if err != nil {
		t.Fatalf("netlink.LinkList() failed: %v", err)
	}
	if len(links) == 0 {
		t.Fatalf("expected at least 1 network link, got 0")
	}
	foundLoInList := false
	for _, l := range links {
		if l.Attrs().Name == "lo" {
			foundLoInList = true
			break
		}
	}
	if !foundLoInList {
		t.Errorf("expected loopback link in LinkList(), got %v", links)
	}
}