Merge pull request #1 from libp2p/feat/init

Library for IP -> ASN mapping

.travis.yml

+os:
+  - linux
+
+language: go
+
+go:
+  - 1.14.x
+  - 1.15.x
+
+env:
+  global:
+    - GOTFLAGS="-race"
+  matrix:
+    - BUILD_DEPTYPE=gomod
+
+
+# disable travis install
+install:
+  - true
+
+script:
+  - bash <(curl -s https://raw.githubusercontent.com/ipfs/ci-helpers/master/travis-ci/run-standard-tests.sh)
+
+
+cache:
+  directories:
+    - $GOPATH/pkg/mod
+    - $HOME/.cache/go-build
+
+notifications:
+  email: false

README.md

+# go-libp2p-asn-util
+===
+
+[![](https://img.shields.io/badge/made%20by-Protocol%20Labs-blue.svg?style=flat-square)](http://protocol.ai)
+[![](https://img.shields.io/badge/project-libp2p-yellow.svg?style=flat-square)](http://github.com/libp2p/libp2p)
+
+A library to lookup the ASN(Autonomous System Number) for an IP address. It uses the IPv6 to ASN database downloaded from https://iptoasn.com/.
+Supports ONLY IPv6 addresses for now.   
+
+## Table of Contents
+
+- [Install](#install)
+- [Usage](#usage)
+- [Documentation](#documentation)
+- [Contribute](#contribute)
+- [License](#license)
+
+## Install
+
+```
+go get github.com/libp2p/go-libp2p-asn-util
+```
+
+## Usage
+
+```go
+import (
+    asn "github.com/libp2p/go-libp2p-asn-util"
+)
+
+func main() {
+   store, err := asn.NewAsnStore()
+   
+   asNumber,err := store.AsnForIP(net.ParseIP("2a03:2880:f003:c07:face:b00c::2"))
+ }
+```
+
+## Contribute
+
+Feel free to join in. All welcome. Open an [issue](https://github.com/libp2p/go-libp2p-asn/issues)!
+
+This repository falls under the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).
+
+## License
+
+MIT
+
+---
\ No newline at end of file

asn.go

+package asnutil
+
+import (
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/libp2p/go-cidranger"
+)
+
+var Store *indirectAsnStore
+
+func init() {
+	Store = newIndirectAsnStore()
+}
+
+type networkWithAsn struct {
+	nn  net.IPNet
+	asn string
+}
+
+func (e *networkWithAsn) Network() net.IPNet {
+	return e.nn
+}
+
+type asnStore struct {
+	cr cidranger.Ranger
+}
+
+// AsnForIPv6 returns the AS number for the given IPv6 address.
+// If no mapping exists for the given IP, this function will
+// return an empty ASN and a nil error.
+func (a *asnStore) AsnForIPv6(ip net.IP) (string, error) {
+	if ip.To16() == nil {
+		return "", errors.New("ONLY IPv6 addresses supported for now")
+	}
+
+	ns, err := a.cr.ContainingNetworks(ip)
+	if err != nil {
+		return "", fmt.Errorf("failed to find matching networks for the given ip: %w", err)
+	}
+
+	if len(ns) == 0 {
+		return "", nil
+	}
+
+	// longest prefix match
+	n := ns[len(ns)-1].(*networkWithAsn)
+	return n.asn, nil
+}
+
+func newAsnStore() (*asnStore, error) {
+	cr := cidranger.NewPCTrieRanger()
+
+	for k, v := range ipv6CidrToAsnMap {
+		_, nn, err := net.ParseCIDR(k)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse CIDR %s: %w", k, err)
+		}
+
+		if err := cr.Insert(&networkWithAsn{*nn, v}); err != nil {
+			return nil, fmt.Errorf("failed to insert CIDR %s in Trie store: %w", k, err)
+		}
+	}
+
+	return &asnStore{cr}, nil
+}
+
+type indirectAsnStore struct {
+	store       *asnStore
+	doneLoading chan struct{}
+}
+
+// AsnForIPv6 returns the AS number for the given IPv6 address.
+// If no mapping exists for the given IP, this function will
+// return an empty ASN and a nil error.
+func (a *indirectAsnStore) AsnForIPv6(ip net.IP) (string, error) {
+	<-a.doneLoading
+	return a.store.AsnForIPv6(ip)
+}
+
+func newIndirectAsnStore() *indirectAsnStore {
+	a := &indirectAsnStore{
+		doneLoading: make(chan struct{}),
+	}
+
+	go func() {
+		defer close(a.doneLoading)
+		store, err := newAsnStore()
+		if err != nil {
+			panic(err)
+		}
+		a.store = store
+	}()
+
+	return a
+}

asn_test.go

+package asnutil
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAsnIpv6(t *testing.T) {
+	tcs := map[string]struct {
+		ip          net.IP
+		expectedASN string
+	}{
+		"google": {
+			ip:          net.ParseIP("2001:4860:4860::8888"),
+			expectedASN: "15169",
+		},
+		"facebook": {
+			ip:          net.ParseIP("2a03:2880:f003:c07:face:b00c::2"),
+			expectedASN: "32934",
+		},
+		"comcast": {
+			ip:          net.ParseIP("2601::"),
+			expectedASN: "7922",
+		},
+		"does not exist": {
+			ip:          net.ParseIP("::"),
+			expectedASN: "",
+		},
+	}
+
+	for name, tc := range tcs {
+		require.NotEmpty(t, tc.ip, name)
+		n, err := Store.AsnForIPv6(tc.ip)
+		require.NoError(t, err)
+		require.Equal(t, tc.expectedASN, n, name)
+	}
+}

generate/main.go

+package main
+
+import (
+	"encoding/csv"
+	"errors"
+	"fmt"
+	"io"
+	"math/bits"
+	"net"
+	"os"
+
+	u "github.com/ipfs/go-ipfs-util"
+)
+
+const (
+	pkgName        = "asnutil"
+	ipv6OutputFile = "ipv6_asn_map.go"
+	ipv6MapName    = "ipv6CidrToAsnMap"
+)
+
+func main() {
+	// file with the ASN mappings for IPv6 CIDRs.
+	// See ipv6_asn.tsv
+	ipv6File := os.Getenv("ASN_IPV6_FILE")
+
+	if len(ipv6File) == 0 {
+		panic(errors.New("environment vars must be provided"))
+	}
+
+	ipv6CidrToAsnMap := readMappingFile(ipv6File)
+	f, err := os.Create(ipv6OutputFile)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+	writeMappingToFile(f, ipv6CidrToAsnMap, ipv6MapName)
+}
+
+func writeMappingToFile(f *os.File, m map[string]string, mapName string) {
+	printf := func(s string, args ...interface{}) {
+		_, err := fmt.Fprintf(f, s, args...)
+		if err != nil {
+			panic(err)
+		}
+	}
+	printf("package %s\n\n", pkgName)
+	printf("// Code generated by generate/main.go DO NOT EDIT\n")
+	printf("var %s = map[string]string {", mapName)
+	for k, v := range m {
+		printf("\n\t \"%s\": \"%s\",", k, v)
+	}
+	printf("\n}")
+}
+
+func readMappingFile(path string) map[string]string {
+	m := make(map[string]string)
+	f, err := os.Open(path)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+	r := csv.NewReader(f)
+	r.Comma = '\t'
+	for {
+		record, err := r.Read()
+		// Stop at EOF.
+		if err == io.EOF {
+			return m
+		}
+
+		startIP := record[0]
+		endIP := record[1]
+		asn := record[2]
+		if asn == "0" {
+			continue
+		}
+
+		s := net.ParseIP(startIP)
+		e := net.ParseIP(endIP)
+		if s.To16() == nil || e.To16() == nil {
+			panic(errors.New("IP should be v6"))
+		}
+
+		prefixLen := zeroPrefixLen(u.XOR(s.To16(), e.To16()))
+		cn := fmt.Sprintf("%s/%d", startIP, prefixLen)
+		m[cn] = asn
+	}
+
+}
+
+func zeroPrefixLen(id []byte) int {
+	for i, b := range id {
+		if b != 0 {
+			return i*8 + bits.LeadingZeros8(uint8(b))
+		}
+	}
+	return len(id) * 8
+}

go.mod

+module github.com/libp2p/go-libp2p-asn-util
+
+go 1.14
+
+require (
+	github.com/ipfs/go-ipfs-util v0.0.2
+	github.com/libp2p/go-cidranger v1.1.0
+	github.com/stretchr/testify v1.4.0
+)

go.sum

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