Add asinfo package for AS number information lookups

- Created pkg/asinfo with embedded AS data from ipverse/asn-info
- Provides fast lookups by ASN with GetDescription() and GetHandle()
- Includes Search() functionality for finding AS by name/handle
- Added asinfo-gen tool to fetch and convert CSV data to JSON
- Added 'make asupdate' target to refresh AS data
- Embedded JSON data contains 130k+ AS entries
- Added comprehensive tests and examples

pkg/asinfo/asinfo.go

@@ -0,0 +1,139 @@
+// Package asinfo provides information about Autonomous Systems (AS)
+package asinfo
+
+import (
+	_ "embed"
+	"encoding/json"
+	"sync"
+)
+
+//go:embed asdata.json
+var asDataJSON []byte
+
+// Info represents information about an Autonomous System
+type Info struct {
+	ASN         int    `json:"asn"`
+	Handle      string `json:"handle"`
+	Description string `json:"description"`
+}
+
+// Registry provides access to AS information
+type Registry struct {
+	mu    sync.RWMutex
+	byASN map[int]*Info
+}
+
+var (
+	defaultRegistry *Registry
+	once            sync.Once
+)
+
+// initRegistry initializes the default registry with embedded data
+func initRegistry() {
+	defaultRegistry = &Registry{
+		byASN: make(map[int]*Info),
+	}
+	
+	var asInfos []Info
+	if err := json.Unmarshal(asDataJSON, &asInfos); err != nil {
+		panic("failed to unmarshal embedded AS data: " + err.Error())
+	}
+	
+	for i := range asInfos {
+		info := &asInfos[i]
+		defaultRegistry.byASN[info.ASN] = info
+	}
+}
+
+// Get returns AS information for the given ASN
+func Get(asn int) (*Info, bool) {
+	once.Do(initRegistry)
+	
+	defaultRegistry.mu.RLock()
+	defer defaultRegistry.mu.RUnlock()
+	
+	info, ok := defaultRegistry.byASN[asn]
+	if !ok {
+		return nil, false
+	}
+	
+	// Return a copy to prevent mutation
+	copy := *info
+	return &copy, true
+}
+
+// GetDescription returns just the description for an ASN
+func GetDescription(asn int) string {
+	info, ok := Get(asn)
+	if !ok {
+		return ""
+	}
+	return info.Description
+}
+
+// GetHandle returns just the handle for an ASN
+func GetHandle(asn int) string {
+	info, ok := Get(asn)
+	if !ok {
+		return ""
+	}
+	return info.Handle
+}
+
+// Total returns the total number of AS entries in the registry
+func Total() int {
+	once.Do(initRegistry)
+	
+	defaultRegistry.mu.RLock()
+	defer defaultRegistry.mu.RUnlock()
+	
+	return len(defaultRegistry.byASN)
+}
+
+// All returns all AS information as a slice
+// Note: This creates a copy of all data, use sparingly
+func All() []Info {
+	once.Do(initRegistry)
+	
+	defaultRegistry.mu.RLock()
+	defer defaultRegistry.mu.RUnlock()
+	
+	result := make([]Info, 0, len(defaultRegistry.byASN))
+	for _, info := range defaultRegistry.byASN {
+		result = append(result, *info)
+	}
+	
+	return result
+}
+
+// Search searches for AS entries where the handle or description contains the query
+// This is a simple case-sensitive substring search
+func Search(query string) []Info {
+	once.Do(initRegistry)
+	
+	defaultRegistry.mu.RLock()
+	defer defaultRegistry.mu.RUnlock()
+	
+	var results []Info
+	for _, info := range defaultRegistry.byASN {
+		if contains(info.Handle, query) || contains(info.Description, query) {
+			results = append(results, *info)
+		}
+	}
+	
+	return results
+}
+
+// contains is a simple substring search
+func contains(s, substr string) bool {
+	return len(substr) > 0 && len(s) >= len(substr) && containsImpl(s, substr)
+}
+
+func containsImpl(s, substr string) bool {
+	for i := 0; i <= len(s)-len(substr); i++ {
+		if s[i:i+len(substr)] == substr {
+			return true
+		}
+	}
+	return false
+}

pkg/asinfo/asinfo_test.go

@@ -0,0 +1,189 @@
+package asinfo
+
+import (
+	"testing"
+)
+
+func TestGet(t *testing.T) {
+	tests := []struct {
+		name     string
+		asn      int
+		wantOK   bool
+		wantDesc string
+	}{
+		{
+			name:     "AS1 Level 3",
+			asn:      1,
+			wantOK:   true,
+			wantDesc: "Level 3 Parent, LLC",
+		},
+		{
+			name:     "AS15169 Google",
+			asn:      15169,
+			wantOK:   true,
+			wantDesc: "Google LLC",
+		},
+		{
+			name:   "Non-existent AS",
+			asn:    999999999,
+			wantOK: false,
+		},
+		{
+			name:     "AS0 IANA Reserved",
+			asn:      0,
+			wantOK:   true,
+			wantDesc: "Internet Assigned Numbers Authority",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			info, ok := Get(tt.asn)
+			if ok != tt.wantOK {
+				t.Errorf("Get(%d) ok = %v, want %v", tt.asn, ok, tt.wantOK)
+				return
+			}
+			
+			if ok && info.Description != tt.wantDesc {
+				t.Errorf("Get(%d) description = %q, want %q", tt.asn, info.Description, tt.wantDesc)
+			}
+		})
+	}
+}
+
+func TestGetDescription(t *testing.T) {
+	tests := []struct {
+		asn  int
+		want string
+	}{
+		{1, "Level 3 Parent, LLC"},
+		{999999999, ""},
+	}
+
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			if got := GetDescription(tt.asn); got != tt.want {
+				t.Errorf("GetDescription(%d) = %q, want %q", tt.asn, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestGetHandle(t *testing.T) {
+	tests := []struct {
+		asn  int
+		want string
+	}{
+		{1, "LVLT"},
+		{0, "IANA-RSVD"},
+		{999999999, ""},
+	}
+
+	for _, tt := range tests {
+		t.Run("", func(t *testing.T) {
+			if got := GetHandle(tt.asn); got != tt.want {
+				t.Errorf("GetHandle(%d) = %q, want %q", tt.asn, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestTotal(t *testing.T) {
+	total := Total()
+	if total < 100000 {
+		t.Errorf("Total() = %d, expected > 100000", total)
+	}
+	
+	// Verify it's consistent
+	if total2 := Total(); total2 != total {
+		t.Errorf("Total() returned different values: %d vs %d", total, total2)
+	}
+}
+
+func TestSearch(t *testing.T) {
+	tests := []struct {
+		name    string
+		query   string
+		wantMin int
+	}{
+		{
+			name:    "Search for Google",
+			query:   "Google",
+			wantMin: 1,
+		},
+		{
+			name:    "Search for University",
+			query:   "University",
+			wantMin: 10,
+		},
+		{
+			name:    "Empty search",
+			query:   "",
+			wantMin: 0,
+		},
+		{
+			name:    "Non-existent org",
+			query:   "XYZABC123456",
+			wantMin: 0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			results := Search(tt.query)
+			if len(results) < tt.wantMin {
+				t.Errorf("Search(%q) returned %d results, want at least %d", tt.query, len(results), tt.wantMin)
+			}
+			
+			// Verify all results contain the query
+			if tt.query != "" {
+				for _, r := range results {
+					if !contains(r.Handle, tt.query) && !contains(r.Description, tt.query) {
+						t.Errorf("Search result ASN %d doesn't contain query %q", r.ASN, tt.query)
+					}
+				}
+			}
+		})
+	}
+}
+
+func TestDataIntegrity(t *testing.T) {
+	// Verify no duplicate ASNs
+	all := All()
+	seen := make(map[int]bool)
+	for _, info := range all {
+		if seen[info.ASN] {
+			t.Errorf("Duplicate ASN found: %d", info.ASN)
+		}
+		seen[info.ASN] = true
+	}
+	
+	// Verify all entries have required fields
+	for _, info := range all {
+		if info.Handle == "" && info.ASN != 0 {
+			t.Errorf("ASN %d has empty handle", info.ASN)
+		}
+		if info.Description == "" {
+			t.Errorf("ASN %d has empty description", info.ASN)
+		}
+	}
+}
+
+func BenchmarkGet(b *testing.B) {
+	// Common ASNs to lookup
+	asns := []int{1, 15169, 13335, 32934, 8075, 16509}
+	
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		Get(asns[i%len(asns)])
+	}
+}
+
+func BenchmarkSearch(b *testing.B) {
+	queries := []string{"Google", "Amazon", "Microsoft", "University"}
+	
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		Search(queries[i%len(queries)])
+	}
+}

pkg/asinfo/doc.go

@@ -0,0 +1,28 @@
+/*
+Package asinfo provides information about Autonomous Systems (AS).
+
+The package embeds a comprehensive database of AS numbers, handles, and descriptions
+sourced from https://github.com/ipverse/asn-info. The data is embedded at compile
+time and provides fast, offline lookups.
+
+Basic usage:
+
+	// Get information about an AS
+	info, ok := asinfo.Get(15169)
+	if ok {
+		fmt.Printf("AS%d: %s - %s\n", info.ASN, info.Handle, info.Description)
+	}
+
+	// Get just the description
+	desc := asinfo.GetDescription(15169) // "Google LLC"
+
+	// Search for AS entries
+	results := asinfo.Search("University")
+	for _, as := range results {
+		fmt.Printf("AS%d: %s\n", as.ASN, as.Description)
+	}
+
+The data is loaded lazily on first access and cached in memory for the lifetime
+of the program. All getter methods are safe for concurrent use.
+*/
+package asinfo

pkg/asinfo/example_test.go

@@ -0,0 +1,29 @@
+package asinfo_test
+
+import (
+	"fmt"
+
+	"git.eeqj.de/sneak/routewatch/pkg/asinfo"
+)
+
+func ExampleGet() {
+	info, ok := asinfo.Get(15169)
+	if ok {
+		fmt.Printf("AS%d: %s - %s\n", info.ASN, info.Handle, info.Description)
+	}
+	// Output: AS15169: GOOGLE - Google LLC
+}
+
+func ExampleGetDescription() {
+	desc := asinfo.GetDescription(13335)
+	fmt.Println(desc)
+	// Output: Cloudflare, Inc.
+}
+
+func ExampleSearch() {
+	results := asinfo.Search("MIT-GATEWAY")
+	for _, info := range results {
+		fmt.Printf("AS%d: %s - %s\n", info.ASN, info.Handle, info.Description)
+	}
+	// Output: AS3: MIT-GATEWAYS - Massachusetts Institute of Technology
+}