Make the home page's AS name search work (closes #151)

The AS Name Search card on the home page said the search was coming
soon. It now asks the new GET /api/v1/search/as?q=<text>, which
searches the AS list built into asinfo, and lists the matches as links
to their AS pages. An empty q answers 400. asinfo.Search now ignores
case and returns its matches in AS number order.

A match can be an AS that the database does not hold yet. Its AS page
and /api/v1/as/{asn} now answer with its handle and description from
asinfo and no prefixes, instead of 404. Empty prefix lists in that JSON
answer are [] rather than null.

Model: opus-5-5

pkg/asinfo/asinfo.go

@@ -2,10 +2,13 @@ package asinfo
 
 import (
 	"bytes"
+	"cmp"
 	"compress/gzip"
 	_ "embed"
 	"encoding/json"
 	"io"
+	"slices"
+	"strings"
 	"sync"
 )
 
@@ -129,36 +132,32 @@ func All() []Info {
 	return result
 }
 
-// Search searches for AS entries where the handle or description contains the query
-// This is a simple case-sensitive substring search
+// Search returns the AS entries whose handle or description contains query,
+// ignoring case, in AS number order. An empty query matches nothing.
 func Search(query string) []Info {
 	once.Do(initRegistry)
 
+	if query == "" {
+		return nil
+	}
+
+	query = strings.ToLower(query)
+
 	defaultRegistry.mu.RLock()
 	defer defaultRegistry.mu.RUnlock()
 
 	var results []Info
 
 	for _, info := range defaultRegistry.byASN {
-		if contains(info.Handle, query) || contains(info.Description, query) {
+		if strings.Contains(strings.ToLower(info.Handle), query) ||
+			strings.Contains(strings.ToLower(info.Description), query) {
 			results = append(results, *info)
 		}
 	}
 
+	slices.SortFunc(results, func(a, b Info) int {
+		return cmp.Compare(a.ASN, b.ASN)
+	})
+
 	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

@@ -1,6 +1,7 @@
 package asinfo_test
 
 import (
+	"slices"
 	"strings"
 	"testing"
 
@@ -140,11 +141,6 @@ func TestSearch(t *testing.T) {
 			query:   "University",
 			wantMin: 10,
 		},
-		{
-			name:    "Empty search",
-			query:   "",
-			wantMin: 0,
-		},
 		{
 			name:    "Non-existent org",
 			query:   "XYZABC123456",
@@ -162,20 +158,65 @@ func TestSearch(t *testing.T) {
 					tt.query, len(results), tt.wantMin)
 			}
 
-			// Verify all results contain the query
-			if tt.query != "" {
-				for _, r := range results {
-					if !strings.Contains(r.Handle, tt.query) &&
-						!strings.Contains(r.Description, tt.query) {
-						t.Errorf("Search result ASN %d doesn't contain query %q",
-							r.ASN, tt.query)
-					}
+			// Verify all results contain the query, ignoring case
+			query := strings.ToLower(tt.query)
+			for _, r := range results {
+				if !strings.Contains(strings.ToLower(r.Handle), query) &&
+					!strings.Contains(strings.ToLower(r.Description), query) {
+					t.Errorf("Search result ASN %d doesn't contain query %q",
+						r.ASN, tt.query)
 				}
 			}
 		})
 	}
 }
 
+// TestSearchEmptyQueryMatchesNothing expects an empty query to match no AS,
+// although every handle contains the empty string.
+func TestSearchEmptyQueryMatchesNothing(t *testing.T) {
+	t.Parallel()
+
+	results := asinfo.Search("")
+	if len(results) != 0 {
+		t.Errorf(`Search("") returned %d results, want none`, len(results))
+	}
+}
+
+// TestSearchIgnoresCase searches for Cloudflare's handle in lower case and its
+// description in upper case, and expects both searches to find AS13335.
+func TestSearchIgnoresCase(t *testing.T) {
+	t.Parallel()
+
+	const cloudflareASN = 13335 // handle CLOUDFLARENET, "Cloudflare, Inc."
+
+	isCloudflare := func(info asinfo.Info) bool {
+		return info.ASN == cloudflareASN
+	}
+
+	for _, query := range []string{"cloudflarenet", "CLOUDFLARE, INC."} {
+		if !slices.ContainsFunc(asinfo.Search(query), isCloudflare) {
+			t.Errorf("Search(%q) did not find AS%d", query, cloudflareASN)
+		}
+	}
+}
+
+// TestSearchOrdersByASN expects the matches of a search with many of them to
+// come in AS number order.
+func TestSearchOrdersByASN(t *testing.T) {
+	t.Parallel()
+
+	const query = "University"
+
+	results := asinfo.Search(query)
+
+	for i := 1; i < len(results); i++ {
+		if results[i-1].ASN >= results[i].ASN {
+			t.Fatalf("Search(%q): AS%d comes after AS%d",
+				query, results[i].ASN, results[i-1].ASN)
+		}
+	}
+}
+
 func TestDataIntegrity(t *testing.T) {
 	t.Parallel()
 

pkg/asinfo/doc.go

@@ -16,8 +16,9 @@ Basic usage:
 	// Get just the description
 	desc := asinfo.GetDescription(15169) // "Google LLC"
 
-	// Search for AS entries
-	results := asinfo.Search("University")
+	// Search the handles and descriptions, ignoring case; the matches come
+	// in AS number order
+	results := asinfo.Search("university")
 	for _, as := range results {
 		fmt.Printf("AS%d: %s\n", as.ASN, as.Description)
 	}

pkg/asinfo/example_test.go

@@ -21,7 +21,7 @@ func ExampleGetDescription() {
 }
 
 func ExampleSearch() {
-	results := asinfo.Search("MIT-GATEWAY")
+	results := asinfo.Search("mit-gateway")
 	for _, info := range results {
 		fmt.Printf("AS%d: %s - %s\n", info.ASN, info.Handle, info.Description)
 	}