From 601227a20fd415ecacf39765f19cdf72acc689f4 Mon Sep 17 00:00:00 2001
From: eltrac <hi@eltr.ac>
Date: Thu, 5 Nov 2026 11:20:32 +0800
Subject: asn: move asn/ to pkg/asn/; add lookup.goq

only export Lookup() and IsDatacenter()
---
 pkg/asn/lookup.go  |  18 +++++++++
 pkg/asn/mapping.go | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+)
 create mode 100644 pkg/asn/lookup.go
 create mode 100644 pkg/asn/mapping.go

(limited to 'pkg')

diff --git a/pkg/asn/lookup.go b/pkg/asn/lookup.go
new file mode 100644
index 0000000..4851a6f
--- /dev/null
+++ b/pkg/asn/lookup.go
@@ -0,0 +1,18 @@
+package asn
+
+var AsnTable AsnMap
+
+// Lookup return metadata of given AS
+func Lookup(ASN int) AsnEntry {
+	if len(AsnTable) == 0 {
+		AsnTable = getMapping()
+	}
+
+	return AsnTable[ASN]
+}
+
+// IsDatacenter return bool value whether an AS is datajjij center or not
+func IsDatacenter(ASN int) bool {
+	// TODO
+	return false
+}
diff --git a/pkg/asn/mapping.go b/pkg/asn/mapping.go
new file mode 100644
index 0000000..14272de
--- /dev/null
+++ b/pkg/asn/mapping.go
@@ -0,0 +1,105 @@
+package asn
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+
+	"github.com/adrg/xdg"
+	"github.com/gocarina/gocsv"
+)
+
+const SOURCE string = "https://cdn.jsdelivr.net/gh/ipverse/as-metadata@master/as.csv"
+
+type AsnEntry struct {
+	ASN         int    `csv:"asn"`
+	Handle      string `csv:"handle"`
+	Description string `csv:"description"`
+	CountryCode string `csv:"country-code"`
+}
+
+type AsnMap map[int]AsnEntry
+
+// localPath returns the destination of local copy of asn metadata
+func localPath() string {
+	return filepath.Join(xdg.DataHome, "/audidi/as.csv")
+}
+
+// downloadAsnSource downloads ASN metadata source to disk
+func downloadAsnSource() error {
+	resp, err := http.Get(SOURCE)
+	if err != nil {
+		return fmt.Errorf("error fetching ASN metadata: %s", err)
+	}
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("error fetching ASN metadata: http %d", resp.StatusCode)
+	}
+	defer resp.Body.Close()
+
+	file, err := os.Create(localPath())
+	if err != nil {
+		return fmt.Errorf("can't open file to write ASN metadata: %s", err)
+	}
+
+	if _, err := io.Copy(file, resp.Body); err != nil {
+		return fmt.Errorf("can't copy ASN metadata to file: %s", err)
+	}
+
+	return nil
+}
+
+// useAsnSource returns either a local cached version of
+// ASN source bytes or download from source
+func useAsnSource() ([]byte, error) {
+	path := localPath()
+	os.MkdirAll(filepath.Dir(path), os.ModePerm)
+
+	if info, err := os.Stat(path); os.IsNotExist(err) || info.Size() == 0 {
+		log.Println("downloading ASN metadata...")
+		if err := downloadAsnSource(); err != nil {
+			return nil, err
+		}
+		log.Println("ASN metadata downloaded")
+	}
+
+	bytes, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("can't open file to read ASN metadata: %s", err)
+	}
+
+	return bytes, nil
+}
+
+// parseMetadata parse raw bytes of ASN metadata into readable entries
+func parseMetadata(bytes []byte) ([]AsnEntry, error) {
+	var entries []AsnEntry
+
+	if err := gocsv.UnmarshalBytes(bytes, &entries); err != nil {
+		return nil, fmt.Errorf("can't parse ASN metadata: %s", err)
+	}
+
+	return entries, nil
+}
+
+// GetMapping returns a pointer to ASN-metadata mappings
+func getMapping() AsnMap {
+	bytes, err := useAsnSource()
+	if err != nil {
+		log.Fatalln("Failed to load ASN metadata: ", err)
+	}
+
+	entries, err := parseMetadata(bytes)
+	if err != nil {
+		log.Fatalln("Failed to parse ASN metadata (Delete data and retry): ", err)
+	}
+
+	mapping := make(AsnMap)
+	for _, entry := range entries {
+		mapping[entry.ASN] = entry
+	}
+
+	return mapping
+}
-- 
cgit v1.2.3