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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
}
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