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preserve/cache.go

53 lines
1.1 KiB
Go

package main
import (
"context"
"crypto/sha256"
"fmt"
"net/http"
"path"
"time"
"github.com/pkg/errors"
)
func renewCache(ctx context.Context, url string) (*meta, error) {
cachePath := urlToCachePath(url)
req, err := http.NewRequest(http.MethodGet, url, nil)
if err != nil {
return nil, errors.Wrap(err, "Unable to create request")
}
if cfg.UserAgent != "" {
req.Header.Set("User-Agent", cfg.UserAgent)
}
resp, err := http.DefaultClient.Do(req)
if err != nil {
return nil, errors.Wrap(err, "Unable to fetch source file")
}
defer resp.Body.Close()
if resp.StatusCode > 299 {
return nil, errors.Errorf("HTTP status signaled failure: %d", resp.StatusCode)
}
lm := time.Now()
if t, err := time.Parse(http.TimeFormat, resp.Header.Get("Last-Modified")); err == nil {
lm = t
}
metadata := &meta{
ContentType: resp.Header.Get("Content-Type"),
LastCached: time.Now(),
LastModified: lm,
}
return metadata, store.StoreFile(ctx, cachePath, metadata, resp.Body)
}
func urlToCachePath(url string) string {
h := fmt.Sprintf("%x", sha256.Sum256([]byte(url)))
return path.Join(h[0:2], h)
}