nel.pet
1package markup
2
3import (
4 "crypto/hmac"
5 "crypto/sha256"
6 "encoding/hex"
7 "fmt"
8
9 "github.com/yuin/goldmark/ast"
10)
11
12func GenerateCamoURL(baseURL, secret, imageURL string) string {
13 h := hmac.New(sha256.New, []byte(secret))
14 h.Write([]byte(imageURL))
15 signature := hex.EncodeToString(h.Sum(nil))
16 hexURL := hex.EncodeToString([]byte(imageURL))
17 return fmt.Sprintf("%s/%s/%s", baseURL, signature, hexURL)
18}
19
20func (rctx *RenderContext) camoImageLinkTransformer(dst string) string {
21 // don't camo on dev
22 if rctx.IsDev {
23 return dst
24 }
25
26 if rctx.CamoUrl != "" && rctx.CamoSecret != "" {
27 return GenerateCamoURL(rctx.CamoUrl, rctx.CamoSecret, dst)
28 }
29
30 return dst
31}
32
33func (rctx *RenderContext) camoImageLinkAstTransformer(img *ast.Image) {
34 dst := string(img.Destination)
35 img.Destination = []byte(rctx.camoImageLinkTransformer(dst))
36}