feat!: proxy images with JWT auth

src/utils/images.go

@@ -0,0 +1,52 @@
+package utils
+
+import (
+	"anonymousoverflow/src/types"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/golang-jwt/jwt/v4"
+)
+
+var imgTagRegex = regexp.MustCompile(`<img[^>]*\s+src\s*=\s*"(.*?)"[^>]*>`)
+
+func ReplaceImgTags(inHtml string) string {
+	// find all img tags
+	imgTags := imgTagRegex.FindAllString(inHtml, -1)
+
+	for _, imgTag := range imgTags {
+		// parse the src="" attribute
+		srcRegex := regexp.MustCompile(`src\s*=\s*"(.*?)"`)
+		src := srcRegex.FindStringSubmatch(imgTag)[1]
+
+		authToken, _ := generateImageProxyAuth(src)
+
+		// replace the img tag with a proxied url
+		inHtml = strings.Replace(inHtml, imgTag, fmt.Sprintf(`<img src="%s/proxy?url=%s&auth=%s">`, os.Getenv("APP_URL"), src, authToken), 1)
+	}
+
+	return inHtml
+}
+
+func generateImageProxyAuth(url string) (string, error) {
+	// generate a jwt with types.ImageProxyClaims
+	claims := types.ImageProxyClaims{
+		Action:   "imageProxy",
+		ImageURL: url,
+		Iss:      time.Now().Unix(),
+		Exp:      time.Now().Add(time.Minute).Unix(),
+	}
+
+	token := jwt.NewWithClaims(jwt.SigningMethodHS512, claims)
+
+	// sign the token
+	ss, err := token.SignedString([]byte(os.Getenv("JWT_SIGNING_SECRET")))
+	if err != nil {
+		return "", err
+	}
+
+	return ss, nil
+}