MichilisandClaude Opus 4.6
617c884012
<img> tags cannot send Authorization headers, so non-public gallery photos were invisible even to authorized viewers. The server now mints short-lived HMAC view tokens (gallery-scoped, hour-bucketed) and embeds them in every file URL for non-public galleries. Access denials return distinct 403 messages per visibility mode, and the frontend renders a matching gate page (private, link-only, ticket-holders, login prompt) with an inline login modal so visitors never leave the gallery page. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
50 lines
1.7 KiB
Go
50 lines
1.7 KiB
Go
package httpapi
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// View tokens solve a browser reality: the gallery JSON is fetched with an
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// Authorization header, but <img> tags cannot send headers, so image
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// requests for non-public galleries would arrive anonymous and be denied.
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// After a viewer passes the gallery access check, the server mints a
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// short-lived HMAC token scoped to that one gallery and appends it to the
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// file URLs it returns — the same idea as an S3 presigned URL. Possession
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// grants view access to that gallery only, until expiry.
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import (
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"crypto/hmac"
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"crypto/sha256"
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"encoding/base64"
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"fmt"
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"strconv"
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"strings"
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"time"
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)
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// Expiries are aligned to hour buckets so repeated requests within the
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// same hour mint the *same* token — image URLs stay stable and the
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// browser cache keeps working across refetches/polls. A token minted at
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// time t expires between 1h and 2h later.
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const viewTokenBucket = int64(3600)
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func mintViewToken(secret []byte, galleryID string) string {
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exp := (time.Now().Unix()/viewTokenBucket + 2) * viewTokenBucket
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return fmt.Sprintf("v1.%d.%s", exp, viewTokenSig(secret, galleryID, exp))
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}
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func verifyViewToken(secret []byte, galleryID, token string) bool {
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parts := strings.Split(token, ".")
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if len(parts) != 3 || parts[0] != "v1" {
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return false
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}
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exp, err := strconv.ParseInt(parts[1], 10, 64)
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if err != nil || time.Now().Unix() > exp {
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return false
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}
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expected := viewTokenSig(secret, galleryID, exp)
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return hmac.Equal([]byte(expected), []byte(parts[2]))
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}
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func viewTokenSig(secret []byte, galleryID string, exp int64) string {
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mac := hmac.New(sha256.New, secret)
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fmt.Fprintf(mac, "photos-view:%s:%d", galleryID, exp)
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return base64.RawURLEncoding.EncodeToString(mac.Sum(nil))
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}
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