54 lines
1.6 KiB
Go
54 lines
1.6 KiB
Go
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//go:build embed || unit
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package web
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import (
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"net/http"
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"path"
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"strings"
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)
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// Vite emits content-hashed filenames under assets/, so the backend can apply
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// immutable caching without relying on a reverse proxy to classify paths.
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const staticAssetsCacheControl = "public, max-age=31536000, immutable"
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// isFingerprintedEmbeddedAssetPath reports whether a cleaned URL path refers to
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// a Vite asset whose filename contains the default eight-character build hash.
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func isFingerprintedEmbeddedAssetPath(cleanPath string) bool {
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cleanPath = strings.TrimPrefix(cleanPath, "/")
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if !strings.HasPrefix(cleanPath, "assets/") {
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return false
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}
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filename := path.Base(cleanPath)
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extension := path.Ext(filename)
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stem := strings.TrimSuffix(filename, extension)
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const fingerprintLength = 8
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delimiterIndex := len(stem) - fingerprintLength - 1
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if extension == "" || delimiterIndex < 1 || stem[delimiterIndex] != '-' {
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return false
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}
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// Vite hashes use URL-safe characters and are stable for immutable caching.
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fingerprint := stem[delimiterIndex+1:]
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for _, char := range fingerprint {
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if (char >= 'a' && char <= 'z') ||
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(char >= 'A' && char <= 'Z') ||
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(char >= '0' && char <= '9') ||
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char == '_' || char == '-' {
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continue
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}
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return false
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}
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return true
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}
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// applyStaticAssetCacheHeaders sets Cache-Control for long-cacheable static paths.
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// index.html / SPA routes must keep no-cache and are not handled here.
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func applyStaticAssetCacheHeaders(header http.Header, cleanPath string) {
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if header == nil || !isFingerprintedEmbeddedAssetPath(cleanPath) {
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return
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}
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header.Set("Cache-Control", staticAssetsCacheControl)
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}
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