72 lines
2.4 KiB
Go
72 lines
2.4 KiB
Go
package header
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import (
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"net/http"
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"strings"
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)
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// Cross-Origin Resource Sharing (CORS) headers.
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const (
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AccessControlAllowOrigin = "Access-Control-Allow-Origin" // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin
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AccessControlAllowHeaders = "Access-Control-Allow-Headers" // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Headers
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AccessControlAllowMethods = "Access-Control-Allow-Methods" // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Methods
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AccessControlMaxAge = "Access-Control-Max-Age" // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Access-Control-Max-Age
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)
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// CORS header defaults.
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var (
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DefaultAccessControlAllowOrigin = ""
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CorsHeaders = []string{Accept, AcceptRanges, ContentDisposition, ContentEncoding, ContentRange, Location}
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DefaultAccessControlAllowHeaders = strings.Join(CorsHeaders, ", ")
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CorsMethods = []string{http.MethodGet, http.MethodHead, http.MethodOptions}
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DefaultAccessControlAllowMethods = strings.Join(CorsMethods, ", ")
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DefaultAccessControlMaxAge = "3600"
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)
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// CorsExt contains all static asset extensions for which a CORS header may be added automatically.
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var CorsExt = map[string]bool{
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".ttf": true,
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".ttc": true,
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".otf": true,
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".eot": true,
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".woff": true,
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".woff2": true,
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".css": true,
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".js": true, // Required for the MapLibre GL RTL text plugin.
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".json": true, // Required for static frontend configuration files.
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".svg": true, // Required for SVG icons that depend on additional styles or fonts.
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}
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// AllowCORS checks if CORS headers can be safely used based on a request's file path.
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// See: https://www.w3.org/TR/css-fonts-3/#font-fetching-requirements
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func AllowCORS(path string) bool {
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// Return false if path is empty.
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if path == "" {
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return false
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}
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// Extract extension from path.
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var ext string
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l := len(path) - 1
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for i := l; i >= 0 && path[i] != '/'; i-- {
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if path[i] == '.' {
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ext = path[i:]
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if l-len(ext) < 0 {
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// Return false if there is no filename.
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return false
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} else if r := path[i-1]; (r < '0' || r > '9') && (r < 'A' || r > 'Z') && (r < 'a' || r > 'z') {
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// Return false if the filename is invalid.
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return false
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}
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break
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}
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}
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// Return false if path does not include an extension.
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if ext == "" {
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return false
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}
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// Check list of allowed extensions.
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return CorsExt[ext]
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}
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