package header import ( "strconv" "github.com/gin-gonic/gin" ) const ( // The CacheControl request and response header field contains directives (instructions) // that control caching in browsers and shared caches (e.g. proxies, CDNs). // See: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control CacheControl = "Cache-Control" // CacheControlDefault indicates that the response remains valid for 604800 seconds (7 days) after it // has been generated. Note that max-age is not the time that has elapsed since the response was received, // but the time that has elapsed since the response was created on the origin server. CacheControlDefault = "max-age=604800" // CacheControlNoStore indicates that caches of any kind (private or shared) should not store the response. CacheControlNoStore = "no-store" // CacheControlNoCache indicates that the response can be stored in caches, but must be validated with // the origin server before each reuse, even when the cache is not connected to the origin server. CacheControlNoCache = "no-cache" // CacheControlPublic indicates that the response can be stored in a shared cache. // Responses to requests with Authorization header fields must not be stored in a shared cache; // however, the public directive causes such responses to be stored in a shared cache. CacheControlPublic = "public" // CacheControlPrivate indicates that the response can only be stored in a private cache (e.g. browsers). // You should add the private directive for personalized content, especially for responses sent after login. CacheControlPrivate = "private" // CacheControlImmutable indicates that the response will not be updated while it's fresh. CacheControlImmutable = "immutable" ) // CacheControl defaults. var ( CacheControlPublicDefault = CacheControlPublic + ", " + CacheControlDefault // public, max-age=604800 CacheControlPrivateDefault = CacheControlPrivate + ", " + CacheControlDefault // private, max-age=604800 ) // CacheControlMaxAge returns a CacheControl header value based on the specified // maxAge time in seconds or the defaults if maxAge is not a positive number. func CacheControlMaxAge(maxAge int, public bool) string { if maxAge < 0 { return CacheControlNoCache } else if maxAge > 31536000 { maxAge = 31536000 } switch { case maxAge > 0 && public: return "public, max-age=" + strconv.Itoa(maxAge) case maxAge > 0: return "private, max-age=" + strconv.Itoa(maxAge) case public: return CacheControlPublicDefault default: return CacheControlPrivateDefault } } // SetCacheControl adds a CacheControl header to the response based on the specified parameters. // If maxAge is 0, the defaults will be used. func SetCacheControl(c *gin.Context, maxAge int, public bool) { if c == nil { return } else if c.Writer == nil { return } c.Header(CacheControl, CacheControlMaxAge(maxAge, public)) } // SetCacheControlImmutable adds a CacheControl header to the response based on the specified parameters // and with the immutable directive set. If maxAge is 0, the defaults will be used. func SetCacheControlImmutable(c *gin.Context, maxAge int, public bool) { if c == nil { return } else if c.Writer == nil { return } if maxAge < 0 { c.Header(CacheControl, CacheControlNoCache) return } c.Header(CacheControl, CacheControlMaxAge(maxAge, public)+", "+CacheControlImmutable) }