136 lines
4.4 KiB
Go
136 lines
4.4 KiB
Go
package headers
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import (
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"net/http"
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"regexp"
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"gitlab.com/gitlab-org/gitlab/workhorse/internal/utils/svg"
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)
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var (
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javaScriptTypeRegex = regexp.MustCompile(`^(text|application)\/javascript$`)
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imageTypeRegex = regexp.MustCompile(`^image/*`)
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svgMimeTypeRegex = regexp.MustCompile(`^image/svg\+xml$`)
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textTypeRegex = regexp.MustCompile(`^text/*`)
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videoTypeRegex = regexp.MustCompile(`^video/*`)
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pdfTypeRegex = regexp.MustCompile(`application\/pdf`)
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attachmentRegex = regexp.MustCompile(`^attachment`)
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inlineRegex = regexp.MustCompile(`^inline`)
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)
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// Mime types that can't be inlined. Usually subtypes of main types
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var forbiddenInlineTypes = []*regexp.Regexp{svgMimeTypeRegex}
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// Mime types that can be inlined. We can add global types like "image/" or
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// specific types like "text/plain". If there is a specific type inside a global
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// allowed type that can't be inlined we must add it to the forbiddenInlineTypes var.
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// One example of this is the mime type "image". We allow all images to be
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// inlined except for SVGs.
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var allowedInlineTypes = []*regexp.Regexp{imageTypeRegex, textTypeRegex, videoTypeRegex, pdfTypeRegex}
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const (
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svgContentType = "image/svg+xml"
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textPlainContentType = "text/plain; charset=utf-8"
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attachmentDispositionText = "attachment"
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inlineDispositionText = "inline"
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)
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func SafeContentHeaders(data []byte, contentDisposition string) (string, string) {
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contentType := safeContentType(data)
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contentDisposition = safeContentDisposition(contentType, contentDisposition)
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// Set attachments to application/octet-stream since browsers can do
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// a better job distinguishing certain types (for example: ZIP files
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// vs. Microsoft .docx files). However, browsers may safely render SVGs even
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// when Content-Disposition is an attachment but only if the SVG
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// Content-Type is set. Note that scripts in an SVG file will only be executed
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// if the file is downloaded separately with an inline Content-Disposition.
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if attachmentRegex.MatchString(contentDisposition) && !isType(contentType, svgMimeTypeRegex) {
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contentType = "application/octet-stream"
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}
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return contentType, contentDisposition
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}
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func safeContentType(data []byte) string {
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// Special case for svg because DetectContentType detects it as text
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if svg.Is(data) {
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return svgContentType
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}
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// Override any existing Content-Type header from other ResponseWriters
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contentType := http.DetectContentType(data)
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// http.DetectContentType does not support JavaScript and would only
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// return text/plain. But for cautionary measures, just in case they start supporting
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// it down the road and start returning application/javascript, we want to handle it now
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// to avoid regressions.
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if isType(contentType, javaScriptTypeRegex) {
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return textPlainContentType
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}
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// If the content is text type, we set to plain, because we don't
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// want to render it inline if they're html or javascript
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if isType(contentType, textTypeRegex) {
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return textPlainContentType
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}
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return contentType
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}
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func safeContentDisposition(contentType string, contentDisposition string) string {
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// If the existing disposition is attachment we return that. This allow us
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// to force a download from GitLab (ie: RawController)
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if attachmentRegex.MatchString(contentDisposition) {
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return contentDisposition
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}
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// Checks for mime types that are forbidden to be inline
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for _, element := range forbiddenInlineTypes {
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if isType(contentType, element) {
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return attachmentDisposition(contentDisposition)
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}
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}
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// Checks for mime types allowed to be inline
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for _, element := range allowedInlineTypes {
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if isType(contentType, element) {
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return inlineDisposition(contentDisposition)
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}
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}
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// Anything else is set to attachment
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return attachmentDisposition(contentDisposition)
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}
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func attachmentDisposition(contentDisposition string) string {
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if contentDisposition == "" {
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return attachmentDispositionText
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}
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if inlineRegex.MatchString(contentDisposition) {
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return inlineRegex.ReplaceAllString(contentDisposition, attachmentDispositionText)
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}
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return contentDisposition
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}
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func inlineDisposition(contentDisposition string) string {
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if contentDisposition == "" {
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return inlineDispositionText
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}
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if attachmentRegex.MatchString(contentDisposition) {
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return attachmentRegex.ReplaceAllString(contentDisposition, inlineDispositionText)
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}
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return contentDisposition
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}
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func isType(contentType string, mimeType *regexp.Regexp) bool {
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return mimeType.MatchString(contentType)
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}
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