66 lines
2.1 KiB
Go
66 lines
2.1 KiB
Go
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// Copyright 2021 the Pinniped contributors. All Rights Reserved.
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// SPDX-License-Identifier: Apache-2.0
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// Package formposthtml defines HTML templates used by the Supervisor.
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//nolint: gochecknoglobals // This package uses globals to ensure that all parsing and minifying happens at init.
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package formposthtml
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import (
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"crypto/sha256"
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_ "embed" // Needed to trigger //go:embed directives below.
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"encoding/base64"
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"html/template"
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"strings"
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"github.com/tdewolff/minify/v2/minify"
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)
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var (
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//go:embed form_post.css
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rawCSS string
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minifiedCSS = mustMinify(minify.CSS(rawCSS))
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//go:embed form_post.js
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rawJS string
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minifiedJS = mustMinify(minify.JS(rawJS))
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//go:embed form_post.gohtml
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rawHTMLTemplate string
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)
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// Parse the Go templated HTML and inject functions providing the minified inline CSS and JS.
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var parsedHTMLTemplate = template.Must(template.New("form_post.gohtml").Funcs(template.FuncMap{
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"minifiedCSS": func() template.CSS { return template.CSS(minifiedCSS) },
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"minifiedJS": func() template.JS { return template.JS(minifiedJS) }, //nolint:gosec // This is 100% static input, not attacker-controlled.
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}).Parse(rawHTMLTemplate))
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// Generate the CSP header value once since it's effectively constant:
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var cspValue = strings.Join([]string{
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`default-src 'none'`,
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`script-src '` + cspHash(minifiedJS) + `'`,
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`style-src '` + cspHash(minifiedCSS) + `'`,
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`img-src data:`,
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`connect-src *`,
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`frame-ancestors 'none'`,
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}, "; ")
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func mustMinify(s string, err error) string {
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if err != nil {
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panic(err)
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}
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return s
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}
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func cspHash(s string) string {
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hashBytes := sha256.Sum256([]byte(s))
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return "sha256-" + base64.StdEncoding.EncodeToString(hashBytes[:])
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}
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// ContentSecurityPolicy returns the Content-Security-Policy header value to make the Template() operate correctly.
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//
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// See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/default-src#:~:text=%27%3Chash-algorithm%3E-%3Cbase64-value%3E%27.
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func ContentSecurityPolicy() string { return cspValue }
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// Template returns the html/template.Template for rendering the response_type=form_post response page.
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func Template() *template.Template { return parsedHTMLTemplate }
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