plugins/base: remove external resources URLs, sanitize CSS
This commit is contained in:
Simon Ser
parent
b9a180b154
commit
3bf17752ab
4 changed files with 198 additions and 9 deletions
8
go.mod
8
go.mod
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@ -3,16 +3,20 @@ module git.sr.ht/~emersion/koushin
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go 1.13
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require (
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github.com/aymerick/douceur v0.2.0
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github.com/chris-ramon/douceur v0.2.0
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github.com/emersion/go-imap v1.0.3
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github.com/emersion/go-imap-move v0.0.0-20190710073258-6e5a51a5b342
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github.com/emersion/go-message v0.11.1
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github.com/emersion/go-sasl v0.0.0-20191210011802-430746ea8b9b
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github.com/emersion/go-smtp v0.12.1
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github.com/gorilla/css v1.0.0 // indirect
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github.com/labstack/echo/v4 v4.1.13
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github.com/labstack/gommon v0.3.0
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github.com/microcosm-cc/bluemonday v1.0.2
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github.com/yuin/gopher-lua v0.0.0-20191220021717-ab39c6098bdb
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golang.org/x/crypto v0.0.0-20200117160349-530e935923ad // indirect
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golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa // indirect
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golang.org/x/sys v0.0.0-20200117145432-59e60aa80a0c // indirect
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golang.org/x/net v0.0.0-20200114155413-6afb5195e5aa
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golang.org/x/sys v0.0.0-20200120151820-655fe14d7479 // indirect
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layeh.com/gopher-luar v1.0.7
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)
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11
go.sum
11
go.sum
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@ -1,3 +1,7 @@
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github.com/aymerick/douceur v0.2.0 h1:Mv+mAeH1Q+n9Fr+oyamOlAkUNPWPlA8PPGR0QAaYuPk=
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github.com/aymerick/douceur v0.2.0/go.mod h1:wlT5vV2O3h55X9m7iVYN0TBM0NH/MmbLnd30/FjWUq4=
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github.com/chris-ramon/douceur v0.2.0 h1:IDMEdxlEUUBYBKE4z/mJnFyVXox+MjuEVDJNN27glkU=
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github.com/chris-ramon/douceur v0.2.0/go.mod h1:wDW5xjJdeoMm1mRt4sD4c/LbF/mWdEpRXQKjTR8nIBE=
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github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
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github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
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github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
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@ -20,6 +24,8 @@ github.com/emersion/go-smtp v0.12.1 h1:1R8BDqrR2HhlGwgFYcOi+BVTvK1bMjAB65QcVpJ5s
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github.com/emersion/go-smtp v0.12.1/go.mod h1:SD9V/xa4ndMw77lR3Mf7htkp8RBNYuPh9UeuBs9tpUQ=
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github.com/emersion/go-textwrapper v0.0.0-20160606182133-d0e65e56babe h1:40SWqY0zE3qCi6ZrtTf5OUdNm5lDnGnjRSq9GgmeTrg=
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github.com/emersion/go-textwrapper v0.0.0-20160606182133-d0e65e56babe/go.mod h1:aqO8z8wPrjkscevZJFVE1wXJrLpC5LtJG7fqLOsPb2U=
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github.com/gorilla/css v1.0.0 h1:BQqNyPTi50JCFMTw/b67hByjMVXZRwGha6wxVGkeihY=
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github.com/gorilla/css v1.0.0/go.mod h1:Dn721qIggHpt4+EFCcTLTU/vk5ySda2ReITrtgBl60c=
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github.com/labstack/echo v3.3.10+incompatible h1:pGRcYk231ExFAyoAjAfD85kQzRJCRI8bbnE7CX5OEgg=
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github.com/labstack/echo v3.3.10+incompatible/go.mod h1:0INS7j/VjnFxD4E2wkz67b8cVwCLbBmJyDaka6Cmk1s=
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github.com/labstack/echo/v4 v4.1.13 h1:JYgKq6NQQSaKbQcsOadAKX1kUVLCUzLGwu8sxN5tC34=
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@ -58,6 +64,7 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
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golang.org/x/crypto v0.0.0-20191227163750-53104e6ec876/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
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golang.org/x/crypto v0.0.0-20200117160349-530e935923ad h1:Jh8cai0fqIK+f6nG0UgPW5wFk8wmiMhM3AyciDBdtQg=
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golang.org/x/crypto v0.0.0-20200117160349-530e935923ad/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
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golang.org/x/net v0.0.0-20181220203305-927f97764cc3/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
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golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
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golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
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golang.org/x/net v0.0.0-20191209160850-c0dbc17a3553 h1:efeOvDhwQ29Dj3SdAV/MJf8oukgn+8D8WgaCaRMchF8=
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@ -72,8 +79,8 @@ golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a h1:aYOabOQFp6Vj6W1F80affTUvO
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golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20191026070338-33540a1f6037/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20200117145432-59e60aa80a0c h1:gUYreENmqtjZb2brVfUas1sC6UivSY8XwKwPo8tloLs=
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golang.org/x/sys v0.0.0-20200117145432-59e60aa80a0c/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/sys v0.0.0-20200120151820-655fe14d7479 h1:LhLiKguPgZL+Tglay4GhVtfF0kb8cvOJ0dHTCBO8YNI=
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golang.org/x/sys v0.0.0-20200120151820-655fe14d7479/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
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golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
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golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
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golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
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@ -244,7 +244,10 @@ func handleGetPart(ctx *koushin.Context, raw bool) error {
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isHTML := false
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if strings.EqualFold(mimeType, "text/html") {
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body = sanitizeHTML(body)
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body, err = sanitizeHTML(body)
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if err != nil {
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return fmt.Errorf("failed to sanitize HTML part: %v", err)
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}
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isHTML = true
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}
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@ -1,18 +1,193 @@
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package koushinbase
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import (
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"bytes"
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"fmt"
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"regexp"
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"strings"
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"golang.org/x/net/html"
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"github.com/microcosm-cc/bluemonday"
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"github.com/aymerick/douceur/css"
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cssparser "github.com/chris-ramon/douceur/parser"
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)
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func sanitizeHTML(b []byte) []byte {
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// TODO: this doesn't accomodate for quoting
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var (
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cssURLRegexp = regexp.MustCompile(`url\([^)]*\)`)
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cssExprRegexp = regexp.MustCompile(`expression\([^)]*\)`)
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)
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var allowedStyles = map[string]bool{
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"direction": true,
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"font": true,
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"font-family": true,
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"font-style": true,
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"font-variant": true,
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"font-size": true,
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"font-weight": true,
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"letter-spacing": true,
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"line-height": true,
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"text-align": true,
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"text-decoration": true,
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"text-indent": true,
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"text-overflow": true,
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"text-shadow": true,
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"text-transform": true,
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"white-space": true,
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"word-spacing": true,
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"word-wrap": true,
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"vertical-align": true,
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"color": true,
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"background": true,
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"background-color": true,
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"background-image": true,
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"background-repeat": true,
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"border": true,
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"border-color": true,
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"border-radius": true,
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"height": true,
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"margin": true,
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"padding": true,
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"width": true,
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"max-width": true,
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"min-width": true,
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"clear": true,
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"float": true,
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"border-collapse": true,
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"border-spacing": true,
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"caption-side": true,
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"empty-cells": true,
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"table-layout": true,
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"list-style-type": true,
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"list-style-position": true,
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}
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func sanitizeCSSDecls(decls []*css.Declaration) []*css.Declaration {
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sanitized := make([]*css.Declaration, 0, len(decls))
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for _, decl := range decls {
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if !allowedStyles[decl.Property] {
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continue
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}
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if cssExprRegexp.FindStringIndex(decl.Value) != nil {
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continue
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}
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// TODO: more robust CSS declaration parsing
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decl.Value = cssURLRegexp.ReplaceAllString(decl.Value, "url(about:blank)")
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sanitized = append(sanitized, decl)
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}
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return sanitized
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}
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func sanitizeCSSRule(rule *css.Rule) {
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// Disallow @import
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if rule.Kind == css.AtRule && strings.EqualFold(rule.Name, "@import") {
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rule.Prelude = "url(about:blank)"
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}
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rule.Declarations = sanitizeCSSDecls(rule.Declarations)
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for _, child := range rule.Rules {
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sanitizeCSSRule(child)
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}
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}
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func sanitizeNode(n *html.Node) {
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if n.Type == html.ElementNode {
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if strings.EqualFold(n.Data, "img") {
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for i := range n.Attr {
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attr := &n.Attr[i]
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if strings.EqualFold(attr.Key, "src") {
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attr.Val = "about:blank"
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}
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}
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} else if strings.EqualFold(n.Data, "style") {
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var s string
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c := n.FirstChild
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for c != nil {
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if c.Type == html.TextNode {
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s += c.Data
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}
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next := c.NextSibling
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n.RemoveChild(c)
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c = next
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}
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stylesheet, err := cssparser.Parse(s)
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if err != nil {
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s = ""
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} else {
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for _, rule := range stylesheet.Rules {
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sanitizeCSSRule(rule)
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}
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s = stylesheet.String()
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}
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n.AppendChild(&html.Node{
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Type: html.TextNode,
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Data: s,
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})
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}
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for i := range n.Attr {
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// Don't use `i, attr := range n.Attr` since `attr` would be a copy
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attr := &n.Attr[i]
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if strings.EqualFold(attr.Key, "style") {
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decls, err := cssparser.ParseDeclarations(attr.Val)
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if err != nil {
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attr.Val = ""
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continue
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}
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decls = sanitizeCSSDecls(decls)
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attr.Val = ""
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for _, d := range decls {
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attr.Val += d.String()
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}
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}
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}
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}
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for c := n.FirstChild; c != nil; c = c.NextSibling {
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sanitizeNode(c)
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}
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}
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func sanitizeHTML(b []byte) ([]byte, error) {
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doc, err := html.Parse(bytes.NewReader(b))
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if err != nil {
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return nil, fmt.Errorf("failed to parse HTML: %v", err)
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}
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sanitizeNode(doc)
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var buf bytes.Buffer
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if err := html.Render(&buf, doc); err != nil {
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return nil, fmt.Errorf("failed to render HTML: %v", err)
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}
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b = buf.Bytes()
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// bluemonday must always be run last
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p := bluemonday.UGCPolicy()
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// TODO: be more strict
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// TODO: use bluemonday's AllowStyles once it's released and
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// supports <style>
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p.AllowElements("style")
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p.AllowAttrs("style")
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p.AllowAttrs("style").Globally()
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p.AddTargetBlankToFullyQualifiedLinks(true)
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p.RequireNoFollowOnLinks(true)
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return p.SanitizeBytes(b)
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return p.SanitizeBytes(b), nil
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}
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