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postrender.go
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postrender.go
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/*
* Copyright © 2018-2020 A Bunch Tell LLC.
*
* This file is part of WriteFreely.
*
* WriteFreely is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, included
* in the LICENSE file in this source code package.
*/
package writefreely
import (
"encoding/json"
"fmt"
"html"
"html/template"
"net/http"
"regexp"
"strings"
"unicode"
"unicode/utf8"
"github.com/microcosm-cc/bluemonday"
stripmd "github.com/writeas/go-strip-markdown"
"github.com/writeas/impart"
blackfriday "github.com/writeas/saturday"
"github.com/writeas/web-core/log"
"github.com/writeas/web-core/stringmanip"
"github.com/writeas/writefreely/config"
"github.com/writeas/writefreely/parse"
)
var (
blockReg = regexp.MustCompile("<(ul|ol|blockquote)>\n")
endBlockReg = regexp.MustCompile("</([a-z]+)>\n</(ul|ol|blockquote)>")
youtubeReg = regexp.MustCompile("(https?://www.youtube.com/embed/[a-zA-Z0-9\\-_]+)(\\?[^\t\n\f\r \"']+)?")
titleElementReg = regexp.MustCompile("</?h[1-6]>")
hashtagReg = regexp.MustCompile(`{{\[\[\|\|([^|]+)\|\|\]\]}}`)
markeddownReg = regexp.MustCompile("<p>(.+)</p>")
mentionReg = regexp.MustCompile(`@([A-Za-z0-9._%+-]+)(@[A-Za-z0-9.-]+\.[A-Za-z]+)\b`)
)
func (p *Post) formatContent(cfg *config.Config, c *Collection, isOwner bool) {
baseURL := c.CanonicalURL()
// TODO: redundant
if !isSingleUser {
baseURL = "/" + c.Alias + "/"
}
p.HTMLTitle = template.HTML(applyBasicMarkdown([]byte(p.Title.String)))
p.HTMLContent = template.HTML(applyMarkdown([]byte(p.Content), baseURL, cfg))
if exc := strings.Index(string(p.Content), "<!--more-->"); exc > -1 {
p.HTMLExcerpt = template.HTML(applyMarkdown([]byte(p.Content[:exc]), baseURL, cfg))
}
}
func (p *PublicPost) formatContent(cfg *config.Config, isOwner bool) {
p.Post.formatContent(cfg, &p.Collection.Collection, isOwner)
}
func applyMarkdown(data []byte, baseURL string, cfg *config.Config) string {
return applyMarkdownSpecial(data, false, baseURL, cfg)
}
func applyMarkdownSpecial(data []byte, skipNoFollow bool, baseURL string, cfg *config.Config) string {
mdExtensions := 0 |
blackfriday.EXTENSION_TABLES |
blackfriday.EXTENSION_FENCED_CODE |
blackfriday.EXTENSION_AUTOLINK |
blackfriday.EXTENSION_STRIKETHROUGH |
blackfriday.EXTENSION_SPACE_HEADERS |
blackfriday.EXTENSION_AUTO_HEADER_IDS
htmlFlags := 0 |
blackfriday.HTML_USE_SMARTYPANTS |
blackfriday.HTML_SMARTYPANTS_DASHES
if baseURL != "" {
htmlFlags |= blackfriday.HTML_HASHTAGS
}
// Generate Markdown
md := blackfriday.Markdown([]byte(data), blackfriday.HtmlRenderer(htmlFlags, "", ""), mdExtensions)
if baseURL != "" {
// Replace special text generated by Markdown parser
tagPrefix := baseURL + "tag:"
if cfg.App.Chorus {
tagPrefix = "/read/t/"
}
md = []byte(hashtagReg.ReplaceAll(md, []byte("<a href=\""+tagPrefix+"$1\" class=\"hashtag\"><span>#</span><span class=\"p-category\">$1</span></a>")))
handlePrefix := cfg.App.Host + "/@/"
md = []byte(mentionReg.ReplaceAll(md, []byte("<a href=\""+handlePrefix+"$1$2\" class=\"mention\">@$1$2</a>")))
}
// Strip out bad HTML
policy := getSanitizationPolicy()
policy.RequireNoFollowOnLinks(!skipNoFollow)
outHTML := string(policy.SanitizeBytes(md))
// Strip newlines on certain block elements that render with them
outHTML = blockReg.ReplaceAllString(outHTML, "<$1>")
outHTML = endBlockReg.ReplaceAllString(outHTML, "</$1></$2>")
// Remove all query parameters on YouTube embed links
// TODO: make this more specific. Taking the nuclear approach here to strip ?autoplay=1
outHTML = youtubeReg.ReplaceAllString(outHTML, "$1")
return outHTML
}
func applyBasicMarkdown(data []byte) string {
mdExtensions := 0 |
blackfriday.EXTENSION_STRIKETHROUGH |
blackfriday.EXTENSION_SPACE_HEADERS |
blackfriday.EXTENSION_HEADER_IDS
htmlFlags := 0 |
blackfriday.HTML_SKIP_HTML |
blackfriday.HTML_USE_SMARTYPANTS |
blackfriday.HTML_SMARTYPANTS_DASHES
// Generate Markdown
md := blackfriday.Markdown([]byte(data), blackfriday.HtmlRenderer(htmlFlags, "", ""), mdExtensions)
// Strip out bad HTML
policy := bluemonday.UGCPolicy()
policy.AllowAttrs("class", "id").Globally()
outHTML := string(policy.SanitizeBytes(md))
outHTML = markeddownReg.ReplaceAllString(outHTML, "$1")
outHTML = strings.TrimRightFunc(outHTML, unicode.IsSpace)
return outHTML
}
func postTitle(content, friendlyId string) string {
const maxTitleLen = 80
// Strip HTML tags with bluemonday's StrictPolicy, then unescape the HTML
// entities added in by sanitizing the content.
content = html.UnescapeString(bluemonday.StrictPolicy().Sanitize(content))
content = strings.TrimLeftFunc(stripmd.Strip(content), unicode.IsSpace)
eol := strings.IndexRune(content, '\n')
blankLine := strings.Index(content, "\n\n")
if blankLine != -1 && blankLine <= eol && blankLine <= assumedTitleLen {
return strings.TrimSpace(content[:blankLine])
} else if utf8.RuneCountInString(content) <= maxTitleLen {
return content
}
return friendlyId
}
// TODO: fix duplicated code from postTitle. postTitle is a widely used func we
// don't have time to investigate right now.
func friendlyPostTitle(content, friendlyId string) string {
const maxTitleLen = 80
// Strip HTML tags with bluemonday's StrictPolicy, then unescape the HTML
// entities added in by sanitizing the content.
content = html.UnescapeString(bluemonday.StrictPolicy().Sanitize(content))
content = strings.TrimLeftFunc(stripmd.Strip(content), unicode.IsSpace)
eol := strings.IndexRune(content, '\n')
blankLine := strings.Index(content, "\n\n")
if blankLine != -1 && blankLine <= eol && blankLine <= assumedTitleLen {
return strings.TrimSpace(content[:blankLine])
} else if eol == -1 && utf8.RuneCountInString(content) <= maxTitleLen {
return content
}
title, truncd := parse.TruncToWord(parse.PostLede(content, true), maxTitleLen)
if truncd {
title += "..."
}
return title
}
func getSanitizationPolicy() *bluemonday.Policy {
policy := bluemonday.UGCPolicy()
policy.AllowAttrs("src", "style").OnElements("iframe", "video", "audio")
policy.AllowAttrs("src", "type").OnElements("source")
policy.AllowAttrs("frameborder", "width", "height").Matching(bluemonday.Integer).OnElements("iframe")
policy.AllowAttrs("allowfullscreen").OnElements("iframe")
policy.AllowAttrs("controls", "loop", "muted", "autoplay").OnElements("video")
policy.AllowAttrs("controls", "loop", "muted", "autoplay", "preload").OnElements("audio")
policy.AllowAttrs("target").OnElements("a")
policy.AllowAttrs("title").OnElements("abbr")
policy.AllowAttrs("style", "class", "id").Globally()
policy.AllowURLSchemes("http", "https", "mailto", "xmpp")
return policy
}
func sanitizePost(content string) string {
return strings.Replace(content, "<", "&lt;", -1)
}
// postDescription generates a description based on the given post content,
// title, and post ID. This doesn't consider a V2 post field, `title` when
// choosing what to generate. In case a post has a title, this function will
// fail, and logic should instead be implemented to skip this when there's no
// title, like so:
// var desc string
// if title == "" {
// desc = postDescription(content, title, friendlyId)
// } else {
// desc = shortPostDescription(content)
// }
func postDescription(content, title, friendlyId string) string {
maxLen := 140
if content == "" {
content = "WriteFreely is a painless, simple, federated blogging platform."
} else {
fmtStr := "%s"
truncation := 0
if utf8.RuneCountInString(content) > maxLen {
// Post is longer than the max description, so let's show a better description
fmtStr = "%s..."
truncation = 3
}
if title == friendlyId {
// No specific title was found; simply truncate the post, starting at the beginning
content = fmt.Sprintf(fmtStr, strings.Replace(stringmanip.Substring(content, 0, maxLen-truncation), "\n", " ", -1))
} else {
// There was a title, so return a real description
blankLine := strings.Index(content, "\n\n")
if blankLine < 0 {
blankLine = 0
}
truncd := stringmanip.Substring(content, blankLine, blankLine+maxLen-truncation)
contentNoNL := strings.Replace(truncd, "\n", " ", -1)
content = strings.TrimSpace(fmt.Sprintf(fmtStr, contentNoNL))
}
}
return content
}
func shortPostDescription(content string) string {
maxLen := 140
fmtStr := "%s"
truncation := 0
if utf8.RuneCountInString(content) > maxLen {
// Post is longer than the max description, so let's show a better description
fmtStr = "%s..."
truncation = 3
}
return strings.TrimSpace(fmt.Sprintf(fmtStr, strings.Replace(stringmanip.Substring(content, 0, maxLen-truncation), "\n", " ", -1)))
}
func handleRenderMarkdown(app *App, w http.ResponseWriter, r *http.Request) error {
if !IsJSON(r) {
return impart.HTTPError{Status: http.StatusUnsupportedMediaType, Message: "Markdown API only supports JSON requests"}
}
in := struct {
CollectionURL string `json:"collection_url"`
RawBody string `json:"raw_body"`
}{}
decoder := json.NewDecoder(r.Body)
err := decoder.Decode(&in)
if err != nil {
log.Error("Couldn't parse markdown JSON request: %v", err)
return ErrBadJSON
}
out := struct {
Body string `json:"body"`
}{
Body: applyMarkdown([]byte(in.RawBody), in.CollectionURL, app.cfg),
}
return impart.WriteSuccess(w, out, http.StatusOK)
}

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