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Improve Discord markdown escaper. Fixes #14

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This commit is contained in:
Tulir Asokan
2022-08-20 10:26:03 +03:00
parent 522ac4e2fe
commit 0b84527eab
3 changed files with 96 additions and 12 deletions
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48
formatter.go
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@@ -91,6 +91,40 @@ func pillConverter(displayname, mxid, eventID string, ctx format.Context) string
return displayname
}
// Discord links start with http:// or https://, contain at least two characters afterwards,
// don't contain < or whitespace anywhere, and don't end with "'),.:;]
//
// Zero-width whitespace is mostly in the Format category and is allowed, except \uFEFF isn't for some reason
var discordLinkRegex = regexp.MustCompile(`https?://[^<\p{Zs}\x{feff}]*[^"'),.:;\]\p{Zs}\x{feff}]`)
var discordMarkdownEscaper = strings.NewReplacer(
`\`, `\\`,
`_`, `\_`,
`*`, `\*`,
`~`, `\~`,
"`", "\\`",
`|`, `\|`,
`<`, `\<`,
)
func escapeDiscordMarkdown(s string) string {
submatches := discordLinkRegex.FindAllStringIndex(s, -1)
if submatches == nil {
return discordMarkdownEscaper.Replace(s)
}
var builder strings.Builder
offset := 0
for _, match := range submatches {
start := match[0]
end := match[1]
builder.WriteString(discordMarkdownEscaper.Replace(s[offset:start]))
builder.WriteString(s[start:end])
offset = end
}
builder.WriteString(discordMarkdownEscaper.Replace(s[offset:]))
return builder.String()
}
var matrixHTMLParser = &format.HTMLParser{
TabsToSpaces: 4,
Newline: "\n",
@@ -102,7 +136,7 @@ var matrixHTMLParser = &format.HTMLParser{
return fmt.Sprintf("__%s__", s)
},
TextConverter: func(s string, context format.Context) string {
return discordMarkdownEscaper.Replace(s)
return escapeDiscordMarkdown(s)
},
SpoilerConverter: func(text, reason string, ctx format.Context) string {
if reason != "" {
@@ -116,16 +150,6 @@ func init() {
matrixHTMLParser.PillConverter = pillConverter
}
var discordMarkdownEscaper = strings.NewReplacer(
`\`, `\\`,
`_`, `\_`,
`*`, `\*`,
`~`, `\~`,
"`", "\\`",
`|`, `\|`,
`<`, `\<`,
)
func (portal *Portal) parseMatrixHTML(user *User, content *event.MessageEventContent) string {
if content.Format == event.FormatHTML && len(content.FormattedBody) > 0 {
return matrixHTMLParser.Parse(content.FormattedBody, format.Context{
@@ -133,6 +157,6 @@ func (portal *Portal) parseMatrixHTML(user *User, content *event.MessageEventCon
formatterContextPortalKey: portal,
})
} else {
return discordMarkdownEscaper.Replace(content.Body)
return escapeDiscordMarkdown(content.Body)
}
}