From 6f8767ac528bb558712bda0aa58d5602156cb377 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Tue, 18 Jun 2024 16:33:38 -0300
Subject: [PATCH] block words and tags based on gleasonator's policies.

---
 content_filtering.go | 74 ++++++++++++++++++++++++++++++++++++++++++++
 render_event.go      | 10 ++++--
 2 files changed, 82 insertions(+), 2 deletions(-)
 create mode 100644 content_filtering.go

diff --git a/content_filtering.go b/content_filtering.go
new file mode 100644
index 0000000..10c8e9a
--- /dev/null
+++ b/content_filtering.go
@@ -0,0 +1,74 @@
+package main
+
+import (
+	"fmt"
+	"regexp"
+	"slices"
+	"strings"
+
+	"github.com/nbd-wtf/go-nostr"
+)
+
+func hasProhibitedWordOrTag(event *nostr.Event) bool {
+	for _, tag := range event.Tags {
+		if len(tag) >= 2 && tag[0] == "t" && slices.Contains(pornTags, tag[1]) {
+			return true
+		}
+	}
+
+	return pornWordsRe.MatchString(event.Content)
+}
+
+// list copied from https://jsr.io/@gleasonator/policy/0.2.0/data/porntags.json
+var pornTags = []string{
+	"adult",
+	"ass",
+	"assworship",
+	"boobs",
+	"boobies",
+	"butt",
+	"cock",
+	"dick",
+	"dickpic",
+	"explosionloli",
+	"femboi",
+	"femboy",
+	"fetish",
+	"fuck",
+	"freeporn",
+	"girls",
+	"loli",
+	"milf",
+	"nude",
+	"nudity",
+	"nsfw",
+	"pantsu",
+	"pussy",
+	"porn",
+	"porno",
+	"porntube",
+	"pornvideo",
+	"sex",
+	"sexpervertsyndicate",
+	"sexporn",
+	"sexy",
+	"slut",
+	"teen",
+	"tits",
+	"teenporn",
+	"teens",
+	"transnsfw",
+	"xxx",
+}
+
+var pornWordsRe = func() *regexp.Regexp {
+	// list copied from https://jsr.io/@gleasonator/policy/0.2.0/data/pornwords.json
+	pornWords := []string{
+		"loli",
+		"nsfw",
+		"teen porn",
+	}
+	concat := strings.Join(pornWords, "|")
+	regex := fmt.Sprintf(`\b()\b`, concat)
+	return regexp.MustCompile(regex)
+}()
diff --git a/render_event.go b/render_event.go
index 44f574d..c381659 100644
--- a/render_event.go
+++ b/render_event.go
@@ -111,11 +111,17 @@ func renderEvent(w http.ResponseWriter, r *http.Request) {
 	//
 
 	// if it's porn we return a 404
-	for _, url := range urlRegex.FindAllString(data.event.Content, len(data.event.Content)+1) {
+	allUrls := urlRegex.FindAllString(data.event.Content, len(data.event.Content)+1)
+	if len(allUrls) > 0 && hasProhibitedWordOrTag(data.event.Event) {
+		log.Warn().Str("event", data.nevent).Msg("detect prohibited porn content")
+		http.Error(w, "event is not allowed", 404)
+		return
+	}
+	for _, url := range allUrls {
 		if imageExtensionMatcher.MatchString(url) {
 			if isImageNSFW(url) {
 				log.Warn().Str("url", url).Str("event", data.nevent).Msg("detect nsfw image")
-				http.Error(w, "event is unsuitable", 404)
+				http.Error(w, "event is unsuitable for work", 404)
 				return
 			}
 		}