From 54b8b60edd5933116cab4c6130cdcb7bfc87a327 Mon Sep 17 00:00:00 2001
From: Jeff Becker <ampernand@gmail.com>
Date: Tue, 8 Aug 2017 09:18:31 -0400
Subject: [PATCH] add initial local spam filter

---
 contrib/backends/srndv2/src/srnd/config.go    | 36 +++++++++++++++++++
 contrib/backends/srndv2/src/srnd/daemon.go    | 10 ++++++
 .../backends/srndv2/src/srnd/frontend_http.go |  2 +-
 contrib/backends/srndv2/src/srnd/nntp.go      |  2 +-
 contrib/backends/srndv2/src/srnd/store.go     |  8 +++--
 5 files changed, 54 insertions(+), 4 deletions(-)

diff --git a/contrib/backends/srndv2/src/srnd/config.go b/contrib/backends/srndv2/src/srnd/config.go
index 9eca5fa..645d30e 100644
--- a/contrib/backends/srndv2/src/srnd/config.go
+++ b/contrib/backends/srndv2/src/srnd/config.go
@@ -5,18 +5,45 @@
 package srnd
 
 import (
+	"bufio"
+	"bytes"
 	"encoding/base32"
 	"fmt"
 	"github.com/majestrate/configparser"
 	"github.com/majestrate/nacl"
+	"io/ioutil"
 	"log"
 	"net"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"time"
 )
 
+type FilterConfig struct {
+	globalFilters []*regexp.Regexp
+}
+
+func (fc *FilterConfig) LoadFile(fname string) (err error) {
+	var data []byte
+	data, err = ioutil.ReadFile(fname)
+	if err == nil {
+		r := bytes.NewReader(data)
+		sc := bufio.NewScanner(r)
+		for sc.Scan() {
+			txt := sc.Text()
+			idx := strings.Index(txt, "#")
+			if idx >= 0 {
+				txt = txt[:idx]
+			}
+			fc.globalFilters = append(fc.globalFilters, regexp.MustCompile(txt))
+		}
+
+	}
+	return
+}
+
 type FeedConfig struct {
 	policy           FeedPolicy
 	quarks           map[string]string
@@ -70,6 +97,7 @@ type SRNdConfig struct {
 	pprof         *ProfilingConfig
 	hooks         []*HookConfig
 	inboundPolicy *FeedPolicy
+	filter        FilterConfig
 }
 
 // check for config files
@@ -417,6 +445,14 @@ func ReadConfig() *SRNdConfig {
 		}
 	}
 
+	filterFile := "filters.txt"
+
+	if CheckFile(filterFile) {
+		err = sconf.filter.LoadFile(filterFile)
+		if err != nil {
+			log.Fatalf("failed to load %s: %s", filterFile, err)
+		}
+	}
 	return &sconf
 }
 
diff --git a/contrib/backends/srndv2/src/srnd/daemon.go b/contrib/backends/srndv2/src/srnd/daemon.go
index 60742be..0166510 100644
--- a/contrib/backends/srndv2/src/srnd/daemon.go
+++ b/contrib/backends/srndv2/src/srnd/daemon.go
@@ -131,6 +131,16 @@ type NNTPDaemon struct {
 	article_lifetime  time.Duration
 }
 
+// return true if text passes all checks and is okay for posting
+func (self *NNTPDaemon) CheckText(text string) bool {
+	for _, re := range self.conf.filter.globalFilters {
+		if re.MatchString(text) {
+			return false
+		}
+	}
+	return true
+}
+
 func (self NNTPDaemon) End() {
 	if self.listener != nil {
 		self.listener.Close()
diff --git a/contrib/backends/srndv2/src/srnd/frontend_http.go b/contrib/backends/srndv2/src/srnd/frontend_http.go
index 1f411a8..4ac4f15 100644
--- a/contrib/backends/srndv2/src/srnd/frontend_http.go
+++ b/contrib/backends/srndv2/src/srnd/frontend_http.go
@@ -393,7 +393,7 @@ func (self *httpFrontend) poll() {
 								R: msg.Body,
 								N: self.daemon.messageSizeLimitFor(nntp.Newsgroup()),
 							}
-							err = self.daemon.store.ProcessMessageBody(f, textproto.MIMEHeader(msg.Header), body)
+							err = self.daemon.store.ProcessMessageBody(f, textproto.MIMEHeader(msg.Header), body, self.daemon.CheckText)
 						}
 					}
 				}
diff --git a/contrib/backends/srndv2/src/srnd/nntp.go b/contrib/backends/srndv2/src/srnd/nntp.go
index 55d6572..e8821bf 100644
--- a/contrib/backends/srndv2/src/srnd/nntp.go
+++ b/contrib/backends/srndv2/src/srnd/nntp.go
@@ -565,7 +565,7 @@ func (self *nntpConnection) storeMessage(daemon *NNTPDaemon, hdr textproto.MIMEH
 	// now store attachments and article
 	err = writeMIMEHeader(f, hdr)
 	if err == nil {
-		err = daemon.store.ProcessMessageBody(f, hdr, body)
+		err = daemon.store.ProcessMessageBody(f, hdr, body, daemon.CheckText)
 		if err == nil {
 			// tell daemon
 			daemon.loadFromInfeed(msgid)
diff --git a/contrib/backends/srndv2/src/srnd/store.go b/contrib/backends/srndv2/src/srnd/store.go
index 06a0d0b..2686338 100644
--- a/contrib/backends/srndv2/src/srnd/store.go
+++ b/contrib/backends/srndv2/src/srnd/store.go
@@ -65,7 +65,7 @@ type ArticleStore interface {
 	// process body of nntp message, register attachments and the article
 	// write the body into writer as we go through the body
 	// does NOT write mime header
-	ProcessMessageBody(wr io.Writer, hdr textproto.MIMEHeader, body *io.LimitedReader) error
+	ProcessMessageBody(wr io.Writer, hdr textproto.MIMEHeader, body *io.LimitedReader, spamfilter func(string) bool) error
 	// register this post with the daemon
 	RegisterPost(nntp NNTPMessage) error
 	// register signed message
@@ -437,8 +437,12 @@ func (self *articleStore) getMIMEHeader(messageID string) (hdr textproto.MIMEHea
 	return hdr
 }
 
-func (self *articleStore) ProcessMessageBody(wr io.Writer, hdr textproto.MIMEHeader, body *io.LimitedReader) (err error) {
+func (self *articleStore) ProcessMessageBody(wr io.Writer, hdr textproto.MIMEHeader, body *io.LimitedReader, spamfilter func(string) bool) (err error) {
 	err = read_message_body(body, hdr, self, wr, false, func(nntp NNTPMessage) {
+		if !spamfilter(nntp.Message()) {
+			err = errors.New("spam message")
+			return
+		}
 		err = self.RegisterPost(nntp)
 		if err == nil {
 			pk := hdr.Get("X-PubKey-Ed25519")