From 6dc8ef3b800aa15476f1c745339d4445e622efbe Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Fri, 4 Mar 2022 13:19:38 +0300
Subject: [PATCH] Do not ACK ACKs

---
 doc/news.ru.texi         |  4 ++
 doc/news.texi            |  4 ++
 ports/nncp/Makefile      |  2 +-
 src/cmd/nncp-ack/main.go | 90 ++++++++++++++++++++++++++++++++++++++++
 src/nncp.go              |  2 +-
 5 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/doc/news.ru.texi b/doc/news.ru.texi
index e814570..f4bdb57 100644
--- a/doc/news.ru.texi
+++ b/doc/news.ru.texi
@@ -5,6 +5,10 @@
 @subsection Релиз 8.7.0
 @itemize
 
+@item
+@command{nncp-ack} не подтверждает ACK-пакеты, предотвращая бесконечную
+петлю из ACK-ов.
+
 @item
 В прошлом, @command{nncp-ack} не удаляла соответствующие @file{hdr/} файлы.
 
diff --git a/doc/news.texi b/doc/news.texi
index 4ed60a0..33d5384 100644
--- a/doc/news.texi
+++ b/doc/news.texi
@@ -8,6 +8,10 @@ See also this page @ref{Новости, on russian}.
 @section Release 8.7.0
 @itemize
 
+@item
+@command{nncp-ack} does not acknowledge ACK-packets, preventing an
+endless loop of ACKs.
+
 @item
 @command{nncp-ack} previously did not remove corresponding @file{hdr/} files.
 
diff --git a/ports/nncp/Makefile b/ports/nncp/Makefile
index 05c0ad1..b959a32 100644
--- a/ports/nncp/Makefile
+++ b/ports/nncp/Makefile
@@ -1,5 +1,5 @@
 PORTNAME=	nncp
-DISTVERSION=	8.6.0
+DISTVERSION=	8.7.0
 CATEGORIES=	net
 MASTER_SITES=	http://www.nncpgo.org/download/
 
diff --git a/src/cmd/nncp-ack/main.go b/src/cmd/nncp-ack/main.go
index e972028..950295a 100644
--- a/src/cmd/nncp-ack/main.go
+++ b/src/cmd/nncp-ack/main.go
@@ -19,13 +19,17 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 package main
 
 import (
+	"bufio"
+	"errors"
 	"flag"
 	"fmt"
+	"io"
 	"log"
 	"os"
 	"path/filepath"
 	"strings"
 
+	xdr "github.com/davecgh/go-xdr/xdr2"
 	"go.cypherpunks.ru/nncp/v8"
 )
 
@@ -127,12 +131,98 @@ func main() {
 		return
 	}
 
+	isBad := false
 	for _, node := range nodes {
 		for job := range ctx.Jobs(node.Id, nncp.TRx) {
 			pktName := filepath.Base(job.Path)
+			sender := ctx.Neigh[*job.PktEnc.Sender]
+			les := nncp.LEs{
+				{K: "Node", V: job.PktEnc.Sender},
+				{K: "Pkt", V: pktName},
+			}
+			logMsg := func(les nncp.LEs) string {
+				return fmt.Sprintf(
+					"ACKing %s/%s",
+					ctx.NodeName(job.PktEnc.Sender), pktName,
+				)
+			}
+			if sender == nil {
+				err := errors.New("unknown node")
+				ctx.LogE("ack-read", les, err, logMsg)
+				isBad = true
+				continue
+			}
+			fd, err := os.Open(job.Path)
+			if err != nil {
+				ctx.LogE("ack-read-open", les, err, func(les nncp.LEs) string {
+					return logMsg(les) + ": opening" + job.Path
+				})
+				isBad = true
+				continue
+			}
+			pktEnc, _, err := ctx.HdrRead(fd)
+			if err != nil {
+				fd.Close()
+				ctx.LogE("ack-read-read", les, err, func(les nncp.LEs) string {
+					return logMsg(les) + ": reading" + job.Path
+				})
+				isBad = true
+				continue
+			}
+			switch pktEnc.Magic {
+			case nncp.MagicNNCPEv1.B:
+				err = nncp.MagicNNCPEv1.TooOld()
+			case nncp.MagicNNCPEv2.B:
+				err = nncp.MagicNNCPEv2.TooOld()
+			case nncp.MagicNNCPEv3.B:
+				err = nncp.MagicNNCPEv3.TooOld()
+			case nncp.MagicNNCPEv4.B:
+				err = nncp.MagicNNCPEv4.TooOld()
+			case nncp.MagicNNCPEv5.B:
+				err = nncp.MagicNNCPEv5.TooOld()
+			case nncp.MagicNNCPEv6.B:
+			default:
+				err = errors.New("is not an encrypted packet")
+			}
+			if err != nil {
+				fd.Close()
+				ctx.LogE("ack-read-magic", les, err, logMsg)
+				isBad = true
+				continue
+			}
+			if _, err = fd.Seek(0, io.SeekStart); err != nil {
+				fd.Close()
+				ctx.LogE("ack-read-seek", les, err, func(les nncp.LEs) string {
+					return logMsg(les) + ": seeking"
+				})
+				isBad = true
+				continue
+			}
+			pipeR, pipeW := io.Pipe()
+			go nncp.PktEncRead(ctx.Self, ctx.Neigh, bufio.NewReader(fd), pipeW, true, nil)
+			var pkt nncp.Pkt
+			_, err = xdr.Unmarshal(pipeR, &pkt)
+			fd.Close()
+			pipeW.Close()
+			if err != nil {
+				ctx.LogE("ack-read-unmarshal", les, err, func(les nncp.LEs) string {
+					return logMsg(les) + ": unmarshal"
+				})
+				isBad = true
+				continue
+			}
+			if pkt.Type == nncp.PktTypeACK {
+				ctx.LogI("ack-read-if-ack", les, func(les nncp.LEs) string {
+					return logMsg(les) + ": it is ACK, skipping"
+				})
+				continue
+			}
 			if err = ctx.TxACK(node, nice, pktName, minSize); err != nil {
 				log.Fatalln(err)
 			}
 		}
 	}
+	if isBad {
+		os.Exit(1)
+	}
 }
diff --git a/src/nncp.go b/src/nncp.go
index 0ae3470..ff817da 100644
--- a/src/nncp.go
+++ b/src/nncp.go
@@ -40,7 +40,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.`
 const Base32Encoded32Len = 52
 
 var (
-	Version string = "8.6.0"
+	Version string = "8.7.0"
 
 	Base32Codec *base32.Encoding = base32.StdEncoding.WithPadding(base32.NoPadding)
 )
-- 
2.44.0