From 081d3752d85b69dc94234ef18a5fedcb3d980276 Mon Sep 17 00:00:00 2001
From: "Lawrence, Rendall" <rlawrence@sot-te.ch>
Date: Mon, 25 Apr 2022 16:05:19 +0300
Subject: [PATCH] (tested) fix static check warnings

* UDP writer: defer buffer close
* HTTP writer: remove duplicated compact4/6
---
 frontend/http/writer.go | 35 +++++++++++++----------------------
 frontend/udp/writer.go  | 10 +++++-----
 2 files changed, 18 insertions(+), 27 deletions(-)

diff --git a/frontend/http/writer.go b/frontend/http/writer.go
index b88fade..79a785e 100644
--- a/frontend/http/writer.go
+++ b/frontend/http/writer.go
@@ -25,7 +25,7 @@ func WriteError(w http.ResponseWriter, err error) {
 	if err = bencode.NewEncoder(w).Encode(map[string]any{
 		"failure reason": message,
 	}); err != nil {
-		log.Error("unable to encode string", log.Err(err))
+		log.Error("unable to encode message", log.Err(err))
 	}
 }
 
@@ -50,21 +50,21 @@ func WriteAnnounceResponse(w http.ResponseWriter, resp *bittorrent.AnnounceRespo
 	// Add the peers to the dictionary in the compact format.
 	if resp.Compact {
 		// Add the IPv4 peers to the dictionary.
-		ipv4CompactDict := make([]byte, 0, (net.IPv4len+2)*len(resp.IPv4Peers))
+		compactAddresses := make([]byte, 0, (net.IPv4len+2)*len(resp.IPv4Peers))
 		for _, peer := range resp.IPv4Peers {
-			ipv4CompactDict = append(ipv4CompactDict, compact4(peer)...)
+			compactAddresses = append(compactAddresses, compactAddress(peer)...)
 		}
-		if len(ipv4CompactDict) > 0 {
-			bdict["peers"] = ipv4CompactDict
+		if len(compactAddresses) > 0 {
+			bdict["peers"] = compactAddresses
 		}
 
 		// Add the IPv6 peers to the dictionary.
-		ipv6CompactDict := make([]byte, 0, (net.IPv6len+2)*len(resp.IPv6Peers)) // IP + port
+		compactAddresses = make([]byte, 0, (net.IPv6len+2)*len(resp.IPv6Peers)) // IP + port
 		for _, peer := range resp.IPv6Peers {
-			ipv6CompactDict = append(ipv6CompactDict, compact6(peer)...)
+			compactAddresses = append(compactAddresses, compactAddress(peer)...)
 		}
-		if len(ipv6CompactDict) > 0 {
-			bdict["peers6"] = ipv6CompactDict
+		if len(compactAddresses) > 0 {
+			bdict["peers6"] = compactAddresses
 		}
 	} else {
 		// Add the peers to the dictionary.
@@ -97,25 +97,16 @@ func WriteScrapeResponse(w http.ResponseWriter, resp *bittorrent.ScrapeResponse)
 	})
 }
 
-func compact4(peer bittorrent.Peer) (buf []byte) {
-	ip := peer.Addr().As4()
-	buf = append(buf, ip[:]...)
+func compactAddress(peer bittorrent.Peer) (buf []byte) {
+	buf = append(buf, peer.Addr().AsSlice()...)
 	port := peer.Port()
-	buf = append(buf, byte(port>>8), byte(port&0xff))
-	return
-}
-
-func compact6(peer bittorrent.Peer) (buf []byte) {
-	ip := peer.Addr().As16()
-	buf = append(buf, ip[:]...)
-	port := peer.Port()
-	buf = append(buf, byte(port>>8), byte(port&0xff))
+	buf = append(buf, byte(port>>8), byte(port))
 	return
 }
 
 func dict(peer bittorrent.Peer) map[string]any {
 	return map[string]any{
-		"peer id": string(peer.ID[:]),
+		"peer id": peer.ID.RawString(),
 		"ip":      peer.Addr(),
 		"port":    peer.Port(),
 	}
diff --git a/frontend/udp/writer.go b/frontend/udp/writer.go
index aa65e46..fe860d3 100644
--- a/frontend/udp/writer.go
+++ b/frontend/udp/writer.go
@@ -14,16 +14,16 @@ import (
 func WriteError(w io.Writer, txID []byte, err error) {
 	// If the client wasn't at fault, acknowledge it.
 	var clientErr bittorrent.ClientError
-	if !errors.As(err, &clientErr) {
+	if !errors.Is(err, &clientErr) {
 		err = fmt.Errorf("internal error occurred: %w", err)
 	}
 
 	buf := newBuffer()
+	defer buf.free()
 	writeHeader(buf, txID, errorActionID)
 	_, _ = buf.WriteString(err.Error())
 	_, _ = buf.WriteRune('\000')
 	_, _ = w.Write(buf.Bytes())
-	buf.free()
 }
 
 // WriteAnnounce encodes an announce response according to BEP 15.
@@ -33,6 +33,7 @@ func WriteError(w io.Writer, txID []byte, err error) {
 // https://web.archive.org/web/20170503181830/http://opentracker.blog.h3q.com/2007/12/28/the-ipv6-situation/
 func WriteAnnounce(w io.Writer, txID []byte, resp *bittorrent.AnnounceResponse, v6Action, v6Peers bool) {
 	buf := newBuffer()
+	defer buf.free()
 
 	if v6Action {
 		writeHeader(buf, txID, announceV6ActionID)
@@ -54,12 +55,12 @@ func WriteAnnounce(w io.Writer, txID []byte, resp *bittorrent.AnnounceResponse,
 	}
 
 	_, _ = w.Write(buf.Bytes())
-	buf.free()
 }
 
 // WriteScrape encodes a scrape response according to BEP 15.
 func WriteScrape(w io.Writer, txID []byte, resp *bittorrent.ScrapeResponse) {
 	buf := newBuffer()
+	defer buf.free()
 
 	writeHeader(buf, txID, scrapeActionID)
 
@@ -70,18 +71,17 @@ func WriteScrape(w io.Writer, txID []byte, resp *bittorrent.ScrapeResponse) {
 	}
 
 	_, _ = w.Write(buf.Bytes())
-	buf.free()
 }
 
 // WriteConnectionID encodes a new connection response according to BEP 15.
 func WriteConnectionID(w io.Writer, txID, connID []byte) {
 	buf := newBuffer()
+	defer buf.free()
 
 	writeHeader(buf, txID, connectActionID)
 	_, _ = buf.Write(connID)
 
 	_, _ = w.Write(buf.Bytes())
-	buf.free()
 }
 
 // writeHeader writes the action and transaction ID to the provided response