From 74d2b9211d1237d4df89c8f4d0125656040e194d Mon Sep 17 00:00:00 2001
From: rachel-mp4 <rachel@moth11.net>
Date: Sun, 20 Jul 2025 12:56:15 -0400
Subject: [PATCH] add nonces to init message based on secret/uri option

---
 crypto.go  | 16 ++++++++++++++++
 go.mod     |  2 +-
 go.sum     |  4 ++--
 options.go | 10 ++++++++++
 server.go  |  6 ++++++
 5 files changed, 35 insertions(+), 3 deletions(-)
 create mode 100644 crypto.go

diff --git a/crypto.go b/crypto.go
new file mode 100644
index 0000000..c3434ad
--- /dev/null
+++ b/crypto.go
@@ -0,0 +1,16 @@
+package lrcd
+
+import (
+	"crypto/sha256"
+	"encoding/binary"
+)
+
+func GenerateNonce(messageID uint32, channelURI string, secret string) []byte {
+	h := sha256.New()
+	idBytes := make([]byte, 4)
+	binary.LittleEndian.PutUint32(idBytes, messageID)
+	h.Write(idBytes)
+	h.Write([]byte(channelURI))
+	h.Write([]byte(secret))
+	return h.Sum(nil)
+}
diff --git a/go.mod b/go.mod
index 1f21e80..bef815a 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,6 @@ go 1.24.2
 
 require (
 	github.com/gorilla/websocket v1.5.3
-	github.com/rachel-mp4/lrcproto v0.0.0-20250527205756-58da8216f98c
+	github.com/rachel-mp4/lrcproto v0.0.0-20250720164211-c6162669b709
 	google.golang.org/protobuf v1.36.6
 )
diff --git a/go.sum b/go.sum
index cf19f68..7b822c6 100644
--- a/go.sum
+++ b/go.sum
@@ -2,8 +2,8 @@ github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
 github.com/gorilla/websocket v1.5.3 h1:saDtZ6Pbx/0u+bgYQ3q96pZgCzfhKXGPqt7kZ72aNNg=
 github.com/gorilla/websocket v1.5.3/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=
-github.com/rachel-mp4/lrcproto v0.0.0-20250527205756-58da8216f98c h1:nOWeKeE7wph0IcwUyUBi0YBynUnAo4JW/J5DM88x4KM=
-github.com/rachel-mp4/lrcproto v0.0.0-20250527205756-58da8216f98c/go.mod h1:hQzO36tQELGbkmRnUtKeM6NMU34t79ZcTlhM+MO7pHw=
+github.com/rachel-mp4/lrcproto v0.0.0-20250720164211-c6162669b709 h1:P//gJE0zFv9Qvfn8dvp9ZrnG0FZh2MVcAX+uOP2flRw=
+github.com/rachel-mp4/lrcproto v0.0.0-20250720164211-c6162669b709/go.mod h1:hQzO36tQELGbkmRnUtKeM6NMU34t79ZcTlhM+MO7pHw=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
diff --git a/options.go b/options.go
index 6f4418e..c0d73a0 100644
--- a/options.go
+++ b/options.go
@@ -9,6 +9,8 @@ import (
 )
 
 type options struct {
+	uri       string
+	secret    string
 	welcome   *string
 	writer    *io.Writer
 	verbose   bool
@@ -66,3 +68,11 @@ func WithPubChannel(pubChan chan PubEvent) Option {
 		return nil
 	}
 }
+
+func WithServerURIAndSecret(uri string, secret string) Option {
+	return func(options *options) error {
+		options.secret = secret
+		options.uri = uri
+		return nil
+	}
+}
diff --git a/server.go b/server.go
index 80b1b7e..0e6f701 100644
--- a/server.go
+++ b/server.go
@@ -14,6 +14,8 @@ import (
 )
 
 type Server struct {
+	secret      string
+	uri         string
 	eventBus    chan clientEvent
 	ctx         context.Context
 	cancel      context.CancelFunc
@@ -88,6 +90,8 @@ func NewServer(opts ...Option) (*Server, error) {
 	if options.initialID != nil {
 		s.lastID = *options.initialID
 	}
+	s.uri = options.uri
+	s.secret = options.secret
 
 	s.clients = make(map[*client]bool)
 	s.clientsMu = sync.Mutex{}
@@ -331,6 +335,7 @@ func (s *Server) handleInit(msg *lrcpb.Event_Init, client *client) {
 	msg.Init.Color = client.color
 	echoed := false
 	msg.Init.Echoed = &echoed
+	msg.Init.Nonce = nil
 	if s.initChan != nil {
 		select {
 		case s.initChan <- *msg:
@@ -348,6 +353,7 @@ func (s *Server) broadcastInit(msg *lrcpb.Event_Init, client *client) {
 	stdData, _ := proto.Marshal(stdEvent)
 	echoed := true
 	msg.Init.Echoed = &echoed
+	msg.Init.Nonce = GenerateNonce(*msg.Init.Id, s.uri, s.secret)
 	echoEvent := &lrcpb.Event{Msg: msg}
 	echoData, _ := proto.Marshal(echoEvent)
 	muteEvent := &lrcpb.Event{Msg: &lrcpb.Event_Mute{Mute: &lrcpb.Mute{Id: msg.Init.GetId()}}}
-- 
2.51.2