multi: report protocol version

looprpc/server.pb.go

@@ -23,15 +23,49 @@ var _ = math.Inf
 // proto package needs to be updated.
 const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
 
+//*
+//This enum defines the protocol versions that clients may adhere to. Note that
+//this is not a flagged enum. If a particular protocol version adds a feature,
+//then in general all the preceding features are also supported. Exception to this
+//is when features get deprecated.
+type ProtocolVersion int32
+
+const (
+	/// No protocol version reported at all.
+	ProtocolVersion_LEGACY ProtocolVersion = 0
+	/// Client may attempt to send the loop out payment in multiple parts.
+	ProtocolVersion_MULTI_LOOP_OUT ProtocolVersion = 1
+)
+
+var ProtocolVersion_name = map[int32]string{
+	0: "LEGACY",
+	1: "MULTI_LOOP_OUT",
+}
+
+var ProtocolVersion_value = map[string]int32{
+	"LEGACY":         0,
+	"MULTI_LOOP_OUT": 1,
+}
+
+func (x ProtocolVersion) String() string {
+	return proto.EnumName(ProtocolVersion_name, int32(x))
+}
+
+func (ProtocolVersion) EnumDescriptor() ([]byte, []int) {
+	return fileDescriptor_ad098daeda4239f7, []int{0}
+}
+
 type ServerLoopOutRequest struct {
 	ReceiverKey []byte `protobuf:"bytes,1,opt,name=receiver_key,json=receiverKey,proto3" json:"receiver_key,omitempty"`
 	SwapHash    []byte `protobuf:"bytes,2,opt,name=swap_hash,json=swapHash,proto3" json:"swap_hash,omitempty"`
 	Amt         uint64 `protobuf:"varint,3,opt,name=amt,proto3" json:"amt,omitempty"`
 	/// The unix time in seconds we want the on-chain swap to be published by.
-	SwapPublicationDeadline int64    `protobuf:"varint,4,opt,name=swap_publication_deadline,json=swapPublicationDeadline,proto3" json:"swap_publication_deadline,omitempty"`
+	SwapPublicationDeadline int64 `protobuf:"varint,4,opt,name=swap_publication_deadline,json=swapPublicationDeadline,proto3" json:"swap_publication_deadline,omitempty"`
-	XXX_NoUnkeyedLiteral    struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized        []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,5,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache           int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopOutRequest) Reset()         { *m = ServerLoopOutRequest{} }
@@ -87,6 +121,13 @@ func (m *ServerLoopOutRequest) GetSwapPublicationDeadline() int64 {
 	return 0
 }
 
+func (m *ServerLoopOutRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopOutResponse struct {
 	SwapInvoice          string   `protobuf:"bytes,1,opt,name=swap_invoice,json=swapInvoice,proto3" json:"swap_invoice,omitempty"`
 	PrepayInvoice        string   `protobuf:"bytes,2,opt,name=prepay_invoice,json=prepayInvoice,proto3" json:"prepay_invoice,omitempty"`
@@ -154,10 +195,12 @@ type ServerLoopOutQuoteRequest struct {
 	/// The swap amount. If zero, a quote for a maximum amt swap will be given.
 	Amt uint64 `protobuf:"varint,1,opt,name=amt,proto3" json:"amt,omitempty"`
 	/// The unix time in seconds we want the on-chain swap to be published by.
-	SwapPublicationDeadline int64    `protobuf:"varint,2,opt,name=swap_publication_deadline,json=swapPublicationDeadline,proto3" json:"swap_publication_deadline,omitempty"`
+	SwapPublicationDeadline int64 `protobuf:"varint,2,opt,name=swap_publication_deadline,json=swapPublicationDeadline,proto3" json:"swap_publication_deadline,omitempty"`
-	XXX_NoUnkeyedLiteral    struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized        []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,3,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache           int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopOutQuoteRequest) Reset()         { *m = ServerLoopOutQuoteRequest{} }
@@ -199,6 +242,13 @@ func (m *ServerLoopOutQuoteRequest) GetSwapPublicationDeadline() int64 {
 	return 0
 }
 
+func (m *ServerLoopOutQuoteRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopOutQuote struct {
 	SwapPaymentDest string `protobuf:"bytes,1,opt,name=swap_payment_dest,json=swapPaymentDest,proto3" json:"swap_payment_dest,omitempty"`
 	/// The total estimated swap fee given the quote amt.
@@ -292,9 +342,11 @@ func (m *ServerLoopOutQuote) GetCltvDelta() int32 {
 }
 
 type ServerLoopOutTermsRequest struct {
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized     []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,1,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache        int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopOutTermsRequest) Reset()         { *m = ServerLoopOutTermsRequest{} }
@@ -322,6 +374,13 @@ func (m *ServerLoopOutTermsRequest) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_ServerLoopOutTermsRequest proto.InternalMessageInfo
 
+func (m *ServerLoopOutTermsRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopOutTerms struct {
 	MinSwapAmount        uint64   `protobuf:"varint,1,opt,name=min_swap_amount,json=minSwapAmount,proto3" json:"min_swap_amount,omitempty"`
 	MaxSwapAmount        uint64   `protobuf:"varint,2,opt,name=max_swap_amount,json=maxSwapAmount,proto3" json:"max_swap_amount,omitempty"`
@@ -370,14 +429,16 @@ func (m *ServerLoopOutTerms) GetMaxSwapAmount() uint64 {
 }
 
 type ServerLoopInRequest struct {
-	SenderKey            []byte   `protobuf:"bytes,1,opt,name=sender_key,json=senderKey,proto3" json:"sender_key,omitempty"`
+	SenderKey   []byte `protobuf:"bytes,1,opt,name=sender_key,json=senderKey,proto3" json:"sender_key,omitempty"`
-	SwapHash             []byte   `protobuf:"bytes,2,opt,name=swap_hash,json=swapHash,proto3" json:"swap_hash,omitempty"`
+	SwapHash    []byte `protobuf:"bytes,2,opt,name=swap_hash,json=swapHash,proto3" json:"swap_hash,omitempty"`
-	Amt                  uint64   `protobuf:"varint,3,opt,name=amt,proto3" json:"amt,omitempty"`
+	Amt         uint64 `protobuf:"varint,3,opt,name=amt,proto3" json:"amt,omitempty"`
-	SwapInvoice          string   `protobuf:"bytes,4,opt,name=swap_invoice,json=swapInvoice,proto3" json:"swap_invoice,omitempty"`
+	SwapInvoice string `protobuf:"bytes,4,opt,name=swap_invoice,json=swapInvoice,proto3" json:"swap_invoice,omitempty"`
-	LastHop              []byte   `protobuf:"bytes,5,opt,name=last_hop,json=lastHop,proto3" json:"last_hop,omitempty"`
+	LastHop     []byte `protobuf:"bytes,5,opt,name=last_hop,json=lastHop,proto3" json:"last_hop,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized     []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,6,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache        int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopInRequest) Reset()         { *m = ServerLoopInRequest{} }
@@ -440,6 +501,13 @@ func (m *ServerLoopInRequest) GetLastHop() []byte {
 	return nil
 }
 
+func (m *ServerLoopInRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopInResponse struct {
 	ReceiverKey          []byte   `protobuf:"bytes,1,opt,name=receiver_key,json=receiverKey,proto3" json:"receiver_key,omitempty"`
 	Expiry               int32    `protobuf:"varint,2,opt,name=expiry,proto3" json:"expiry,omitempty"`
@@ -489,10 +557,12 @@ func (m *ServerLoopInResponse) GetExpiry() int32 {
 
 type ServerLoopInQuoteRequest struct {
 	/// The swap amount. If zero, a quote for a maximum amt swap will be given.
-	Amt                  uint64   `protobuf:"varint,1,opt,name=amt,proto3" json:"amt,omitempty"`
+	Amt uint64 `protobuf:"varint,1,opt,name=amt,proto3" json:"amt,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized     []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,2,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache        int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopInQuoteRequest) Reset()         { *m = ServerLoopInQuoteRequest{} }
@@ -527,6 +597,13 @@ func (m *ServerLoopInQuoteRequest) GetAmt() uint64 {
 	return 0
 }
 
+func (m *ServerLoopInQuoteRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopInQuoteResponse struct {
 	SwapFee              int64    `protobuf:"varint,1,opt,name=swap_fee,json=swapFee,proto3" json:"swap_fee,omitempty"`
 	SwapFeeRate          int64    `protobuf:"varint,2,opt,name=swap_fee_rate,json=swapFeeRate,proto3" json:"swap_fee_rate,omitempty"`       // Deprecated: Do not use.
@@ -602,9 +679,11 @@ func (m *ServerLoopInQuoteResponse) GetCltvDelta() int32 {
 }
 
 type ServerLoopInTermsRequest struct {
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	/// The protocol version that the client adheres to.
-	XXX_unrecognized     []byte   `json:"-"`
+	ProtocolVersion      ProtocolVersion `protobuf:"varint,1,opt,name=protocol_version,json=protocolVersion,proto3,enum=looprpc.ProtocolVersion" json:"protocol_version,omitempty"`
-	XXX_sizecache        int32    `json:"-"`
+	XXX_NoUnkeyedLiteral struct{}        `json:"-"`
+	XXX_unrecognized     []byte          `json:"-"`
+	XXX_sizecache        int32           `json:"-"`
 }
 
 func (m *ServerLoopInTermsRequest) Reset()         { *m = ServerLoopInTermsRequest{} }
@@ -632,6 +711,13 @@ func (m *ServerLoopInTermsRequest) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_ServerLoopInTermsRequest proto.InternalMessageInfo
 
+func (m *ServerLoopInTermsRequest) GetProtocolVersion() ProtocolVersion {
+	if m != nil {
+		return m.ProtocolVersion
+	}
+	return ProtocolVersion_LEGACY
+}
+
 type ServerLoopInTerms struct {
 	MinSwapAmount        uint64   `protobuf:"varint,1,opt,name=min_swap_amount,json=minSwapAmount,proto3" json:"min_swap_amount,omitempty"`
 	MaxSwapAmount        uint64   `protobuf:"varint,2,opt,name=max_swap_amount,json=maxSwapAmount,proto3" json:"max_swap_amount,omitempty"`
@@ -680,6 +766,7 @@ func (m *ServerLoopInTerms) GetMaxSwapAmount() uint64 {
 }
 
 func init() {
+	proto.RegisterEnum("looprpc.ProtocolVersion", ProtocolVersion_name, ProtocolVersion_value)
 	proto.RegisterType((*ServerLoopOutRequest)(nil), "looprpc.ServerLoopOutRequest")
 	proto.RegisterType((*ServerLoopOutResponse)(nil), "looprpc.ServerLoopOutResponse")
 	proto.RegisterType((*ServerLoopOutQuoteRequest)(nil), "looprpc.ServerLoopOutQuoteRequest")
@@ -697,51 +784,57 @@ func init() {
 func init() { proto.RegisterFile("server.proto", fileDescriptor_ad098daeda4239f7) }
 
 var fileDescriptor_ad098daeda4239f7 = []byte{
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+	0xd1, 0x21, 0x1b, 0x99, 0x5c, 0x2c, 0x4d, 0x5a, 0x34, 0x2a, 0x0c, 0x75, 0xf3, 0xf4, 0x8a, 0x5a,
-	0xa9, 0x24, 0xd9, 0x99, 0x66, 0xaa, 0x17, 0x55, 0x62, 0xb9, 0x33, 0xcd, 0xd2, 0x36, 0xb8, 0x3c,
+	0x7b, 0xe2, 0x40, 0x60, 0xe9, 0x75, 0x04, 0x9b, 0x09, 0x61, 0xe9, 0x75, 0x08, 0x5b, 0x03, 0xe8,
-	0x43, 0xf7, 0xa7, 0x05, 0xff, 0x4f, 0xda, 0x9c, 0xc6, 0x99, 0x09, 0x8a, 0xc6, 0xb2, 0xca, 0xc6,
+	0x19, 0x7c, 0xac, 0xf5, 0xd1, 0xe0, 0x54, 0xc9, 0x8a, 0x49, 0xe6, 0xdc, 0xca, 0x81, 0x5b, 0x68,
-	0x7a, 0xe2, 0x19, 0x95, 0x0d, 0x5f, 0x9d, 0x36, 0x7c, 0x1b, 0x96, 0x43, 0x9a, 0x0a, 0x7f, 0xc0,
+	0x7c, 0x8d, 0xcd, 0xb2, 0x8b, 0xf6, 0xd0, 0x09, 0x66, 0x99, 0xe4, 0xbe, 0xb4, 0xa8, 0xfb, 0xfd,
-	0xb8, 0xd2, 0xbe, 0xe9, 0xd5, 0xe5, 0xfb, 0x84, 0x71, 0xf7, 0x22, 0x7f, 0xee, 0x92, 0xe2, 0xe4,
+	0x98, 0xf9, 0xe2, 0x06, 0xb2, 0x39, 0x2b, 0xd7, 0x5b, 0x99, 0x98, 0xd4, 0xcd, 0x59, 0xa9, 0xb2,
-	0x8c, 0x1e, 0x3a, 0xf7, 0xc9, 0x01, 0xd8, 0x85, 0x03, 0x78, 0x03, 0x4e, 0xbe, 0xe4, 0x62, 0xff,
+	0x8f, 0x0b, 0xcb, 0x6c, 0xfc, 0x91, 0xe0, 0xf1, 0xf4, 0x9a, 0x96, 0x19, 0x48, 0x88, 0xee, 0xb8,
-	0xbb, 0xbf, 0xad, 0xfc, 0xa2, 0xee, 0xe1, 0x86, 0x46, 0xde, 0x9e, 0xd6, 0x03, 0xf6, 0xb4, 0x67,
+	0x14, 0xdf, 0xf1, 0x05, 0x9f, 0x85, 0x78, 0xf6, 0xd2, 0xb3, 0xd9, 0xab, 0xc0, 0xb2, 0x41, 0x1d,
-	0xdb, 0x73, 0x86, 0xff, 0xaa, 0x4f, 0xf0, 0xdf, 0xd2, 0xe3, 0xfc, 0x57, 0x2b, 0xfb, 0xaf, 0x53,
+	0xae, 0x0d, 0x98, 0x25, 0x06, 0x98, 0x57, 0xb3, 0xee, 0xf7, 0x11, 0xb3, 0x12, 0xed, 0xcc, 0x2c,
-	0x54, 0xa1, 0x60, 0xbf, 0x1e, 0xac, 0x4f, 0xe5, 0xfe, 0xb5, 0xfb, 0xde, 0xfe, 0xa9, 0x00, 0xc8,
+	0x6a, 0xe7, 0x49, 0xf8, 0x0d, 0x74, 0x75, 0x4e, 0x9f, 0x85, 0xbb, 0xde, 0xc0, 0x69, 0xa0, 0xe5,
-	0xa7, 0xee, 0x44, 0xce, 0xa1, 0x59, 0x30, 0xbb, 0xbb, 0x6f, 0x3e, 0x08, 0xfb, 0x73, 0xcf, 0xa4,
+	0x48, 0xa0, 0x2f, 0x41, 0x09, 0xb7, 0xbc, 0x23, 0xce, 0x49, 0x2a, 0xe4, 0x45, 0x55, 0xfc, 0x8e,
-	0xb3, 0xb1, 0x00, 0x43, 0xce, 0x61, 0xf5, 0x13, 0xde, 0x9a, 0x90, 0x6c, 0x44, 0xba, 0xb3, 0xe1,
+	0xbc, 0x21, 0x37, 0x77, 0xfa, 0x5a, 0xc2, 0x69, 0x93, 0xee, 0x48, 0x9b, 0x9c, 0x9c, 0xb6, 0x84,
-	0x59, 0xb5, 0x57, 0xf3, 0xd2, 0x66, 0xd7, 0x13, 0x86, 0xfa, 0x67, 0x6c, 0x0e, 0xc3, 0xbc, 0x9f,
+	0x38, 0xa5, 0x17, 0x88, 0xd3, 0xd2, 0xfd, 0xe2, 0x94, 0x89, 0xc7, 0x49, 0x8b, 0x5a, 0xf9, 0xf0,
-	0xe6, 0x31, 0xd4, 0x05, 0xce, 0x60, 0x25, 0x2f, 0xf0, 0xf6, 0x0c, 0x6c, 0x71, 0x31, 0x9d, 0xce,
+	0x69, 0xea, 0xc1, 0xea, 0xcc, 0x05, 0x0f, 0x1d, 0xa6, 0xad, 0x57, 0x50, 0x8a, 0x11, 0x21, 0x00,
-	0x7c, 0x08, 0x39, 0x83, 0x96, 0x99, 0xf7, 0x54, 0xad, 0x83, 0x6c, 0xce, 0x04, 0x67, 0xa5, 0xba,
+	0x99, 0xf6, 0xbb, 0xf7, 0x7b, 0xfb, 0x5f, 0xca, 0x8f, 0x08, 0x81, 0xe2, 0xc7, 0xb3, 0x76, 0xb7,
-	0x73, 0xb2, 0x66, 0xd8, 0xab, 0x8c, 0x9b, 0xa6, 0x3a, 0x9b, 0x5b, 0x61, 0x54, 0x77, 0x11, 0x44,
+	0xa5, 0xb5, 0x3b, 0x9d, 0x63, 0xad, 0x73, 0xd6, 0x2d, 0x4b, 0xbb, 0xff, 0x52, 0x00, 0x6e, 0x07,
-	0x57, 0xbd, 0xae, 0xa9, 0x8f, 0xf8, 0xbb, 0xbf, 0x01, 0x00, 0x00, 0xff, 0xff, 0x6c, 0x99, 0x4f,
+	0x8f, 0x1c, 0xe9, 0x40, 0x3e, 0x12, 0xf7, 0xc6, 0x8d, 0xc2, 0xb9, 0xaf, 0x4d, 0x75, 0xed, 0x16,
-	0x5f, 0xfb, 0x07, 0x00, 0x00,
+	0x0c, 0xe9, 0x40, 0xf1, 0x13, 0x5e, 0xf9, 0x25, 0xf7, 0x22, 0x52, 0x4b, 0x86, 0x07, 0xdd, 0x5e,
+	0xcc, 0x3b, 0xf6, 0x77, 0x6c, 0xca, 0xd0, 0xfb, 0x35, 0x98, 0xc3, 0x30, 0x1c, 0x86, 0x79, 0x0c,
+	0xbd, 0x06, 0x6d, 0x58, 0x09, 0xcf, 0x64, 0x23, 0x01, 0x1b, 0x5d, 0x88, 0x6a, 0x75, 0x3e, 0x84,
+	0xb4, 0xa1, 0xe0, 0xeb, 0x6d, 0x89, 0x09, 0x92, 0xf5, 0x44, 0x70, 0xd0, 0xaa, 0x36, 0xe7, 0xd4,
+	0x17, 0xdb, 0x0d, 0xb8, 0x79, 0x54, 0x93, 0xb9, 0x45, 0xa4, 0x36, 0x6e, 0x83, 0x78, 0x5d, 0xcf,
+	0x33, 0x62, 0x39, 0x5f, 0xff, 0x0f, 0x00, 0x00, 0xff, 0xff, 0xd4, 0x54, 0xd0, 0xf3, 0xcd, 0x09,
+	0x00, 0x00,
 }
 
 // Reference imports to suppress errors if they are not otherwise used.

looprpc/server.proto

@@ -19,6 +19,20 @@ service SwapServer {
         returns (ServerLoopInQuoteResponse);
 }
 
+/**
+This enum defines the protocol versions that clients may adhere to. Note that
+this is not a flagged enum. If a particular protocol version adds a feature,
+then in general all the preceding features are also supported. Exception to this
+is when features get deprecated.
+*/
+enum ProtocolVersion {
+    /// No protocol version reported at all.
+    LEGACY = 0;
+
+    /// Client may attempt to send the loop out payment in multiple parts.
+    MULTI_LOOP_OUT = 1;
+}
+
 message ServerLoopOutRequest {
     bytes receiver_key = 1;
 
@@ -28,6 +42,9 @@ message ServerLoopOutRequest {
 
     /// The unix time in seconds we want the on-chain swap to be published by.
     int64 swap_publication_deadline = 4;
+
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 5;
 }
 
 message ServerLoopOutResponse {
@@ -46,6 +63,9 @@ message ServerLoopOutQuoteRequest {
 
     /// The unix time in seconds we want the on-chain swap to be published by.
     int64 swap_publication_deadline = 2;
+
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 3;
 }
 
 message ServerLoopOutQuote {
@@ -67,6 +87,8 @@ message ServerLoopOutQuote {
 }
 
 message ServerLoopOutTermsRequest {
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 1;
 }
 
 message ServerLoopOutTerms {
@@ -80,6 +102,9 @@ message ServerLoopInRequest {
     uint64 amt = 3;
     string swap_invoice = 4;
     bytes last_hop = 5;
+
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 6;
 }
 
 message ServerLoopInResponse {
@@ -90,6 +115,9 @@ message ServerLoopInResponse {
 message ServerLoopInQuoteRequest {
     /// The swap amount. If zero, a quote for a maximum amt swap will be given.
     uint64 amt = 1;
+
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 2;
 }
 
 message ServerLoopInQuoteResponse {
@@ -101,6 +129,8 @@ message ServerLoopInQuoteResponse {
 }
 
 message ServerLoopInTermsRequest {
+    /// The protocol version that the client adheres to.
+    ProtocolVersion protocol_version = 1;
 }
 
 message ServerLoopInTerms {

swap_server_client.go

@@ -21,6 +21,10 @@ import (
 	"google.golang.org/grpc/credentials"
 )
 
+// protocolVersion defines the version of the protocol that is currently
+// supported by the loop client.
+const protocolVersion = looprpc.ProtocolVersion_MULTI_LOOP_OUT
+
 type swapServerClient interface {
 	GetLoopOutTerms(ctx context.Context) (
 		*LoopOutTerms, error)
@@ -84,7 +88,9 @@ func (s *grpcSwapServerClient) GetLoopOutTerms(ctx context.Context) (
 	rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout)
 	defer rpcCancel()
 	terms, err := s.server.LoopOutTerms(rpcCtx,
-		&looprpc.ServerLoopOutTermsRequest{},
+		&looprpc.ServerLoopOutTermsRequest{
+			ProtocolVersion: protocolVersion,
+		},
 	)
 	if err != nil {
 		return nil, err
@@ -106,6 +112,7 @@ func (s *grpcSwapServerClient) GetLoopOutQuote(ctx context.Context,
 		&looprpc.ServerLoopOutQuoteRequest{
 			Amt:                     uint64(amt),
 			SwapPublicationDeadline: swapPublicationDeadline.Unix(),
+			ProtocolVersion:         protocolVersion,
 		},
 	)
 	if err != nil {
@@ -136,7 +143,9 @@ func (s *grpcSwapServerClient) GetLoopInTerms(ctx context.Context) (
 	rpcCtx, rpcCancel := context.WithTimeout(ctx, globalCallTimeout)
 	defer rpcCancel()
 	terms, err := s.server.LoopInTerms(rpcCtx,
-		&looprpc.ServerLoopInTermsRequest{},
+		&looprpc.ServerLoopInTermsRequest{
+			ProtocolVersion: protocolVersion,
+		},
 	)
 	if err != nil {
 		return nil, err
@@ -155,7 +164,8 @@ func (s *grpcSwapServerClient) GetLoopInQuote(ctx context.Context,
 	defer rpcCancel()
 	quoteResp, err := s.server.LoopInQuote(rpcCtx,
 		&looprpc.ServerLoopInQuoteRequest{
-			Amt: uint64(amt),
+			Amt:             uint64(amt),
+			ProtocolVersion: protocolVersion,
 		},
 	)
 	if err != nil {
@@ -181,6 +191,7 @@ func (s *grpcSwapServerClient) NewLoopOutSwap(ctx context.Context,
 			Amt:                     uint64(amount),
 			ReceiverKey:             receiverKey[:],
 			SwapPublicationDeadline: swapPublicationDeadline.Unix(),
+			ProtocolVersion:         protocolVersion,
 		},
 	)
 	if err != nil {
@@ -212,10 +223,11 @@ func (s *grpcSwapServerClient) NewLoopInSwap(ctx context.Context,
 	defer rpcCancel()
 
 	req := &looprpc.ServerLoopInRequest{
-		SwapHash:    swapHash[:],
+		SwapHash:        swapHash[:],
-		Amt:         uint64(amount),
+		Amt:             uint64(amount),
-		SenderKey:   senderKey[:],
+		SenderKey:       senderKey[:],
-		SwapInvoice: swapInvoice,
+		SwapInvoice:     swapInvoice,
+		ProtocolVersion: protocolVersion,
 	}
 	if lastHop != nil {
 		req.LastHop = lastHop[:]