Disallow increasing O price during the streaming session

server/broadcast.go

@@ -835,6 +835,7 @@ func selectOrchestrator(ctx context.Context, n *core.LivepeerNode, params *core.
 			Balance:           balance,
 			lock:              &sync.RWMutex{},
 			OrchestratorScore: oScore,
+			InitialPrice:      od.RemoteInfo.PriceInfo,
 		}
 
 		sessions = append(sessions, session)

server/rpc.go

@@ -118,6 +118,7 @@ type BroadcastSession struct {
 	OrchestratorOS   drivers.OSSession
 	PMSessionID      string
 	Balance          Balance
+	InitialPrice     *net.PriceInfo
 }
 
 func (bs *BroadcastSession) Transcoder() string {

server/rpc_test.go

@@ -696,7 +696,23 @@ func TestValidatePrice(t *testing.T) {
 	err = validatePrice(s)
 	assert.Nil(err)
 
+	// O Initial Price == O Price
+	s.InitialPrice = oinfo.PriceInfo
+	err = validatePrice(s)
+	assert.Nil(err)
+
+	// O Initial Price higher than O Price
+	s.InitialPrice = &net.PriceInfo{PricePerUnit: 10, PixelsPerUnit: 3}
+	err = validatePrice(s)
+	assert.Nil(err)
+
+	// O Initial Price lower than O Price
+	s.InitialPrice = &net.PriceInfo{PricePerUnit: 1, PixelsPerUnit: 10}
+	err = validatePrice(s)
+	assert.ErrorContains(err, "price has changed")
+
 	// B MaxPrice < O Price
+	s.InitialPrice = nil
 	BroadcastCfg.SetMaxPrice(big.NewRat(1, 5))
 	err = validatePrice(s)
 	assert.EqualError(err, fmt.Sprintf("Orchestrator price higher than the set maximum price of %v wei per %v pixels", int64(1), int64(5)))

server/segment_rpc.go

@@ -864,6 +864,11 @@ func validatePrice(sess *BroadcastSession) error {
 	if maxPrice != nil && oPrice.Cmp(maxPrice) == 1 {
 		return fmt.Errorf("Orchestrator price higher than the set maximum price of %v wei per %v pixels", maxPrice.Num().Int64(), maxPrice.Denom().Int64())
 	}
+	iPrice, err := common.RatPriceInfo(sess.InitialPrice)
+	if err == nil && iPrice != nil && oPrice.Cmp(iPrice) == 1 {
+		return fmt.Errorf("Orchestrator price has changed, Orchestrator price: %v, Orchestrator initial price: %v", oPrice, iPrice)
+	}
+
 	return nil
 }