package core import ( "context" "errors" "fmt" "time" tmpubsub "github.com/tendermint/tendermint/libs/pubsub" tmquery "github.com/tendermint/tendermint/libs/pubsub/query" "github.com/tendermint/tendermint/rpc/coretypes" rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types" ) const ( // Buffer on the Tendermint (server) side to allow some slowness in clients. subBufferSize = 100 // maxQueryLength is the maximum length of a query string that will be // accepted. This is just a safety check to avoid outlandish queries. maxQueryLength = 512 ) // Subscribe for events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/subscribe func (env *Environment) Subscribe(ctx *rpctypes.Context, query string) (*coretypes.ResultSubscribe, error) { addr := ctx.RemoteAddr() if env.EventBus.NumClients() >= env.Config.MaxSubscriptionClients { return nil, fmt.Errorf("max_subscription_clients %d reached", env.Config.MaxSubscriptionClients) } else if env.EventBus.NumClientSubscriptions(addr) >= env.Config.MaxSubscriptionsPerClient { return nil, fmt.Errorf("max_subscriptions_per_client %d reached", env.Config.MaxSubscriptionsPerClient) } else if len(query) > maxQueryLength { return nil, errors.New("maximum query length exceeded") } env.Logger.Info("Subscribe to query", "remote", addr, "query", query) q, err := tmquery.New(query) if err != nil { return nil, fmt.Errorf("failed to parse query: %w", err) } subCtx, cancel := context.WithTimeout(ctx.Context(), SubscribeTimeout) defer cancel() sub, err := env.EventBus.SubscribeWithArgs(subCtx, tmpubsub.SubscribeArgs{ ClientID: addr, Query: q, Limit: subBufferSize, }) if err != nil { return nil, err } // Capture the current ID, since it can change in the future. subscriptionID := ctx.JSONReq.ID go func() { opctx, opcancel := context.WithCancel(context.Background()) defer opcancel() for { msg, err := sub.Next(opctx) if errors.Is(err, tmpubsub.ErrUnsubscribed) { // The subscription was removed by the client. return } else if errors.Is(err, tmpubsub.ErrTerminated) { // The subscription was terminated by the publisher. resp := rpctypes.RPCServerError(subscriptionID, err) ok := ctx.WSConn.TryWriteRPCResponse(opctx, resp) if !ok { env.Logger.Info("Unable to write response (slow client)", "to", addr, "subscriptionID", subscriptionID, "err", err) } return } // We have a message to deliver to the client. resp := rpctypes.NewRPCSuccessResponse(subscriptionID, &coretypes.ResultEvent{ Query: query, Data: msg.Data(), Events: msg.Events(), }) wctx, cancel := context.WithTimeout(opctx, 10*time.Second) err = ctx.WSConn.WriteRPCResponse(wctx, resp) cancel() if err != nil { env.Logger.Info("Unable to write response (slow client)", "to", addr, "subscriptionID", subscriptionID, "err", err) } } }() return &coretypes.ResultSubscribe{}, nil } // Unsubscribe from events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe func (env *Environment) Unsubscribe(ctx *rpctypes.Context, query string) (*coretypes.ResultUnsubscribe, error) { args := tmpubsub.UnsubscribeArgs{Subscriber: ctx.RemoteAddr()} env.Logger.Info("Unsubscribe from query", "remote", args.Subscriber, "subscription", query) var err error args.Query, err = tmquery.New(query) if err != nil { args.ID = query } err = env.EventBus.Unsubscribe(ctx.Context(), args) if err != nil { return nil, err } return &coretypes.ResultUnsubscribe{}, nil } // UnsubscribeAll from all events via WebSocket. // More: https://docs.tendermint.com/master/rpc/#/Websocket/unsubscribe_all func (env *Environment) UnsubscribeAll(ctx *rpctypes.Context) (*coretypes.ResultUnsubscribe, error) { addr := ctx.RemoteAddr() env.Logger.Info("Unsubscribe from all", "remote", addr) err := env.EventBus.UnsubscribeAll(ctx.Context(), addr) if err != nil { return nil, err } return &coretypes.ResultUnsubscribe{}, nil }