1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
//! Tendermint configuration file types (with serde parsers/serializers)
//!
//! This module contains types which correspond to the following config files:
//!
//! - `config.toml`: `config::TendermintConfig`
//! - `node_key.rs`: `config::node_key::NodeKey`
//! - `priv_validator_key.rs`: `config::priv_validator_key::PrivValidatorKey`

mod node_key;
mod priv_validator_key;

pub use self::{node_key::NodeKey, priv_validator_key::PrivValidatorKey};

use crate::{
    error::{Error, Kind},
    genesis::Genesis,
    net, node, Moniker, Timeout,
};
use anomaly::{fail, format_err};
use serde::{de, de::Error as _, ser, Deserialize, Serialize};
use std::{
    collections::BTreeMap,
    fmt, fs,
    path::{Path, PathBuf},
    str::FromStr,
};

/// Tendermint `config.toml` file
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct TendermintConfig {
    /// TCP or UNIX socket address of the ABCI application,
    /// or the name of an ABCI application compiled in with the Tendermint binary.
    pub proxy_app: net::Address,

    /// A custom human readable name for this node
    pub moniker: Moniker,

    /// If this node is many blocks behind the tip of the chain, FastSync
    /// allows them to catchup quickly by downloading blocks in parallel
    /// and verifying their commits
    pub fast_sync: bool,

    /// Database backend: `goleveldb | cleveldb | boltdb | rocksdb | badgerdb`
    pub db_backend: DbBackend,

    /// Database directory
    pub db_dir: PathBuf,

    /// Output level for logging, including package level options
    pub log_level: LogLevel,

    /// Output format: 'plain' (colored text) or 'json'
    pub log_format: LogFormat,

    /// Path to the JSON file containing the initial validator set and other meta data
    pub genesis_file: PathBuf,

    /// Path to the JSON file containing the private key to use as a validator in the consensus
    /// protocol
    pub priv_validator_key_file: Option<PathBuf>,

    /// Path to the JSON file containing the last sign state of a validator
    pub priv_validator_state_file: PathBuf,

    /// TCP or UNIX socket address for Tendermint to listen on for
    /// connections from an external PrivValidator process
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub priv_validator_laddr: Option<net::Address>,

    /// Path to the JSON file containing the private key to use for node authentication in the p2p
    /// protocol
    pub node_key_file: PathBuf,

    /// Mechanism to connect to the ABCI application: socket | grpc
    pub abci: AbciMode,

    /// If `true`, query the ABCI app on connecting to a new peer
    /// so the app can decide if we should keep the connection or not
    pub filter_peers: bool,

    /// rpc server configuration options
    pub rpc: RpcConfig,

    /// peer to peer configuration options
    pub p2p: P2PConfig,

    /// mempool configuration options
    pub mempool: MempoolConfig,

    /// consensus configuration options
    pub consensus: ConsensusConfig,

    /// transactions indexer configuration options
    pub tx_index: TxIndexConfig,

    /// instrumentation configuration options
    pub instrumentation: InstrumentationConfig,

    /// statesync configuration options
    pub statesync: StatesyncConfig,

    /// fastsync configuration options
    pub fastsync: FastsyncConfig,
}

impl TendermintConfig {
    /// Parse Tendermint `config.toml`
    pub fn parse_toml<T: AsRef<str>>(toml_string: T) -> Result<Self, Error> {
        Ok(toml::from_str(toml_string.as_ref())?)
    }

    /// Load `config.toml` from a file
    pub fn load_toml_file<P>(path: &P) -> Result<Self, Error>
    where
        P: AsRef<Path>,
    {
        let toml_string = fs::read_to_string(path).map_err(|e| {
            format_err!(
                Kind::Parse,
                "couldn't open {}: {}",
                path.as_ref().display(),
                e
            )
        })?;

        Self::parse_toml(toml_string)
    }

    /// Load `genesis.json` file from the configured location
    pub fn load_genesis_file(&self, home: impl AsRef<Path>) -> Result<Genesis, Error> {
        let path = home.as_ref().join(&self.genesis_file);
        let genesis_json = fs::read_to_string(&path)
            .map_err(|e| format_err!(Kind::Parse, "couldn't open {}: {}", path.display(), e))?;

        Ok(serde_json::from_str(genesis_json.as_ref())?)
    }

    /// Load `node_key.json` file from the configured location
    pub fn load_node_key(&self, home: impl AsRef<Path>) -> Result<NodeKey, Error> {
        let path = home.as_ref().join(&self.node_key_file);
        NodeKey::load_json_file(&path)
    }
}

/// Database backend
#[derive(Copy, Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
pub enum DbBackend {
    /// GoLevelDB backend
    #[serde(rename = "goleveldb")]
    GoLevelDb,

    /// CLevelDB backend
    #[serde(rename = "cleveldb")]
    CLevelDb,

    /// BoltDB backend
    #[serde(rename = "boltdb")]
    BoltDb,

    /// RocksDB backend
    #[serde(rename = "rocksdb")]
    RocksDb,

    /// BadgerDB backend
    #[serde(rename = "badgerdb")]
    BadgerDb,
}

/// Loglevel configuration
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct LogLevel {
    /// A global log level
    pub global: Option<String>,
    components: BTreeMap<String, String>,
}

impl LogLevel {
    /// Get the setting for the given key. If not found, returns the global setting, if any.
    pub fn get<S>(&self, key: S) -> Option<&str>
    where
        S: AsRef<str>,
    {
        self.components
            .get(key.as_ref())
            .or_else(|| self.global.as_ref())
            .map(AsRef::as_ref)
    }

    /// Iterate over the levels. This doesn't include the global setting, if any.
    pub fn iter(&self) -> LogLevelIter<'_> {
        self.components.iter()
    }
}

/// Iterator over log levels
pub type LogLevelIter<'a> = std::collections::btree_map::Iter<'a, String, String>;

impl FromStr for LogLevel {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut global = None;
        let mut components = BTreeMap::new();

        for level in s.split(',') {
            let parts = level.split(':').collect::<Vec<_>>();

            if parts.len() == 1 {
                global = Some(parts[0].to_owned());
                continue;
            } else if parts.len() != 2 {
                fail!(Kind::Parse, "error parsing log level: {}", level);
            }

            let key = parts[0].to_owned();
            let value = parts[1].to_owned();

            if components.insert(key, value).is_some() {
                fail!(Kind::Parse, "duplicate log level setting for: {}", level);
            }
        }

        Ok(LogLevel { global, components })
    }
}

impl fmt::Display for LogLevel {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if let Some(global) = &self.global {
            write!(f, "{}", global)?;
            if !self.components.is_empty() {
                write!(f, ",")?;
            }
        }
        for (i, (k, v)) in self.components.iter().enumerate() {
            write!(f, "{}:{}", k, v)?;

            if i < self.components.len() - 1 {
                write!(f, ",")?;
            }
        }

        Ok(())
    }
}

impl<'de> Deserialize<'de> for LogLevel {
    fn deserialize<D: de::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
        let levels = String::deserialize(deserializer)?;
        Self::from_str(&levels).map_err(|e| D::Error::custom(format!("{}", e)))
    }
}

impl Serialize for LogLevel {
    fn serialize<S: ser::Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> {
        self.to_string().serialize(serializer)
    }
}

/// Logging format
#[derive(Copy, Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
pub enum LogFormat {
    /// Plain (colored text)
    #[serde(rename = "plain")]
    Plain,

    /// JSON
    #[serde(rename = "json")]
    Json,
}

/// Mechanism to connect to the ABCI application: socket | grpc
#[derive(Copy, Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
pub enum AbciMode {
    /// Socket
    #[serde(rename = "socket")]
    Socket,

    /// GRPC
    #[serde(rename = "grpc")]
    Grpc,
}

/// Tendermint `config.toml` file's `[rpc]` section
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct RpcConfig {
    /// TCP or UNIX socket address for the RPC server to listen on
    pub laddr: net::Address,

    /// A list of origins a cross-domain request can be executed from
    /// Default value `[]` disables cors support
    /// Use `["*"]` to allow any origin
    pub cors_allowed_origins: Vec<CorsOrigin>,

    /// A list of methods the client is allowed to use with cross-domain requests
    pub cors_allowed_methods: Vec<CorsMethod>,

    /// A list of non simple headers the client is allowed to use with cross-domain requests
    pub cors_allowed_headers: Vec<CorsHeader>,

    /// TCP or UNIX socket address for the gRPC server to listen on
    /// NOTE: This server only supports `/broadcast_tx_commit`
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub grpc_laddr: Option<net::Address>,

    /// Maximum number of simultaneous GRPC connections.
    /// Does not include RPC (HTTP&WebSocket) connections. See `max_open_connections`.
    pub grpc_max_open_connections: u64,

    /// Activate unsafe RPC commands like `/dial_seeds` and `/unsafe_flush_mempool`
    #[serde(rename = "unsafe")]
    pub unsafe_commands: bool,

    /// Maximum number of simultaneous connections (including WebSocket).
    /// Does not include gRPC connections. See `grpc_max_open_connections`.
    pub max_open_connections: u64,

    /// Maximum number of unique clientIDs that can `/subscribe`.
    pub max_subscription_clients: u64,

    /// Maximum number of unique queries a given client can `/subscribe` to.
    pub max_subscriptions_per_client: u64,

    /// How long to wait for a tx to be committed during `/broadcast_tx_commit`.
    pub timeout_broadcast_tx_commit: Timeout,

    /// Maximum size of request body, in bytes
    pub max_body_bytes: u64,

    /// Maximum size of request header, in bytes
    pub max_header_bytes: u64,

    /// The name of a file containing certificate that is used to create the HTTPS server.
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub tls_cert_file: Option<PathBuf>,

    /// The name of a file containing matching private key that is used to create the HTTPS server.
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub tls_key_file: Option<PathBuf>,

    /// pprof listen address <https://golang.org/pkg/net/http/pprof>
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub pprof_laddr: Option<net::Address>,
}

/// Origin hosts allowed with CORS requests to the RPC API
// TODO(tarcieri): parse and validate this string
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct CorsOrigin(String);

impl AsRef<str> for CorsOrigin {
    fn as_ref(&self) -> &str {
        self.0.as_ref()
    }
}

impl fmt::Display for CorsOrigin {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", &self.0)
    }
}

/// HTTP methods allowed with CORS requests to the RPC API
// TODO(tarcieri): parse and validate this string
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct CorsMethod(String);

impl AsRef<str> for CorsMethod {
    fn as_ref(&self) -> &str {
        self.0.as_ref()
    }
}

impl fmt::Display for CorsMethod {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", &self.0)
    }
}

/// HTTP headers allowed to be sent via CORS to the RPC API
// TODO(tarcieri): parse and validate this string
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct CorsHeader(String);

impl AsRef<str> for CorsHeader {
    fn as_ref(&self) -> &str {
        self.0.as_ref()
    }
}

impl fmt::Display for CorsHeader {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}", &self.0)
    }
}

/// peer to peer configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct P2PConfig {
    /// Address to listen for incoming connections
    pub laddr: net::Address,

    /// Address to advertise to peers for them to dial
    /// If empty, will use the same port as the laddr,
    /// and will introspect on the listener or use UPnP
    /// to figure out the address.
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub external_address: Option<net::Address>,

    /// Comma separated list of seed nodes to connect to
    #[serde(
        serialize_with = "serialize_comma_separated_list",
        deserialize_with = "deserialize_comma_separated_list"
    )]
    pub seeds: Vec<net::Address>,

    /// Comma separated list of nodes to keep persistent connections to
    #[serde(
        serialize_with = "serialize_comma_separated_list",
        deserialize_with = "deserialize_comma_separated_list"
    )]
    pub persistent_peers: Vec<net::Address>,

    /// UPNP port forwarding
    pub upnp: bool,

    /// Path to address book
    pub addr_book_file: PathBuf,

    /// Set `true` for strict address routability rules
    /// Set `false` for private or local networks
    pub addr_book_strict: bool,

    /// Maximum number of inbound peers
    pub max_num_inbound_peers: u64,

    /// Maximum number of outbound peers to connect to, excluding persistent peers
    pub max_num_outbound_peers: u64,

    /// List of node IDs, to which a connection will be (re)established ignoring any existing limits
    #[serde(
        serialize_with = "serialize_comma_separated_list",
        deserialize_with = "deserialize_comma_separated_list"
    )]
    pub unconditional_peer_ids: Vec<node::Id>,

    /// Maximum pause when redialing a persistent peer (if zero, exponential backoff is used)
    pub persistent_peers_max_dial_period: Timeout,

    /// Time to wait before flushing messages out on the connection
    pub flush_throttle_timeout: Timeout,

    /// Maximum size of a message packet payload, in bytes
    pub max_packet_msg_payload_size: u64,

    /// Rate at which packets can be sent, in bytes/second
    pub send_rate: TransferRate,

    /// Rate at which packets can be received, in bytes/second
    pub recv_rate: TransferRate,

    /// Set `true` to enable the peer-exchange reactor
    pub pex: bool,

    /// Seed mode, in which node constantly crawls the network and looks for
    /// peers. If another node asks it for addresses, it responds and disconnects.
    ///
    /// Does not work if the peer-exchange reactor is disabled.
    pub seed_mode: bool,

    /// Comma separated list of peer IDs to keep private (will not be gossiped to other peers)
    #[serde(
        serialize_with = "serialize_comma_separated_list",
        deserialize_with = "deserialize_comma_separated_list"
    )]
    pub private_peer_ids: Vec<node::Id>,

    /// Toggle to disable guard against peers connecting from the same ip.
    pub allow_duplicate_ip: bool,

    /// Handshake timeout
    pub handshake_timeout: Timeout,

    /// Timeout when dialing other peers
    pub dial_timeout: Timeout,
}

/// mempool configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct MempoolConfig {
    /// Recheck enabled
    pub recheck: bool,

    /// Broadcast enabled
    pub broadcast: bool,

    /// WAL dir
    #[serde(
        deserialize_with = "deserialize_optional_value",
        serialize_with = "serialize_optional_value"
    )]
    pub wal_dir: Option<PathBuf>,

    /// Maximum number of transactions in the mempool
    pub size: u64,

    /// Limit the total size of all txs in the mempool.
    /// This only accounts for raw transactions (e.g. given 1MB transactions and
    /// `max_txs_bytes`=5MB, mempool will only accept 5 transactions).
    pub max_txs_bytes: u64,

    /// Size of the cache (used to filter transactions we saw earlier) in transactions
    pub cache_size: u64,

    /// Do not remove invalid transactions from the cache (default: false)
    /// Set to true if it's not possible for any invalid transaction to become valid
    /// again in the future.
    #[serde(rename = "keep-invalid-txs-in-cache")]
    pub keep_invalid_txs_in_cache: bool,

    /// Maximum size of a single transaction.
    /// NOTE: the max size of a tx transmitted over the network is {max-tx-bytes}.
    pub max_tx_bytes: u64,

    /// Maximum size of a batch of transactions to send to a peer
    /// Including space needed by encoding (one varint per transaction).
    /// XXX: Unused due to <https://github.com/tendermint/tendermint/issues/5796>
    pub max_batch_bytes: u64,
}

/// consensus configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct ConsensusConfig {
    /// Path to WAL file
    pub wal_file: PathBuf,

    /// Propose timeout
    pub timeout_propose: Timeout,

    /// Propose timeout delta
    pub timeout_propose_delta: Timeout,

    /// Prevote timeout
    pub timeout_prevote: Timeout,

    /// Prevote timeout delta
    pub timeout_prevote_delta: Timeout,

    /// Precommit timeout
    pub timeout_precommit: Timeout,

    /// Precommit timeout delta
    pub timeout_precommit_delta: Timeout,

    /// Commit timeout
    pub timeout_commit: Timeout,

    /// How many blocks to look back to check existence of the node's consensus votes before joining consensus
    /// When non-zero, the node will panic upon restart
    /// if the same consensus key was used to sign {double-sign-check-height} last blocks.
    /// So, validators should stop the state machine, wait for some blocks, and then restart the state machine to avoid panic.
    pub double_sign_check_height: u64,

    /// Make progress as soon as we have all the precommits (as if TimeoutCommit = 0)
    pub skip_timeout_commit: bool,

    /// EmptyBlocks mode
    pub create_empty_blocks: bool,

    /// Interval between empty blocks
    pub create_empty_blocks_interval: Timeout,

    /// Reactor sleep duration
    pub peer_gossip_sleep_duration: Timeout,

    /// Reactor query sleep duration
    pub peer_query_maj23_sleep_duration: Timeout,
}

/// transactions indexer configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct TxIndexConfig {
    /// What indexer to use for transactions
    #[serde(default)]
    pub indexer: TxIndexer,
}

/// What indexer to use for transactions
#[derive(Copy, Clone, Debug, Deserialize, Eq, Hash, PartialEq, Serialize)]
pub enum TxIndexer {
    /// "null"
    // TODO(tarcieri): use an `Option` type here?
    #[serde(rename = "null")]
    Null,

    /// "kv" (default) - the simplest possible indexer, backed by key-value storage (defaults to
    /// levelDB; see DBBackend).
    #[serde(rename = "kv")]
    Kv,
}

impl Default for TxIndexer {
    fn default() -> TxIndexer {
        TxIndexer::Kv
    }
}

/// instrumentation configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct InstrumentationConfig {
    /// When `true`, Prometheus metrics are served under /metrics on
    /// PrometheusListenAddr.
    pub prometheus: bool,

    /// Address to listen for Prometheus collector(s) connections
    // TODO(tarcieri): parse to `tendermint::net::Addr`
    pub prometheus_listen_addr: String,

    /// Maximum number of simultaneous connections.
    pub max_open_connections: u64,

    /// Instrumentation namespace
    pub namespace: String,
}

/// statesync configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct StatesyncConfig {
    /// State sync rapidly bootstraps a new node by discovering, fetching, and restoring a state machine
    /// snapshot from peers instead of fetching and replaying historical blocks. Requires some peers in
    /// the network to take and serve state machine snapshots. State sync is not attempted if the node
    /// has any local state (LastBlockHeight > 0). The node will have a truncated block history,
    /// starting from the height of the snapshot.
    pub enable: bool,

    /// RPC servers (comma-separated) for light client verification of the synced state machine and
    /// retrieval of state data for node bootstrapping. Also needs a trusted height and corresponding
    /// header hash obtained from a trusted source, and a period during which validators can be trusted.
    ///
    /// For Cosmos SDK-based chains, trust-period should usually be about 2/3 of the unbonding time (~2
    /// weeks) during which they can be financially punished (slashed) for misbehavior.
    #[serde(
        serialize_with = "serialize_comma_separated_list",
        deserialize_with = "deserialize_comma_separated_list"
    )]
    pub rpc_servers: Vec<String>,

    /// Trust height. See `rpc_servers` above.
    pub trust_height: u64,

    /// Trust hash. See `rpc_servers` above.
    pub trust_hash: String,

    /// Trust period. See `rpc_servers` above.
    pub trust_period: String,

    /// Time to spend discovering snapshots before initiating a restore.
    pub discovery_time: Timeout,

    /// Temporary directory for state sync snapshot chunks, defaults to the OS tempdir (typically /tmp).
    /// Will create a new, randomly named directory within, and remove it when done.
    pub temp_dir: String,
}

/// fastsync configuration options
#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct FastsyncConfig {
    /// Fast Sync version to use:
    ///   1) "v0" (default) - the legacy fast sync implementation
    ///   2) "v2" - complete redesign of v0, optimized for testability & readability
    pub version: String,
}

/// Rate at which bytes can be sent/received
#[derive(Copy, Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct TransferRate(u64);

impl TransferRate {
    /// Get the trasfer rate in bytes per second
    pub fn bytes_per_sec(self) -> u64 {
        self.0
    }
}

/// Deserialize `Option<T: FromStr>` where an empty string indicates `None`
fn deserialize_optional_value<'de, D, T, E>(deserializer: D) -> Result<Option<T>, D::Error>
where
    D: de::Deserializer<'de>,
    T: FromStr<Err = E>,
    E: fmt::Display,
{
    let string = Option::<String>::deserialize(deserializer).map(|str| str.unwrap_or_default())?;

    if string.is_empty() {
        return Ok(None);
    }

    string
        .parse()
        .map(Some)
        .map_err(|e| D::Error::custom(format!("{}", e)))
}

fn serialize_optional_value<S, T>(value: &Option<T>, serializer: S) -> Result<S::Ok, S::Error>
where
    S: ser::Serializer,
    T: Serialize,
{
    match value {
        Some(value) => value.serialize(serializer),
        None => "".serialize(serializer),
    }
}

/// Deserialize a comma separated list of types that impl `FromStr` as a `Vec`
fn deserialize_comma_separated_list<'de, D, T, E>(deserializer: D) -> Result<Vec<T>, D::Error>
where
    D: de::Deserializer<'de>,
    T: FromStr<Err = E>,
    E: fmt::Display,
{
    let mut result = vec![];
    let string = String::deserialize(deserializer)?;

    if string.is_empty() {
        return Ok(result);
    }

    for item in string.split(',') {
        result.push(
            item.parse()
                .map_err(|e| D::Error::custom(format!("{}", e)))?,
        );
    }

    Ok(result)
}

/// Serialize a comma separated list types that impl `ToString`
fn serialize_comma_separated_list<S, T>(list: &[T], serializer: S) -> Result<S::Ok, S::Error>
where
    S: ser::Serializer,
    T: ToString,
{
    let str_list = list.iter().map(|addr| addr.to_string()).collect::<Vec<_>>();
    str_list.join(",").serialize(serializer)
}