config: introduce new flags to accept/reject non-std transactions

This commit adds two new cli flags: one for accepting non-std
transactions, and the other for rejecting non-std transactions.

The two flag are rejected when using concurrently. Config parsing is
set up such that, the desired policy expressed via the config always
overrides the policy set by default for a particular chain.

The doc.go files and the sample-btcd.conf file have been updated to document
the new flags exposing further policy control.

config.go

@@ -141,6 +141,8 @@ type config struct {
 	DropTxIndex        bool          `long:"droptxindex" description:"Deletes the hash-based transaction index from the database on start up and then exits."`
 	AddrIndex          bool          `long:"addrindex" description:"Maintain a full address-based transaction index which makes the searchrawtransactions RPC available"`
 	DropAddrIndex      bool          `long:"dropaddrindex" description:"Deletes the address-based transaction index from the database on start up and then exits."`
+	RelayNonStd        bool          `long:"relaynonstd" description:"Relay non-standard transactions regardless of the default settings for the active network."`
+	RejectNonStd       bool          `long:"rejectnonstd" description:"Reject non-standard transactions regardless of the default settings for the active network."`
 	onionlookup        func(string) ([]net.IP, error)
 	lookup             func(string) ([]net.IP, error)
 	oniondial          func(string, string) (net.Conn, error)
@@ -479,6 +481,26 @@ func loadConfig() (*config, []string, error) {
 		return nil, nil, err
 	}
 
+	// Set the default policy for relaying non-standard transactions
+	// according to the default of the active network. The set
+	// configuration value takes precedence over the default value for the
+	// selected network.
+	relayNonStd := activeNetParams.RelayNonStdTxs
+	switch {
+	case cfg.RelayNonStd && cfg.RejectNonStd:
+		str := "%s: rejectnonstd and relaynonstd cannot be used " +
+			"together -- choose only one"
+		err := fmt.Errorf(str, funcName)
+		fmt.Fprintln(os.Stderr, err)
+		fmt.Fprintln(os.Stderr, usageMessage)
+		return nil, nil, err
+	case cfg.RejectNonStd:
+		relayNonStd = false
+	case cfg.RelayNonStd:
+		relayNonStd = true
+	}
+	cfg.RelayNonStd = relayNonStd
+
 	// Append the network type to the data directory so it is "namespaced"
 	// per network.  In addition to the block database, there are other
 	// pieces of data that are saved to disk such as address manager state.

doc.go

@@ -108,6 +108,10 @@ Application Options:
       --sigcachemaxsize=    The maximum number of entries in the signature
                             verification cache.
       --blocksonly          Do not accept transactions from remote peers.
+      --relaynonstd         Relay non-standard transactions regardless of the
+                            default settings for the active network.
+      --rejectnonstd        Reject non-standard transactions regardless of the
+                            default settings for the active network.
 
 Help Options:
   -h, --help           Show this help message

sample-btcd.conf

@@ -238,6 +238,12 @@
 ; Do not accept transactions from remote peers.
 ; blocksonly=1
 
+; Relay non-standard transactions regardless of default network settings.
+; relaynonstd=1
+
+; Reject non-standard transactions regardless of default network settings.
+; rejectnonstd=1
+
 
 ; ------------------------------------------------------------------------------
 ; Optional Transaction Indexes

server.go

@@ -2519,7 +2519,7 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 	txC := mempool.Config{
 		Policy: mempool.Policy{
 			DisableRelayPriority: cfg.NoRelayPriority,
-			RelayNonStd:          chainParams.RelayNonStdTxs,
+			RelayNonStd:          cfg.RelayNonStd,
 			FreeTxRelayLimit:     cfg.FreeTxRelayLimit,
 			MaxOrphanTxs:         cfg.MaxOrphanTxs,
 			MaxOrphanTxSize:      defaultMaxOrphanTxSize,