sampleconfig: Use embed with external files.

This updates the sampleconfig package to make use of Go's embed
functionality introduced in Go 1.16 which is acceptable since the
containing module requires Go 1.19.

Embedded files are preferable because they bring the benefits of both
external files in the repository that are easier to work with for
external tools and the ability to access their content programmatically
without having to deal with the various issues typically brought about
by programmatically accessing external files.

Also, when this was last updated to change the exported variable for
dcrd's sample config file over to a function (so it can't be mutated and
the implementation details can be changed if needed), the case for
dcrctl was missed.  Moreover, the existence of both configs makes the
func name FileContents ambiguous.

Unfortunately, those things can't be changed now without causing a major
module version bump to the main dcrd module which we really want to
avoid.

So, in order to address those things without needing a major module
version bump, this deprecates the FileContents func and
DcrctlSampleConfig variable and introduces two new functions named Dcrd
and Dcrctl that return the respective embedded sample configs.

config.go

@@ -472,7 +472,7 @@ func createDefaultConfigFile(destPath string, authType string) error {
 		return err
 	}
 
-	cfg := sampleconfig.FileContents()
+	cfg := sampleconfig.Dcrd()
 
 	// Set a randomized rpcuser and rpcpass if the authorization type is basic.
 	if authType == authTypeBasic {

sampleconfig/sample-dcrctl.conf

@@ -0,0 +1,39 @@
+[Application Options]
+
+; ------------------------------------------------------------------------------
+; Network settings
+; ------------------------------------------------------------------------------
+
+; Use testnet (cannot be used with simnet=1).
+; testnet=1
+
+; Use simnet (cannot be used with testnet=1).
+; simnet=1
+
+; The duration of inactivity before a peer is timed out.
+; Valid time units are {s,m,h}. Minimum 15 seconds.
+; peeridletimeout=120s
+
+
+; ------------------------------------------------------------------------------
+; RPC client settings
+; ------------------------------------------------------------------------------
+
+; Connect via a SOCKS5 proxy.
+; proxy=127.0.0.1:9050
+; proxyuser=
+; proxypass=
+
+; Username and password to authenticate connections to a Decred RPC server
+; (usually dcrd or dcrwallet)
+; rpcuser=
+; rpcpass=
+
+; RPC server to connect to
+; rpcserver=localhost
+
+; Wallet RPC server to connect to
+; walletrpcserver=localhost
+
+; RPC server certificate chain file for validation
+; rpccert=~/.dcrd/rpc.cert

sampleconfig/sample-dcrd.conf

@@ -0,0 +1,346 @@
+[Application Options]
+
+; ------------------------------------------------------------------------------
+; Data settings
+; ------------------------------------------------------------------------------
+
+; The directory to store data such as the block chain and peer addresses.  The
+; block chain takes several GB, so this location must have a lot of free space.
+; The default is ~/.dcrd/data on POSIX OSes, $LOCALAPPDATA/Dcrd/data on Windows,
+; ~/Library/Application Support/Dcrd/data on macOS, and $homed/dcrd/data on
+; Plan9.  Environment variables are expanded so they may be used.  NOTE: Windows
+; environment variables are typically %VARIABLE%, but they must be accessed with
+; $VARIABLE here.
+; datadir=~/.dcrd/data                            ; Unix
+; datadir=$LOCALAPPDATA/Dcrd/data                 ; Windows
+; datadir=~/Library/Application Support/Dcrd/data ; macOS
+
+
+; ------------------------------------------------------------------------------
+; Network settings
+; ------------------------------------------------------------------------------
+
+; Use testnet.
+; testnet=1
+
+; Use simnet.
+; simnet=1
+
+; Change how long to wait for TCP connection completion.  Valid time units are
+; {s, m, h}.  Minimum 1 second".
+; dialtimeout=30s
+
+; Connect via a SOCKS5 proxy.  NOTE: Specifying a proxy will disable listening
+; for incoming connections unless listen addresses are provided via the 'listen'
+; option.
+; proxy=127.0.0.1:9050
+; proxyuser=
+; proxypass=
+
+; The SOCKS5 proxy above is assumed to be Tor (https://www.torproject.org).
+; If the proxy is not tor, the following may be used to prevent using
+; tor specific SOCKS queries to lookup addresses (this increases anonymity when
+; tor is used by preventing your IP being leaked via DNS).
+; noonion=1
+
+; Use an alternative proxy to connect to .onion addresses. The proxy is assumed
+; to be a Tor node. Non .onion addresses will be contacted with the main proxy
+; or without a proxy if none is set.
+; onion=127.0.0.1:9051
+; onionuser=
+; onionpass=
+
+; Enable Tor stream isolation by randomizing proxy user credentials resulting in
+; Tor creating a new circuit for each connection.  This makes it more difficult
+; to correlate connections.
+; torisolation=1
+
+; Use Universal Plug and Play (UPnP) to automatically open the listen port
+; and obtain the external IP address from supported devices.  NOTE: This option
+; will have no effect if external IP addresses are specified.
+; upnp=1
+
+; Specify the external IP addresses your node is listening on.  One address per
+; line.  dcrd will not contact 3rd-party sites to obtain external ip addresses.
+; This means if you are behind NAT, your node will not be able to advertise a
+; reachable address unless you specify it here or enable the 'upnp' option (and
+; have a supported device).
+; externalip=1.2.3.4
+; externalip=2002::1234
+
+; ******************************************************************************
+; Summary of 'addpeer' versus 'connect'.
+;
+; Only one of the following two options, 'addpeer' and 'connect', may be
+; specified.  Both allow you to specify peers that you want to stay connected
+; with, but the behavior is slightly different.  By default, dcrd will query DNS
+; to find peers to connect to, so unless you have a specific reason such as
+; those described below, you probably won't need to modify anything here.
+;
+; 'addpeer' does not prevent connections to other peers discovered from
+; the peers you are connected to and also lets the remote peers know you are
+; available so they can notify other peers they can to connect to you.  This
+; option might be useful if you are having problems finding a node for some
+; reason (perhaps due to a firewall).
+;
+; 'connect', on the other hand, will ONLY connect to the specified peers and
+; no others.  It also disables listening (unless you explicitly set listen
+; addresses via the 'listen' option) and DNS seeding, so you will not be
+; advertised as an available peer to the peers you connect to and won't accept
+; connections from any other peers.  So, the 'connect' option effectively allows
+; you to only connect to "trusted" peers.
+; ******************************************************************************
+
+; Add persistent peers to connect to as desired.  One peer per line.
+; You may specify each IP address with or without a port.  The default port will
+; be added automatically if one is not specified here.
+; addpeer=192.168.1.1
+; addpeer=10.0.0.2:9108
+; addpeer=fe80::1
+; addpeer=[fe80::2]:9108
+
+; Add persistent peers that you ONLY want to connect to as desired.  One peer
+; per line.  You may specify each IP address with or without a port.  The
+; default port will be added automatically if one is not specified here.
+; NOTE: Specifying this option has other side effects as described above in
+; the 'addpeer' versus 'connect' summary section.
+; connect=192.168.1.1
+; connect=10.0.0.2:9108
+; connect=fe80::1
+; connect=[fe80::2]:9108
+
+; Maximum number of inbound and outbound peers.
+; maxpeers=8
+
+; Disable banning of misbehaving peers.
+; nobanning=1
+
+; Maximum allowed ban score before disconnecting and banning misbehaving peers.
+; banthreshold=100
+
+; How long to ban misbehaving peers. Valid time units are {s, m, h}.
+; Minimum 1s.
+; banduration=24h
+; banduration=11h30m15s
+
+; Add whitelisted IP networks and IPs. Connected peers whose IP matches a
+; whitelist will not have their ban score increased.
+; whitelist=127.0.0.1
+; whitelist=::1
+; whitelist=192.168.0.0/24
+; whitelist=fd00::/16
+
+; Disable seeding for peer discovery.  By default, when dcrd starts, it will use
+; HTTPS to query for available peers to connect with.
+; noseeders=1
+
+; Specify the interfaces to listen on.  One listen address per line.
+; NOTE: The default port is modified by some options such as 'testnet', so it is
+; recommended to not specify a port and allow a proper default to be chosen
+; unless you have a specific reason to do otherwise.
+; All interfaces on default port (this is the default):
+;  listen=
+; All ipv4 interfaces on default port:
+;  listen=0.0.0.0
+; All ipv6 interfaces on default port:
+;   listen=::
+; All interfaces on port 9108:
+;   listen=:9108
+; All ipv4 interfaces on port 9108:
+;   listen=0.0.0.0:9108
+; All ipv6 interfaces on port 9108:
+;   listen=[::]:9108
+; Only ipv4 localhost on port 9108:
+;   listen=127.0.0.1:9108
+; Only ipv6 localhost on port 9108:
+;   listen=[::1]:9108
+; Only ipv4 localhost on non-standard port 8336:
+;   listen=127.0.0.1:8336
+; All interfaces on non-standard port 8336:
+;   listen=:8336
+; All ipv4 interfaces on non-standard port 8336:
+;   listen=0.0.0.0:8336
+; All ipv6 interfaces on non-standard port 8336:
+;   listen=[::]:8336
+
+; Disable listening for incoming connections.  This will override all listeners.
+; nolisten=1
+
+
+; ------------------------------------------------------------------------------
+; RPC server options - The following options control the built-in RPC server
+; which is used to control and query information from a running dcrd process.
+;
+; NOTE: The RPC server is disabled by default if no rpcuser or rpcpass is
+; specified.
+; ------------------------------------------------------------------------------
+
+; Secure the RPC API by specifying the username and password if the 
+; authorization type is basic. You must specify both if so or the RPC 
+; server will be disabled.
+; rpcuser=whatever_username_you_want
+; rpcpass=
+
+; Specify the interfaces for the RPC server listen on.  One listen address per
+; line.  NOTE: The default port is modified by some options such as 'testnet',
+; so it is recommended to not specify a port and allow a proper default to be
+; chosen unless you have a specific reason to do otherwise.  By default, the
+; RPC server will only listen on localhost for IPv4 and IPv6.
+; All interfaces on default port:
+;   rpclisten=
+; All ipv4 interfaces on default port:
+;   rpclisten=0.0.0.0
+; All ipv6 interfaces on default port:
+;   rpclisten=::
+; All interfaces on port 9109:
+;   rpclisten=:9109
+; All ipv4 interfaces on port 9109:
+;   rpclisten=0.0.0.0:9109
+; All ipv6 interfaces on port 9109:
+;   rpclisten=[::]:9109
+; Only ipv4 localhost on port 9109:
+;   rpclisten=127.0.0.1:9109
+; Only ipv6 localhost on port 9109:
+;   rpclisten=[::1]:9109
+; Only ipv4 localhost on non-standard port 8337:
+;   rpclisten=127.0.0.1:8337
+; All interfaces on non-standard port 8337:
+;   rpclisten=:8337
+; All ipv4 interfaces on non-standard port 8337:
+;   rpclisten=0.0.0.0:8337
+; All ipv6 interfaces on non-standard port 8337:
+;   rpclisten=[::]:8337
+
+; Specify the maximum number of concurrent RPC clients for standard connections.
+; rpcmaxclients=10
+
+; Specify the maximum number of concurrent RPC websocket clients.
+; rpcmaxwebsockets=25
+
+; Use the following setting to disable the RPC server even if the rpcuser and
+; rpcpass are specified above.  This allows one to quickly disable the RPC
+; server without having to remove credentials from the config file.
+; norpc=1
+
+; Specify the curve to use when generating TLS keypairs for the rpc endpoint.
+; Note that after changing this the rpccert/rpckey files need to be deleted so
+; that they are recreated with the new curve.
+;
+; Supported curves: P-521, P-256.
+; tlscurve=P-521
+
+
+; ------------------------------------------------------------------------------
+; Mempool Settings
+; ------------------------------------------------------------------------------
+
+; Set the minimum transaction fee to be considered a non-zero fee,
+; minrelaytxfee=0.0001
+
+; Limit orphan transaction pool to 100 transactions.
+; maxorphantx=100
+
+; Do not accept transactions from remote peers.
+; blocksonly=1
+
+; Accept and relay non-standard transactions to the network regardless of the
+; default network settings.
+; acceptnonstd=1
+
+; Reject non-standard transactions regardless of default network settings.
+; rejectnonstd=1
+
+
+; ------------------------------------------------------------------------------
+; Optional Indexes
+; ------------------------------------------------------------------------------
+
+; Build and maintain a full hash-based transaction index which makes all
+; transactions available via the getrawtransaction RPC.
+; txindex=1
+
+
+; ------------------------------------------------------------------------------
+; Signature Verification Cache
+; ------------------------------------------------------------------------------
+
+; Limit the signature cache to a max of 50000 entries.
+; sigcachemaxsize=50000
+
+; ------------------------------------------------------------------------------
+; Unspent Transaction Output (UTXO) Cache
+; ------------------------------------------------------------------------------
+
+; Limit the utxo cache to a max of 100 MiB.
+; utxocachemaxsize=150
+
+; ------------------------------------------------------------------------------
+; Coin Generation (Mining) Settings - The following options control the
+; generation of block templates used by external mining applications through RPC
+; calls as well as the built-in CPU miner (if enabled).
+; ------------------------------------------------------------------------------
+
+; Enable built-in CPU mining.
+;
+; NOTE: This is typically only useful for testing purposes such as testnet or
+; simnet since the difficulty on mainnet is far too high for CPU mining to be
+; worth your while.
+; generate=false
+
+; Add addresses to pay mined blocks to for CPU mining and the block templates
+; generated for the getwork RPC as desired.  One address per line.
+; miningaddr=youraddress
+; miningaddr=youraddress2
+; miningaddr=youraddress3
+
+; Specify the maximum block size in bytes to create.  This value will be limited
+; to the consensus limit.
+; blockmaxsize=375000
+
+; Allow block templates to be generated even when the chain is not considered
+; synced and there are no connections to other nodes on networks other than the
+; main network.  Specifying this option with the main network will result in a
+; configuration parse error.  This option is automatically enabled when the
+; simulation network is active.
+;
+; NOTE: This is an advanced option and should not be used unless you understand
+; exactly why it exists and what implications it carries.
+; allowunsyncedmining=0
+
+; ------------------------------------------------------------------------------
+; Logging
+; ------------------------------------------------------------------------------
+
+; Log directory.
+; logdir=~/.dcrd/logs
+
+; Size of log file before it is rotated and compressed.
+; logsize=10M
+
+; Disable application file logging entirely and log exclusively to standard
+; output.
+; nofilelogging=false
+
+; Log verbosity.
+; Valid levels are {trace, debug, info, warn, error, critical}
+; You may also specify <subsystem>=<level>,<subsystem2>=<level>,... to set
+; log level for individual subsystems.  Use dcrd --debuglevel=show to list
+; available subsystems.
+; debuglevel=info
+
+; ------------------------------------------------------------------------------
+; Profile - enable the HTTP profiler
+; ------------------------------------------------------------------------------
+
+; The profile server will be disabled if this option is not specified.  Profile
+; information can be accessed at http://ipaddr:<profileport>/debug/pprof once
+; running.  Note that the IP address will default to 127.0.0.1 if an IP address
+; is not specified, so that the profiler is not accessible on the network.
+; Listen on selected port on localhost only:
+;   profile=6061
+; Listen on selected port on all network interfaces:
+;   profile=:6061
+; Listen on single network ipv4 interface:
+;   profile=192.168.1.123:6061
+; Listen on ipv6 loopback interface:
+;   profile=[::1]:6061