feat: add support for custom drip amounts (#23)

* Add support for custom drip amounts

* Minor tidy

* Fix typo

* Revert go mod changes from previous versions

cmd/serve.go

@@ -112,10 +112,10 @@ func (c *faucetCfg) registerRootFlags(fs *flag.FlagSet) {
 	)
 
 	fs.StringVar(
-		&c.config.SendAmount,
+		&c.config.MaxSendAmount,
 		"send-amount",
-		config.DefaultSendAmount,
-		"the static send amount (native currency)",
+		config.DefaultMaxSendAmount,
+		"the static max send amount per drip (native currency)",
 	)
 
 	fs.StringVar(

config/config.go

@@ -11,7 +11,7 @@ import (
 const (
 	DefaultListenAddress = "0.0.0.0:8545"
 	DefaultChainID       = "dev"
-	DefaultSendAmount    = "1000000ugnot"
+	DefaultMaxSendAmount = "1000000ugnot"
 	//nolint:lll // Mnemonic is naturally long
 	DefaultMnemonic    = "source bonus chronic canvas draft south burst lottery vacant surface solve popular case indicate oppose farm nothing bullet exhibit title speed wink action roast"
 	DefaultNumAccounts = uint64(1)
@@ -45,9 +45,9 @@ type Config struct {
 	// The mnemonic for the faucet
 	Mnemonic string `toml:"mnemonic"`
 
-	// The static send amount (native currency).
+	// The static max send amount (native currency).
 	// Format should be: <AMOUNT>ugnot
-	SendAmount string `toml:"send_amount"`
+	MaxSendAmount string `toml:"send_amount"`
 
 	// The number of faucet accounts,
 	// based on the mnemonic (account 0, index x)
@@ -59,7 +59,7 @@ func DefaultConfig() *Config {
 	return &Config{
 		ListenAddress: DefaultListenAddress,
 		ChainID:       DefaultChainID,
-		SendAmount:    DefaultSendAmount,
+		MaxSendAmount: DefaultMaxSendAmount,
 		Mnemonic:      DefaultMnemonic,
 		NumAccounts:   DefaultNumAccounts,
 		CORSConfig:    DefaultCORSConfig(),
@@ -79,7 +79,7 @@ func ValidateConfig(config *Config) error {
 	}
 
 	// validate the send amount
-	if !amountRegex.MatchString(config.SendAmount) {
+	if !amountRegex.MatchString(config.MaxSendAmount) {
 		return ErrInvalidSendAmount
 	}
 

config/config_test.go

@@ -31,7 +31,7 @@ func TestConfig_ValidateConfig(t *testing.T) {
 		t.Parallel()
 
 		cfg := DefaultConfig()
-		cfg.SendAmount = "1000goo" // invalid denom
+		cfg.MaxSendAmount = "1000goo" // invalid denom
 
 		assert.ErrorIs(t, ValidateConfig(cfg), ErrInvalidSendAmount)
 	})

faucet.go

@@ -35,7 +35,7 @@ type Faucet struct {
 	handlers       []Handler          // request handlers
 	prepareTxMsgFn PrepareTxMessageFn // transaction message creator
 
-	sendAmount std.Coins // for fast lookup
+	maxSendAmount std.Coins // the max send amount per drip
 }
 
 var noopLogger = slog.New(slog.NewTextHandler(io.Discard, nil))
@@ -76,8 +76,8 @@ func NewFaucet(
 	}
 
 	// Set the send amount
-	//nolint:errcheck // SendAmount is validated beforehand
-	f.sendAmount, _ = std.ParseCoins(f.config.SendAmount)
+	//nolint:errcheck // MaxSendAmount is validated beforehand
+	f.maxSendAmount, _ = std.ParseCoins(f.config.MaxSendAmount)
 
 	// Generate the in-memory keyring
 	f.keyring = memory.New(f.config.Mnemonic, f.config.NumAccounts)

go.mod

@@ -3,12 +3,12 @@ module github.com/gnolang/faucet
 go 1.21
 
 require (
-	github.com/gnolang/gno v0.0.0-20240308113041-45c8f900a1a3
+	github.com/gnolang/gno v0.0.0-20240313211052-3481a03c98bc
 	github.com/go-chi/chi/v5 v5.0.12
 	github.com/pelletier/go-toml v1.9.5
 	github.com/peterbourgon/ff/v3 v3.4.0
 	github.com/rs/cors v1.10.1
-	github.com/stretchr/testify v1.9.0
+	github.com/stretchr/testify v1.8.4
 	golang.org/x/sync v0.6.0
 )
 
@@ -22,8 +22,8 @@ require (
 	github.com/gorilla/websocket v1.5.1 // indirect
 	github.com/jaekwon/testify v1.6.1 // indirect
 	github.com/kr/pretty v0.1.0 // indirect
+	github.com/kr/text v0.2.0 // indirect
 	github.com/libp2p/go-buffer-pool v0.1.0 // indirect
-	github.com/linxGnu/grocksdb v1.8.4 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/crypto v0.19.0 // indirect
 	golang.org/x/exp v0.0.0-20240222234643-814bf88cf225 // indirect

go.sum

@@ -28,6 +28,7 @@ github.com/btcsuite/websocket v0.0.0-20150119174127-31079b680792/go.mod h1:ghJtE
 github.com/btcsuite/winsvc v1.0.0/go.mod h1:jsenWakMcC0zFBFurPLEAyrnc/teJEM1O46fmI40EZs=
 github.com/cockroachdb/apd/v3 v3.2.1 h1:U+8j7t0axsIgvQUqthuNm82HIrYXodOV2iWLWtEaIwg=
 github.com/cockroachdb/apd/v3 v3.2.1/go.mod h1:klXJcjp+FffLTHlhIG69tezTDvdP065naDsHzKhYSqc=
+github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
 github.com/davecgh/go-spew v0.0.0-20171005155431-ecdeabc65495/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -43,8 +44,8 @@ github.com/fortytw2/leaktest v1.3.0 h1:u8491cBMTQ8ft8aeV+adlcytMZylmA5nnwwkRZjI8
 github.com/fortytw2/leaktest v1.3.0/go.mod h1:jDsjWgpAGjm2CA7WthBh/CdZYEPF31XHquHwclZch5g=
 github.com/fsnotify/fsnotify v1.4.7/go.mod h1:jwhsz4b93w/PPRr/qN1Yymfu8t87LnFCMoQvtojpjFo=
 github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4IgpuI1SZQ=
-github.com/gnolang/gno v0.0.0-20240308113041-45c8f900a1a3 h1:jD9i4n582op16xHU7aKPtp3Oo7rJ8Q5+jpR6nE/ad6U=
-github.com/gnolang/gno v0.0.0-20240308113041-45c8f900a1a3/go.mod h1:jDARzJA+/H5YwCGpWuouqo4D0LMSNZVVgFQK/r/R7As=
+github.com/gnolang/gno v0.0.0-20240313211052-3481a03c98bc h1:aYkkNfumtt9z8DeI7ZiFC+vMgFFadaGY0A97pXpOqZU=
+github.com/gnolang/gno v0.0.0-20240313211052-3481a03c98bc/go.mod h1:jDARzJA+/H5YwCGpWuouqo4D0LMSNZVVgFQK/r/R7As=
 github.com/gnolang/goleveldb v0.0.9 h1:Q7rGko9oXMKtQA+Apeeed5a3sjba/mcDhzJGoTVLCKE=
 github.com/gnolang/goleveldb v0.0.9/go.mod h1:Dz6p9bmpy/FBESTgduiThZt5mToVDipcHGzj/zUOo8E=
 github.com/gnolang/overflow v0.0.0-20170615021017-4d914c927216 h1:GKvsK3oLWG9B1GL7WP/VqwM6C92j5tIvB844oggL9Lk=
@@ -83,14 +84,15 @@ github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23/go.mod h1:J+Gs4SYgM6
 github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
-github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
+github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
 github.com/lib/pq v1.10.7 h1:p7ZhMD+KsSRozJr34udlUrhboJwWAgCg34+/ZZNvZZw=
 github.com/lib/pq v1.10.7/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/libp2p/go-buffer-pool v0.1.0 h1:oK4mSFcQz7cTQIfqbe4MIj9gLW+mnanjyFtc6cdF0Y8=
 github.com/libp2p/go-buffer-pool v0.1.0/go.mod h1:N+vh8gMqimBzdKkSMVuydVDq+UV5QTWy5HSiZacSbPg=
-github.com/linxGnu/grocksdb v1.8.4 h1:ZMsBpPpJNtRLHiKKp0mI7gW+NT4s7UgfD5xHxx1jVRo=
-github.com/linxGnu/grocksdb v1.8.4/go.mod h1:xZCIb5Muw+nhbDK4Y5UJuOrin5MceOuiXkVUR7vp4WY=
+github.com/linxGnu/grocksdb v1.6.20 h1:C0SNv12/OBr/zOdGw6reXS+mKpIdQGb/AkZWjHYnO64=
+github.com/linxGnu/grocksdb v1.6.20/go.mod h1:IbTMGpmWg/1pg2hcG9LlxkqyqiJymdCweaUrzsLRFmg=
 github.com/nxadm/tail v1.4.4/go.mod h1:kenIhsEOeOJmVchQTgglprH7qJGnHDVpk1VPCcaMI8A=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
 github.com/onsi/ginkgo v1.7.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=
@@ -111,8 +113,8 @@ github.com/rs/cors v1.10.1/go.mod h1:XyqrcTp5zjWr1wsJ8PIRZssZ8b/WMcMf71DJnit4EMU
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
-github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7/go.mod h1:q4W45IWZaF22tdD+VEXcAWRA037jwmWEB5VWYORlTpc=
 go.etcd.io/bbolt v1.3.8 h1:xs88BrvEv273UsB79e0hcVrlUWmS0a8upikMFhSyAtA=
 go.etcd.io/bbolt v1.3.8/go.mod h1:N9Mkw9X8x5fupy0IKsmuqVtoGDyxsaDlbk4Rd05IAQw=

handler.go

@@ -6,18 +6,25 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"regexp"
 
 	"github.com/gnolang/faucet/writer"
 	httpWriter "github.com/gnolang/faucet/writer/http"
 	"github.com/gnolang/gno/tm2/pkg/crypto"
+	"github.com/gnolang/gno/tm2/pkg/std"
 )
 
 const (
 	unableToHandleRequest = "unable to handle faucet request"
 	faucetSuccess         = "successfully executed faucet transfer"
 )
 
-var errInvalidBeneficiary = errors.New("invalid beneficiary address")
+var (
+	errInvalidBeneficiary = errors.New("invalid beneficiary address")
+	errInvalidSendAmount  = errors.New("invalid send amount")
+)
+
+var amountRegex = regexp.MustCompile(`^\d+ugnot$`)
 
 // defaultHTTPHandler is the default faucet transfer handler
 func (f *Faucet) defaultHTTPHandler(w http.ResponseWriter, r *http.Request) {
@@ -74,8 +81,39 @@ func (f *Faucet) handleRequest(writer writer.ResponseWriter, requests Requests)
 			continue
 		}
 
+		// Extract the send amount
+		amount, err := extractSendAmount(baseRequest)
+		if err != nil {
+			// Save the error response
+			responses[i] = Response{
+				Result: unableToHandleRequest,
+				Error:  err.Error(),
+			}
+
+			continue
+		}
+
+		// Check if the amount is set
+		if amount.IsZero() {
+			// Drip amount is not set, use
+			// the max faucet drip amount
+			amount = f.maxSendAmount
+		}
+
+		// Check if the amount exceeds the max
+		// drip amount for the faucet
+		if amount.IsAllGT(f.maxSendAmount) {
+			// Save the error response
+			responses[i] = Response{
+				Result: unableToHandleRequest,
+				Error:  errInvalidSendAmount.Error(),
+			}
+
+			continue
+		}
+
 		// Run the method handler
-		if err := f.transferFunds(beneficiary); err != nil {
+		if err := f.transferFunds(beneficiary, amount); err != nil {
 			f.logger.Debug(
 				unableToHandleRequest,
 				"request",
@@ -144,3 +182,23 @@ func extractBeneficiary(request Request) (crypto.Address, error) {
 
 	return beneficiary, nil
 }
+
+// extractSendAmount extracts the drip amount from the base faucet request, if any
+func extractSendAmount(request Request) (std.Coins, error) {
+	// Check if the amount is set
+	if request.Amount == "" {
+		return std.Coins{}, nil
+	}
+
+	// Validate the send amount is valid
+	if !amountRegex.MatchString(request.Amount) {
+		return std.Coins{}, errInvalidSendAmount
+	}
+
+	amount, err := std.ParseCoins(request.Amount)
+	if err != nil {
+		return std.Coins{}, fmt.Errorf("%w, %w", errInvalidSendAmount, err)
+	}
+
+	return amount, nil
+}

handler_test.go

@@ -82,7 +82,7 @@ func TestFaucet_Serve_ValidRequests(t *testing.T) {
 
 	var (
 		gasFee     = std.MustParseCoin("1ugnot")
-		sendAmount = std.MustParseCoins(config.DefaultSendAmount)
+		sendAmount = std.MustParseCoins(config.DefaultMaxSendAmount)
 	)
 
 	var (
@@ -295,7 +295,7 @@ func TestFaucet_Serve_InvalidRequests(t *testing.T) {
 
 	var (
 		gasFee     = std.MustParseCoin("1ugnot")
-		sendAmount = std.MustParseCoins(config.DefaultSendAmount)
+		sendAmount = std.MustParseCoins(config.DefaultMaxSendAmount)
 	)
 
 	var (
@@ -569,7 +569,7 @@ func TestFaucet_Serve_NoFundedAccounts(t *testing.T) {
 
 	var (
 		gasFee     = std.MustParseCoin("1ugnot")
-		sendAmount = std.MustParseCoins(config.DefaultSendAmount)
+		sendAmount = std.MustParseCoins(config.DefaultMaxSendAmount)
 	)
 
 	var (
@@ -713,3 +713,100 @@ func TestFaucet_Serve_NoFundedAccounts(t *testing.T) {
 	// Validate the broadcast tx
 	assert.Nil(t, capturedTxs)
 }
+
+func TestFaucet_Serve_InvalidSendAmount(t *testing.T) {
+	t.Parallel()
+
+	// Extract the default send amount
+	maxSendAmount := std.MustParseCoins(config.DefaultMaxSendAmount)
+
+	testTable := []struct {
+		name       string
+		sendAmount std.Coins
+	}{
+		{
+			"invalid send amount",
+			std.NewCoins(std.NewCoin("atom", 10)),
+		},
+		{
+			"excessive send amount",
+			maxSendAmount.Add(std.MustParseCoins("100ugnot")),
+		},
+	}
+
+	for _, testCase := range testTable {
+		testCase := testCase
+
+		t.Run(testCase.name, func(t *testing.T) {
+			t.Parallel()
+
+			var (
+				validAddress = crypto.MustAddressFromString("g155n659f89cfak0zgy575yqma64sm4tv6exqk99")
+				gasFee       = std.MustParseCoin("1ugnot")
+
+				singleInvalidRequest = Request{
+					To:     validAddress.String(),
+					Amount: testCase.sendAmount.String(),
+				}
+			)
+
+			encodedSingleInvalidRequest, err := json.Marshal(
+				singleInvalidRequest,
+			)
+			require.NoError(t, err)
+
+			getFaucetURL := func(address string) string {
+				return fmt.Sprintf("http://%s", address)
+			}
+
+			// Create a new faucet with default params
+			cfg := config.DefaultConfig()
+			cfg.ListenAddress = fmt.Sprintf("127.0.0.1:%d", getFreePort(t))
+			cfg.MaxSendAmount = maxSendAmount.String()
+
+			f, err := NewFaucet(
+				static.New(gasFee, 100000),
+				&mockClient{},
+				WithConfig(cfg),
+			)
+
+			require.NoError(t, err)
+			require.NotNil(t, f)
+
+			// Start the faucet
+			ctx, cancelFn := context.WithCancel(context.Background())
+			defer cancelFn()
+
+			g, gCtx := errgroup.WithContext(ctx)
+
+			g.Go(func() error {
+				return f.Serve(gCtx)
+			})
+
+			url := getFaucetURL(f.config.ListenAddress)
+
+			// Wait for the faucet to be started
+			waitForServer(t, url)
+
+			// Execute the request
+			respRaw, err := http.Post(
+				url,
+				jsonMimeType,
+				bytes.NewBuffer(encodedSingleInvalidRequest),
+			)
+			require.NoError(t, err)
+
+			respBytes, err := io.ReadAll(respRaw.Body)
+			require.NoError(t, err)
+
+			response := decodeResponse[Response](t, respBytes)
+
+			assert.Contains(t, response.Error, errInvalidSendAmount.Error())
+			assert.Equal(t, unableToHandleRequest, response.Result)
+
+			// Stop the faucet and wait for it to finish
+			cancelFn()
+			assert.NoError(t, g.Wait())
+		})
+	}
+}