Add configurable greeter

config.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"reflect"
 	"strings"
+	"text/template"
 	"time"
 
 	"github.com/flashmob/go-guerrilla/backends"
@@ -60,6 +61,9 @@ type ServerConfig struct {
 	// XClientOn when using a proxy such as Nginx, XCLIENT command is used to pass the
 	// original client's IP address & client's HELO
 	XClientOn bool `json:"xclient_on,omitempty"`
+	// GreeterTemplate will be used to greet the client.
+	// Defaults to defaultGreeterString
+	GreeterTemplate *template.Template `json:"greeter_template"`
 }
 
 type ServerTLSConfig struct {
@@ -151,10 +155,13 @@ var TLSClientAuthTypes = map[string]tls.ClientAuthType{
 	"RequireAndVerifyClientCert": tls.RequireAndVerifyClientCert,
 }
 
-const defaultMaxClients = 100
-const defaultTimeout = 30
-const defaultInterface = "127.0.0.1:2525"
-const defaultMaxSize = int64(10 << 20) // 10 Mebibytes
+const (
+	defaultMaxClients    = 100
+	defaultTimeout       = 30
+	defaultInterface     = "127.0.0.1:2525"
+	defaultMaxSize       = int64(10 << 20) // 10 Mebibytes
+	defaultGreeterString = "220 {{ .Hostname }} SMTP Guerrilla({{ .Version }}) #{{ .ClientID }} ({{ .ActiveClientsCount }}) {{ .Time }}"
+)
 
 // Unmarshalls json data into AppConfig struct and any other initialization of the struct
 // also does validation, returns error if validation failed or something went wrong
@@ -279,6 +286,10 @@ func (c *AppConfig) setDefaults() error {
 	if err != nil {
 		return err
 	}
+	defaultGreeterTemplate, err := template.New("greeter").Parse(defaultGreeterString)
+	if err != nil {
+		return fmt.Errorf("unable to parse template: %v", err)
+	}
 	if len(c.Servers) == 0 {
 		sc := ServerConfig{}
 		sc.LogFile = c.LogFile
@@ -288,6 +299,7 @@ func (c *AppConfig) setDefaults() error {
 		sc.MaxClients = defaultMaxClients
 		sc.Timeout = defaultTimeout
 		sc.MaxSize = defaultMaxSize
+		sc.GreeterTemplate = defaultGreeterTemplate
 		c.Servers = append(c.Servers, sc)
 	} else {
 		// make sure each server has defaults correctly configured
@@ -304,6 +316,9 @@ func (c *AppConfig) setDefaults() error {
 			if c.Servers[i].MaxSize == 0 {
 				c.Servers[i].MaxSize = defaultMaxSize // 10 Mebibytes
 			}
+			if c.Servers[i].GreeterTemplate == nil {
+				c.Servers[i].GreeterTemplate = defaultGreeterTemplate
+			}
 			if c.Servers[i].ListenInterface == "" {
 				return fmt.Errorf("listen interface not specified for server at index %d", i)
 			}

go.mod

@@ -0,0 +1,19 @@
+module github.com/flashmob/go-guerrilla
+
+go 1.15
+
+require (
+	github.com/asaskevich/EventBus v0.0.0-20180103000110-68a521d7cbbb
+	github.com/go-sql-driver/mysql v1.4.1
+	github.com/gomodule/redigo v2.0.0+incompatible
+	github.com/inconshreveable/mousetrap v1.0.0
+	github.com/konsorten/go-windows-terminal-sequences v1.0.2
+	github.com/sirupsen/logrus v1.4.2
+	github.com/spf13/cobra v0.0.3
+	github.com/spf13/pflag v1.0.3
+	golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c
+	golang.org/x/sys v0.0.0-20190422165155-953cdadca894
+	golang.org/x/text v0.3.2
+	google.golang.org/appengine v1.5.0
+	gopkg.in/iconv.v1 v1.1.1
+)

go.sum

@@ -0,0 +1,25 @@
+github.com/asaskevich/EventBus v0.0.0-20180103000110-68a521d7cbbb/go.mod h1:JS7hed4L1fj0hXcyEejnW57/7LCetXggd+vwrRnYeII=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-sql-driver/mysql v1.4.1/go.mod h1:zAC/RDZ24gD3HViQzih4MyKcchzm+sOG5ZlKdlhCg5w=
+github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/gomodule/redigo v2.0.0+incompatible/go.mod h1:B4C85qUVwatsJoIUNIfCRsp7qO0iAmpGFZ4EELWSbC4=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/sirupsen/logrus v1.4.2/go.mod h1:tLMulIdttU9McNUspp0xgXVQah82FyeX6MwdIuYE2rE=
+github.com/spf13/cobra v0.0.3/go.mod h1:1l0Ry5zgKvJasoi3XT1TypsSe7PqH0Sj9dhYf7v3XqQ=
+github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/sys v0.0.0-20180308152046-7dca6fe1f437/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+google.golang.org/appengine v1.5.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
+gopkg.in/iconv.v1 v1.1.1/go.mod h1:/kbQb/JfuKJjly48VfSKmiHkdA0nAzSsgDWOc3Jcb08=

server.go

@@ -6,7 +6,6 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"fmt"
-	"github.com/sirupsen/logrus"
 	"io"
 	"io/ioutil"
 	"net"
@@ -16,6 +15,8 @@ import (
 	"sync/atomic"
 	"time"
 
+	"github.com/sirupsen/logrus"
+
 	"github.com/flashmob/go-guerrilla/backends"
 	"github.com/flashmob/go-guerrilla/log"
 	"github.com/flashmob/go-guerrilla/mail"
@@ -66,6 +67,14 @@ type allowedHosts struct {
 	sync.Mutex                 // guard access to the map
 }
 
+type greeterData struct {
+	Hostname           string
+	Version            string
+	ClientID           uint64
+	ActiveClientsCount int
+	Time               string
+}
+
 type command []byte
 
 var (
@@ -367,9 +376,16 @@ func (s *server) handleClient(client *client) {
 	s.log().Infof("Handle client [%s], id: %d", client.RemoteIP, client.ID)
 
 	// Initial greeting
-	greeting := fmt.Sprintf("220 %s SMTP Guerrilla(%s) #%d (%d) %s",
-		sc.Hostname, Version, client.ID,
-		s.clientPool.GetActiveClientsCount(), time.Now().Format(time.RFC3339))
+	greeterData := greeterData{
+		Hostname:           sc.Hostname,
+		Version:            Version,
+		ClientID:           client.ID,
+		ActiveClientsCount: s.clientPool.GetActiveClientsCount(),
+		Time:               time.Now().Format(time.RFC3339),
+	}
+
+	var greeting bytes.Buffer
+	sc.GreeterTemplate.Execute(&greeting, greeterData)
 
 	helo := fmt.Sprintf("250 %s Hello", sc.Hostname)
 	// ehlo is a multi-line reply and need additional \r\n at the end
@@ -404,7 +420,7 @@ func (s *server) handleClient(client *client) {
 	for client.isAlive() {
 		switch client.state {
 		case ClientGreeting:
-			client.sendResponse(greeting)
+			client.sendResponse(greeting.String())
 			client.state = ClientCmd
 		case ClientCmd:
 			client.bufin.setLimit(CommandLineMaxLength)