├── .idea
    ├── markdown-navigator
    │   └── profiles_settings.xml
    ├── misc.xml
    ├── vcs.xml
    ├── modules.xml
    ├── check-smtp.iml
    └── markdown-navigator.xml
├── .gitignore
├── test-email
    ├── test_mail_request.go
    └── content.go
├── http
    └── handlers
    │   ├── health.go
    │   └── check_transport.go
├── main.go
├── lib
    ├── mail-sender
    │   ├── connection.go
    │   ├── smtp-commands
    │   │   └── commands.go
    │   └── client.go
    ├── results.go
    ├── tls_parser
    │   └── tls_parser.go
    ├── transport_server.go
    └── environment-vars
    │   └── environment.go
├── Dockerfile
├── Gopkg.toml
├── Gopkg.lock
├── Jenkinsfile
├── README.md
└── LICENSE


/.idea/markdown-navigator/profiles_settings.xml:
--------------------------------------------------------------------------------
1 | <component name="MarkdownNavigator.ProfileManager">
2 |   <settings default="" pdf-export="" />
3 | </component>


--------------------------------------------------------------------------------
/.idea/misc.xml:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <project version="4">
3 |   <component name="JavaScriptSettings">
4 |     <option name="languageLevel" value="ES6" />
5 |   </component>
6 | </project>


--------------------------------------------------------------------------------
/.idea/vcs.xml:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <project version="4">
3 |   <component name="VcsDirectoryMappings">
4 |     <mapping directory="$PROJECT_DIR$" vcs="Git" />
5 |   </component>
6 | </project>


--------------------------------------------------------------------------------
/.gitignore:
--------------------------------------------------------------------------------
 1 | # Binaries for programs and plugins
 2 | *.exe
 3 | *.exe~
 4 | *.dll
 5 | *.so
 6 | *.dylib
 7 | 
 8 | # Test binary, build with `go test -c`
 9 | *.test
10 | 
11 | # Output of the go coverage tool, specifically when used with LiteIDE
12 | *.out
13 | .idea
14 | main
15 | 
16 | vendor/
17 | 


--------------------------------------------------------------------------------
/.idea/modules.xml:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <project version="4">
3 |   <component name="ProjectModuleManager">
4 |     <modules>
5 |       <module fileurl="file://$PROJECT_DIR$/.idea/check-smtp.iml" filepath="$PROJECT_DIR$/.idea/check-smtp.iml" />
6 |     </modules>
7 |   </component>
8 | </project>


--------------------------------------------------------------------------------
/.idea/check-smtp.iml:
--------------------------------------------------------------------------------
1 | <?xml version="1.0" encoding="UTF-8"?>
2 | <module type="WEB_MODULE" version="4">
3 |   <component name="Go" enabled="true" />
4 |   <component name="NewModuleRootManager">
5 |     <content url="file://$MODULE_DIR$" />
6 |     <orderEntry type="inheritedJdk" />
7 |     <orderEntry type="sourceFolder" forTests="false" />
8 |   </component>
9 | </module>


--------------------------------------------------------------------------------
/test-email/test_mail_request.go:
--------------------------------------------------------------------------------
 1 | package test_email
 2 | 
 3 | import "github.com/zerospam/check-smtp/lib"
 4 | 
 5 | type TestEmailRequest struct {
 6 | 	From    string               `json:"from"`
 7 | 	Body    string               `json:"body"`
 8 | 	Subject string               `json:"subject"`
 9 | 	Server  *lib.TransportServer `json:"server"`
10 | }
11 | 
12 | func (t *TestEmailRequest) ToTestEmail() *Email {
13 | 	return NewTestEmail(t.Subject, t.Body, t.From, t.Server.TestEmail)
14 | }
15 | 


--------------------------------------------------------------------------------
/http/handlers/health.go:
--------------------------------------------------------------------------------
 1 | package handlers
 2 | 
 3 | import (
 4 | 	"io"
 5 | 	"net/http"
 6 | )
 7 | 
 8 | // e.g. http.HandleFunc("/healthz", HealthCheck)
 9 | func HealthCheck(w http.ResponseWriter, r *http.Request) {
10 | 	// A very simple health check.
11 | 	w.WriteHeader(http.StatusOK)
12 | 	w.Header().Set("Content-Type", "application/json")
13 | 
14 | 	// In the future we could report back on the status of our DB, or our cache
15 | 	// (e.g. Redis) by performing a simple PING, and include them in the response.
16 | 	io.WriteString(w, `{"alive": true}`)
17 | }
18 | 


--------------------------------------------------------------------------------
/main.go:
--------------------------------------------------------------------------------
 1 | package main
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | 	"github.com/zerospam/check-smtp/http/handlers"
 6 | 	"github.com/zerospam/check-smtp/lib/environment-vars"
 7 | 	"net/http"
 8 | 	"os"
 9 | )
10 | 
11 | func init() {
12 | 	http.HandleFunc("/check", handlers.CheckTransport)
13 | 	http.HandleFunc("/healthz", handlers.HealthCheck)
14 | }
15 | 
16 | func main() {
17 | 	os.Setenv("GODEBUG", os.Getenv("GODEBUG")+",tls13=1")
18 | 	err := http.ListenAndServe(fmt.Sprintf(":%s", environmentvars.GetVars().ApplicationPort), nil)
19 | 	if err != nil {
20 | 		panic(err)
21 | 	}
22 | }
23 | 


--------------------------------------------------------------------------------
/lib/mail-sender/connection.go:
--------------------------------------------------------------------------------
 1 | package mail_sender
 2 | 
 3 | import (
 4 | 	"net"
 5 | )
 6 | 
 7 | type Conn struct {
 8 | 	net.Conn
 9 | 	firstRead     []byte
10 | 	firstLineRead bool
11 | }
12 | 
13 | func (c *Conn) Read(b []byte) (n int, err error) {
14 | 	read, err := c.Conn.Read(b)
15 | 	if err != nil {
16 | 		return read, err
17 | 	}
18 | 	if c.firstLineRead {
19 | 		return read, err
20 | 	}
21 | 
22 | 	c.firstRead = b
23 | 	c.firstLineRead = true
24 | 
25 | 	return read, err
26 | }
27 | 
28 | func NewConnection(conn net.Conn) *Conn {
29 | 	return &Conn{Conn: conn, firstLineRead: false}
30 | }
31 | 


--------------------------------------------------------------------------------
/Dockerfile:
--------------------------------------------------------------------------------
 1 | ARG APP_PACKAGE="github.com/zerospam/check-smtp"
 2 | ARG APP_PATH="/go/src/${APP_PACKAGE}"
 3 | ARG APP_NAME="smtpChecker"
 4 | 
 5 | FROM zerospam/go-dep-docker as builder
 6 | 
 7 | ENV CGO_ENABLED=0
 8 | ENV GOOS=linux
 9 | 
10 | ARG APP_PACKAGE
11 | ARG APP_PATH
12 | ARG APP_NAME
13 | 
14 | COPY . $APP_PATH
15 | WORKDIR $APP_PATH
16 | 
17 | RUN dep ensure
18 | RUN go build -a -installsuffix cgo -o $APP_NAME
19 | 
20 | FROM alpine:latest
21 | 
22 | ARG APP_PATH
23 | ARG APP_NAME
24 | RUN sed -i -e 's/dl-cdn/dl-4/' /etc/apk/repositories \
25 |     && apk --update --no-cache add ca-certificates
26 | 
27 | COPY --from=builder ${APP_PATH}/${APP_NAME} /${APP_NAME}
28 | 
29 | CMD ["/smtpChecker"]
30 | 


--------------------------------------------------------------------------------
/Gopkg.toml:
--------------------------------------------------------------------------------
 1 | # Gopkg.toml example
 2 | #
 3 | # Refer to https://golang.github.io/dep/docs/Gopkg.toml.html
 4 | # for detailed Gopkg.toml documentation.
 5 | #
 6 | # required = ["github.com/user/thing/cmd/thing"]
 7 | # ignored = ["github.com/user/project/pkgX", "bitbucket.org/user/project/pkgA/pkgY"]
 8 | #
 9 | # [[constraint]]
10 | #   name = "github.com/user/project"
11 | #   version = "1.0.0"
12 | #
13 | # [[constraint]]
14 | #   name = "github.com/user/project2"
15 | #   branch = "dev"
16 | #   source = "github.com/myfork/project2"
17 | #
18 | # [[override]]
19 | #   name = "github.com/x/y"
20 | #   version = "2.4.0"
21 | #
22 | # [prune]
23 | #   non-go = false
24 | #   go-tests = true
25 | #   unused-packages = true
26 | 
27 | 
28 | [prune]
29 |   go-tests = true
30 |   unused-packages = true
31 | 
32 | [metadata.heroku]
33 |   root-package = "github.com/zerospam/check-smtp"
34 |   go-version = "1.11"


--------------------------------------------------------------------------------
/Gopkg.lock:
--------------------------------------------------------------------------------
 1 | # This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
 2 | 
 3 | 
 4 | [[projects]]
 5 |   digest = "1:2e76a73cb51f42d63a2a1a85b3dc5731fd4faf6821b434bd0ef2c099186031d6"
 6 |   name = "github.com/rs/xid"
 7 |   packages = ["."]
 8 |   pruneopts = "UT"
 9 |   revision = "15d26544def341f036c5f8dca987a4cbe575032c"
10 |   version = "v1.2.1"
11 | 
12 | [[projects]]
13 |   branch = "master"
14 |   digest = "1:cd596abe1695f597a9acb7041e6f450b6c856452f9cbf643863784825fffeaaf"
15 |   name = "github.com/zerospam/check-firewall"
16 |   packages = ["lib/tls-generator"]
17 |   pruneopts = "UT"
18 |   revision = "ba18e040fc4052dc248c5a43aac02f4c785bb75c"
19 | 
20 | [solve-meta]
21 |   analyzer-name = "dep"
22 |   analyzer-version = 1
23 |   input-imports = [
24 |     "github.com/rs/xid",
25 |     "github.com/zerospam/check-firewall/lib/tls-generator",
26 |   ]
27 |   solver-name = "gps-cdcl"
28 |   solver-version = 1
29 | 


--------------------------------------------------------------------------------
/lib/results.go:
--------------------------------------------------------------------------------
 1 | package lib
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | 	"github.com/zerospam/check-smtp/lib/mail-sender/smtp-commands"
 6 | )
 7 | 
 8 | type SmtpError struct {
 9 | 	Command      smtp_commands.Commands `json:"command"`
10 | 	ErrorMessage string                 `json:"error_msg"`
11 | }
12 | 
13 | type CheckResult struct {
14 | 	Success     bool                     `json:"success"`
15 | 	HelloBanner string                   `json:"hello_banner"`
16 | 	TlsVersion  string                   `json:"tls_version"`
17 | 	Error       *SmtpError               `json:"error_message,omitempty"`
18 | 	GeneralLog  smtp_commands.CommandLog `json:"general_log"`
19 | 	SPFLog      smtp_commands.CommandLog `json:"spf_log"`
20 | }
21 | 
22 | func NewSmtpError(Op smtp_commands.Commands, err error) *SmtpError {
23 | 	return &SmtpError{Command: Op, ErrorMessage: err.Error()}
24 | }
25 | 
26 | func (se *SmtpError) String() string {
27 | 	return fmt.Sprintf("%s: %s", se.Command, se.ErrorMessage)
28 | }
29 | 


--------------------------------------------------------------------------------
/Jenkinsfile:
--------------------------------------------------------------------------------
 1 | def label = "replicator-${UUID.randomUUID().toString()}"
 2 | podTemplate(label: label, inheritFrom: 'docker') {
 3 |     def image="zerospam/check-smtp"
 4 |     def tag = "1.2.2"
 5 |     def builtImage = null
 6 | 
 7 |     node (label) {
 8 |         gitInfo = checkout scm
 9 |          container('docker') {
10 |             stage('Build & Test') {
11 |                builtImage = docker.build("${image}:${env.BUILD_ID}")
12 |             }
13 | 
14 |             if (gitInfo.GIT_BRANCH.equals('master')) {
15 |                 // master branch release
16 |                 stage('Push docker image to Docker Hub') {
17 |                     docker.withRegistry('https://index.docker.io/v1/', 'docker-hub') {
18 |                             builtImage.push('latest')
19 |                             builtImage.push("${tag}")
20 |                     }
21 |                 } // stage
22 |             } // if master branch
23 | 
24 |         } //container
25 |     } //node
26 | } //pipeline


--------------------------------------------------------------------------------
/lib/tls_parser/tls_parser.go:
--------------------------------------------------------------------------------
 1 | package tls_parser
 2 | 
 3 | import (
 4 | 	"crypto/tls"
 5 | 	"fmt"
 6 | )
 7 | 
 8 | func DecodeString(str string) (uint16, error) {
 9 | 	switch str {
10 | 	case "SSL30":
11 | 		return tls.VersionSSL30, nil
12 | 	case "TLS10":
13 | 		return tls.VersionTLS10, nil
14 | 	case "TLS11":
15 | 		return tls.VersionTLS11, nil
16 | 	case "TLS12":
17 | 		return tls.VersionTLS12, nil
18 | 	case "TLS13":
19 | 		return tls.VersionTLS13, nil
20 | 	default:
21 | 		return 0, fmt.Errorf("%s unrecognized TLS version", str)
22 | 	}
23 | }
24 | 
25 | func ToString(version uint16) (string, error) {
26 | 	switch version {
27 | 	case tls.VersionSSL30:
28 | 		return "VersionSSL30", nil
29 | 	case tls.VersionTLS10:
30 | 		return "VersionTLS10", nil
31 | 	case tls.VersionTLS11:
32 | 		return "VersionTLS11", nil
33 | 	case tls.VersionTLS12:
34 | 		return "VersionTLS12", nil
35 | 	case tls.VersionTLS13:
36 | 		return "VersionTLS13", nil
37 | 	default:
38 | 		return "", fmt.Errorf("%x unrecognized TLS version", version)
39 | 	}
40 | }
41 | 


--------------------------------------------------------------------------------
/lib/transport_server.go:
--------------------------------------------------------------------------------
 1 | package lib
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | 	"net"
 6 | 	"time"
 7 | )
 8 | 
 9 | type TransportServer struct {
10 | 	Server    string `json:"server"`
11 | 	Port      int    `json:"port"`
12 | 	OnMx      bool   `json:"mx"`
13 | 	TestEmail string `json:"test_email"`
14 | }
15 | 
16 | func (t *TransportServer) Address() (string, error) {
17 | 
18 | 	if !t.OnMx {
19 | 		return fmt.Sprintf("%s:%d", t.Server, t.Port), nil
20 | 	}
21 | 
22 | 	mxRecords, errorMx := net.LookupMX(t.Server)
23 | 	if errorMx != nil {
24 | 		return "", fmt.Errorf("MX Records: no mx records found for %s\n%s", t.Server, errorMx)
25 | 	}
26 | 	if len(mxRecords) == 0 {
27 | 		return "", fmt.Errorf("MX Records: no mx records found for %s", t.Server)
28 | 	}
29 | 	return fmt.Sprintf("%s:%d", mxRecords[0].Host, t.Port), nil
30 | 
31 | }
32 | 
33 | func (t *TransportServer) Connect(timeout time.Duration) (conn net.Conn, err error) {
34 | 	address, err := t.Address()
35 | 	if err != nil {
36 | 		return nil, err
37 | 	}
38 | 
39 | 	return net.DialTimeout("tcp", address, timeout)
40 | }
41 | 


--------------------------------------------------------------------------------
/lib/mail-sender/smtp-commands/commands.go:
--------------------------------------------------------------------------------
 1 | package smtp_commands
 2 | 
 3 | import (
 4 | 	"bytes"
 5 | 	"encoding/json"
 6 | 	"fmt"
 7 | )
 8 | 
 9 | type Commands int
10 | 
11 | const (
12 | 	Timeout Commands = iota
13 | 	Connection
14 | 	Ehlo
15 | 	StartTls
16 | 	MailFrom
17 | 	RcptTo
18 | 	Data
19 | 	Quit
20 | 	SpfFail
21 | )
22 | 
23 | type CommandLog map[Commands]string
24 | 
25 | func (c Commands) String() string {
26 | 	names := []string{
27 | 		"TIMEOUT",
28 | 		"CONNECTION",
29 | 		"EHLO",
30 | 		"STARTTLS",
31 | 		"MAIL FROM",
32 | 		"RCPT TO",
33 | 		"DATA",
34 | 		"QUIT",
35 | 		"SPF-FAIL"}
36 | 
37 | 	if c < Timeout || c > SpfFail {
38 | 		return "Unknown"
39 | 	}
40 | 
41 | 	return names[c]
42 | }
43 | 
44 | func (c *Commands) MarshalJSON() ([]byte, error) {
45 | 	buffer := bytes.NewBufferString(`"`)
46 | 	buffer.WriteString(c.String())
47 | 	buffer.WriteString(`"`)
48 | 	return buffer.Bytes(), nil
49 | }
50 | 
51 | func (i CommandLog) MarshalJSON() ([]byte, error) {
52 | 	x := make(map[string]string)
53 | 	for k, v := range i {
54 | 		x[fmt.Sprintf("%d/%s", k, k.String())] = v
55 | 	}
56 | 	marshal, e := json.Marshal(x)
57 | 	return marshal, e
58 | }
59 | 


--------------------------------------------------------------------------------
/test-email/content.go:
--------------------------------------------------------------------------------
 1 | package test_email
 2 | 
 3 | import (
 4 | 	"crypto/sha1"
 5 | 	"fmt"
 6 | 	"github.com/rs/xid"
 7 | 	"io"
 8 | 	"strings"
 9 | 	"time"
10 | )
11 | 
12 | type Email struct {
13 | 	From    string
14 | 	To      string
15 | 	Body    string
16 | 	Subject string
17 | 	Headers map[string]string
18 | }
19 | 
20 | func (e *Email) generateMessageId(localName string) string {
21 | 	hasherSha1 := sha1.New()
22 | 
23 | 	io.WriteString(hasherSha1, e.Subject)
24 | 	io.WriteString(hasherSha1, e.From)
25 | 	io.WriteString(hasherSha1, e.To)
26 | 	guid := xid.New()
27 | 
28 | 	return fmt.Sprintf("%s-%x@%s", guid, sha1.Sum(nil), localName)
29 | }
30 | 
31 | func (e *Email) PrepareHeaders(localName string) {
32 | 
33 | 	e.Headers = map[string]string{
34 | 		"From":       fmt.Sprintf("Mail Server Tester <%s>", e.From),
35 | 		"To":         fmt.Sprintf("Mail Server Tester Receiver <%s>", e.To),
36 | 		"Subject":    e.Subject,
37 | 		"Date":       time.Now().Format(time.RFC1123Z),
38 | 		"Message-Id": fmt.Sprintf("<%s>", e.generateMessageId(localName)),
39 | 
40 | 		"MIME-Version":              "1.0",
41 | 		"Content-Transfer-Encoding": "8bit",
42 | 
43 | 		"Auto-Submitted": "auto-generated",
44 | 		"X-Mailer":       "SMTP Server Tester",
45 | 		"Content-Type":   "text/plain; charset=\"UTF-8\"",
46 | 	}
47 | }
48 | 
49 | func NewTestEmail(subject string, body string, from string, to string) *Email {
50 | 
51 | 	return &Email{
52 | 		Body:    body,
53 | 		From:    from,
54 | 		To:      to,
55 | 		Subject: subject,
56 | 	}
57 | }
58 | 
59 | func (e *Email) String() string {
60 | 	var builder strings.Builder
61 | 	builder.Grow(len(e.Body) + len(e.Headers)*10)
62 | 	for header, value := range e.Headers {
63 | 		builder.WriteString(fmt.Sprintf("%s: %s\r\n", header, value))
64 | 	}
65 | 
66 | 	builder.WriteString("\r\n")
67 | 	builder.WriteString(e.Body)
68 | 	var replaced = strings.ReplaceAll(builder.String(),"\r\n", "\n")
69 | 
70 | 	return strings.ReplaceAll(replaced, "\n", "\r\n")
71 | }
72 | 


--------------------------------------------------------------------------------
/lib/environment-vars/environment.go:
--------------------------------------------------------------------------------
  1 | package environmentvars
  2 | 
  3 | import (
  4 | 	"crypto/tls"
  5 | 	"github.com/zerospam/check-smtp/lib"
  6 | 	"github.com/zerospam/check-smtp/lib/mail-sender"
  7 | 	"github.com/zerospam/check-smtp/lib/tls_parser"
  8 | 	"net/mail"
  9 | 	"os"
 10 | 	"sync"
 11 | 	"time"
 12 | )
 13 | 
 14 | type Env struct {
 15 | 	ApplicationPort       string
 16 | 	SharedKey             string
 17 | 	SmtpCN                string
 18 | 	SmtpMailFrom          *mail.Address
 19 | 	SmtpConnectionTimeout time.Duration
 20 | 	SmtpOperationTimeout  time.Duration
 21 | 	SmtpMailSpoof         *mail.Address
 22 | 	TLSMinVersion         uint16
 23 | }
 24 | 
 25 | var instance *Env
 26 | var once sync.Once
 27 | 
 28 | func GetVars() *Env {
 29 | 	once.Do(func() {
 30 | 		hostname, err := os.Hostname()
 31 | 		if err != nil {
 32 | 			panic(err)
 33 | 		}
 34 | 
 35 | 		commonName := os.Getenv("SMTP_CN")
 36 | 		if commonName == "" {
 37 | 			commonName = hostname
 38 | 		}
 39 | 
 40 | 		var emailSpoof *mail.Address
 41 | 		emailFromSpoof := os.Getenv("SMTP_FROM_SPOOF")
 42 | 
 43 | 		if emailFromSpoof == "" {
 44 | 			emailFromSpoof = "spoof@amazon.com"
 45 | 		}
 46 | 
 47 | 		emailSpoof, err = mail.ParseAddress(emailFromSpoof)
 48 | 		if err != nil {
 49 | 			panic(err)
 50 | 		}
 51 | 
 52 | 		port := os.Getenv("PORT")
 53 | 		if port == "" {
 54 | 			port = "80"
 55 | 		}
 56 | 
 57 | 		timeoutParsed := 30 * time.Second
 58 | 		timeout := os.Getenv("SMTP_CONN_TIMEOUT")
 59 | 		if timeout != "" {
 60 | 			timeoutParsed, err = time.ParseDuration(timeout)
 61 | 			if err != nil {
 62 | 				panic(err)
 63 | 			}
 64 | 		}
 65 | 
 66 | 		timeoutOptParsed := 30 * time.Second
 67 | 		timeoutOpt := os.Getenv("SMTP_OPT_TIMEOUT")
 68 | 		if timeoutOpt != "" {
 69 | 			timeoutOptParsed, err = time.ParseDuration(timeoutOpt)
 70 | 			if err != nil {
 71 | 				panic(err)
 72 | 			}
 73 | 		}
 74 | 
 75 | 		tlsVersionParsed := uint16(tls.VersionTLS12)
 76 | 		tlsVersion := os.Getenv("TLS_MIN_VERSION")
 77 | 		if tlsVersion != "" {
 78 | 			tlsVersionParsed, err = tls_parser.DecodeString(tlsVersion)
 79 | 			if err != nil {
 80 | 				panic(err)
 81 | 			}
 82 | 		}
 83 | 
 84 | 		instance = &Env{
 85 | 			ApplicationPort:       port,
 86 | 			SharedKey:             os.Getenv("SHARED_KEY"),
 87 | 			SmtpCN:                commonName,
 88 | 			SmtpConnectionTimeout: timeoutParsed,
 89 | 			SmtpOperationTimeout:  timeoutOptParsed,
 90 | 			SmtpMailSpoof:         emailSpoof,
 91 | 			TLSMinVersion:         tlsVersionParsed,
 92 | 		}
 93 | 	})
 94 | 	return instance
 95 | }
 96 | 
 97 | func (e *Env) NewSmtpClient(server *lib.TransportServer) (*mail_sender.Client, *lib.SmtpError) {
 98 | 	return mail_sender.NewClient(server, e.SmtpCN, e.SmtpConnectionTimeout, e.SmtpOperationTimeout, e.TLSMinVersion)
 99 | }
100 | 


--------------------------------------------------------------------------------
/http/handlers/check_transport.go:
--------------------------------------------------------------------------------
  1 | package handlers
  2 | 
  3 | import (
  4 | 	"encoding/json"
  5 | 	"github.com/zerospam/check-smtp/lib"
  6 | 	"github.com/zerospam/check-smtp/lib/environment-vars"
  7 | 	"github.com/zerospam/check-smtp/lib/mail-sender/smtp-commands"
  8 | 	"github.com/zerospam/check-smtp/test-email"
  9 | 	"log"
 10 | 	"net/http"
 11 | 	"strings"
 12 | )
 13 | 
 14 | func getRequestIp(req *http.Request) string {
 15 | 	if header := req.Header.Get("X-Forwarded-For"); header != "" {
 16 | 		exploded := strings.Split(header, ",")
 17 | 		return strings.Trim(exploded[len(exploded)-1], " ")
 18 | 	}
 19 | 
 20 | 	return req.RemoteAddr
 21 | }
 22 | 
 23 | func generateResult(smtpError *lib.SmtpError, banner string, tlsVersion string, generalLog smtp_commands.CommandLog, spfLog smtp_commands.CommandLog) lib.CheckResult {
 24 | 	success := smtpError == nil
 25 | 	return lib.CheckResult{
 26 | 		Error:       smtpError,
 27 | 		Success:     success,
 28 | 		TlsVersion:  tlsVersion,
 29 | 		HelloBanner: banner,
 30 | 		GeneralLog:  generalLog,
 31 | 		SPFLog:      spfLog,
 32 | 	}
 33 | }
 34 | 
 35 | func testServer(server *lib.TransportServer, email *test_email.Email) lib.CheckResult {
 36 | 	client, err := environmentvars.GetVars().NewSmtpClient(server)
 37 | 	if err != nil {
 38 | 		return generateResult(err, "", "", make(smtp_commands.CommandLog), make(smtp_commands.CommandLog))
 39 | 	}
 40 | 
 41 | 	err = client.SendTestEmail(email)
 42 | 
 43 | 	if err != nil {
 44 | 		banner, tlsVersion := client.GetHelloBanner()
 45 | 		return generateResult(err, banner, tlsVersion, client.GetCommandLog(), make(smtp_commands.CommandLog))
 46 | 	}
 47 | 
 48 | 	generalLog := client.GetCommandLog()
 49 | 	//new client to do the spoofing
 50 | 	//Can't reuse previous client as it closed the connection
 51 | 	client, err = environmentvars.GetVars().NewSmtpClient(server)
 52 | 	if err != nil {
 53 | 		banner, tlsVersion := client.GetHelloBanner()
 54 | 		return generateResult(err, banner, tlsVersion, generalLog, client.GetCommandLog())
 55 | 	}
 56 | 
 57 | 	err = client.SpoofingTest(environmentvars.GetVars().SmtpMailSpoof.Address)
 58 | 
 59 | 	if err != nil {
 60 | 		if err.Command == smtp_commands.RcptTo || err.Command == smtp_commands.MailFrom {
 61 | 			err.Command = smtp_commands.SpfFail
 62 | 		}
 63 | 		banner, tlsVersion := client.GetHelloBanner()
 64 | 		return generateResult(err, banner, tlsVersion, generalLog, client.GetCommandLog())
 65 | 	}
 66 | 
 67 | 	banner, tlsVersion := client.GetHelloBanner()
 68 | 	return generateResult(err, banner, tlsVersion, generalLog, client.GetCommandLog())
 69 | 
 70 | }
 71 | 
 72 | func CheckTransport(w http.ResponseWriter, req *http.Request) {
 73 | 	var testEmailRequest test_email.TestEmailRequest
 74 | 
 75 | 	if req.Method != "POST" {
 76 | 		http.Error(w, "Only POST accepted.", 405)
 77 | 		return
 78 | 	}
 79 | 
 80 | 	if req.Header.Get("Authorization") != environmentvars.GetVars().SharedKey {
 81 | 		http.Error(w, "Wrong Key sent.", 402)
 82 | 		log.Printf("[%s] - %s - %v\n", req.RemoteAddr, req.Method, "REJECT")
 83 | 		return
 84 | 	}
 85 | 
 86 | 	if req.Body == nil {
 87 | 		http.Error(w, "Please send a request body", 400)
 88 | 		return
 89 | 	}
 90 | 
 91 | 	defer req.Body.Close()
 92 | 	json.NewDecoder(req.Body).Decode(&testEmailRequest)
 93 | 
 94 | 	w.Header().Add("Content-Type", "application/json")
 95 | 	email := testEmailRequest.ToTestEmail()
 96 | 	server := testEmailRequest.Server
 97 | 
 98 | 	result := testServer(server, email)
 99 | 
100 | 	json.NewEncoder(w).Encode(result)
101 | 
102 | 	log.Printf("[%s] - %s (%s:%d) - %v\n", getRequestIp(req), req.Method, testEmailRequest.Server.Server, testEmailRequest.Server.Port, result.Success)
103 | 
104 | }
105 | 


--------------------------------------------------------------------------------
/README.md:
--------------------------------------------------------------------------------
  1 | # Check SMTP
  2 | 
  3 | Mini HTTP service that takes a JSON with server information and check
  4 |  if it's accessible from the application and if it can receive emails.
  5 | 
  6 | ## Env
  7 | 
  8 | | Key        | Requirement           | Explanation                                                                                   |
  9 | |------------|-----------------------|-----------------------------------------------------------------------------------------------|
 10 | | SHARED_KEY | mandatory              | Secret shared between main app and this one. (Needs to be sent in the header *Authorization*) |
 11 | | PORT       | optional (default 80)  | Port used for the application                                                                 |
 12 | | SMTP_CN | optional (default hostname)| Common Name to use for client certificate when doing a STARTTLS                                                                |
 13 | | SMTP_FROM_SPOOF | optional (default spoof@amazon.com)| Email to check for SPF checks (spoofing this email as MAIL FROM)                                              |
 14 | | SMTP_CONN_TIMEOUT | optional (30 seconds)| How long to wait for the SMTP server to answer|
 15 | | SMTP_OPT_TIMEOUT | optional (30 seconds)| How long to wait for the SMTP server to answer each command|
 16 | |TLS_MIN_VERSION| optional (TLS1.2) | Check TLS Table for acceptable values. This is used when doing a STARTTLS on server that supports it.|
 17 | 
 18 | ### TLS
 19 | 
 20 | | TLS Version | EnvVar |
 21 | |-------------|--------|
 22 | | SSLv3.0     | SSL30  |
 23 | | TLSv1       | TLS10  |
 24 | | TLSv1.1     | TLS11  |
 25 | | TLS1.2      | TLS12  |
 26 | | TLS1.3      | TLS13  |
 27 | 
 28 | ## Data
 29 | ```json
 30 | {
 31 |   "from": "bounce@myserver.com",
 32 |   "body": "Hello World\n Are you doing well ?\n\nTester",
 33 |   "subject": "Hello World",
 34 |   "server": {
 35 |     "server": "example.com",
 36 |     "port": 25,
 37 |     "mx": false,
 38 |     "test_email": "test@example.com"
 39 |   }
 40 | }
 41 | ```
 42 | 
 43 | 
 44 | | Key    | Explanation                                                                    |
 45 | |--------|--------------------------------------------------------------------------------|
 46 | | from | Address to use in the MAIL FROM|
 47 | | body | Body of the mail|
 48 | | subject | Subject of the mail|
 49 | | server.server | Server to check                                                                |
 50 | | server.port   | Port to use to attempt the connection                                          |
 51 | | server.mx     | Instead of resolving the IP, resolve the MX of the server first then check IPs |
 52 | | server.test_email     | Used as RCPT TO when doing SMTP checks |
 53 | 
 54 | 
 55 | ## Response
 56 | 
 57 | ### Success
 58 | ```json
 59 | {
 60 |     "success": true,
 61 |     "hello_banner": "220 example.com ESMTP Postfix (Debian/GNU)",
 62 |     "tls_version": "VersionTLS12",
 63 |     "general_log": {
 64 |         "1/CONNECTION": "192.168.22.3:25",
 65 |         "2/EHLO": "tardis.example.com",
 66 |         "3/STARTTLS": "VersionTLS12",
 67 |         "4/MAIL FROM": "test@example.com",
 68 |         "5/RCPT TO": "me@example.com",
 69 |         "6/DATA": "\nHello World\nAre you doing well ?\n\nTester",
 70 |         "7/QUIT": ""
 71 |     },
 72 |     "spf_log": {
 73 |         "1/CONNECTION": "192.168.22.3:25",
 74 |         "2/EHLO": "tardis.zerospam.ca",
 75 |         "3/STARTTLS": "",
 76 |         "8/SPF-FAIL": "antoineaf@admincmd.com"
 77 |     }
 78 | }
 79 | ```
 80 | 
 81 | ### Error
 82 | ```json
 83 | {
 84 |     "success": false,
 85 |     "hello_banner": "220 set.example.com ESMTP Postfix (Debian/GNU)",
 86 |     "tls_version": "VersionTLS12",
 87 |     "error_message": {
 88 |         "command": "STARTTLS",
 89 |         "error_msg": "x509: certificate is valid for example.com, not set.example.com"
 90 |     },
 91 |     "general_log": {
 92 |         "1/CONNECTION": "192.168.22.3:25",
 93 |         "2/EHLO": "tardis.example.com",
 94 |         "3/STARTTLS": ""       
 95 |     },
 96 |     "spf_log": {
 97 |     }
 98 | }
 99 | ```
100 | 


--------------------------------------------------------------------------------
/.idea/markdown-navigator.xml:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project version="4">
 3 |   <component name="MarkdownProjectSettings" wasCopied="true">
 4 |     <PreviewSettings splitEditorLayout="SPLIT" splitEditorPreview="PREVIEW" useGrayscaleRendering="false" zoomFactor="1.0" maxImageWidth="0" showGitHubPageIfSynced="false" allowBrowsingInPreview="false" synchronizePreviewPosition="true" highlightPreviewType="NONE" highlightFadeOut="5" highlightOnTyping="true" synchronizeSourcePosition="true" verticallyAlignSourceAndPreviewSyncPosition="true" showSearchHighlightsInPreview="false" showSelectionInPreview="true" openRemoteLinks="true" replaceUnicodeEmoji="false" lastLayoutSetsDefault="false">
 5 |       <PanelProvider>
 6 |         <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.panel" providerName="Default - Swing" />
 7 |       </PanelProvider>
 8 |     </PreviewSettings>
 9 |     <ParserSettings gitHubSyntaxChange="false" emojiShortcuts="1" emojiImages="0">
10 |       <PegdownExtensions>
11 |         <option name="ABBREVIATIONS" value="false" />
12 |         <option name="ANCHORLINKS" value="true" />
13 |         <option name="ASIDE" value="false" />
14 |         <option name="ATXHEADERSPACE" value="true" />
15 |         <option name="AUTOLINKS" value="true" />
16 |         <option name="DEFINITIONS" value="false" />
17 |         <option name="DEFINITION_BREAK_DOUBLE_BLANK_LINE" value="false" />
18 |         <option name="FENCED_CODE_BLOCKS" value="true" />
19 |         <option name="FOOTNOTES" value="false" />
20 |         <option name="HARDWRAPS" value="false" />
21 |         <option name="HTML_DEEP_PARSER" value="false" />
22 |         <option name="INSERTED" value="false" />
23 |         <option name="QUOTES" value="false" />
24 |         <option name="RELAXEDHRULES" value="true" />
25 |         <option name="SMARTS" value="false" />
26 |         <option name="STRIKETHROUGH" value="true" />
27 |         <option name="SUBSCRIPT" value="false" />
28 |         <option name="SUPERSCRIPT" value="false" />
29 |         <option name="SUPPRESS_HTML_BLOCKS" value="false" />
30 |         <option name="SUPPRESS_INLINE_HTML" value="false" />
31 |         <option name="TABLES" value="true" />
32 |         <option name="TASKLISTITEMS" value="true" />
33 |         <option name="TOC" value="false" />
34 |         <option name="WIKILINKS" value="true" />
35 |       </PegdownExtensions>
36 |       <ParserOptions>
37 |         <option name="ADMONITION_EXT" value="false" />
38 |         <option name="ATTRIBUTES_EXT" value="false" />
39 |         <option name="COMMONMARK_LISTS" value="true" />
40 |         <option name="DUMMY" value="false" />
41 |         <option name="EMOJI_SHORTCUTS" value="true" />
42 |         <option name="ENUMERATED_REFERENCES_EXT" value="false" />
43 |         <option name="FLEXMARK_FRONT_MATTER" value="false" />
44 |         <option name="GFM_LOOSE_BLANK_LINE_AFTER_ITEM_PARA" value="false" />
45 |         <option name="GFM_TABLE_RENDERING" value="true" />
46 |         <option name="GITBOOK_URL_ENCODING" value="false" />
47 |         <option name="GITHUB_LISTS" value="false" />
48 |         <option name="GITHUB_WIKI_LINKS" value="true" />
49 |         <option name="HEADER_ID_NO_DUPED_DASHES" value="false" />
50 |         <option name="JEKYLL_FRONT_MATTER" value="false" />
51 |         <option name="NO_TEXT_ATTRIBUTES" value="false" />
52 |         <option name="PARSE_HTML_ANCHOR_ID" value="false" />
53 |         <option name="SIM_TOC_BLANK_LINE_SPACER" value="true" />
54 |       </ParserOptions>
55 |     </ParserSettings>
56 |     <HtmlSettings headerTopEnabled="false" headerBottomEnabled="false" bodyTopEnabled="false" bodyBottomEnabled="false" embedUrlContent="false" addPageHeader="true" embedImages="false" embedHttpImages="false" imageUriSerials="false">
57 |       <GeneratorProvider>
58 |         <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.generator" providerName="Default Swing HTML Generator" />
59 |       </GeneratorProvider>
60 |       <headerTop />
61 |       <headerBottom />
62 |       <bodyTop />
63 |       <bodyBottom />
64 |     </HtmlSettings>
65 |     <CssSettings previewScheme="UI_SCHEME" cssUri="" isCssUriEnabled="false" isCssUriSerial="false" isCssTextEnabled="false" isDynamicPageWidth="true">
66 |       <StylesheetProvider>
67 |         <provider providerId="com.vladsch.idea.multimarkdown.editor.swing.html.css" providerName="Default Swing Stylesheet" />
68 |       </StylesheetProvider>
69 |       <ScriptProviders />
70 |       <cssText />
71 |       <cssUriHistory />
72 |     </CssSettings>
73 |     <HtmlExportSettings updateOnSave="false" parentDir="" targetDir="" cssDir="" scriptDir="" plainHtml="false" imageDir="" copyLinkedImages="false" imageUniquifyType="0" targetExt="" useTargetExt="false" noCssNoScripts="false" linkToExportedHtml="true" exportOnSettingsChange="true" regenerateOnProjectOpen="false" linkFormatType="HTTP_ABSOLUTE" />
74 |     <LinkMapSettings>
75 |       <textMaps />
76 |     </LinkMapSettings>
77 |   </component>
78 | </project>


--------------------------------------------------------------------------------
/lib/mail-sender/client.go:
--------------------------------------------------------------------------------
  1 | package mail_sender
  2 | 
  3 | import (
  4 | 	"crypto/tls"
  5 | 	"fmt"
  6 | 	"github.com/zerospam/check-firewall/lib/tls-generator"
  7 | 	"github.com/zerospam/check-smtp/lib"
  8 | 	"github.com/zerospam/check-smtp/lib/mail-sender/smtp-commands"
  9 | 	"github.com/zerospam/check-smtp/lib/tls_parser"
 10 | 	"github.com/zerospam/check-smtp/test-email"
 11 | 	"net/smtp"
 12 | 	"strings"
 13 | 	"time"
 14 | )
 15 | 
 16 | type Client struct {
 17 | 	*smtp.Client
 18 | 	server         *lib.TransportServer
 19 | 	localName      string
 20 | 	tlsGenerator   *tlsgenerator.CertificateGenerator
 21 | 	optTimeout     time.Duration
 22 | 	lastError      *lib.SmtpError
 23 | 	lastCommand    *smtp_commands.Commands
 24 | 	sentTestEmail  bool
 25 | 	helloBanner    string
 26 | 	tlsMinVersion  uint16
 27 | 	tlsVersionUsed uint16
 28 | 	commandLog     smtp_commands.CommandLog
 29 | }
 30 | 
 31 | type SmtpOperation func() error
 32 | 
 33 | //Create new client to send the test email and test the SMTP server
 34 | func NewClient(server *lib.TransportServer, localName string, connTimeout time.Duration, optTimeout time.Duration, tlsMinVersion uint16) (*Client, *lib.SmtpError) {
 35 | 	conn, err := server.Connect(connTimeout)
 36 | 	if err != nil {
 37 | 		return nil, lib.NewSmtpError(smtp_commands.Connection, err)
 38 | 	}
 39 | 
 40 | 	connection := NewConnection(conn)
 41 | 	client, err := smtp.NewClient(connection, server.Server)
 42 | 
 43 | 	if err != nil {
 44 | 		return nil, lib.NewSmtpError(smtp_commands.Connection, err)
 45 | 	}
 46 | 
 47 | 	banner := strings.Trim(string(connection.firstRead), "\u0000\r\n")
 48 | 
 49 | 	return &Client{
 50 | 		Client:         client,
 51 | 		localName:      localName,
 52 | 		server:         server,
 53 | 		optTimeout:     optTimeout,
 54 | 		helloBanner:    banner,
 55 | 		tlsMinVersion:  tlsMinVersion,
 56 | 		tlsVersionUsed: 0,
 57 | 		commandLog: smtp_commands.CommandLog{
 58 | 			smtp_commands.Connection: conn.RemoteAddr().String(),
 59 | 		},
 60 | 	}, nil
 61 | }
 62 | 
 63 | func (c *Client) GetLastCommand() (*smtp_commands.Commands, *lib.SmtpError) {
 64 | 	return c.lastCommand, c.lastError
 65 | }
 66 | 
 67 | func (c *Client) GetCommandLog() smtp_commands.CommandLog {
 68 | 	return c.commandLog
 69 | }
 70 | 
 71 | func (c *Client) GetHelloBanner() (banner string, tlsVersion string) {
 72 | 
 73 | 	if c.tlsVersionUsed == 0 {
 74 | 		return c.helloBanner, "None"
 75 | 	}
 76 | 
 77 | 	tlsVersion, err := tls_parser.ToString(c.tlsVersionUsed)
 78 | 	if err != nil {
 79 | 		tlsVersion = err.Error()
 80 | 	}
 81 | 
 82 | 	return c.helloBanner, tlsVersion
 83 | }
 84 | 
 85 | func (c *Client) getClientTLSConfig(commonName string) *tls.Config {
 86 | 	if c.tlsGenerator == nil {
 87 | 		c.tlsGenerator = tlsgenerator.NewClient(time.Now(), 30*365*24*time.Hour)
 88 | 	}
 89 | 
 90 | 	return c.tlsGenerator.GetTlsClientConfig(commonName)
 91 | }
 92 | 
 93 | func (c *Client) doCommand(command smtp_commands.Commands, optCallback SmtpOperation, argument string) {
 94 | 
 95 | 	if c.lastError != nil {
 96 | 		return
 97 | 	}
 98 | 
 99 | 	c.lastCommand = &command
100 | 	c.commandLog[command] = argument
101 | 	//second parameter to not wait for a receiver.
102 | 	//This happen in the case the timeout returns before the command
103 | 	ch := make(chan error, 1)
104 | 
105 | 	go func() {
106 | 		ch <- optCallback()
107 | 	}()
108 | 
109 | 	timer := time.NewTimer(c.optTimeout)
110 | 	select {
111 | 	case err := <-ch:
112 | 		//Stop the timer as the command returned a result
113 | 		//@see https://golang.org/pkg/time/#After
114 | 		//Avoiding having a hanging timers
115 | 		timer.Stop()
116 | 		if err != nil {
117 | 			c.lastError = lib.NewSmtpError(command, err)
118 | 		}
119 | 		break
120 | 
121 | 	case <-timer.C:
122 | 		c.lastError = lib.NewSmtpError(smtp_commands.Timeout, fmt.Errorf("CMD [%s] Timed out after %s", command, c.optTimeout))
123 | 		break
124 | 	}
125 | 
126 | }
127 | 
128 | func (c *Client) setTls() error {
129 | 	if tlsSupport, _ := c.Client.Extension("STARTTLS"); !tlsSupport {
130 | 		return nil
131 | 	}
132 | 	tlsConfig := c.getClientTLSConfig(c.localName)
133 | 	tlsConfig.ServerName = c.server.Server
134 | 	tlsConfig.MinVersion = c.tlsMinVersion
135 | 	//It's impossible to verify correctly the server in the case of a SMTP transaction
136 | 	//Better be permissive
137 | 	tlsConfig.InsecureSkipVerify = true
138 | 	err := c.Client.StartTLS(tlsConfig)
139 | 	if err != nil {
140 | 		return err
141 | 	}
142 | 	state, _ := c.Client.TLSConnectionState()
143 | 	c.tlsVersionUsed = state.Version
144 | 
145 | 	return nil
146 | }
147 | 
148 | //Try to send the test email
149 | func (c *Client) SendTestEmail(email *test_email.Email) *lib.SmtpError {
150 | 
151 | 	defer c.Client.Close()
152 | 
153 | 	c.doCommand(smtp_commands.Ehlo, func() error {
154 | 		return c.Client.Hello(c.localName)
155 | 	}, c.localName)
156 | 
157 | 	c.doCommand(smtp_commands.StartTls, func() error {
158 | 		result := c.setTls()
159 | 		if c.tlsVersionUsed != 0 {
160 | 			versionUsed, _ := tls_parser.ToString(c.tlsVersionUsed)
161 | 			c.commandLog[smtp_commands.StartTls] = versionUsed
162 | 		}
163 | 		return result
164 | 	}, "")
165 | 
166 | 	c.doCommand(smtp_commands.MailFrom, func() error {
167 | 		return c.Client.Mail(email.From)
168 | 	}, email.From)
169 | 	c.doCommand(smtp_commands.RcptTo, func() error {
170 | 		return c.Client.Rcpt(c.server.TestEmail)
171 | 	}, c.server.TestEmail)
172 | 
173 | 	c.doCommand(smtp_commands.Data, func() error {
174 | 		w, err := c.Data()
175 | 
176 | 		if err != nil {
177 | 			return err
178 | 		}
179 | 
180 | 		email.PrepareHeaders(c.localName)
181 | 
182 | 		_, err = w.Write([]byte(email.String()))
183 | 		if err != nil {
184 | 			return err
185 | 		}
186 | 
187 | 		err = w.Close()
188 | 
189 | 		return err
190 | 	}, email.String())
191 | 
192 | 	c.doCommand(smtp_commands.Quit, func() error {
193 | 		return c.Client.Quit()
194 | 	}, "")
195 | 
196 | 	return c.lastError
197 | }
198 | 
199 | //Try to send the test email
200 | func (c *Client) SpoofingTest(from string) *lib.SmtpError {
201 | 
202 | 	defer c.Client.Quit()
203 | 	defer c.Client.Close()
204 | 
205 | 	c.doCommand(smtp_commands.Ehlo, func() error {
206 | 		return c.Client.Hello(c.localName)
207 | 	}, c.localName)
208 | 
209 | 	c.doCommand(smtp_commands.StartTls, func() error {
210 | 		return c.setTls()
211 | 	}, "")
212 | 
213 | 	c.doCommand(smtp_commands.MailFrom, func() error {
214 | 		return c.Client.Mail(from)
215 | 	}, from)
216 | 	c.doCommand(smtp_commands.RcptTo, func() error {
217 | 		return c.Client.Rcpt(c.server.TestEmail)
218 | 	}, c.server.TestEmail)
219 | 
220 | 	return c.lastError
221 | }
222 | 


--------------------------------------------------------------------------------
/LICENSE:
--------------------------------------------------------------------------------
  1 |                                  Apache License
  2 |                            Version 2.0, January 2004
  3 |                         http://www.apache.org/licenses/
  4 | 
  5 |    TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
  6 | 
  7 |    1. Definitions.
  8 | 
  9 |       "License" shall mean the terms and conditions for use, reproduction,
 10 |       and distribution as defined by Sections 1 through 9 of this document.
 11 | 
 12 |       "Licensor" shall mean the copyright owner or entity authorized by
 13 |       the copyright owner that is granting the License.
 14 | 
 15 |       "Legal Entity" shall mean the union of the acting entity and all
 16 |       other entities that control, are controlled by, or are under common
 17 |       control with that entity. For the purposes of this definition,
 18 |       "control" means (i) the power, direct or indirect, to cause the
 19 |       direction or management of such entity, whether by contract or
 20 |       otherwise, or (ii) ownership of fifty percent (50%) or more of the
 21 |       outstanding shares, or (iii) beneficial ownership of such entity.
 22 | 
 23 |       "You" (or "Your") shall mean an individual or Legal Entity
 24 |       exercising permissions granted by this License.
 25 | 
 26 |       "Source" form shall mean the preferred form for making modifications,
 27 |       including but not limited to software source code, documentation
 28 |       source, and configuration files.
 29 | 
 30 |       "Object" form shall mean any form resulting from mechanical
 31 |       transformation or translation of a Source form, including but
 32 |       not limited to compiled object code, generated documentation,
 33 |       and conversions to other media types.
 34 | 
 35 |       "Work" shall mean the work of authorship, whether in Source or
 36 |       Object form, made available under the License, as indicated by a
 37 |       copyright notice that is included in or attached to the work
 38 |       (an example is provided in the Appendix below).
 39 | 
 40 |       "Derivative Works" shall mean any work, whether in Source or Object
 41 |       form, that is based on (or derived from) the Work and for which the
 42 |       editorial revisions, annotations, elaborations, or other modifications
 43 |       represent, as a whole, an original work of authorship. For the purposes
 44 |       of this License, Derivative Works shall not include works that remain
 45 |       separable from, or merely link (or bind by name) to the interfaces of,
 46 |       the Work and Derivative Works thereof.
 47 | 
 48 |       "Contribution" shall mean any work of authorship, including
 49 |       the original version of the Work and any modifications or additions
 50 |       to that Work or Derivative Works thereof, that is intentionally
 51 |       submitted to Licensor for inclusion in the Work by the copyright owner
 52 |       or by an individual or Legal Entity authorized to submit on behalf of
 53 |       the copyright owner. For the purposes of this definition, "submitted"
 54 |       means any form of electronic, verbal, or written communication sent
 55 |       to the Licensor or its representatives, including but not limited to
 56 |       communication on electronic mailing lists, source code control systems,
 57 |       and issue tracking systems that are managed by, or on behalf of, the
 58 |       Licensor for the purpose of discussing and improving the Work, but
 59 |       excluding communication that is conspicuously marked or otherwise
 60 |       designated in writing by the copyright owner as "Not a Contribution."
 61 | 
 62 |       "Contributor" shall mean Licensor and any individual or Legal Entity
 63 |       on behalf of whom a Contribution has been received by Licensor and
 64 |       subsequently incorporated within the Work.
 65 | 
 66 |    2. Grant of Copyright License. Subject to the terms and conditions of
 67 |       this License, each Contributor hereby grants to You a perpetual,
 68 |       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 69 |       copyright license to reproduce, prepare Derivative Works of,
 70 |       publicly display, publicly perform, sublicense, and distribute the
 71 |       Work and such Derivative Works in Source or Object form.
 72 | 
 73 |    3. Grant of Patent License. Subject to the terms and conditions of
 74 |       this License, each Contributor hereby grants to You a perpetual,
 75 |       worldwide, non-exclusive, no-charge, royalty-free, irrevocable
 76 |       (except as stated in this section) patent license to make, have made,
 77 |       use, offer to sell, sell, import, and otherwise transfer the Work,
 78 |       where such license applies only to those patent claims licensable
 79 |       by such Contributor that are necessarily infringed by their
 80 |       Contribution(s) alone or by combination of their Contribution(s)
 81 |       with the Work to which such Contribution(s) was submitted. If You
 82 |       institute patent litigation against any entity (including a
 83 |       cross-claim or counterclaim in a lawsuit) alleging that the Work
 84 |       or a Contribution incorporated within the Work constitutes direct
 85 |       or contributory patent infringement, then any patent licenses
 86 |       granted to You under this License for that Work shall terminate
 87 |       as of the date such litigation is filed.
 88 | 
 89 |    4. Redistribution. You may reproduce and distribute copies of the
 90 |       Work or Derivative Works thereof in any medium, with or without
 91 |       modifications, and in Source or Object form, provided that You
 92 |       meet the following conditions:
 93 | 
 94 |       (a) You must give any other recipients of the Work or
 95 |           Derivative Works a copy of this License; and
 96 | 
 97 |       (b) You must cause any modified files to carry prominent notices
 98 |           stating that You changed the files; and
 99 | 
100 |       (c) You must retain, in the Source form of any Derivative Works
101 |           that You distribute, all copyright, patent, trademark, and
102 |           attribution notices from the Source form of the Work,
103 |           excluding those notices that do not pertain to any part of
104 |           the Derivative Works; and
105 | 
106 |       (d) If the Work includes a "NOTICE" text file as part of its
107 |           distribution, then any Derivative Works that You distribute must
108 |           include a readable copy of the attribution notices contained
109 |           within such NOTICE file, excluding those notices that do not
110 |           pertain to any part of the Derivative Works, in at least one
111 |           of the following places: within a NOTICE text file distributed
112 |           as part of the Derivative Works; within the Source form or
113 |           documentation, if provided along with the Derivative Works; or,
114 |           within a display generated by the Derivative Works, if and
115 |           wherever such third-party notices normally appear. The contents
116 |           of the NOTICE file are for informational purposes only and
117 |           do not modify the License. You may add Your own attribution
118 |           notices within Derivative Works that You distribute, alongside
119 |           or as an addendum to the NOTICE text from the Work, provided
120 |           that such additional attribution notices cannot be construed
121 |           as modifying the License.
122 | 
123 |       You may add Your own copyright statement to Your modifications and
124 |       may provide additional or different license terms and conditions
125 |       for use, reproduction, or distribution of Your modifications, or
126 |       for any such Derivative Works as a whole, provided Your use,
127 |       reproduction, and distribution of the Work otherwise complies with
128 |       the conditions stated in this License.
129 | 
130 |    5. Submission of Contributions. Unless You explicitly state otherwise,
131 |       any Contribution intentionally submitted for inclusion in the Work
132 |       by You to the Licensor shall be under the terms and conditions of
133 |       this License, without any additional terms or conditions.
134 |       Notwithstanding the above, nothing herein shall supersede or modify
135 |       the terms of any separate license agreement you may have executed
136 |       with Licensor regarding such Contributions.
137 | 
138 |    6. Trademarks. This License does not grant permission to use the trade
139 |       names, trademarks, service marks, or product names of the Licensor,
140 |       except as required for reasonable and customary use in describing the
141 |       origin of the Work and reproducing the content of the NOTICE file.
142 | 
143 |    7. Disclaimer of Warranty. Unless required by applicable law or
144 |       agreed to in writing, Licensor provides the Work (and each
145 |       Contributor provides its Contributions) on an "AS IS" BASIS,
146 |       WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
147 |       implied, including, without limitation, any warranties or conditions
148 |       of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
149 |       PARTICULAR PURPOSE. You are solely responsible for determining the
150 |       appropriateness of using or redistributing the Work and assume any
151 |       risks associated with Your exercise of permissions under this License.
152 | 
153 |    8. Limitation of Liability. In no event and under no legal theory,
154 |       whether in tort (including negligence), contract, or otherwise,
155 |       unless required by applicable law (such as deliberate and grossly
156 |       negligent acts) or agreed to in writing, shall any Contributor be
157 |       liable to You for damages, including any direct, indirect, special,
158 |       incidental, or consequential damages of any character arising as a
159 |       result of this License or out of the use or inability to use the
160 |       Work (including but not limited to damages for loss of goodwill,
161 |       work stoppage, computer failure or malfunction, or any and all
162 |       other commercial damages or losses), even if such Contributor
163 |       has been advised of the possibility of such damages.
164 | 
165 |    9. Accepting Warranty or Additional Liability. While redistributing
166 |       the Work or Derivative Works thereof, You may choose to offer,
167 |       and charge a fee for, acceptance of support, warranty, indemnity,
168 |       or other liability obligations and/or rights consistent with this
169 |       License. However, in accepting such obligations, You may act only
170 |       on Your own behalf and on Your sole responsibility, not on behalf
171 |       of any other Contributor, and only if You agree to indemnify,
172 |       defend, and hold each Contributor harmless for any liability
173 |       incurred by, or claims asserted against, such Contributor by reason
174 |       of your accepting any such warranty or additional liability.
175 | 
176 |    END OF TERMS AND CONDITIONS
177 | 
178 |    APPENDIX: How to apply the Apache License to your work.
179 | 
180 |       To apply the Apache License to your work, attach the following
181 |       boilerplate notice, with the fields enclosed by brackets "[]"
182 |       replaced with your own identifying information. (Don't include
183 |       the brackets!)  The text should be enclosed in the appropriate
184 |       comment syntax for the file format. We also recommend that a
185 |       file or class name and description of purpose be included on the
186 |       same "printed page" as the copyright notice for easier
187 |       identification within third-party archives.
188 | 
189 |    Copyright [yyyy] [name of copyright owner]
190 | 
191 |    Licensed under the Apache License, Version 2.0 (the "License");
192 |    you may not use this file except in compliance with the License.
193 |    You may obtain a copy of the License at
194 | 
195 |        http://www.apache.org/licenses/LICENSE-2.0
196 | 
197 |    Unless required by applicable law or agreed to in writing, software
198 |    distributed under the License is distributed on an "AS IS" BASIS,
199 |    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
200 |    See the License for the specific language governing permissions and
201 |    limitations under the License.
202 | 


--------------------------------------------------------------------------------