Initial commit

.drone.yml

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+pipeline:
+  docker:
+    image: plugins/docker
+    registry: registry.labs.0x.no
+    repo: registry.labs.0x.no/email-collector
+    tags:
+      - latest

.gitignore

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+email-collector

Dockerfile

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+FROM golang:1.10-alpine as go
+
+WORKDIR /go/src/email-collector
+COPY . .
+ENV CGO_ENABLED=0
+ENV GOOS=linux
+ENV GOARCH=amd64
+RUN go build -ldflags '-extldflags "-static"' -o email-collector
+
+
+FROM scratch
+
+EXPOSE 8080
+COPY --from=go /go/src/email-collector/email-collector email-collector
+
+ENTRYPOINT ["/email-collector"]

LICENSE

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+MIT License
+
+Copyright (c) 2017 Ambrose Chua
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+
+# email-collector
+
+A simple email collector
+

checkmail/checkmail.go

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+package checkmail
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"net/smtp"
+	"regexp"
+	"strings"
+	"time"
+)
+
+type SmtpError struct {
+	Err error
+}
+
+func (e SmtpError) Error() string {
+	return e.Err.Error()
+}
+
+func (e SmtpError) Code() string {
+	return e.Err.Error()[0:3]
+}
+
+func NewSmtpError(err error) SmtpError {
+	return SmtpError{
+		Err: err,
+	}
+}
+
+const forceDisconnectAfter = time.Second * 10
+
+var (
+	ErrBadFormat        = errors.New("invalid format")
+	ErrUnresolvableHost = errors.New("unresolvable host")
+
+	//emailRegexp = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
+	emailRegexp = regexp.MustCompile("^.+?@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
+)
+
+func ValidateFormat(email string) error {
+	if !emailRegexp.MatchString(email) {
+		return ErrBadFormat
+	}
+	return nil
+}
+
+func ValidateHost(email string) error {
+	_, host := split(email)
+	mx, err := net.LookupMX(host)
+	if err != nil {
+		return ErrUnresolvableHost
+	}
+
+	client, err := smtp.Dial(fmt.Sprintf("%s:%d", mx[0].Host, 25))
+	if err != nil {
+		return NewSmtpError(err)
+	}
+	defer client.Close()
+
+	t := time.AfterFunc(forceDisconnectAfter, func() { client.Close() })
+	defer t.Stop()
+
+	err = client.Hello("checkmail.me")
+	if err != nil {
+		return NewSmtpError(err)
+	}
+	err = client.Mail("lansome-cowboy@gmail.com")
+	if err != nil {
+		return NewSmtpError(err)
+	}
+	err = client.Rcpt(email)
+	if err != nil {
+		return NewSmtpError(err)
+	}
+	return nil
+}
+
+func split(email string) (account, host string) {
+	i := strings.LastIndexByte(email, '@')
+	account = email[:i]
+	host = email[i+1:]
+	return
+}

checkmail/checkmail_test.go

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+package checkmail_test
+
+import (
+	"testing"
+
+	"github.com/badoux/checkmail"
+)
+
+var (
+	samples = []struct {
+		mail    string
+		format  bool
+		account bool //host+user
+	}{
+		{mail: "florian@carrere.cc", format: true, account: true},
+		{mail: " florian@carrere.cc", format: false, account: false},
+		{mail: "florian@carrere.cc ", format: false, account: false},
+		{mail: "test@912-wrong-domain902.com", format: true, account: false},
+		{mail: "0932910-qsdcqozuioqkdmqpeidj8793@gmail.com", format: true, account: false},
+		{mail: "@gmail.com", format: false, account: false},
+		{mail: "test@gmail@gmail.com", format: false, account: false},
+		{mail: "test test@gmail.com", format: false, account: false},
+		{mail: " test@gmail.com", format: false, account: false},
+		{mail: "test@wrong domain.com", format: false, account: false},
+		{mail: "é&ààà@gmail.com", format: false, account: false},
+		{mail: "admin@jalopyjournal.com", format: true, account: true},
+		{mail: "admin@busyboo.com", format: true, account: true},
+		{mail: "a@gmail.fi", format: true, account: false},
+	}
+)
+
+func TestValidateHost(t *testing.T) {
+	for _, s := range samples {
+		if !s.format {
+			continue
+		}
+
+		err := checkmail.ValidateHost(s.mail)
+		if err != nil && s.account == true {
+			t.Errorf(`"%s" => unexpected error: "%v"`, s.mail, err)
+		}
+		if err == nil && s.account == false {
+			t.Errorf(`"%s" => expected error`, s.mail)
+		}
+	}
+}
+
+func TestValidateFormat(t *testing.T) {
+	for _, s := range samples {
+		err := checkmail.ValidateFormat(s.mail)
+		if err != nil && s.format == true {
+			t.Errorf(`"%s" => unexpected error: "%v"`, s.mail, err)
+		}
+		if err == nil && s.format == false {
+			t.Errorf(`"%s" => expected error`, s.mail)
+		}
+	}
+}

email-collector.go

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+package main // import "github.com/productionwentdown/email-collector"
+
+import (
+	"encoding/csv"
+	"log"
+	"net/http"
+	"os"
+	"sync"
+	"time"
+
+	// modified from @badoux's checkmail
+	"github.com/productionwentdown/email-collector/checkmail"
+)
+
+func main() {
+
+	csvMutex := &sync.Mutex{}
+	csvFile, err := os.OpenFile("list.csv", os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	defer csvFile.Close()
+	if err != nil {
+		log.Fatal(err)
+	}
+	csvWriter := csv.NewWriter(csvFile)
+
+	http.HandleFunc("/subscribe", func(w http.ResponseWriter, r *http.Request) {
+		err := r.ParseForm()
+		if err != nil {
+			log.Println(err)
+			w.WriteHeader(400)
+			w.Write([]byte("An error occurred. Please try again"))
+			return
+		}
+		email := r.Form.Get("email")
+		if err := checkmail.ValidateFormat(email); err != nil {
+			log.Println(email, err)
+			w.WriteHeader(400)
+			w.Write([]byte("Email is not valid"))
+			return
+		}
+		err = checkmail.ValidateHost(email)
+		if _, ok := err.(checkmail.SmtpError); !ok && err != nil {
+			log.Println(email, err)
+			w.WriteHeader(400)
+			w.Write([]byte("Email is not valid"))
+			return
+		}
+		log.Println(email, "success")
+		csvMutex.Lock()
+		csvWriter.Write([]string{email, time.Now().String()})
+		csvWriter.Flush()
+		csvMutex.Unlock()
+		w.Header().Add("Location", "/subscribed")
+		w.WriteHeader(303)
+	})
+
+	log.Fatal(http.ListenAndServe(":8080", nil))
+
+}

go.mod

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+module github.com/productionwentdown/email-collector

list.csv

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+ambrose.chua.cm@gmail.com,2018-07-01 15:44:58.882682933 +0800 +08 m=+6.293630824
+ambrose.chua.cm@gmail.com,2018-07-01 15:45:54.537033441 +0800 +08 m=+2.937844629
+ambrose.chua.cm@gmail.com,2018-07-01 15:45:59.691625135 +0800 +08 m=+8.092381750
+ambrose.chua.cm@gmail.com,2018-07-01 15:46:06.580296689 +0800 +08 m=+2.869616704