initial commit

.gitignore

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+main
+*.db

README.md

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+# Nothing Mail
+
+A temporary email service

cmd/mail_server/main.go

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+package main
+
+import (
+	"database/sql"
+	"io"
+	"log"
+	"time"
+
+	"github.com/emersion/go-smtp"
+	_ "github.com/mattn/go-sqlite3"
+)
+
+type Backend struct {
+	db *sql.DB
+}
+
+func (backend *Backend) NewSession(c *smtp.Conn) (smtp.Session, error) {
+	tx, err := backend.db.Begin()
+	if err != nil {
+		return nil, err
+	}
+
+	return &Session{
+		tx: tx,
+	}, nil
+}
+
+type Session struct {
+	tx           *sql.Tx
+	from, rcpt   string
+	rcpt_addr_id int64
+}
+
+func (session *Session) AuthPlain(username, password string) error {
+	return nil
+}
+
+func (session *Session) Mail(from string, opts *smtp.MailOptions) error {
+	session.from = from
+	return nil
+}
+
+func (session *Session) Rcpt(to string, opts *smtp.RcptOptions) error {
+	session.rcpt = to
+
+	stmt, err := session.tx.Prepare("INSERT OR IGNORE INTO inboxes (addr) VALUES (?) RETURNING id")
+	if err != nil {
+		return err
+	}
+	defer stmt.Close()
+
+	res, err := stmt.Exec(to)
+	if err != nil {
+		return err
+	}
+
+    // sometimes does not work and returns 0
+    // see https://github.com/mattn/go-sqlite3/issues/1140
+	id, err := res.LastInsertId()
+	if err != nil {
+		return err
+	}
+
+	log.Println("Last id: ", id)
+
+	session.rcpt_addr_id = id
+
+	return nil
+}
+
+func (session *Session) Data(reader io.Reader) error {
+	if bytes, err := io.ReadAll(reader); err != nil {
+		return err
+	} else {
+
+		stmt, err := session.tx.Prepare("INSERT INTO mails (inbox_id, from_addr, data) VALUES (?, ?, ?)")
+		if err != nil {
+			return err
+		}
+
+		_, err = stmt.Exec(session.rcpt_addr_id, session.from, bytes)
+		if err != nil {
+			return err
+		}
+
+		err = session.tx.Commit()
+		if err != nil {
+			return err
+		}
+
+		log.Println("New mail from <", session.from, "> to <", session.rcpt, ">")
+		log.Println("Data:", string(bytes))
+
+	}
+	return nil
+}
+
+func (session *Session) Reset() {}
+
+func (session *Session) Logout() error {
+	return nil
+}
+
+func main() {
+	db, err := sql.Open("sqlite3", "./db.db")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer db.Close()
+
+	backend := &Backend{
+		db: db,
+	}
+
+	server := smtp.NewServer(backend)
+
+	server.Addr = "localhost:1025"
+	server.Domain = "localhost"
+	server.WriteTimeout = 60 * time.Second
+	server.ReadTimeout = 60 * time.Second
+	server.MaxMessageBytes = 1024 * 1024
+	server.MaxRecipients = 50
+	server.AllowInsecureAuth = true
+
+	log.Println("Starting server at", server.Addr)
+	if err := server.ListenAndServe(); err != nil {
+		log.Fatal(err)
+	}
+}

go.mod

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+module github.com/GRFreire/nthmail
+
+go 1.21.6
+
+require (
+	github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 // indirect
+	github.com/emersion/go-smtp v0.20.2 // indirect
+	github.com/mattn/go-sqlite3 v1.14.22 // indirect
+)

go.sum

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+github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21 h1:OJyUGMJTzHTd1XQp98QTaHernxMYzRaOasRir9hUlFQ=
+github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21/go.mod h1:iL2twTeMvZnrg54ZoPDNfJaJaqy0xIQFuBdrLsmspwQ=
+github.com/emersion/go-smtp v0.20.2 h1:peX42Qnh5Q0q3vrAnRy43R/JwTnnv75AebxbkTL7Ia4=
+github.com/emersion/go-smtp v0.20.2/go.mod h1:qm27SGYgoIPRot6ubfQ/GpiPy/g3PaZAVRxiO/sDUgQ=
+github.com/mattn/go-sqlite3 v1.14.22 h1:2gZY6PC6kBnID23Tichd1K+Z0oS6nE/XwU+Vz/5o4kU=
+github.com/mattn/go-sqlite3 v1.14.22/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=

migration.sql

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+CREATE TABLE inboxes (
+    id integer not null primary key,
+    addr text unique
+);
+
+CREATE TABLE mails (
+    id integer not null primary key,
+    inbox_id id,
+    from_addr text,
+    data blob,
+    FOREIGN KEY(inbox_id) REFERENCES inboxes(id)
+);