1 925168e0 2022-04-14 o package mailmux
  2 925168e0 2022-04-14 o 
  3 925168e0 2022-04-14 o import (
  4 925168e0 2022-04-14 o 	"database/sql"
  5 cb474497 2022-04-19 o 	"errors"
  6 925168e0 2022-04-14 o 	"fmt"
  7 052981c3 2022-04-16 o 	"os"
  8 925168e0 2022-04-14 o 	"time"
  9 925168e0 2022-04-14 o )
 10 925168e0 2022-04-14 o 
 11 cb474497 2022-04-19 o // An Alias is used by a server to forward mail it receives.
 12 cb474497 2022-04-19 o // Mail addressed to Recipient is forwarded to Destination.
 13 925168e0 2022-04-14 o type Alias struct {
 14 71bdede3 2022-04-21 o 	// Recipient is just the username part of a publicly visible email address.
 15 71bdede3 2022-04-21 o 	// The domain(s) available for accepting mail depend on the SMTP server
 16 cb474497 2022-04-19 o 	// implementation.
 17 71bdede3 2022-04-21 o 	Recipient string
 18 cb474497 2022-04-19 o 	// Destination contains an email address, with domain suffix,
 19 cb474497 2022-04-19 o 	// to which mail will be forwarded.
 20 925168e0 2022-04-14 o 	Destination string
 21 cb474497 2022-04-19 o 	// Expiry specifies a time after which the alias is considered inactive;
 22 cb474497 2022-04-19 o 	// that is, mail addressed to Recipient should be bounced.
 23 71bdede3 2022-04-21 o 	Expiry time.Time
 24 cb474497 2022-04-19 o 	// Note contains user-defined text that can be used to,
 25 cb474497 2022-04-19 o 	// for example, identify the alias.
 26 71bdede3 2022-04-21 o 	Note string
 27 f7343271 2022-04-25 o 	// modTime contains the time the alias was last modified.
 28 f7343271 2022-04-25 o 	modTime time.Time
 29 925168e0 2022-04-14 o }
 30 925168e0 2022-04-14 o 
 31 c6eb8eaf 2022-04-25 o // Equal reports whether a and b represent the same Alias.
 32 c6eb8eaf 2022-04-25 o // This is required since an alias' expiry is a time.Time value which has pitfalls
 33 c6eb8eaf 2022-04-25 o // when doing comparisons using reflect.DeepEqual or the == operator.
 34 c6eb8eaf 2022-04-25 o func (a Alias) Equal(b Alias) bool {
 35 c6eb8eaf 2022-04-25 o 	switch {
 36 c6eb8eaf 2022-04-25 o 	case a.Recipient != b.Recipient:
 37 c6eb8eaf 2022-04-25 o 		return false
 38 c6eb8eaf 2022-04-25 o 	case a.Destination != b.Destination:
 39 c6eb8eaf 2022-04-25 o 		return false
 40 c6eb8eaf 2022-04-25 o 	case !a.Expiry.Equal(b.Expiry):
 41 c6eb8eaf 2022-04-25 o 		return false
 42 c6eb8eaf 2022-04-25 o 	case a.Note != b.Note:
 43 c6eb8eaf 2022-04-25 o 		return false
 44 c6eb8eaf 2022-04-25 o 	}
 45 c6eb8eaf 2022-04-25 o 	return true
 46 c6eb8eaf 2022-04-25 o }
 47 c6eb8eaf 2022-04-25 o 
 48 925168e0 2022-04-14 o type AliasStore interface {
 49 925168e0 2022-04-14 o 	Create(dest string) (Alias, error)
 50 71bdede3 2022-04-21 o 	Put(alias Alias) error
 51 925168e0 2022-04-14 o 	Aliases(dest string) ([]Alias, error)
 52 925168e0 2022-04-14 o 	Delete(rcpt string) error
 53 925168e0 2022-04-14 o }
 54 925168e0 2022-04-14 o 
 55 cb474497 2022-04-19 o // AliasDB is an implementation of AliasStore backed by a sqlite3 database.
 56 925168e0 2022-04-14 o type AliasDB struct {
 57 925168e0 2022-04-14 o 	*sql.DB
 58 925168e0 2022-04-14 o 	dictpath string
 59 925168e0 2022-04-14 o }
 60 925168e0 2022-04-14 o 
 61 cb474497 2022-04-19 o var errRecipientNotExist = errors.New("no such recipient")
 62 cb474497 2022-04-19 o 
 63 cb474497 2022-04-19 o // OpenAliasDB opens the named database file, using the file at dictpath for
 64 71bdede3 2022-04-21 o // generating recipient names for new aliases. The database is created and
 65 cb474497 2022-04-19 o // initialised if it doesn't already exist.
 66 925168e0 2022-04-14 o func OpenAliasDB(name, dictpath string) (*AliasDB, error) {
 67 925168e0 2022-04-14 o 	db, err := sql.Open("sqlite3", name)
 68 925168e0 2022-04-14 o 	if err != nil {
 69 925168e0 2022-04-14 o 		return nil, err
 70 925168e0 2022-04-14 o 	}
 71 925168e0 2022-04-14 o 	stmt := `
 72 925168e0 2022-04-14 o CREATE TABLE IF NOT EXISTS aliases (
 73 925168e0 2022-04-14 o 	recipient TEXT PRIMARY KEY,
 74 925168e0 2022-04-14 o 	destination TEXT NOT NULL,
 75 cb474497 2022-04-19 o 	expiry INTEGER NOT NULL,
 76 f7343271 2022-04-25 o 	note TEXT NOT NULL,
 77 e2ab3f7c 2022-04-25 o 	modtime INTEGER NOT NULL DEFAULT (unixepoch())
 78 925168e0 2022-04-14 o );`
 79 925168e0 2022-04-14 o 	_, err = db.Exec(stmt)
 80 052981c3 2022-04-16 o 	if err != nil {
 81 052981c3 2022-04-16 o 		return nil, err
 82 052981c3 2022-04-16 o 	}
 83 052981c3 2022-04-16 o 	_, err = os.Stat(dictpath)
 84 925168e0 2022-04-14 o 	return &AliasDB{db, dictpath}, err
 85 925168e0 2022-04-14 o }
 86 925168e0 2022-04-14 o 
 87 cb474497 2022-04-19 o // Create is a convenience method for creating a new random alias for destination.
 88 cb474497 2022-04-19 o // To set more Alias attributes, such as setting an expiry date, use Put.
 89 cb474497 2022-04-19 o func (db *AliasDB) Create(destination string) (Alias, error) {
 90 925168e0 2022-04-14 o 	rcpt, err := RandomUsername(db.dictpath)
 91 925168e0 2022-04-14 o 	if err != nil {
 92 925168e0 2022-04-14 o 		return Alias{}, fmt.Errorf("create alias: %w", err)
 93 925168e0 2022-04-14 o 	}
 94 cb474497 2022-04-19 o 	a := Alias{
 95 cb474497 2022-04-19 o 		Recipient:   rcpt,
 96 cb474497 2022-04-19 o 		Destination: destination,
 97 925168e0 2022-04-14 o 	}
 98 cb474497 2022-04-19 o 	if err := db.Put(a); err != nil {
 99 cb474497 2022-04-19 o 		return Alias{}, fmt.Errorf("put %s: %w", a.Recipient, err)
100 cb474497 2022-04-19 o 	}
101 cb474497 2022-04-19 o 	return a, nil
102 925168e0 2022-04-14 o }
103 925168e0 2022-04-14 o 
104 cb474497 2022-04-19 o // Put creates or updates the given alias in db.
105 cb474497 2022-04-19 o func (db *AliasDB) Put(a Alias) error {
106 cb474497 2022-04-19 o 	_, err := db.Lookup(a.Recipient)
107 cb474497 2022-04-19 o 	if err != nil && !errors.Is(err, errRecipientNotExist) {
108 cb474497 2022-04-19 o 		return fmt.Errorf("lookup %s: %w", a.Recipient, err)
109 cb474497 2022-04-19 o 	}
110 cb474497 2022-04-19 o 	var q string
111 cb474497 2022-04-19 o 	if errors.Is(err, errRecipientNotExist) {
112 e2ab3f7c 2022-04-25 o 		q = "INSERT INTO aliases (recipient, destination, expiry, note) VALUES (?, ?, ?, ?)"
113 e2ab3f7c 2022-04-25 o 		_, err = db.Exec(q, a.Recipient, a.Destination, a.Expiry.Unix(), a.Note)
114 cb474497 2022-04-19 o 	} else if err == nil {
115 e2ab3f7c 2022-04-25 o 		q = "UPDATE aliases SET recipient = ?, destination = ?, expiry = ?, note = ?, modtime = unixepoch() WHERE recipient = ?"
116 e2ab3f7c 2022-04-25 o 		_, err = db.Exec(q, a.Recipient, a.Destination, a.Expiry.Unix(), a.Note, a.Recipient)
117 cb474497 2022-04-19 o 	}
118 cb474497 2022-04-19 o 	return err
119 cb474497 2022-04-19 o }
120 cb474497 2022-04-19 o 
121 cb474497 2022-04-19 o // Lookup returns the Alias with the recipient rcpt. If no alias exists, an error is returned.
122 cb474497 2022-04-19 o func (db *AliasDB) Lookup(rcpt string) (Alias, error) {
123 cb474497 2022-04-19 o 	var a Alias
124 f7343271 2022-04-25 o 	q := "SELECT recipient, destination, expiry, note, modtime FROM ALIASES WHERE recipient = ?"
125 71bdede3 2022-04-21 o 	var expiry int64
126 f7343271 2022-04-25 o 	var modtime int64
127 f7343271 2022-04-25 o 	err := db.QueryRow(q, rcpt).Scan(&a.Recipient, &a.Destination, &expiry, &a.Note, &modtime)
128 cb474497 2022-04-19 o 	if errors.Is(err, sql.ErrNoRows) {
129 cb474497 2022-04-19 o 		return Alias{}, errRecipientNotExist
130 cb474497 2022-04-19 o 	} else if err != nil {
131 cb474497 2022-04-19 o 		return Alias{}, err
132 cb474497 2022-04-19 o 	}
133 71bdede3 2022-04-21 o 	a.Expiry = time.Unix(expiry, 0)
134 f7343271 2022-04-25 o 	a.modTime = time.Unix(modtime, 0)
135 cb474497 2022-04-19 o 	return a, nil
136 cb474497 2022-04-19 o }
137 cb474497 2022-04-19 o 
138 cb474497 2022-04-19 o // Aliases returns all aliases who have their destination address as dest.
139 925168e0 2022-04-14 o func (db *AliasDB) Aliases(dest string) ([]Alias, error) {
140 f7343271 2022-04-25 o 	q := "SELECT recipient, destination, expiry, note FROM aliases WHERE destination = ?"
141 f7343271 2022-04-25 o 	rows, err := db.Query(q, dest)
142 925168e0 2022-04-14 o 	if err != nil {
143 cb474497 2022-04-19 o 		return nil, err
144 925168e0 2022-04-14 o 	}
145 925168e0 2022-04-14 o 	defer rows.Close()
146 925168e0 2022-04-14 o 	var aliases []Alias
147 925168e0 2022-04-14 o 	for rows.Next() {
148 925168e0 2022-04-14 o 		var a Alias
149 cb474497 2022-04-19 o 		var sec int64
150 cb474497 2022-04-19 o 		if err := rows.Scan(&a.Recipient, &a.Destination, &sec, &a.Note); err != nil {
151 925168e0 2022-04-14 o 			return aliases, err
152 925168e0 2022-04-14 o 		}
153 cb474497 2022-04-19 o 		a.Expiry = time.Unix(sec, 0)
154 925168e0 2022-04-14 o 		aliases = append(aliases, a)
155 925168e0 2022-04-14 o 	}
156 925168e0 2022-04-14 o 	return aliases, rows.Err()
157 925168e0 2022-04-14 o }
158 925168e0 2022-04-14 o 
159 cb474497 2022-04-19 o // Delete deletes any alias with recipient rcpt.
160 cb474497 2022-04-19 o // No error is returned if no alias exists with the given recipient.
161 925168e0 2022-04-14 o func (db *AliasDB) Delete(rcpt string) error {
162 925168e0 2022-04-14 o 	_, err := db.Exec("DELETE FROM aliases WHERE recipient = ?", rcpt)
163 925168e0 2022-04-14 o 	if err != nil {
164 925168e0 2022-04-14 o 		return fmt.Errorf("delete %s: %w", rcpt, err)
165 925168e0 2022-04-14 o 	}
166 925168e0 2022-04-14 o 	return nil
167 925168e0 2022-04-14 o }