1 package mailmux
2 
3 import (
4 	"database/sql"
5 	"errors"
6 	"fmt"
7 	"net/mail"
8 	"os"
9 	"path"
10 
11 	_ "github.com/mattn/go-sqlite3"
12 	"golang.org/x/crypto/bcrypt"
13 )
14 
15 // UserDB is an implementation of UserStore backed by a SQLite3 database.
16 // Users are fully authenticated after confirming ownership of their
17 // email address by supplying a matching ticket to a generated ticket file.
18 type UserDB struct {
19 	*sql.DB
20 	TicketDir string
21 }
22 
23 // CreateUserDB creates the named user database file and ticket directory.
24 // If the database file already exists, it is truncated. If successfullly created,
25 // the database's tables are initialised so the database is ready to use.
26 func CreateUserDB(name, ticketDir string) (*UserDB, error) {
27 	_, err := os.Create(name)
28 	if err != nil {
29 		return nil, err
30 	}
31 	if err := os.MkdirAll(ticketDir, 0666); err != nil {
32 		return nil, fmt.Errorf("create user db: %w", err)
33 	}
34 	db, err := OpenUserDB(name, ticketDir)
35 	if err != nil {
36 		return nil, fmt.Errorf("create user db: %w", err)
37 	}
38 	return db, db.initialise()
39 }
40 
41 // OpenUserDB opens the named user database file and ticket directory.
42 func OpenUserDB(name, dir string) (*UserDB, error) {
43 	db, err := sql.Open("sqlite3", name)
44 	if err != nil {
45 		return nil, err
46 	}
47 	return &UserDB{db, dir}, db.Ping()
48 }
49 
50 func (db *UserDB) initialise() error {
51 	stmt := `CREATE TABLE IF NOT EXISTS users (
52 	username TEXT PRIMARY KEY,
53 	password BLOB NOT NULL
54 );`
55 	_, err := db.Exec(stmt)
56 	return err
57 }
58 
59 func (db *UserDB) Lookup(name string) (User, error) {
60 	var u User
61 	row := db.QueryRow("SELECT username, password FROM users WHERE username = ?", name)
62 	if err := row.Scan(&u.name, &u.password); err != nil {
63 		if errors.Is(err, sql.ErrNoRows) {
64 			return User{}, fmt.Errorf("lookup %s: %w", name, ErrUnknownUser)
65 		}
66 		return User{}, fmt.Errorf("lookup %s: %w", name, err)
67 	}
68 	return u, nil
69 }
70 
71 func (db *UserDB) add(username string, pw Password) error {
72 	addr, err := mail.ParseAddress(username)
73 	if err != nil {
74 		return fmt.Errorf("add %s: invalid username: %w", username, err)
75 	}
76 	if addr.Name != "" {
77 		return fmt.Errorf("add %s: proper name present", username)
78 	}
79 
80 	hashed, err := bcrypt.GenerateFromPassword(pw, bcrypt.DefaultCost)
81 	if err != nil {
82 		return fmt.Errorf("add %s: %w", username, err)
83 	}
84 	_, err = db.Exec("INSERT INTO users (username, password) VALUES (?, ?)", username, hashed)
85 	if err != nil {
86 		return fmt.Errorf("add %s: %w", username, err)
87 	}
88 	if err := createTicket(db.TicketDir, username, pw); err != nil {
89 		return fmt.Errorf("add %s: create ticket: %w", username, err)
90 	}
91 	return nil
92 }
93 
94 func (db *UserDB) Change(name string, new Password) error {
95 	_, err := db.Lookup(name)
96 	if errors.Is(err, ErrUnknownUser) {
97 		return db.add(name, new)
98 	}
99 	if err != nil {
100 		return fmt.Errorf("change %s: %w", name, err)
101 	}
102 
103 	hashed, err := bcrypt.GenerateFromPassword(new, bcrypt.DefaultCost)
104 	if err != nil {
105 		return fmt.Errorf("change %s: %w", name, err)
106 	}
107 	_, err = db.Exec("UPDATE users SET password = ? WHERE username = ?", hashed, name)
108 	if err != nil {
109 		return fmt.Errorf("change %s: %w", name, err)
110 	}
111 	return nil
112 }
113 
114 func (db *UserDB) Delete(name string) error {
115 	_, err := db.Lookup(name)
116 	if err != nil {
117 		return fmt.Errorf("delete %s: %w", name, err)
118 	}
119 	_, err = db.Exec("DELETE FROM users WHERE username = ?", name)
120 	if err != nil {
121 		return fmt.Errorf("delete %s: %w", name, err)
122 	}
123 	return nil
124 }
125 
126 func (db *UserDB) Authenticate(name string, pw Password) error {
127 	u, err := db.Lookup(name)
128 	if err != nil {
129 		return fmt.Errorf("authenticate %s: %w", name, err)
130 	}
131 	if err := bcrypt.CompareHashAndPassword(u.password, pw); err != nil {
132 		return fmt.Errorf("authenticate %s: %w", name, err)
133 	}
134 	return nil
135 }
136 
137 // TODO tickets aren't implemented yet
138 func createTicket(dir, username string, pw Password) error {
139 	f, err := os.Create(path.Join(dir, username))
140 	if err != nil {
141 		return err
142 	}
143 	defer f.Close()
144 
145 	// TODO hash username, password, random bytes
146 	// _, err := f.Write(b)
147 	if _, err := f.Write(testTicket); err != nil {
148 		return err
149 	}
150 	return nil
151 }