1 files changed, 80 insertions, 0 deletions
diff --git a/db/auth.go b/db/auth.go
new file mode 100644
index 0000000..e2bac38
--- /dev/null
+++ b/db/auth.go
@@ -0,0 +1,80 @@
+package db
+
+import (
+	"crypto/subtle"
+	"database/sql"
+)
+
+type AuthProvider interface {
+	SaltedHash(username string) [32]byte
+	Salt(username string) [16]byte
+	UserExists(username string) bool
+}
+
+type DBAuthProvider struct {
+	db *sql.DB
+}
+
+func NewDBAuthProvider(db *sql.DB) AuthProvider {
+	provider := new(DBAuthProvider)
+	provider.db = db
+
+	return provider
+}
+
+func (dbAuth DBAuthProvider) Close() {
+	dbAuth.db.Close()
+}
+
+func (dbAuth DBAuthProvider) SaltedHash(username string) [32]byte {
+	row := dbAuth.db.QueryRow(`
+    SELECT saltedhash FROM users WHERE username = ?
+    `, username)
+
+	buf := make([]byte, 32)
+	should_copy := 1
+
+	saltedHash := [32]byte{0}
+
+	err := row.Scan(&buf)
+	if err != nil {
+		should_copy = 0
+	}
+
+	subtle.ConstantTimeCopy(should_copy, saltedHash[:], buf[:32])
+
+	return saltedHash
+}
+
+func (dbAuth DBAuthProvider) Salt(username string) [16]byte {
+	row := dbAuth.db.QueryRow(`
+    SELECT salt FROM users WHERE username = ?
+    `, username)
+
+	buf := make([]byte, 16)
+	should_copy := 1
+
+	salt := [16]byte{0}
+
+	err := row.Scan(&buf)
+	if err != nil {
+		should_copy = 0
+	}
+
+	subtle.ConstantTimeCopy(should_copy, salt[:], buf[:16])
+
+	return salt
+}
+
+func (dbAuth DBAuthProvider) UserExists(username string) bool {
+	row := dbAuth.db.QueryRow(`
+    SELECT 1 FROM users WHERE username = ?
+    `, username)
+
+	err := row.Scan(new(int))
+	if err != nil {
+		return false
+	}
+
+	return true
+}