Fully separate authentication from IMAP access

Now imapsql module does not handle authentication. (it was not doing it so well
anyway)

sql_table module was introduced and used in the default configuration as
a replacement for functionality that was implemented by imapsql before.

Parts of maddyctl code were rewritten to make it work transparently with
any IMAP backend or credentials store.

Closes #212.

internal/table/sql_table.go

@@ -0,0 +1,121 @@
+package table
+
+import (
+	"fmt"
+
+	"github.com/foxcpp/maddy/internal/config"
+	"github.com/foxcpp/maddy/internal/module"
+	_ "github.com/lib/pq"
+)
+
+type SQLTable struct {
+	modName  string
+	instName string
+
+	wrapped *SQL
+}
+
+func NewSQLTable(modName, instName string, _, _ []string) (module.Module, error) {
+	return &SQLTable{
+		modName:  modName,
+		instName: instName,
+
+		wrapped: &SQL{
+			modName:  modName,
+			instName: instName,
+		},
+	}, nil
+}
+
+func (s *SQLTable) Name() string {
+	return s.modName
+}
+
+func (s *SQLTable) InstanceName() string {
+	return s.instName
+}
+
+func (s *SQLTable) Init(cfg *config.Map) error {
+	var (
+		driver      string
+		dsnParts    []string
+		tableName   string
+		keyColumn   string
+		valueColumn string
+	)
+	cfg.String("driver", false, true, "", &driver)
+	cfg.StringList("dsn", false, true, nil, &dsnParts)
+	cfg.String("table_name", false, true, "", &tableName)
+	cfg.String("key_column", false, false, "key", &keyColumn)
+	cfg.String("value_column", false, false, "value", &valueColumn)
+	if _, err := cfg.Process(); err != nil {
+		return err
+	}
+
+	// sql_table module literally wraps the sql_query module by generating a
+	// configuration block for it.
+
+	return s.wrapped.Init(config.NewMap(cfg.Globals, config.Node{
+		Children: []config.Node{
+			{
+				Name: "driver",
+				Args: []string{driver},
+			},
+			{
+				Name: "dsn",
+				Args: dsnParts,
+			},
+			{
+				Name: "lookup",
+				Args: []string{fmt.Sprintf("SELECT %s FROM %s WHERE %s = $1", valueColumn, tableName, keyColumn)},
+			},
+			{
+				Name: "add",
+				Args: []string{fmt.Sprintf("INSERT INTO %s(%s, %s) VALUES($1, $2)", tableName, keyColumn, valueColumn)},
+			},
+			{
+				Name: "list",
+				Args: []string{fmt.Sprintf("SELECT %s from %s", keyColumn, tableName)},
+			},
+			{
+				Name: "set",
+				Args: []string{fmt.Sprintf("UPDATE %s SET %s = $2 WHERE %s = $1", tableName, valueColumn, keyColumn)},
+			},
+			{
+				Name: "del",
+				Args: []string{fmt.Sprintf("DELETE FROM %s WHERE %s = $1", tableName, keyColumn)},
+			},
+			{
+				Name: "init",
+				Args: []string{fmt.Sprintf(`CREATE TABLE IF NOT EXISTS %s (
+					%s LONGTEXT PRIMARY KEY NOT NULL,
+					%s LONGTEXT NOT NULL
+				)`, tableName, keyColumn, valueColumn)},
+			},
+		},
+	}))
+}
+
+func (s *SQLTable) Close() error {
+	return s.wrapped.Close()
+}
+
+func (s *SQLTable) Lookup(val string) (string, bool, error) {
+	return s.wrapped.Lookup(val)
+}
+
+func (s *SQLTable) Keys() ([]string, error) {
+	return s.wrapped.Keys()
+}
+
+func (s *SQLTable) RemoveKey(k string) error {
+	return s.wrapped.RemoveKey(k)
+}
+
+func (s *SQLTable) SetKey(k, v string) error {
+	return s.wrapped.SetKey(k, v)
+}
+
+func init() {
+	module.Register("sql_table", NewSQLTable)
+}