vault/builtin/logical/database/dbplugin/plugin.go

package dbplugin

import (
	"context"
	"fmt"
	"net/rpc"
	"time"

	"google.golang.org/grpc"

	"github.com/hashicorp/go-plugin"
	"github.com/hashicorp/vault/helper/pluginutil"
	log "github.com/mgutz/logxi/v1"
)

// Database is the interface that all database objects must implement.
type Database interface {
	Type() (string, error)
	CreateUser(ctx context.Context, statements Statements, usernameConfig UsernameConfig, expiration time.Time) (username string, password string, err error)
	RenewUser(ctx context.Context, statements Statements, username string, expiration time.Time) error
	RevokeUser(ctx context.Context, statements Statements, username string) error

	Initialize(ctx context.Context, config map[string]interface{}, verifyConnection bool) error
	Close() error
}

// PluginFactory is used to build plugin database types. It wraps the database
// object in a logging and metrics middleware.
func PluginFactory(pluginName string, sys pluginutil.LookRunnerUtil, logger log.Logger) (Database, error) {
	// Look for plugin in the plugin catalog
	pluginRunner, err := sys.LookupPlugin(pluginName)
	if err != nil {
		return nil, err
	}

	var transport string
	var db Database
	if pluginRunner.Builtin {
		// Plugin is builtin so we can retrieve an instance of the interface
		// from the pluginRunner. Then cast it to a Database.
		dbRaw, err := pluginRunner.BuiltinFactory()
		if err != nil {
			return nil, fmt.Errorf("error getting plugin type: %s", err)
		}

		var ok bool
		db, ok = dbRaw.(Database)
		if !ok {
			return nil, fmt.Errorf("unsuported database type: %s", pluginName)
		}

		transport = "builtin"

	} else {
		// create a DatabasePluginClient instance
		db, err = newPluginClient(sys, pluginRunner, logger)
		if err != nil {
			return nil, err
		}

		// Switch on the underlying database client type to get the transport
		// method.
		switch db.(*DatabasePluginClient).Database.(type) {
		case *gRPCClient:
			transport = "gRPC"
		case *databasePluginRPCClient:
			transport = "netRPC"
		}

	}

	typeStr, err := db.Type()
	if err != nil {
		return nil, fmt.Errorf("error getting plugin type: %s", err)
	}

	// Wrap with metrics middleware
	db = &databaseMetricsMiddleware{
		next:    db,
		typeStr: typeStr,
	}

	// Wrap with tracing middleware
	if logger.IsTrace() {
		db = &databaseTracingMiddleware{
			transport: transport,
			next:      db,
			typeStr:   typeStr,
			logger:    logger,
		}
	}

	return db, nil
}

// handshakeConfigs are used to just do a basic handshake between
// a plugin and host. If the handshake fails, a user friendly error is shown.
// This prevents users from executing bad plugins or executing a plugin
// directory. It is a UX feature, not a security feature.
var handshakeConfig = plugin.HandshakeConfig{
	ProtocolVersion:  3,
	MagicCookieKey:   "VAULT_DATABASE_PLUGIN",
	MagicCookieValue: "926a0820-aea2-be28-51d6-83cdf00e8edb",
}

// DatabasePlugin implements go-plugin's Plugin interface. It has methods for
// retrieving a server and a client instance of the plugin.
type DatabasePlugin struct {
	impl Database
}

func (d DatabasePlugin) Server(*plugin.MuxBroker) (interface{}, error) {
	return &databasePluginRPCServer{impl: d.impl}, nil
}

func (DatabasePlugin) Client(b *plugin.MuxBroker, c *rpc.Client) (interface{}, error) {
	return &databasePluginRPCClient{client: c}, nil
}

func (d DatabasePlugin) GRPCServer(s *grpc.Server) error {
	RegisterDatabaseServer(s, &gRPCServer{impl: d.impl})
	return nil
}

func (DatabasePlugin) GRPCClient(c *grpc.ClientConn) (interface{}, error) {
	return &gRPCClient{
		client:     NewDatabaseClient(c),
		clientConn: c,
	}, nil
}