273 lines
10 KiB
Go
273 lines
10 KiB
Go
package rpc
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import (
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"encoding/binary"
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"fmt"
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"github.com/iamxvbaba/td/bin"
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"github.com/iamxvbaba/td/tg"
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appfiles "telesrv/internal/app/files"
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"telesrv/internal/domain"
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)
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const tlVectorTypeID = uint32(0x1cb5c415)
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type requestVectorPolicy struct {
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vectorOffset int
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max int
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minElemBytes int
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tooLong func() error
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}
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type rpcPreflightWire interface {
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WireSize() int
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ByteAt(offset int) (byte, error)
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Uint32At(offset int) (uint32, error)
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}
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type rawRPCPreflightWire []byte
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func (w rawRPCPreflightWire) WireSize() int { return len(w) }
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func (w rawRPCPreflightWire) ByteAt(offset int) (byte, error) {
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if offset < 0 || offset >= len(w) {
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return 0, fmt.Errorf("byte offset %d outside request size %d", offset, len(w))
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}
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return w[offset], nil
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}
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func (w rawRPCPreflightWire) Uint32At(offset int) (uint32, error) {
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if offset < 0 || offset > len(w) || len(w)-offset < 4 {
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return 0, fmt.Errorf("uint32 offset %d outside request size %d", offset, len(w))
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}
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return binary.LittleEndian.Uint32(w[offset:]), nil
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}
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// requestVectorPolicies mirrors limits already enforced by typed handlers, but does so before
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// gotd's generated decoder materializes attacker-controlled interface slices. users.getUsers is
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// the one newly introduced cap: TDesktop's four current call sites all send exactly one user.
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var requestVectorPolicies = map[uint32]requestVectorPolicy{
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tg.UsersGetUsersRequestTypeID: {vectorOffset: 4, max: 100, minElemBytes: 4, tooLong: inputRequestTooLongErr},
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tg.UsersGetRequirementsToContactRequestTypeID: {vectorOffset: 4, max: maxRequirementsToContactUsers, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.ContactsImportContactsRequestTypeID: {vectorOffset: 4, max: maxContactImportBatch, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.ContactsDeleteContactsRequestTypeID: {vectorOffset: 4, max: maxContactDeleteBatch, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.ContactsEditCloseFriendsRequestTypeID: {vectorOffset: 4, max: maxCloseFriendsCount, minElemBytes: 8, tooLong: limitInvalidErr},
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tg.ContactsSetBlockedRequestTypeID: {vectorOffset: 8, max: maxContactSetBlocked, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.MessagesGetMessagesRequestTypeID: {vectorOffset: 4, max: maxGetMessagesIDs, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.MessagesGetChatsRequestTypeID: {vectorOffset: 4, max: maxGetMessagesIDs, minElemBytes: 8, tooLong: limitInvalidErr},
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tg.MessagesGetPeerDialogsRequestTypeID: {vectorOffset: 4, max: maxDialogInputPeers, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.MessagesReadMessageContentsRequestTypeID: {vectorOffset: 4, max: maxGetMessagesIDs, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.MessagesGetCustomEmojiDocumentsRequestTypeID: {vectorOffset: 4, max: maxEmojiDocuments, minElemBytes: 8, tooLong: limitInvalidErr},
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tg.MessagesDeleteMessagesRequestTypeID: {vectorOffset: 8, max: domain.MaxDeleteMessageIDs, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.MessagesCreateChatRequestTypeID: {vectorOffset: 8, max: 200, minElemBytes: 4, tooLong: limitInvalidErr},
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tg.ChannelsGetChannelsRequestTypeID: {vectorOffset: 4, max: maxGetMessagesIDs, minElemBytes: 4, tooLong: limitInvalidErr},
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}
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// layerRPCVectorPolicies bind resource limits to generated semantic field
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// identities, not constructor CRCs, profile-specific field order, flags bits,
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// or byte offsets. gotdgen proves at generation time that each registered
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// field exposes the same metric in every routable profile. Importing a future
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// schema therefore either extends these policies automatically or makes
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// dispatcher construction fail closed until an explicit conversion policy is
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// supplied.
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var layerRPCVectorPolicies = []struct {
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fieldID tg.LayerRPCFieldID
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max int
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tooLong func() error
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}{
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{tg.LayerRPCFieldUsersGetUsersID, 100, inputRequestTooLongErr},
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{tg.LayerRPCFieldUsersGetRequirementsToContactID, maxRequirementsToContactUsers, limitInvalidErr},
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{tg.LayerRPCFieldContactsImportContactsContacts, maxContactImportBatch, limitInvalidErr},
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{tg.LayerRPCFieldContactsDeleteContactsID, maxContactDeleteBatch, limitInvalidErr},
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{tg.LayerRPCFieldContactsEditCloseFriendsID, maxCloseFriendsCount, limitInvalidErr},
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{tg.LayerRPCFieldContactsSetBlockedID, maxContactSetBlocked, limitInvalidErr},
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{tg.LayerRPCFieldMessagesGetMessagesID, maxGetMessagesIDs, limitInvalidErr},
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{tg.LayerRPCFieldMessagesGetChatsID, maxGetMessagesIDs, limitInvalidErr},
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{tg.LayerRPCFieldMessagesGetPeerDialogsPeers, maxDialogInputPeers, limitInvalidErr},
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{tg.LayerRPCFieldMessagesReadMessageContentsID, maxGetMessagesIDs, limitInvalidErr},
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{tg.LayerRPCFieldMessagesGetCustomEmojiDocumentsDocumentID, maxEmojiDocuments, limitInvalidErr},
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{tg.LayerRPCFieldMessagesDeleteMessagesID, domain.MaxDeleteMessageIDs, limitInvalidErr},
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{tg.LayerRPCFieldMessagesCreateChatUsers, 200, limitInvalidErr},
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{tg.LayerRPCFieldChannelsGetChannelsID, maxGetMessagesIDs, limitInvalidErr},
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}
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func registerLayerRPCAdmissionFieldPreflights(d *tg.ServerDispatcher) error {
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if d == nil {
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return fmt.Errorf("nil layer RPC dispatcher")
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}
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for _, policy := range layerRPCVectorPolicies {
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policy := policy
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if err := d.OnLayerRPCAdmissionFieldPreflight(policy.fieldID, func(view tg.LayerRPCAdmissionFieldView) error {
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length, ok := view.VectorLength()
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if !ok {
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return inputRequestInvalidErr()
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}
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if length <= policy.max {
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return nil
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}
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if policy.tooLong != nil {
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return policy.tooLong()
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}
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return inputRequestTooLongErr()
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}); err != nil {
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return fmt.Errorf("register vector field %#016x: %w", uint64(policy.fieldID), err)
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}
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}
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for _, fieldID := range []tg.LayerRPCFieldID{
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tg.LayerRPCFieldUploadSaveFilePartBytes,
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tg.LayerRPCFieldUploadSaveBigFilePartBytes,
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} {
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if err := d.OnLayerRPCAdmissionFieldPreflight(fieldID, func(view tg.LayerRPCAdmissionFieldView) error {
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length, ok := view.BytesLength()
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if !ok {
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return inputRequestInvalidErr()
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}
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if length > appfiles.MaxUploadPartBytes {
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return filePartTooBigErr()
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}
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return nil
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}); err != nil {
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return fmt.Errorf("register upload bytes field %#016x: %w", uint64(fieldID), err)
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}
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}
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if err := d.OnLayerRPCAdmissionFieldPreflight(
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tg.LayerRPCFieldUploadSaveBigFilePartFileTotalParts,
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func(view tg.LayerRPCAdmissionFieldView) error {
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totalParts, ok := view.Int32()
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if !ok {
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return inputRequestInvalidErr()
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}
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if totalParts <= 0 || totalParts > int32(appfiles.MaxUploadParts) {
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return filePartInvalidErr()
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}
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return nil
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},
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); err != nil {
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return fmt.Errorf("register upload total-parts field: %w", err)
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}
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return nil
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}
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func preflightRPCRequest(id uint32, b *bin.Buffer) error {
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if b == nil {
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return inputRequestInvalidErr()
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}
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return preflightRPCWire(id, rawRPCPreflightWire(b.Buf))
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}
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func preflightRPCWire(id uint32, wire rpcPreflightWire) error {
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if wire == nil {
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return inputRequestInvalidErr()
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}
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if policy, ok := requestVectorPolicies[id]; ok {
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if err := preflightFixedVector(wire, policy); err != nil {
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return err
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}
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}
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switch id {
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case tg.UploadSaveFilePartRequestTypeID:
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return preflightUploadPart(wire, 16, false)
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case tg.UploadSaveBigFilePartRequestTypeID:
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return preflightUploadPart(wire, 20, true)
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default:
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return nil
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}
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}
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func preflightFixedVector(wire rpcPreflightWire, policy requestVectorPolicy) error {
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if policy.vectorOffset < 4 || policy.minElemBytes <= 0 || wire.WireSize() < policy.vectorOffset+8 {
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return inputRequestInvalidErr()
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}
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typeID, err := wire.Uint32At(policy.vectorOffset)
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if err != nil || typeID != tlVectorTypeID {
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return inputRequestInvalidErr()
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}
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rawCount, err := wire.Uint32At(policy.vectorOffset + 4)
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if err != nil {
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return inputRequestInvalidErr()
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}
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count := int64(int32(rawCount))
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if count < 0 {
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return inputRequestInvalidErr()
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}
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remaining := int64(wire.WireSize() - policy.vectorOffset - 8)
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// Check the cheapest possible encoding before the policy cap. A forged MaxInt32 count with
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// a truncated body is malformed, not merely a large valid request, and is rejected O(1).
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if count > remaining/int64(policy.minElemBytes) {
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return inputRequestInvalidErr()
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}
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if count > int64(policy.max) {
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if policy.tooLong != nil {
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return policy.tooLong()
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}
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return inputRequestTooLongErr()
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}
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return nil
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}
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func preflightUploadPart(wire rpcPreflightWire, bytesOffset int, big bool) error {
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if big {
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if wire.WireSize() < 20 {
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return inputRequestInvalidErr()
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}
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rawTotalParts, err := wire.Uint32At(16)
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if err != nil {
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return inputRequestInvalidErr()
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}
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totalParts := int32(rawTotalParts)
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if totalParts <= 0 || totalParts > appfiles.MaxUploadParts {
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return filePartInvalidErr()
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}
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}
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n, encoded, err := tlBytesSizeAt(wire, bytesOffset)
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if err != nil {
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return inputRequestInvalidErr()
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}
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if encoded != wire.WireSize()-bytesOffset {
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return inputRequestInvalidErr()
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}
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if n > appfiles.MaxUploadPartBytes {
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return filePartTooBigErr()
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}
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return nil
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}
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// tlBytesSizeAt parses a TL bytes prefix without copying the payload. encoded includes prefix,
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// payload and 4-byte padding.
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func tlBytesSizeAt(wire rpcPreflightWire, offset int) (n, encoded int, err error) {
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if offset < 0 || offset >= wire.WireSize() {
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return 0, 0, fmt.Errorf("bytes prefix out of range")
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}
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first, err := wire.ByteAt(offset)
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if err != nil {
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return 0, 0, err
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}
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prefix := 1
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switch {
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case first < 254:
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n = int(first)
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case first == 254:
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if wire.WireSize()-offset < 4 {
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return 0, 0, fmt.Errorf("truncated long bytes prefix")
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}
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second, secondErr := wire.ByteAt(offset + 1)
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third, thirdErr := wire.ByteAt(offset + 2)
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fourth, fourthErr := wire.ByteAt(offset + 3)
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if secondErr != nil || thirdErr != nil || fourthErr != nil {
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return 0, 0, fmt.Errorf("truncated long bytes prefix")
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}
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n = int(second) | int(third)<<8 | int(fourth)<<16
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prefix = 4
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default:
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return 0, 0, fmt.Errorf("invalid bytes prefix")
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}
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total := prefix + n
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padding := (4 - total%4) % 4
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if total > wire.WireSize()-offset-padding {
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return 0, 0, fmt.Errorf("truncated bytes payload")
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}
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return n, total + padding, nil
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}
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