Mesh rc 0.4.3

[nodiesBlade]

Description

We should invalidate sessions based of some new errors before a relay / after a relay is handled in order to serve the least amount of free relays.

Here are all the invalid session errors we should account for

func (s Session) Validate(node sdk.Address, app appexported.ApplicationI, sessionNodeCount int) sdk.Error {
	// validate chain
	if len(s.SessionHeader.Chain) == 0 {
		return NewEmptyNonNativeChainError(ModuleName)
	}
	// validate sessionBlockHeight
	if s.SessionHeader.SessionBlockHeight < 1 {
		return NewInvalidBlockHeightError(ModuleName)
	}
	// validate the app public key
	if err := PubKeyVerification(s.SessionHeader.ApplicationPubKey); err != nil {
		return err
	}
	// validate app corresponds to appPubKey
	if app.GetPublicKey().RawString() != s.SessionHeader.ApplicationPubKey {
		return NewInvalidAppPubKeyError(ModuleName)
	}
	// validate app chains
	chains := app.GetChains()
	found := false
	for _, c := range chains {
		if c == s.SessionHeader.Chain {
			found = true
			break
		}
	}
	if !found {
		return NewUnsupportedBlockchainAppError(ModuleName)
	}
	// validate sessionNodes
	err := s.SessionNodes.Validate(sessionNodeCount)
	if err != nil {
		return err
	}
	// validate node is of the session
	if !s.SessionNodes.Contains(node) {
		return NewInvalidSessionError(ModuleName)
	}
	return nil
}

This was inspired after seeing portal send us relays with an invalid app and we were serving them for free (but not retrying to send to full node)