Make tx size limits consistent across the codebase

[marta-lokhova]

This issue tracks a slight inconsistency between the tx queue and overlay when it comes to validating transactions against max allowed size. Specifically, tx queue takes into account envelope size only (

stellar-core/src/transactions/TransactionFrame.cpp

Line 603 in 287fe4c

auto txSize = xdr::xdr_size(mEnvelope.v1().tx);

), while overlay computes the size of the whole message (which includes signatures)

stellar-core/src/overlay/FlowControlCapacity.cpp

Line 76 in 287fe4c

return static_cast<uint64_t>(xdr::xdr_argpack_size(msg));

We should ensure we validate size consistently to prevent any unnecessary drops at the overlay layer.

[dmkozh]

We'll use full tx size for the fees, so there won't be discrepancy. I'll keep this open to update when the change is merged.

[marta-lokhova]

@dmkozh Looks like there are still discrepancies in two places:

• tx validation

  stellar-core/src/transactions/TransactionFrame.cpp

  Line 738 in 03fa3a7

  auto txSize = xdr::xdr_size(mEnvelope.v1().tx);

• tx resource count

  stellar-core/src/transactions/TransactionFrame.cpp

  Line 233 in 03fa3a7

  int64_t txSize = xdr::xdr_size(mEnvelope.v1().tx);

I thought the idea was to use full tx size across codebase; the limit itself is bandwidth-related, and we never flood just the tx portion of the tx envelope, so it makes sense to count the whole transaction. If we don't, this is also problematic for overlay as it relies on txMaxSizeBytes for calculations that expect full tx size.