Since our cryptopacket limits us to 2 bytes, and since people will
send 1-message-per-crypto-packet and nobody will test the
multiple-messages-in-one-cryptopacket code, let's just restrict to
64k messages.
1. Make cryptopacket length not include the HMAC, so we can actually send
64k messages.
2. Remove len prefix from packet, make type 2 bytes, note alignment properties.
3. Change message internal lengths/counts from 4 to 2 bytes, since more
is nonsensical anyway, and this removes a need to check before allocating:
- init feature bitfield length
- error message length
- shutdown scriptpubkey length
- commit_sig number of HTLC signatures
- revoke_and_ack number of HTLC-timeout signatures
4. Change max-accepted-htlcs to two bytes, and limit it to 511 to ensure
that commit_sig will always be under 64k.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Calculations are put in 05-onchain.md, and referred to by 02-peer-protocol.
The number is 600, comfortably under the 626 theoretical limit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
