add primitive p2sh tx estimation support

jmbitcoin/jmbitcoin/secp256k1_main.py

@@ -433,9 +433,16 @@ def estimate_tx_size(ins, outs, txtype='p2pkh'):
     out: 8+1+3+2+20=34, in: 1+32+4+1+1+~73+1+1+33=147,
     ver:4,seq:4, +2 (len in,out)
     total ~= 34*len_out + 147*len_in + 10 (sig sizes vary slightly)
+    Assuming p2sh M of N multisig:
+    "ins" must contain M, N so ins= (numins, M, N) (crude assuming all same)
+    74*M + 34*N + 45 per input, so total ins ~ len_ins * (45+74M+34N)
+    so total ~ 34*len_out + (45+74M+34N)*len_in + 10
     '''
     if txtype == 'p2pkh':
         return 10 + ins * 147 + 34 * outs
+    elif txtype == 'p2shMofN':
+        ins, M, N = ins
+        return 10 + (45 + 74*M + 34*N) * ins + 34 * outs
     else:
-        raise NotImplementedError("Non p2pkh transaction size estimation not" +
+        raise NotImplementedError("Transaction size estimation not" +
-                                  "yet implemented")
+                                  "yet implemented for type: " + txtype)

jmclient/jmclient/__init__.py

@@ -21,7 +21,7 @@ from .wallet import (AbstractWallet, BitcoinCoreInterface, Wallet,
                      create_wallet_file)
 from .configure import (load_program_config, jm_single, get_p2pk_vbyte,
     get_network, jm_single, get_network, validate_address, get_irc_mchannels,
-    check_utxo_blacklist, get_blockchain_interface_instance)
+    check_utxo_blacklist, get_blockchain_interface_instance, get_p2sh_vbyte)
 from .blockchaininterface import (BlockrInterface, BlockchainInterface, sync_wallet,
                                   RegtestBitcoinCoreInterface, BitcoinCoreInterface)
 from .electruminterface import ElectrumInterface