Use Esplora for fee estimation and tx broadcast for blocksonly nodes

src/jmclient/blockchaininterface.py

@@ -14,6 +14,7 @@
 from jmbase.support import get_log, jmprint, EXIT_FAILURE
 from jmclient.configure import jm_single
 from jmclient.jsonrpc import JsonRpc, JsonRpcConnectionError, JsonRpcError
+from jmclient.esplora_api_client import EsploraApiClient
 
 
 # an inaccessible blockheight; consider rewriting in 1900 years
@@ -365,6 +366,11 @@ def __init__(self, jsonRpc: JsonRpc, network: str, wallet_name: str) -> None:
                     "setting in joinmarket.cfg) instead. See docs/USAGE.md "
                     "for details.")
 
+        self.no_local_mempool = not self._rpc("getnetworkinfo", [])["localrelay"]
+        if self.no_local_mempool:
+            log.debug("Bitcoin Core running in blocksonly mode.")
+        self.esplora_api_client = EsploraApiClient()
+
     def is_address_imported(self, addr: str) -> bool:
         return len(self._rpc('getaddressinfo', [addr])['labels']) > 0
 
@@ -531,6 +537,13 @@ def pushtx(self, txbin: bytes) -> bool:
         """ Given a binary serialized valid bitcoin transaction,
         broadcasts it to the network.
         """
+        # If don't have local mempool, try pushing tx using Blockstream
+        # Esplora API first for privacy reasons.
+        if self.no_local_mempool:
+            result = self.esplora_api_client.pushtx(txbin)
+            if result:
+                return result
+
         txhex = bintohex(txbin)
         try:
             txid = self._rpc('sendrawtransaction', [txhex])
@@ -594,7 +607,11 @@ def _estimate_fee_basic(self,
         # should be used instead of falling back to hardcoded values
         tries = 2 if conf_target == 1 else 1
         for i in range(tries):
-            rpc_result = self._rpc('estimatesmartfee', [conf_target + i])
+            try:
+                rpc_result = self._rpc('estimatesmartfee', [conf_target + i])
+            except JsonRpcError:
+                # Handle jmclient.jsonrpc.JsonRpcError: {'code': -32603, 'message': 'Fee estimation disabled'}
+                continue
             if not rpc_result:
                 # in case of connection error:
                 return None
@@ -605,9 +622,17 @@ def _estimate_fee_basic(self,
             # the 'feerate' key is found and contains a positive value:
             if estimate and estimate > 0:
                 return (btc.btc_to_sat(estimate), rpc_result.get('blocks'))
+
         # cannot get a valid estimate after `tries` tries:
-        log.warn("Could not source a fee estimate from Core")
-        return None
+        log.info("Could not source a fee estimate from Core")
+        # Try Esplora (Blockstream) as a fallback
+        esplora_fee = self.esplora_api_client.estimate_fee_basic(conf_target)
+        if esplora_fee:
+            log.info("Local fee estimation failed, using one from Esplora API.")
+            return esplora_fee
+        else:
+            log.warn("Could not source a fee estimate neither from Core nor Esplora API.")
+            return None
 
     def get_current_block_height(self) -> int:
         try:

src/jmclient/esplora_api_client.py

@@ -0,0 +1,88 @@
+import collections
+import json
+import requests
+from math import ceil
+from typing import Optional
+
+from jmbase import bintohex, get_log
+from jmclient.configure import jm_single
+
+
+jlog = get_log()
+
+
+class EsploraApiClient():
+
+    _API_URL_BASE_MAINNET = "http://explorerzydxu5ecjrkwceayqybizmpjjznk5izmitf2modhcusuqlid.onion/api/"
+    _API_URL_BASE_TESTNET = "http://explorerzydxu5ecjrkwceayqybizmpjjznk5izmitf2modhcusuqlid.onion/testnet/api/"
+
+    def __init__(self, api_base_url: Optional[str] = None) -> None:
+        jcg = jm_single().config.get
+        if api_base_url:
+            self.api_base_url = api_base_url
+        else:
+            network = jcg("BLOCKCHAIN", "network")
+            if network == "mainnet":
+                self.api_base_url = self._API_URL_BASE_MAINNET
+            elif network == "testnet":
+                if jcg("BLOCKCHAIN", "blockchain_source") != "regtest":
+                    self.api_base_url = self._API_URL_BASE_TESTNET
+                else:
+                    return
+            else:
+                jlog.debug("Esplora API not available for signet.")
+                return
+        jlog.debug("Esplora API will use {} backend.".format(self.api_base_url))
+        onion_socks5_host = jcg("PAYJOIN", "onion_socks5_host")
+        onion_socks5_port = jcg("PAYJOIN", "onion_socks5_port")
+        self.session = requests.session()
+        self.proxies = {
+            "http": "socks5h://" +
+                onion_socks5_host + ":" + onion_socks5_port,
+            "https": "socks5h://" +
+                onion_socks5_host + ":" + onion_socks5_port
+        }
+
+    def _do_request(self, uri: str, body: Optional[str] = None) -> bytes:
+        url = self.api_base_url + uri
+        jlog.debug("Doing request to " + url)
+        if body:
+            response = self.session.post(url, data=body, proxies=self.proxies)
+        else:
+            response = self.session.get(url, proxies=self.proxies)
+        jlog.debug(str(response.content))
+        return response.content
+
+    def pushtx(self, txbin: bytes) -> bool:
+        if not self.api_base_url:
+            return False
+        txhex = bintohex(txbin)
+        txid = self._do_request("tx", txhex)
+        return True if len(txid) == 64 else False
+
+    def estimate_fee_basic(self, conf_target: int) -> Optional[int]:
+        if not self.api_base_url:
+            return None
+        try:
+            estimates = json.loads(self._do_request("fee-estimates"))
+            estimates = { int(k):v for k,v in estimates.items() }
+        except Exception as e:
+            jlog.debug(e)
+            return None
+        sorted_estimates = collections.OrderedDict(sorted(estimates.items()))
+        prev = None
+        for k, v in sorted_estimates.items():
+            if k > conf_target:
+                break
+            prev = v
+        return ceil(prev * 1000) if prev else None
+
+if __name__ == "__main__":
+    from jmclient import load_program_config
+    load_program_config()
+    ec = EsploraApiClient()
+    est = ec.estimate_fee_basic(3)
+    print(est)
+    est = ec.estimate_fee_basic(999)
+    print(est)
+