Add an RPC server

And associated electrumx_rpc command

electrumx_rpc.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+
+# See the file "LICENSE" for information about the copyright
+# and warranty status of this software.
+
+import argparse
+import asyncio
+import json
+from os import environ
+
+import aiohttp
+
+
+async def send(url, payload):
+    data = json.dumps(payload)
+
+    async with aiohttp.post(url, data = data) as resp:
+        return await resp.json()
+
+
+def main():
+    '''Send the RPC command to the server and print the result.'''
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--port', metavar='port_num', type=int,
+                        help='specify the RPC port number')
+    parser.add_argument('command', nargs='*', default=[],
+                        help='send a command to the server')
+    args = parser.parse_args()
+
+    if args.port is None:
+        args.port = int(environ.get('ELECTRUMX_RPC_PORT', 8000))
+
+    url = 'http://127.0.0.1:{:d}/'.format(args.port)
+    payload = {'method': args.command[0], 'params': args.command[1:]}
+    task = send(url, payload)
+
+    loop = asyncio.get_event_loop()
+    try:
+        result = loop.run_until_complete(task)
+    finally:
+        loop.close()
+
+    print(result)
+
+
+if __name__ == '__main__':
+    main()

server/env.py

@@ -22,6 +22,7 @@ class Env(object):
         self.db_dir = self.required('DB_DIRECTORY')
         self.utxo_MB = self.integer('UTXO_MB', 1000)
         self.hist_MB = self.integer('HIST_MB', 250)
+        self.electrumx_rpc_port = self.integer('ELECTRUMX_RPC_PORT', 8000)
         self.rpc_url = self.build_rpc_url()
 
     def default(self, envvar, default):

server/rpc.py

@@ -0,0 +1,60 @@
+# See the file "LICENSE" for information about the copyright
+# and warranty status of this software.
+
+import logging
+import traceback
+
+from aiohttp import web
+
+
+class ElectrumRPCServer(object):
+    '''ElectrumX's RPC server for localhost.'''
+
+    def __init__(self, server):
+        self.logger = logging.getLogger('RPCServer')
+        self.logger.setLevel(logging.INFO)
+        self.server = server
+
+    async def request_handler(self, request):
+        json_request = await request.json()
+        try:
+            err, result = await self.json_handler(json_request)
+        except Exception as e:
+            traceback.print_exc()
+            err, result = 1, 'caught exception: {}'.format(e)
+
+        id_ = request.get('id')
+        if err is None:
+            response = {
+                'id': id_,
+                'error': None,
+                'result': result,
+            }
+        else:
+            response = {
+                'id': id_,
+                'error': {'code': err, 'message': result},
+                'result': None,
+            }
+
+        return web.json_response(response)
+
+    async def json_handler(self, request):
+        method = request.get('method')
+        id_ = request.get('id')
+        params = request.get('params', [])
+        handler = getattr(self.server, 'handle_rpc_{}'.format(method), None)
+        if not handler:
+            return 1, 'unknown method "{}"'.format(method)
+        else:
+            return await handler(params)
+
+    def tasks(self, port):
+        self.logger.info('listening on port {:d}'.format(port))
+        app = web.Application()
+        app.router.add_post('/', self.request_handler)
+        host = '0.0.0.0'
+        loop = app.loop
+        handler = app.make_handler()
+        server = loop.create_server(handler, host, port)
+        return [server, app.startup()]

server/server.py

@@ -2,16 +2,13 @@
 # and warranty status of this software.
 
 import asyncio
-import json
 import logging
-import os
 import signal
 import time
 from functools import partial
 
-import aiohttp
-
 from server.db import DB
+from server.rpc import ElectrumRPCServer
 
 
 class Server(object):
@@ -20,16 +17,40 @@ class Server(object):
         self.env = env
         self.db = DB(env)
         self.block_cache = BlockCache(env, self.db)
-        self.tasks = [
-            asyncio.ensure_future(self.block_cache.catch_up()),
-            asyncio.ensure_future(self.block_cache.process_cache()),
-        ]
+        self.rpc_server = ElectrumRPCServer(self)
 
+        # Signal handlers
         loop = asyncio.get_event_loop()
         for signame in ('SIGINT', 'SIGTERM'):
             loop.add_signal_handler(getattr(signal, signame),
                                     partial(self.on_signal, signame))
 
+        coros = self.rpc_server.tasks(env.electrumx_rpc_port)
+        coros += [self.block_cache.catch_up(),
+                  self.block_cache.process_cache()]
+        self.tasks = [asyncio.ensure_future(coro) for coro in coros]
+
+    async def handle_rpc_getinfo(self, params):
+        return None, {
+            'blocks': self.db.height,
+            'peers': 0,
+            'sessions': 0,
+            'watched': 0,
+            'cached': 0,
+        }
+
+    async def handle_rpc_sessions(self, params):
+        return None, []
+
+    async def handle_rpc_numsessions(self, params):
+        return None, 0
+
+    async def handle_rpc_peers(self, params):
+        return None, []
+
+    async def handle_rpc_banner_update(self, params):
+        return None, 'FIXME'
+
     def on_signal(self, signame):
         logging.warning('received {} signal, preparing to shut down'
                         .format(signame))
@@ -150,8 +171,7 @@ class BlockCache(object):
         data = json.dumps(payload)
         while True:
             try:
-                async with aiohttp.request('POST', self.rpc_url,
-                                           data = data)  as resp:
+                async with aiohttp.post(self.rpc_url, data = data) as resp:
                     result = await resp.json()
             except asyncio.CancelledError:
                 raise