Bump default value of MAX_SEND to 1m bytes.

Otherwise historic large txs could not be served to clients.

RELEASE-NOTES

@@ -1,3 +1,11 @@
+version 0.7.11
+--------------
+
+- increased MAX_SEND default value to 1 million bytes so as to be able
+  to serve large historical transactions of up to 500K in size.  The
+  MAX_SEND floor remains at 350,000 bytes so you can reduct it if you
+  wish.
+
 version 0.7.10
 --------------
 

docs/ENV-NOTES

@@ -45,20 +45,22 @@ each and are processed efficiently.  I feel the defaults are low and
 encourage you to raise them.
 
 MAX_SEND         - maximum size of a response message to send over the wire,
-                   in bytes.  Defaults to 350,000 and will treat smaller
-                   values as the same because standard Electrum protocol
-                   header chunk requests are nearly that large.
+                   in bytes.  Defaults to 1,000,000 and will treat values
+                   smaller than 350,000 as 350,000 because standard Electrum
+                   protocol header chunk requests are almost that large.
                    The Electrum protocol has a flaw in that address
                    histories must be served all at once or not at all,
                    an obvious avenue for abuse.  MAX_SEND is a
                    stop-gap until the protocol is improved to admit
                    incremental history requests.  Each history entry
                    is appoximately 100 bytes so the default is
-                   equivalent to a history limit of around 3,500
+                   equivalent to a history limit of around 10,000
                    entries, which should be ample for most legitimate
-                   users.  Increasing by a single-digit factor is
-                   likely fine but bear in mind one client can request
-                   history for multiple addresses.
+                   users.  If you increase this bear in mind one client
+                   can request history for multiple addresses.  Also,
+                   the largest raw transaction you will be able to serve
+                   to a client is just under half of MAX_SEND, as each raw
+                   byte becomes 2 hexadecimal ASCII characters on the wire.
 MAX_SUBS         - maximum number of address subscriptions across all
                    sessions.  Defaults to 250,000.
 MAX_SESSION_SUBS - maximum number of address subscriptions permitted to a

server/env.py

@@ -45,7 +45,7 @@ class Env(LoggedClass):
         self.donation_address = self.default('DONATION_ADDRESS', '')
         self.db_engine = self.default('DB_ENGINE', 'leveldb')
         # Server limits to help prevent DoS
-        self.max_send = self.integer('MAX_SEND', 250000)
+        self.max_send = self.integer('MAX_SEND', 1000000)
         self.max_subs = self.integer('MAX_SUBS', 250000)
         self.max_session_subs = self.integer('MAX_SESSION_SUBS', 50000)
         # IRC