callback shouldn't be just "dcc" since it only happens on DCC SEND

src/irc.lua

@@ -513,7 +513,7 @@ end
 function ctcp_handlers.on_dcc(from, to, message)
     local type, argument, address, port, size = base.unpack(misc._split(message, " ", nil, '"', '"'))
     if type == "SEND" then
-        if callback("dcc", from, to, argument, address, port, size) then
+        if callback("dcc_send", from, to, argument, address, port, size) then
             dcc._accept(argument, address, port)
         end
     elseif type == "CHAT" then

test/test.lua

@@ -216,9 +216,9 @@ local function on_devoice(chan, from, nick)
 end
 irc.register_callback("devoice", on_devoice)
 
-local function on_dcc()
+local function on_dcc_send()
     return true
 end
-irc.register_callback("dcc", on_dcc)
+irc.register_callback("dcc_send", on_dcc_send)
 
 irc.connect{network = "irc.freenode.net", nick = "doylua", pass = "doylua"}