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Create (and close) a new socket in rpc Connect, don't reuse one.

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It appears that connecting more than one with the same nse_nsock socket
leaks socket descriptor. For example,

local s = nmap.new_socket()
s:connect(host, port) --> TIMEOUT
s:connect(host, port) --> TIMEOUT
s:close()

leaks a socket descriptor, the one used in the first connect. Nsock
should really take care of this, but let's do this workaround because
rpc-grind has been causing problems due to using the above pattern:

http://seclists.org/nmap-dev/2012/q3/864
http://seclists.org/nmap-dev/2012/q3/872
http://seclists.org/nmap-dev/2012/q3/949

The difficulty is that the rpc library will tolerate around 400 of those
timeouts per RPC connection, which leads to rapidly running out of
descriptors.
This commit is contained in:
david
2012-09-21 01:08:14 +00:00
parent f712477644
commit 23625913a8
1 changed files with 4 additions and 2 deletions
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6
nselib/rpc.lua
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@@ -164,26 +164,28 @@ Comm = {
return status, err return status, err
end end
if ( port.protocol == "tcp" ) then if ( port.protocol == "tcp" ) then
socket = nmap.new_socket()
if nmap.is_privileged() then if nmap.is_privileged() then
-- Try to bind to a reserved port -- Try to bind to a reserved port
for resvport = 600, 1024, 1 do for resvport = 600, 1024, 1 do
socket = nmap.new_socket()
status, err = socket:bind(nil, resvport) status, err = socket:bind(nil, resvport)
if status then if status then
status, err = socket:connect(host, port) status, err = socket:connect(host, port)
if status then break end if status then break end
socket:close()
end end
end end
else else
status, err = socket:connect(host, port) status, err = socket:connect(host, port)
end end
else else
socket = nmap.new_socket("udp")
if nmap.is_privileged() then if nmap.is_privileged() then
-- Try to bind to a reserved port -- Try to bind to a reserved port
for resvport = 600, 1024, 1 do for resvport = 600, 1024, 1 do
socket = nmap.new_socket("udp")
status, err = socket:bind(nil, resvport) status, err = socket:bind(nil, resvport)
if status then break end if status then break end
socket:close()
end end
end end
end end