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require 'socket'
require 'fileutils'
module LDAP
class Server
# Accept connections on a port, and for each one start a new thread
# and run the given block. Returns the Thread object for the listener.
#
# FIXME:
# - have a limit on total number of concurrent connects
# - have a limit on connections from a single IP, or from a /24
# (to avoid the trivial DoS that the first limit creates)
# - ACL using source IP address (or perhaps that belongs in application)
#
# Options:
# :port=>port number [required]
# :bindaddr=>"IP address"
# :user=>"username" - drop privileges after bind
# :group=>"groupname" - ditto
# :logger=>object - implements << method
# :listen=>number - listen queue depth
# :nodelay=>true - set TCP_NODELAY option
def self.tcpserver(opt, &blk)
if opt[:socket]
server = UNIXServer.new(opt[:socket])
FileUtils.chmod(0777, opt[:socket])
else
server = TCPServer.new(opt[:bindaddr] || "0.0.0.0", opt[:port])
end
# Drop privileges if requested
require 'etc' if opt[:group] or opt[:user]
Process.gid = Process.egid = Etc.getgrnam(opt[:group]).gid if opt[:group]
Process.uid = Process.euid = Etc.getpwnam(opt[:user]).uid if opt[:user]
Process.gid = opt[:gid] if opt[:gid]
Process.uid = opt[:uid] if opt[:uid]
if opt[:socket]
FileUtils.chown((opt[:user] || opt[:uid]), (opt[:group] || opt[:gid]), opt[:socket])
end
# Typically the O/S will buffer response data for 100ms before sending.
# If the response is sent as a single write() then there's no need for it.
if opt[:nodelay]
begin
server.setsockopt(Socket::IPPROTO_TCP, Socket::TCP_NODELAY, 1)
rescue Exception
end
end
# set queue size for incoming connections (default is 5)
server.listen(opt[:listen]) if opt[:listen]
Thread.new do
while true
begin
session = server.accept
# subtlety: copy 'session' into a block-local variable because
# it will change when the next session is accepted
Thread.new(session) do |s|
begin
s.instance_eval(&blk)
rescue Exception => e
opt[:logger].error(s.peeraddr[3]) {"#{e}: #{e.backtrace[0]}"}
ensure
s.close
end
end
rescue Interrupt
# This exception can be raised to shut the server down
server.close if server and not server.closed?
break
end
end
end
end
end # class Server
end # module LDAP
if __FILE__ == $0
# simple test
puts "Running a test POP3 server on port 1110"
t = LDAP::Server.tcpserver(:port=>1110) do
print "+OK I am a fake POP3 server\r\n"
while line = gets
case line
when /^quit/i
break
when /^crash/i
raise Errno::EPERM, "dammit!"
else
print "-ERR I don't understand #{line}"
end
end
print "+OK bye\r\n"
end
#sleep 10; t.raise Interrupt # uncomment to run for fixed time period
t.join
end