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87 lines (62 sloc) 2.069 kB
dgram = require('dgram')
SQL_SERVER_BROWSER_PORT = 1434
TIMEOUT = 2 * 1000
RETRIES = 3
# There are three bytes at the start of the response, whose purpose is unknown.
MYSTERY_HEADER_LENGTH = 3
# Most of the functionality has been determined from from jTDS's MSSqlServerInfo class.
exports.instanceLookup = (server, instanceName, callback, timeout, retries) ->
timeout = timeout || TIMEOUT
retriesLeft = retries || RETRIES
timer = undefined
socket = undefined
message = (message, rinfo) ->
if timer
clearTimeout(timer)
timer = undefined
message = message.toString('ascii', MYSTERY_HEADER_LENGTH)
port = parseBrowserResponse(message, instanceName)
socket.close()
if port
callback(undefined, port)
else
callback("Port for #{instanceName} not found in #{message}")
error = (err) ->
if timer
clearTimeout(timer)
timer = undefined
socket.close()
callback("Failed to lookup instance on #{server} : #{err}")
timedOut = () ->
timer = undefined
socket.close()
makeAttempt()
makeAttempt = () ->
if retriesLeft > 0
retriesLeft--
request = new Buffer([0x02])
socket = dgram.createSocket('udp4')
socket.on('error', error)
socket.on('message', message)
socket.send(request, 0, request.length, SQL_SERVER_BROWSER_PORT, server)
timer = setTimeout(timedOut, timeout)
else
callback("Failed to get response from SQL Server Browser on #{server}")
makeAttempt()
parseBrowserResponse = (response, instanceName) ->
instances = response.split(';;')
for instance in instances
parts = instance.split(';')
for p in [0..parts.length - 1] by 2
name = parts[p]
value = parts[p + 1]
if (name == 'tcp' && getPort)
port = parseInt(value, 10)
return port
if name == 'InstanceName'
if value.toUpperCase() == instanceName.toUpperCase()
getPort = true
else
getPort = false
undefined
exports.parseBrowserResponse = parseBrowserResponse
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