DNS lookupService fails with internal C error when given a string port number.

[rgrannell1]

The DNS module's lookupService method throws an unwrapped C error when given a string for a port number. This isn't ideal; preferably a TypeError would be thrown instead, or the function would just parse the string to an integer.

The following error messages is given for the failing test cases shown below.

node: ../src/cares_wrap.cc:1098: void node::cares_wrap::GetNameInfo(const v8::FunctionCallbackInfo<v8::Value>&): Assertion `args[2]->IsUint32()' failed.
Aborted

If I'm missing any important information, please tell me and I'll update this issue.

Environment:

• Node v5.4.1
• Npm 3.5.3
• Linux 4.2.0-23-generic (Ubuntu)

Test-Case:

Failing Test Cases:

require('dns').lookupService('0.0.0.0', '0', (err, hostname, service) => {

})

require('dns').lookupService('127.0.0.1', '443', (err, hostname, service) => {

})

Control Test Cases:

Both these cases behave normally; they don't throw a C error.

require('dns').lookupService('0.0.0.0', 0, (err, hostname, service) => {

})

require('dns').lookupService('127.0.0.1', 443, (err, hostname, service) => {

})

[evanlucas]

PR incoming to fix