POSIX getaddrinfo allocates memory that must later be freed using freeaddrinfo.
See http://manpages.ubuntu.com/manpages/xenial/en/man3/getaddrinfo.3.html
To simplify the API, I've created this function:
import Foundation
enum SystemError: Swift.Error {
case getaddrinfo(Int32, Int32?)
}
public func getaddrinfo(node: String?, service: String?, hints:
addrinfo?) throws -> [addrinfo] {
var err: Int32
var res: UnsafeMutablePointer<addrinfo>?
if var hints = hints {
err = getaddrinfo(node, service, &hints, &res)
} else {
err = getaddrinfo(node, service, nil, &res)
}
if err == EAI_SYSTEM {
throw SystemError.getaddrinfo(err, errno)
}
if err != 0 {
throw SystemError.getaddrinfo(err, nil)
}
defer {
freeaddrinfo(res)
}
var result = [addrinfo]()
var ai = res?.pointee
while ai != nil {
result.append(ai!)
ai = ai!.ai_next?.pointee
}
return result
}
I don't feel that the function is correct, though.
• How can the Swift memory model know that getaddrinfo allocates memory, and
that Swift should not overwrite that memory with own stuff?
• How can Swift know that freeaddrinfo deletes the whole list, and that it
should copy out ai information that has been assigned to the result array?
What's the correct way to interface with getaddrinfo?
Thanks
Etan
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