feat: add support for OpenBSD (#703)

Closes https://github.com/ooni/probe/issues/2052

internal/netxlite/errno_openbsd.go

@@ -0,0 +1,112 @@
+// Code generated by go generate; DO NOT EDIT.
+// Generated: 2022-03-05 00:39:22.759235545 +0200 EET m=+5.562977793
+
+package netxlite
+
+import (
+	"errors"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+)
+
+// This enumeration provides a canonical name for
+// every system-call error we support. Note: this list
+// is system dependent. You're currently looking at
+// the list of errors for openbsd.
+const (
+	ECONNREFUSED    = unix.ECONNREFUSED
+	ECONNRESET      = unix.ECONNRESET
+	EHOSTUNREACH    = unix.EHOSTUNREACH
+	ETIMEDOUT       = unix.ETIMEDOUT
+	EAFNOSUPPORT    = unix.EAFNOSUPPORT
+	EADDRINUSE      = unix.EADDRINUSE
+	EADDRNOTAVAIL   = unix.EADDRNOTAVAIL
+	EISCONN         = unix.EISCONN
+	EFAULT          = unix.EFAULT
+	EBADF           = unix.EBADF
+	ECONNABORTED    = unix.ECONNABORTED
+	EALREADY        = unix.EALREADY
+	EDESTADDRREQ    = unix.EDESTADDRREQ
+	EINTR           = unix.EINTR
+	EINVAL          = unix.EINVAL
+	EMSGSIZE        = unix.EMSGSIZE
+	ENETDOWN        = unix.ENETDOWN
+	ENETRESET       = unix.ENETRESET
+	ENETUNREACH     = unix.ENETUNREACH
+	ENOBUFS         = unix.ENOBUFS
+	ENOPROTOOPT     = unix.ENOPROTOOPT
+	ENOTSOCK        = unix.ENOTSOCK
+	ENOTCONN        = unix.ENOTCONN
+	EWOULDBLOCK     = unix.EWOULDBLOCK
+	EACCES          = unix.EACCES
+	EPROTONOSUPPORT = unix.EPROTONOSUPPORT
+	EPROTOTYPE      = unix.EPROTOTYPE
+)
+
+// classifySyscallError converts a syscall error to the
+// proper OONI error. Returns the OONI error string
+// on success, an empty string otherwise.
+func classifySyscallError(err error) string {
+	var errno syscall.Errno
+	if !errors.As(err, &errno) {
+		return ""
+	}
+	switch errno {
+	case unix.ECONNREFUSED:
+		return FailureConnectionRefused
+	case unix.ECONNRESET:
+		return FailureConnectionReset
+	case unix.EHOSTUNREACH:
+		return FailureHostUnreachable
+	case unix.ETIMEDOUT:
+		return FailureTimedOut
+	case unix.EAFNOSUPPORT:
+		return FailureAddressFamilyNotSupported
+	case unix.EADDRINUSE:
+		return FailureAddressInUse
+	case unix.EADDRNOTAVAIL:
+		return FailureAddressNotAvailable
+	case unix.EISCONN:
+		return FailureAlreadyConnected
+	case unix.EFAULT:
+		return FailureBadAddress
+	case unix.EBADF:
+		return FailureBadFileDescriptor
+	case unix.ECONNABORTED:
+		return FailureConnectionAborted
+	case unix.EALREADY:
+		return FailureConnectionAlreadyInProgress
+	case unix.EDESTADDRREQ:
+		return FailureDestinationAddressRequired
+	case unix.EINTR:
+		return FailureInterrupted
+	case unix.EINVAL:
+		return FailureInvalidArgument
+	case unix.EMSGSIZE:
+		return FailureMessageSize
+	case unix.ENETDOWN:
+		return FailureNetworkDown
+	case unix.ENETRESET:
+		return FailureNetworkReset
+	case unix.ENETUNREACH:
+		return FailureNetworkUnreachable
+	case unix.ENOBUFS:
+		return FailureNoBufferSpace
+	case unix.ENOPROTOOPT:
+		return FailureNoProtocolOption
+	case unix.ENOTSOCK:
+		return FailureNotASocket
+	case unix.ENOTCONN:
+		return FailureNotConnected
+	case unix.EWOULDBLOCK:
+		return FailureOperationWouldBlock
+	case unix.EACCES:
+		return FailurePermissionDenied
+	case unix.EPROTONOSUPPORT:
+		return FailureProtocolNotSupported
+	case unix.EPROTOTYPE:
+		return FailureWrongProtocolType
+	}
+	return ""
+}