libnmdc/libnmdc.go

package libnmdc

import (
	"errors"
	"fmt"
	"regexp"
	"strings"
	"time"
)

const (
	DEFAULT_CLIENT_TAG               string        = "libnmdc.go"
	DEFAULT_CLIENT_VERSION           string        = "0.15"
	DEFAULT_HUB_NAME                 string        = "(unknown)"
	SEND_KEEPALIVE_EVERY             time.Duration = 29 * time.Second
	AUTO_RECONNECT_AFTER             time.Duration = 30 * time.Second
	RECONNECT_IF_NO_DATA_RECIEVED_IN time.Duration = 24 * time.Hour // we expect keepalives wayyyy more frequently than this
)

var rx_protocolMessage *regexp.Regexp
var rx_publicChat *regexp.Regexp
var rx_incomingTo *regexp.Regexp
var rx_userCommand *regexp.Regexp
var ErrNotConnected error = errors.New("Not connected")

func init() {
	// With the `m` flag, use \A instead of ^ to anchor to start
	// This fixes accidentally finding a better match in the middle of a multi-line message

	rx_protocolMessage = regexp.MustCompile(`(?ms)\A[^|]*\|`)
	rx_publicChat = regexp.MustCompile(`(?ms)\A<([^>]*)> (.*)$`)
	rx_incomingTo = regexp.MustCompile(`(?ms)\A([^ ]+) From: ([^ ]+) \$<([^>]*)> (.*)`)
	rx_userCommand = regexp.MustCompile(`(?ms)\A(\d+) (\d+)\s?([^\$]*)\$?(.*)`)
}

func Unescape(encoded string) string {
	v1 := strings.Replace(encoded, "&#36;", "$", -1)
	v2 := strings.Replace(v1, "&#124;", "|", -1)
	return strings.Replace(v2, "&amp;", "&", -1)
}

func Escape(plaintext string) string {
	v1 := strings.Replace(plaintext, "&", "&amp;", -1)
	v2 := strings.Replace(v1, "|", "&#124;", -1)
	return strings.Replace(v2, "$", "&#36;", -1)
}

func unlock(lock []byte) string {

	nibble_swap := func(b byte) byte {
		return ((b << 4) & 0xF0) | ((b >> 4) & 0x0F)
	}

	chr := func(b byte) string {
		if b == 0 || b == 5 || b == 36 || b == 96 || b == 124 || b == 126 {
			return fmt.Sprintf("/%%DCN%04d%%/", b)
		} else {
			return string(b)
		}
	}

	key := chr(nibble_swap(lock[0] ^ lock[len(lock)-2] ^ lock[len(lock)-3] ^ 5))
	for i := 1; i < len(lock); i += 1 {
		key += chr(nibble_swap(lock[i] ^ lock[i-1]))
	}

	return key
}