utils.go

package logrus_sentry

import (
	"fmt"
	"strings"
)

/*
Copyright (c) 2009,2014 Google Inc. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

// A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC
// 4122.
type uuid []byte

// parseUUID decodes s into a UUID or returns nil.  Both the UUID form of
// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx and
// xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx and
// urn:uuid:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx are decoded.
func parseUUID(s string) uuid {
	//If it is in no dash format "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
	if len(s) == 32 {
		uuid := make([]byte, 16)
		for i, x := range []int{
			0, 2, 4, 6, 8, 10,
			12, 14, 16, 18, 20,
			22, 24, 26, 28, 30} {
			if v, ok := xtob(s[x:]); !ok {
				return nil
			} else {
				uuid[i] = v
			}
		}
		return uuid
	}

	if len(s) == 36+9 {
		if strings.ToLower(s[:9]) != "urn:uuid:" {
			return nil
		}
		s = s[9:]
	} else if len(s) != 36 {
		return nil
	}
	if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
		return nil
	}
	uuid := make([]byte, 16)
	for i, x := range []int{
		0, 2, 4, 6,
		9, 11,
		14, 16,
		19, 21,
		24, 26, 28, 30, 32, 34} {
		if v, ok := xtob(s[x:]); !ok {
			return nil
		} else {
			uuid[i] = v
		}
	}
	return uuid
}

// String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
// , or "" if uuid is invalid.
func (uuid uuid) string() string {
	if uuid == nil || len(uuid) != 16 {
		return ""
	}
	b := []byte(uuid)
	return fmt.Sprintf("%08x-%04x-%04x-%04x-%012x",
		b[:4], b[4:6], b[6:8], b[8:10], b[10:])
}

func (uuid uuid) noDashString() string {
	if uuid == nil || len(uuid) != 16 {
		return ""
	}
	b := []byte(uuid)
	return fmt.Sprintf("%08x%04x%04x%04x%012x",
		b[:4], b[4:6], b[6:8], b[8:10], b[10:])
}

// xvalues returns the value of a byte as a hexadecimal digit or 255.
var xvalues = []byte{
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 255, 255, 255, 255, 255, 255,
	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 10, 11, 12, 13, 14, 15, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
	255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
}

// xtob converts the the first two hex bytes of x into a byte.
func xtob(x string) (byte, bool) {
	b1 := xvalues[x[0]]
	b2 := xvalues[x[1]]
	return (b1 << 4) | b2, b1 != 255 && b2 != 255
}