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url.encode.go
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url.encode.go
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/*
*/
// Copyright © 2020 Hedzr Yeh.
package unsorted
import (
"net/url"
"strconv"
)
// URLEncodedSimple encodes a string like Javascript's encodeURIComponent()
// Example: Turns "My String" to "My%20String"
func URLEncodedSimple(str string) (string, error) {
u, err := url.Parse(str)
if err != nil {
return "", err
}
return u.String(), nil
}
// URLComponent Encode/Decode
const (
encodePath encoding = 1 + iota
encodeHost
encodeUserPassword
encodeQueryComponent
encodeFragment
)
type encoding int
// EscapeError is an error type
type EscapeError string
func (e EscapeError) Error() string {
return "invalid URL escape " + strconv.Quote(string(e))
}
func ishex(c byte) bool {
switch {
case '0' <= c && c <= '9':
return true
case 'a' <= c && c <= 'f':
return true
case 'A' <= c && c <= 'F':
return true
}
return false
}
func unhex(c byte) byte {
switch {
case '0' <= c && c <= '9':
return c - '0'
case 'a' <= c && c <= 'f':
return c - 'a' + 10
case 'A' <= c && c <= 'F':
return c - 'A' + 10
}
return 0
}
// Return true if the specified character should be escaped when
// appearing in a URL string, according to RFC 3986.
//
// Please be informed that for now shouldEscape does not check all
// reserved characters correctly. See golang.org/issue/5684.
func shouldEscape(c byte, mode encoding) bool {
// §2.3 Unreserved characters (alphanum)
if 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' {
return false
}
if mode == encodeHost {
// §3.2.2 Host allows
// sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "="
// as part of reg-name.
// We add : because we include :port as part of host.
// We add [ ] because we include [ipv6]:port as part of host
switch c {
case '!', '$', '&', '\'', '(', ')', '*', '+', ',', ';', '=', ':', '[', ']':
return false
}
}
switch c {
case '-', '_', '.', '~': // §2.3 Unreserved characters (mark)
return false
case '$', '&', '+', ',', '/', ':', ';', '=', '?', '@': // §2.2 Reserved characters (reserved)
// Different sections of the URL allow a few of
// the reserved characters to appear unescaped.
switch mode {
case encodePath: // §3.3
// The RFC allows : @ & = + $ but saves / ; , for assigning
// meaning to individual path segments. This package
// only manipulates the path as a whole, so we allow those
// last two as well. That leaves only ? to escape.
return c == '?'
case encodeUserPassword: // §3.2.1
// The RFC allows ';', ':', '&', '=', '+', '$', and ',' in
// userinfo, so we must escape only '@', '/', and '?'.
// The parsing of userinfo treats ':' as special so we must escape
// that too.
return c == '@' || c == '/' || c == '?' || c == ':'
case encodeQueryComponent: // §3.4
// The RFC reserves (so we must escape) everything.
return true
case encodeFragment: // §4.1
// The RFC text is silent but the grammar allows
// everything, so escape nothing.
return false
}
}
// Everything else must be escaped.
return true
}
func escape(s string, mode encoding) string {
spaceCount, hexCount := 0, 0
for i := 0; i < len(s); i++ {
c := s[i]
if shouldEscape(c, mode) {
if c == ' ' && mode == encodeQueryComponent {
spaceCount++
} else {
hexCount++
}
}
}
if spaceCount == 0 && hexCount == 0 {
return s
}
t := make([]byte, len(s)+2*hexCount)
j := 0
for i := 0; i < len(s); i++ {
switch c := s[i]; {
case c == ' ' && mode == encodeQueryComponent:
t[j] = '+'
j++
case shouldEscape(c, mode):
t[j] = '%'
t[j+1] = "0123456789ABCDEF"[c>>4]
t[j+2] = "0123456789ABCDEF"[c&15]
j += 3
default:
t[j] = s[i]
j++
}
}
return string(t)
}
// unescape unescapes a string; the mode specifies
// which section of the URL string is being unescaped.
func unescape(s string, mode encoding) (string, error) {
// Count %, check that they're well-formed.
n := 0
hasPlus := false
for i := 0; i < len(s); {
switch s[i] {
case '%':
n++
if i+2 >= len(s) || !ishex(s[i+1]) || !ishex(s[i+2]) {
s = s[i:]
if len(s) > 3 {
s = s[:3]
}
return "", EscapeError(s)
}
i += 3
case '+':
hasPlus = mode == encodeQueryComponent
i++
default:
i++
}
}
if n == 0 && !hasPlus {
return s, nil
}
t := make([]byte, len(s)-2*n)
j := 0
for i := 0; i < len(s); {
switch s[i] {
case '%':
t[j] = unhex(s[i+1])<<4 | unhex(s[i+2])
j++
i += 3
case '+':
if mode == encodeQueryComponent {
t[j] = ' '
} else {
t[j] = '+'
}
j++
i++
default:
t[j] = s[i]
j++
i++
}
}
return string(t), nil
}
// EncodeURIComponent convert 'a b/c' -> 'a+b%2fc'
// origin := "äöüHel/lo world"
// encoded := EncodeURIComponent(origin)
// fmt.Println(encoded)
//
// s, _ := DecodeUriCompontent(encoded)
// fmt.Println(s)
func EncodeURIComponent(rawString string) string {
return escape(rawString, encodeFragment)
}
// DecodeURIComponent reverts the working by EncodeURIComponent
func DecodeURIComponent(encoded string) (string, error) {
return unescape(encoded, encodeQueryComponent)
}