CODEWITHSUNDEEP
urlescapinggo
Sergi Mansilla
Sergi Mansilla

Reputation: 12793

Encode / decode URLs

What's the recommended way of encoding and decoding entire URLs in Go? I am aware of the methods url.QueryEscape and url.QueryUnescape, but they don't seem to be exactly what I am looking for. Specifically I am looking for methods like JavaScript's encodeURIComponent and decodeURIComponent.

Upvotes: 81

Views: 73211

Answers (8)

Nick Craig-Wood
Nick Craig-Wood

Reputation: 54079

You can do all the URL encoding you want with the net/url module. It doesn't break out the individual encoding functions for the parts of the URL, you have to let it construct the whole URL. Having had a squint at the source code I think it does a very good and standards compliant job.

Here is an example (playground link)

package main

import (
    "fmt"
    "net/url"
)

func main() {

    Url, err := url.Parse("http://www.example.com")
    if err != nil {
        panic("boom")
    }

    Url.Path += "/some/path/or/other_with_funny_characters?_or_not/"
    parameters := url.Values{}
    parameters.Add("hello", "42")
    parameters.Add("hello", "54")
    parameters.Add("vegetable", "potato")
    Url.RawQuery = parameters.Encode()

    fmt.Printf("Encoded URL is %q\n", Url.String())
}

Which prints-

Encoded URL is "http://www.example.com/some/path/or/other_with_funny_characters%3F_or_not/?vegetable=potato&hello=42&hello=54"

Upvotes: 101

Black_Dreams
Black_Dreams

Reputation: 610

Hope this helps

 // url encoded
func UrlEncodedISO(str string) (string, error) {
    u, err := url.Parse(str)
    if err != nil {
        return "", err
    }
    q := u.Query()
    return q.Encode(), nil
}

 * encoded into %2A
 # encoded into %23
 % encoded into %25
 < encoded into %3C
 > encoded into %3E
 + encoded into %2B
 enter key (#13#10) is encoded into %0D%0A

Upvotes: -2

pixeloverflow
pixeloverflow

Reputation: 579

If someone wants to get the exact result compare to the JS encodeURIComponent Try my function it's dirty but works well.

https://gist.github.com/czyang/7ae30f4f625fee14cfc40c143e1b78bf

// #Warning! You Should Use this Code Carefully, and As Your Own Risk.
    package main

    import (
    "fmt"
    "net/url"
    "strings"
)
/*
After hours searching, I can't find any method can get the result exact as the JS encodeURIComponent function.
In my situation I need to write a sign method which need encode the user input exact same as the JS encodeURIComponent.
This function does solved my problem.
*/
func main() {
    params := url.Values{
        "test_string": {"+!+'( )*-._~0-👿  👿9a-zA-Z 中文测试 test with ❤️ !@#$%^&&*()~<>?/.,;'[][]:{{}|{}|"},
    }
    urlEncode := params.Encode()
    fmt.Println(urlEncode)
    urlEncode = compatibleRFC3986Encode(urlEncode)
    fmt.Println("RFC3986", urlEncode)
    urlEncode = compatibleJSEncodeURIComponent(urlEncode)
    fmt.Println("JS encodeURIComponent", urlEncode)
}

// Compatible with RFC 3986.
func compatibleRFC3986Encode(str string) string {
    resultStr := str
    resultStr = strings.Replace(resultStr, "+", "%20", -1)
    return resultStr
}

// This func mimic JS encodeURIComponent, JS is wild and not very strict.
func compatibleJSEncodeURIComponent(str string) string {
    resultStr := str
    resultStr = strings.Replace(resultStr, "+", "%20", -1)
    resultStr = strings.Replace(resultStr, "%21", "!", -1)
    resultStr = strings.Replace(resultStr, "%27", "'", -1)
    resultStr = strings.Replace(resultStr, "%28", "(", -1)
    resultStr = strings.Replace(resultStr, "%29", ")", -1)
    resultStr = strings.Replace(resultStr, "%2A", "*", -1)
    return resultStr
}

Upvotes: 4

Jonathan Hall
Jonathan Hall

Reputation: 79584

As of Go 1.8, this situation has changed. We now have access to PathEscape in addition to the older QueryEscape to encode path components, along with the unescape counterpart PathUnescape.

Upvotes: 11

Xian Shu
Xian Shu

Reputation: 708

How about this:

template.URLQueryEscaper(path)

Upvotes: 5

Stefan Steiger
Stefan Steiger

Reputation: 82186

Here's an implementation of escape and unescape (ripped from go source):

package main


import (  
    "fmt"
    "strconv"
)


const (
    encodePath encoding = 1 + iota
    encodeHost
    encodeUserPassword
    encodeQueryComponent
    encodeFragment
)

type encoding int
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
}


func EncodeUriComponent(rawString string) string{
    return escape(rawString, encodeFragment)
}

func DecodeUriCompontent(encoded string) (string, error){
    return unescape(encoded, encodeQueryComponent)
}


// https://golang.org/src/net/url/url.go
// http://remove-line-numbers.ruurtjan.com/
func main() {
    // http://www.url-encode-decode.com/
    origin := "äöüHel/lo world"
    encoded := EncodeUriComponent(origin)
    fmt.Println(encoded)

    s, _ := DecodeUriCompontent(encoded)
    fmt.Println(s)
}



// -------------------------------------------------------

/*
func UrlEncoded(str string) (string, error) {
    u, err := url.Parse(str)
    if err != nil {
        return "", err
    }
    return u.String(), nil
}


// http://stackoverflow.com/questions/13820280/encode-decode-urls
// import "net/url"
func old_main() {
    a,err := UrlEncoded("hello world")
    if err != nil {
           fmt.Println(err)
    }
    fmt.Println(a)

    // https://gobyexample.com/url-parsing
    //s := "postgres://user:[email protected]:5432/path?k=v#f"
    s := "postgres://user:[email protected]:5432/path?k=vbla%23fooa#f"
    u, err := url.Parse(s)
    if err != nil {
        panic(err)
    }


    fmt.Println(u.RawQuery)
    fmt.Println(u.Fragment)
    fmt.Println(u.String())
    m, _ := url.ParseQuery(u.RawQuery)
    fmt.Println(m)
    fmt.Println(m["k"][0])

}
*/

// -------------------------------------------------------

Upvotes: -2

Mike Rapadas
Mike Rapadas

Reputation: 4703

For mimicking Javascript's encodeURIComponent(), I created a string helper function.

Example: Turns "My String" to "My%20String"

https://github.com/mrap/stringutil/blob/master/urlencode.go

import "net/url"

// UrlEncoded encodes a string like Javascript's encodeURIComponent()
func UrlEncoded(str string) (string, error) {
    u, err := url.Parse(str)
    if err != nil {
        return "", err
    }
    return u.String(), nil
}

Upvotes: 5

mna
mna

Reputation: 23963

From MDN on encodeURIComponent:

encodeURIComponent escapes all characters except the following: alphabetic, decimal digits, '-', '_', '.', '!', '~', '*', ''', '(', ')'

From Go's implementation of url.QueryEscape (specifically, the shouldEscape private function), escapes all characters except the following: alphabetic, decimal digits, '-', '_', '.', '~'.

Unlike Javascript, Go's QueryEscape() will escape '!', '*', ''', '(', ')'. Basically, Go's version is strictly RFC-3986 compliant. Javascript's is looser. Again from MDN:

If one wishes to be more stringent in adhering to RFC 3986 (which reserves !, ', (, ), and *), even though these characters have no formalized URI delimiting uses, the following can be safely used:

function fixedEncodeURIComponent (str) {
  return encodeURIComponent(str).replace(/[!'()]/g, escape).replace(/\*/g, "%2A");
}

Upvotes: 14

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