Query string values imporperly handled (URI encoding forced for = character)

[misiek08]

Hello! Today I encountered interesting problem. I've got = sign in query string value. I know I could trim the character from some base64 strings, but remote proxy (not managed by me) requires them. I try to proxy those args and fasthttp is treating values as args.

Smallest test case I could produce for fasthttp:

package main

import (
    "testing"

    "github.com/stretchr/testify/assert"
    "github.com/valyala/fasthttp"
)

func TestFastHTTPURLEncoding(t *testing.T) {
    input := "/some/file?arg1=value1=&arg2=value2"
    uri := fasthttp.AcquireURI()
    defer fasthttp.ReleaseURI(uri)

    err := uri.Parse(nil, []byte(input))
    assert.NoError(t, err)

    assert.Equal(t, input, string(uri.RequestURI()))
}

func TestFastHTTPURLEncodingBUG(t *testing.T) {
    input := "/some/file?arg1=value1=&arg2=value2"
    uri := fasthttp.AcquireURI()
    defer fasthttp.ReleaseURI(uri)

    err := uri.Parse(nil, []byte(input))
    assert.NoError(t, err)

    assert.NotNil(t, uri.QueryArgs()) // without this line it works good, u.parseQueryArgs called here messing with values

    assert.Equal(t, input, string(uri.RequestURI()))
}

func TestGoURLParsing(t *testing.T) {
    input := "/some/file?arg1=value1=&arg2=value2"

    parsedURL, err := url.Parse(input)
    assert.NoError(t, err)

    assert.Equal(t, input, parsedURL.String())
}

Result:

=== RUN   TestFastHTTPURLEncodingBUG
    fasthttp_bug_test.go:32:
                Error Trace:    fasthttp_bug_test.go:32
                Error:          Not equal:
                                expected: "/some/file?arg1=value1=&arg2=value2"
                                actual  : "/some/file?arg1=value1%3D&arg2=value2"

                                Diff:
                                --- Expected
                                +++ Actual
                                @@ -1 +1 @@
                                -/some/file?arg1=value1=&arg2=value2
                                +/some/file?arg1=value1%3D&arg2=value2
                Test:           TestFastHTTPURLEncodingBUG
--- FAIL: TestFastHTTPURLEncodingBUG (0.00s)
FAIL

TestFastHTTPURLEncoding - correct behavior TestFastHTTPURLEncodingBUG - incorrect behavior.

Same test for net/url called TestGoURLParsing passing.

To keep "clean" issue format:

Expected

At least = character is not being encoded in query args values.

Actual behavior

Query args values are being encoded and at least = is being replaced with %3D.

[erikdubbelboer]

I'm afraid that this is intended behavior. When you call uri.QueryArgs() it returns an object you can use to modify the query params. When you then call uri.RequestURI() it re-builds the query params and re-encodes all the values. When re-encoding the values it changes = in the value to %3D as is expected (net/url also does this).

[misiek08]

Wow, I tried adding params and URL.Encode() is encoding them too. Thanks and I'm sorry I didn't go through net/url deep enough. So we will need to force workaround on backend for this :(

Thanks!