net/gclient: fix parameters containing equal signs were tampered

[fghwett]

Fixed the issue where parameters containing equal signs were tampered with when there were file parameters in the same form.

Example:

gclient.New().Post(context.Background(), "https://example.com", fmt.Sprintf("source=https://exmaple.com/rand?type=girls&image=@file:filename.png"))

// gclient_request.go:233 this will cause the parameters to be divided into three sections. [source, https://exmaple.com/rand?type, girls] 
for _, item := range strings.Split(params, "&") {
	array := strings.Split(item, "=")
	...
}

//  gclient_request.go:232 this will cause the third and subsequent parameters to be lost.
var (
	fieldName  = array[0]
	fieldValue = array[1]
)
if err = writer.WriteField(fieldName, fieldValue); err != nil {
	err = gerror.Wrapf(err, `write form field failed with "%s", "%s"`, fieldName, fieldValue)
	return nil, err
}

[gqcn]

@fghwett Good enhancement! Would you please add associated unit testing case for this update?

[fghwett]

When I was writing the test case, I found a problem with more than just containing equal signs. After looking at the code, I decided it was the '@file:' parameter and noUrlEncode, so I made some adjustments.
Now, as long as the @file: parameter is included, it will be encoded and decoded in the corresponding processing place. This is the processing scheme I have come up with at present, I don't know whether it can be accepted.

[gqcn]

Fixed the issue where parameters containing equal signs were tampered with when there were file parameters in the same form.

Example:

gclient.New().Post(context.Background(), "https://example.com", fmt.Sprintf("source=https://exmaple.com/rand?type=girls&image=@file:filename.png"))

// gclient_request.go:233 this will cause the parameters to be divided into three sections. [source, https://exmaple.com/rand?type, girls] 
for _, item := range strings.Split(params, "&") {
	array := strings.Split(item, "=")
	...
}

//  gclient_request.go:232 this will cause the third and subsequent parameters to be lost.
var (
	fieldName  = array[0]
	fieldValue = array[1]
)
if err = writer.WriteField(fieldName, fieldValue); err != nil {
	err = gerror.Wrapf(err, `write form field failed with "%s", "%s"`, fieldName, fieldValue)
	return nil, err
}

@fghwett or you can urlencode your parameters? like:

g.Client().Post(
    context.Background(), 
    "https://example.com", 
    "source=https%3A%2F%2Fexmaple.com%2Frand%3Ftype%3Dgirls%26image%3D%40file%3Afilename.png",
)

[fghwett]

Fixed the issue where parameters containing equal signs were tampered with when there were file parameters in the same form.
Example:

gclient.New().Post(context.Background(), "https://example.com", fmt.Sprintf("source=https://exmaple.com/rand?type=girls&image=@file:filename.png"))

// gclient_request.go:233 this will cause the parameters to be divided into three sections. [source, https://exmaple.com/rand?type, girls] 
for _, item := range strings.Split(params, "&") {
	array := strings.Split(item, "=")
	...
}

//  gclient_request.go:232 this will cause the third and subsequent parameters to be lost.
var (
	fieldName  = array[0]
	fieldValue = array[1]
)
if err = writer.WriteField(fieldName, fieldValue); err != nil {
	err = gerror.Wrapf(err, `write form field failed with "%s", "%s"`, fieldName, fieldValue)
	return nil, err
}

@fghwett or you can urlencode your parameters? like:

g.Client().Post(
    context.Background(), 
    "https://example.com", 
    "source=https%3A%2F%2Fexmaple.com%2Frand%3Ftype%3Dgirls%26image%3D%40file%3Afilename.png",
)

I tried the following two ways and got wrong results.

# Only the parameters other than the file are encoded, and the backend will receive the encoded URL. However, in terms of business logic, the backend does not perform URL de-encoding processing.
resp, err := gclient.New().
	Post(context.Background(), "https://exmaple.com",
	fmt.Sprintf("source=%s&image=@file:%s", gurl.Encode("https://exmaple.com/rand?type=girls"), "filepath.jpg"),
)

# Encode all parameters, gclient will think they are uploaded in json format.
resp, err := gclient.New().
	Post(context.Background(), "https://example.com",
	gurl.Encode("source=https://exmaple.com/rand?type=girls&image=@file:filename.jpg"),
)

In the business logic, I need to upload a photo along with the original URL of the photo.

[gqcn]

@fghwett What you expect is the server side receiving the normal source parameter (https://exmaple.com/rand?type=girls) and the uploaded file, or the complete source parameter containing file parameter(https://exmaple.com/rand?type=girls&image=@file:filename.png)?

[fghwett]

@fghwett What you expect is the server side receiving the normal source parameter (https://exmaple.com/rand?type=girls) and the uploaded file, or the complete source parameter containing file parameter(https://exmaple.com/rand?type=girls&image=@file:filename.png)?

I'm the first case.

[gqcn]

I'm still handling on this.