Change of URL encoding behaviour doesn't seem right

This issue is probably related to #1189 but is focused on the encoding of path variables instead. We’ve recently upgraded to Spring Cloud to Hoxton.SR3 which includes a bump of Spring Cloud OpenFeign from 2.2.1.RELEASE to 2.2.2.RELEASE. This patch version bumps OpenFeign from 10.4.0 to 10.7.4 which seems to contain quite a few important changes.

In particular, there is a change of behaviour around url encoding (#1138) which in our case has broken a couple of things with using path variables. I’ve created a sandbox project at https://github.com/sguillope/openfeign-url-encoding-issue to make it easier to reproduce the issue.

The 2 problems we’ve hit are as follows when using a path variable:

• The colon : character now gets url-encoded to %3A. While not really incorrect, it’s not actually required as a colon is a valid character in a path segment (https://tools.ietf.org/html/rfc3986#section-3.3), except for one case which shouldn’t apply here. This only broke our integration tests, not production code, so we can easily fix that.
• The most problematic one is the handling of the forward slash / character. With the latest version, it doesn’t get url-encoded in path variables. Fortunately this was caught by our integration tests, otherwise it would have broken our production code. We can’t pre-encode it because it will then get double-encoded as %252F instead of %2F.

To summarise:

Input	Result	Expected
a:path/variable	a%3Apath/variable	a:path%2Fvariable
path/variable	path/variable	path%2Fvariable
a:path	a%3Apath	a:path

Let me know if you need more details. Thanks

[sguillope]

Hi @kdavisk6, thanks for the thorough reply, much appreciated.

Unfortunately because we use Spring Cloud OpenFeign, I believe there isn’t much control we have over the decodeSlash parameter (arguably that’s a Spring Cloud problem)

That said, I’ve added more test cases to my test project sguillope/openfeign-url-encoding-issue with using pre-encoded path variables.

Test Case	Input	Result	Expected
Encoded /	path%2Fvariable	path/variable	path%2Fvariable
Encoded : and /	a%3Apath%2Fvariable	a%3Apath/variable	a%3Apath%2Fvariable
Unencoded : and encoded /	a:path%2Fvariable	a%3Apath%252Fvariable	a:path%2Fvariable
Encoded : and unencoded /	a%3Apath/variable	a%253Apath/variable	?

For some reason, when Feign detects the variable as already being encoded, it ends up decoding %2F back to /.

As you can see without control over the decodeSlash behaviour it’s impossible to get the / to be encoded.

[apereznavarro99]

Same issue here, in my case I was trying to integrate with Google Analitycs 4, they require parameters with “:” in the requests.

I solved it by changing this

@FeignClient
interface AwesomeClient {

    @PostMapping("/awesome_request")
    fun request(
        @RequestParam("param_with_colon") param: String
    )
}

To this

@FeignClient
interface AwesomeClient {

    @PostMapping("/awesome_request")
    fun request(
        @SpringQueryMap(encoded = true) params: ParamWithColon
    )
}

class ParamWithColon(
    val param_with_colon: String 
)