x-www-form-urlencoded escaping leads to truncated request

[lukasz7251]

In Spring Boot Web, starting from version 3.2.0, there is an issue where the request body is truncated if it contains characters that need to be escaped, such as ":" or "=".

Steps to reproduce:
1. Create a basic Spring Boot Web app with version 3.2.0 or greater.
2. Create a sample controller with the following code:
   ```kotlin
   @PostMapping("/test")
   fun testRequest(@RequestBody requestAsString: String) {
       requestAsString.split("&").forEach { println(it) }
   }

3. Invoke the controller with parameters, including one with a special character, using the following curl command:

   curl -X POST \
   'http://localhost:8080/test' \
   -d 'A=0:1' \
   -d 'B=123'

Actual output (>=3.2.0):

A=0%3A1
B=1

Expected output (=3.1.10):

A=0%3A1
B=123

[bclozel]

I don't think this is strictly a Spring issue. As of Spring Framework 6.1, we only read the amount of bytes that are declared in the Content-Length header of the request.

Using httpie and Spring Boot 3.2.x, I'm getting the correct result:

http -vvv --form POST localhost:8080/test A='0:1' B='123'
POST /test HTTP/1.1
Accept: */*
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 13
Content-Type: application/x-www-form-urlencoded; charset=utf-8
Host: localhost:8080
User-Agent: HTTPie/3.2.2

A=0%3A1&B=123

HTTP/1.1 200
Connection: keep-alive
Content-Length: 0
Date: Mon, 25 Mar 2024 18:17:16 GMT
Keep-Alive: timeout=60

Note, the "Content-Length" header shows "13".

With the curl command listed above, the content is URL encoded but somehow the Content-Length is only 10.

curl -vv -X POST 'http://localhost:8080/test' -d 'A=0:1' -d 'B=123'
Note: Unnecessary use of -X or --request, POST is already inferred.
*   Trying [::1]:8080...
* Connected to localhost (::1) port 8080
> POST /test HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/8.4.0
> Accept: */*
> Content-Length: 11
> Content-Type: application/x-www-form-urlencoded
>
< HTTP/1.1 200
< Content-Length: 0
< Date: Mon, 25 Mar 2024 18:22:18 GMT
<
* Connection #0 to host localhost left intact

I'm not a curl expert, so I don't know if this is a bug or the expected behavior. I do know though that using the --data-urlencode option fixes things:

curl -X POST 'http://localhost:8080/test' --data-urlencode 'A=0:1' -d 'B=123'

I'm closing this issue as a result, as there's nothing we can do from our side since the request is invalid in the first place when the problem happens.

Thanks for your report!