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Bug: Prefix option causes http: invalid Read on closed Body in downstream handlers #49
Description
Summary
While experimenting with echov5, this was observed. Later trying it on echo/v4, the issue could be reproduced.
When Options.Prefix is set, the middleware reads and closes the request body during validation but fails to restore it on the original echo.Context request. Downstream handlers that try to read the body receive http: invalid Read on closed Body or EOF.
Reproduction
package main
import (
"context"
"tryecho/api"
"github.com/labstack/echo/v4"
echomiddleware "github.com/oapi-codegen/echo-middleware"
)
type Server struct{}
func (s *Server) CreateItem(ctx context.Context, request api.CreateItemRequestObject) (api.CreateItemResponseObject, error) {
return api.CreateItem201JSONResponse{
Name: &request.Body.Name,
}, nil
}
func main() {
e := echo.New()
spec, err := api.GetSwagger()
if err != nil {
panic(err)
}
spec.Servers = nil
g := e.Group("/api")
g.Use(echomiddleware.OapiRequestValidatorWithOptions(spec, &echomiddleware.Options{
Prefix: "/api",
}))
myServer := &Server{}
strictHandler := api.NewStrictHandler(myServer, nil)
api.RegisterHandlers(g, strictHandler)
e.Logger.Fatal(e.Start(":8080"))
}➜ tryecho curl --location 'localhost:8080/api/items' \
--header 'Content-Type: application/json' \
--data '{
"name":""
}'
{"message":"http: invalid Read on closed Body"}Workaround (until fixed)
Consumers using Prefix must pre-buffer the body themselves so GetBody is set before the middleware runs:
g.Use(func(next echo.HandlerFunc) echo.HandlerFunc {
return func(c echo.Context) error {
req := c.Request()
if req.Body != nil && req.Body != http.NoBody {
data, _ := io.ReadAll(req.Body)
req.Body.Close()
req.GetBody = func() (io.ReadCloser, error) {
return io.NopCloser(bytes.NewReader(data)), nil
}
req.Body, _ = req.GetBody()
}
return next(c)
}
})
g.Use(OapiRequestValidatorWithOptions(spec, &Options{Prefix: "/api"}))
Activity
jinuthankachan commentedon Apr 15, 2026
The issue exists in current main branch.
Tested with echo/v4
jinuthankachan commentedon Apr 15, 2026
This could be fixed via jinuthankachan@ebc95b6#diff-215bd2f3b5dc6e861b4a3a3fd643fda09e01ca5e377e9b2ef7f88abe1666cec5
Trim the prefix in place instead of validating a clone