Description

Panic in tree.go:446 when calling router.HandleContext on a context that does not have params parsed

How to reproduce

package main

import (
    "fmt"
    "net/http"
    "net/http/httptest"

    "github.com/gin-gonic/gin"
)

func main() {
    w := httptest.NewRecorder()
    ctx, engine := gin.CreateTestContext(w)
    engine.GET("/hello/:name", func(ctx *gin.Context) {
        ctx.String(http.StatusOK, "Hello %s", ctx.Param("name"))
    })
    var err error
    ctx.Request, err = http.NewRequest(http.MethodGet, "/hello/something", nil)
    if err != nil {
        panic(err)
    }
    engine.HandleContext(ctx)

    fmt.Print("We should get here")
}

Expectations

$ curl http://localhost:8201/hello/world
We should get here

Actual result

$ curl -i http://localhost:8201/hello/world
[GIN-debug] GET    /hello/:name              --> main.main.func1 (1 handlers)
panic: runtime error: slice bounds out of range [:1] with capacity 0

goroutine 1 [running]:
github.com/gin-gonic/gin.(*node).getValue(0xc000327a40, 0x18464ce, 0x9, 0xc00031a120, 0x1000001010c00, 0x0, 0x0, 0x0, 0xc00031a120, 0x0, ...)
      /go/pkg/mod/github.com/gin-gonic/gin@v1.7.1/tree.go:446 +0x1105
github.com/gin-gonic/gin.(*Engine).handleHTTPRequest(0xc00037e4e0, 0xc000310100)
       /go/pkg/mod/github.com/gin-gonic/gin@v1.7.1/gin.go:482 +0x2f9
github.com/gin-gonic/gin.(*Engine).HandleContext(0xc00037e4e0, 0xc000310100)
      /go/pkg/mod/github.com/gin-gonic/gin@v1.7.1/gin.go:456 +0x52
main.main()
       cmd/scratch/main.go:22 +0x27d
Exiting.

Environment

  • go version: 1.16.3
  • gin version (or commit ref): 1.7.1
  • operating system: macosx

Comment From: jhartman86

Just ran into this as well. Seems the code attempting to expand the capacity of the params slice at line 446 in tree.go doesn't handle expanding the underlying capacity properly.

Comment From: linxing

@mamil stil can not get the param

Comment From: jhartman86

Issue still seems to be present w/ version 1.7.4

Comment From: plaffitt

I'm also getting this issue

Comment From: ossan-dev

Hey, I rerun the code in the issue and I got the following result:

go run .
[GIN-debug] [WARNING] Running in "debug" mode. Switch to "release" mode in production.
 - using env:   export GIN_MODE=release
 - using code:  gin.SetMode(gin.ReleaseMode)

[GIN-debug] GET    /hello/:name              --> main.main.func1 (1 handlers)
We should get here

I think that the issue could be closed. Thanks

Comment From: appleboy

fixed in https://github.com/gin-gonic/gin/pull/3502