mux.Router can't handle root path or no path ("/")

[palsivertsen]

Setting up a handler for the root path ("/") or no path ("") does not work.

Example:

package main

import (
    "bytes"
    "context"
    "log"
    "time"

    "github.com/plgd-dev/go-coap/v3"
    "github.com/plgd-dev/go-coap/v3/message"
    "github.com/plgd-dev/go-coap/v3/message/codes"
    "github.com/plgd-dev/go-coap/v3/mux"
    "github.com/plgd-dev/go-coap/v3/udp"
)

func main() {
    go serve()
    time.Sleep(time.Second)

    testPath("")
    testPath("/")
    testPath("/a")
}

func testPath(path string) {
    co, err := udp.Dial("localhost:5688")
    if err != nil {
        log.Fatalf("Error dialing: %v", err)
    }

    resp, err := co.Get(context.Background(), path)
    if err != nil {
        log.Fatalf("Error sending request: %v", err)
    }
    log.Printf("Response for %q: %s", path, resp.Code())
}

func serve() {
    r := mux.NewRouter()
    r.Handle("", mux.HandlerFunc(handleA))
    r.Handle("/", mux.HandlerFunc(handleA))
    r.Handle("/a", mux.HandlerFunc(handleA))

    log.Fatal(coap.ListenAndServe("udp", ":5688", r))
}

func handleA(w mux.ResponseWriter, r *mux.Message) {
    err := w.SetResponse(codes.Content, message.TextPlain, bytes.NewReader([]byte("hello world")))
    if err != nil {
        log.Printf("cannot set response: %v", err)
    }
}

Expected output:

2023/05/03 20:16:05 Response for "": Content
2023/05/03 20:16:05 Response for "/": Content
2023/05/03 20:16:05 Response for "/a": Content

Actual output:

2023/05/03 20:16:05 Response for "": NotFound
2023/05/03 20:16:05 Response for "/": NotFound
2023/05/03 20:16:05 Response for "/a": Content

[jkralik]

This is a bug. Thx for reporting.

[HRogge]

Should be fixed by PR #498

[palsivertsen]

498 did not resolve this issue.

Tested using github.com/plgd-dev/go-coap/v3 v3.1.6-0.20231026111111-38e3fa428a85