net/http: http.ServerMux, paths ending in * wildcard are not recognized.

[tatang26]

Go version

go version go1.23rc2 darwin/arm64

Output of go env in your module/workspace:

GO111MODULE='on'
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/tatan/Library/Caches/go-build'
GOENV='/Users/tatan/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/tatan/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/tatan/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/usr/local/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/usr/local/go/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.23rc2'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/tatan/Library/Application Support/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='clang'
CXX='clang++'
CGO_ENABLED='1'
GOMOD='/Users/tatan/code/playground/go.mod'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -ffile-prefix-map=/var/folders/t_/vwcgfn5j3p7dy1y6t4fb1f740000gn/T/go-build1796478944=/tmp/go-build -gno-record-gcc-switches -fno-common'

What did you do?

In Go 1.23, it appears that http.ServeMux is not interpreting correctly the * character as a wildcard in route patterns. Instead, * is being treated as a literal path segment, which leads to unexpected behavior. For instance, I have this route

r.HandleFunc("/public/*", assetsHandler)

And when I make a call like:

curl http://localhost:3000/public/image.jpeg

What did you see happen?

I expect the file is served in my web app

What did you expect to see?

I get a 404 page not found

but if I make a request like:

In Go.122 works well

[seankhliao]

Nowhere in the go docs is * suggested as a wildcard.

[gabyhelp]

Related Issues and Documentation

• net/http ServeMux Wildcard No Compilation Error When Using * and No Documentation on * #68676 (closed)
• net/http: Conflicts with pattern when using NewServeMux #68838 (closed)
• http.StripPrefix not properly handling wildcards with muxes #66510 (closed)
• net/http: ServeMux behaves inconsistently across operating systems #66288 (closed)
• net/http: precedence in dynamic urls doesn't work as expected when using http.ServeMux #68030 (closed)
• net/http: panic if path value is an asterisk #67067 (closed)
• http.Handle("/", ...) effectively hijacks pages from being not found (due to trailing "/" in the "pattern") #231 (closed)
• net/http: add example for ServeMux to make "/.*" behavior clear #4799 (closed)
• net/http: ServeMux should not cleanup requests path and redirect by default #19481 (closed)
• net/http: infinite redirect on path variable followed by trailing slash #67657 (closed)

_{(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)}

[tatang26]

Thanks @seankhliao !

[tomqwpl]

Nowhere in the go docs is * suggested as a wildcard.
Whilst this is true, this does represent a change in behaviour. * used to work just fine as a wildcard, and it's not unreasonable for it to be interpreted as such. Indeed chi/mux does treat * as a wildcard. I suspect a number of people will be broken by this change. We certainly were.