mime: ParseMediaType should not return an error if mediatype is empty #69551
Description
Go version
go version 1.23.0
Output of go env in your module/workspace:
GO111MODULE=''
GOARCH='arm64'
GOBIN=''
GOCACHE='/Users/alden/Library/Caches/go-build'
GOENV='/Users/alden/Library/Application Support/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='arm64'
GOHOSTOS='darwin'
GOINSECURE=''
GOMODCACHE='/Users/alden/go/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='darwin'
GOPATH='/Users/alden/go'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org,direct'
GOROOT='/opt/homebrew/Cellar/go/1.23.1/libexec'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='local'
GOTOOLDIR='/opt/homebrew/Cellar/go/1.23.1/libexec/pkg/tool/darwin_arm64'
GOVCS=''
GOVERSION='go1.23.1'
GODEBUG=''
GOTELEMETRY='local'
GOTELEMETRYDIR='/Users/alden/Library/Application Support/go/telemetry'
GCCGO='gccgo'
GOARM64='v8.0'
AR='ar'
CC='cc'
CXX='c++'
CGO_ENABLED='1'
GOMOD='/dev/null'
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/_h/_w_mjtt91s1dws8zlxnnjpzm0000gn/T/go-build1772735711=/tmp/go-build -gno-record-gcc-switches -fno-common'What did you do?
I have a file server that returns Content-Disposition headers like this: ;filename*=UTF-8''hello-world.pdf
Example: https://go.dev/play/p/rxRNVZGDOQu
What did you see happen?
mime.ParseMediaType fails with the error "mime: no media type" (from here in code)
What did you expect to see?
mime.ParseMediaTypesucceeds, returning mediatype""andparams["filename"]hello-world.pdf- Note that all modern browsers and email clients parse a blank mediatype correctly
- rfc6266 and rfc2183 both say
Unknown or unhandled disposition types SHOULD be handled by recipients the same way as "attachment", and presumably an empty string disposition type fits into that