prometheus/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/mux.go
2017-07-06 14:38:20 +02:00

133 lines
4.3 KiB
Go

package runtime
import (
"net/http"
"strings"
"golang.org/x/net/context"
"github.com/golang/protobuf/proto"
)
// A HandlerFunc handles a specific pair of path pattern and HTTP method.
type HandlerFunc func(w http.ResponseWriter, r *http.Request, pathParams map[string]string)
// ServeMux is a request multiplexer for grpc-gateway.
// It matches http requests to patterns and invokes the corresponding handler.
type ServeMux struct {
// handlers maps HTTP method to a list of handlers.
handlers map[string][]handler
forwardResponseOptions []func(context.Context, http.ResponseWriter, proto.Message) error
marshalers marshalerRegistry
}
// ServeMuxOption is an option that can be given to a ServeMux on construction.
type ServeMuxOption func(*ServeMux)
// WithForwardResponseOption returns a ServeMuxOption representing the forwardResponseOption.
//
// forwardResponseOption is an option that will be called on the relevant context.Context,
// http.ResponseWriter, and proto.Message before every forwarded response.
//
// The message may be nil in the case where just a header is being sent.
func WithForwardResponseOption(forwardResponseOption func(context.Context, http.ResponseWriter, proto.Message) error) ServeMuxOption {
return func(serveMux *ServeMux) {
serveMux.forwardResponseOptions = append(serveMux.forwardResponseOptions, forwardResponseOption)
}
}
// NewServeMux returns a new ServeMux whose internal mapping is empty.
func NewServeMux(opts ...ServeMuxOption) *ServeMux {
serveMux := &ServeMux{
handlers: make(map[string][]handler),
forwardResponseOptions: make([]func(context.Context, http.ResponseWriter, proto.Message) error, 0),
marshalers: makeMarshalerMIMERegistry(),
}
for _, opt := range opts {
opt(serveMux)
}
return serveMux
}
// Handle associates "h" to the pair of HTTP method and path pattern.
func (s *ServeMux) Handle(meth string, pat Pattern, h HandlerFunc) {
s.handlers[meth] = append(s.handlers[meth], handler{pat: pat, h: h})
}
// ServeHTTP dispatches the request to the first handler whose pattern matches to r.Method and r.Path.
func (s *ServeMux) ServeHTTP(w http.ResponseWriter, r *http.Request) {
path := r.URL.Path
if !strings.HasPrefix(path, "/") {
OtherErrorHandler(w, r, http.StatusText(http.StatusBadRequest), http.StatusBadRequest)
return
}
components := strings.Split(path[1:], "/")
l := len(components)
var verb string
if idx := strings.LastIndex(components[l-1], ":"); idx == 0 {
OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound)
return
} else if idx > 0 {
c := components[l-1]
components[l-1], verb = c[:idx], c[idx+1:]
}
if override := r.Header.Get("X-HTTP-Method-Override"); override != "" && isPathLengthFallback(r) {
r.Method = strings.ToUpper(override)
if err := r.ParseForm(); err != nil {
OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest)
return
}
}
for _, h := range s.handlers[r.Method] {
pathParams, err := h.pat.Match(components, verb)
if err != nil {
continue
}
h.h(w, r, pathParams)
return
}
// lookup other methods to handle fallback from GET to POST and
// to determine if it is MethodNotAllowed or NotFound.
for m, handlers := range s.handlers {
if m == r.Method {
continue
}
for _, h := range handlers {
pathParams, err := h.pat.Match(components, verb)
if err != nil {
continue
}
// X-HTTP-Method-Override is optional. Always allow fallback to POST.
if isPathLengthFallback(r) {
if err := r.ParseForm(); err != nil {
OtherErrorHandler(w, r, err.Error(), http.StatusBadRequest)
return
}
h.h(w, r, pathParams)
return
}
OtherErrorHandler(w, r, http.StatusText(http.StatusMethodNotAllowed), http.StatusMethodNotAllowed)
return
}
}
OtherErrorHandler(w, r, http.StatusText(http.StatusNotFound), http.StatusNotFound)
}
// GetForwardResponseOptions returns the ForwardResponseOptions associated with this ServeMux.
func (s *ServeMux) GetForwardResponseOptions() []func(context.Context, http.ResponseWriter, proto.Message) error {
return s.forwardResponseOptions
}
func isPathLengthFallback(r *http.Request) bool {
return r.Method == "POST" && r.Header.Get("Content-Type") == "application/x-www-form-urlencoded"
}
type handler struct {
pat Pattern
h HandlerFunc
}