mediocre-go-lib/mhttp/mhttp.go

95 lines
2.9 KiB
Go

// Package mhttp extends the standard package with extra functionality which is
// commonly useful
package mhttp
import (
"context"
"net"
"net/http"
"net/http/httputil"
"net/url"
"strings"
"github.com/mediocregopher/mediocre-go-lib/mctx"
"github.com/mediocregopher/mediocre-go-lib/merr"
"github.com/mediocregopher/mediocre-go-lib/mlog"
"github.com/mediocregopher/mediocre-go-lib/mnet"
"github.com/mediocregopher/mediocre-go-lib/mrun"
)
// MListenAndServe returns an http.Server which will be initialized and have
// ListenAndServe called on it (asynchronously) when the start event is
// triggered on ctx (see mrun.Start). The Server will have Shutdown called on it
// when the stop event is triggered on ctx (see mrun.Stop).
//
// This function automatically handles setting up configuration parameters via
// mcfg. The default listen address is ":0".
func MListenAndServe(ctx mctx.Context, h http.Handler) *http.Server {
ctx = mctx.ChildOf(ctx, "http")
listener := mnet.MListen(ctx, "tcp", "")
listener.NoCloseOnStop = true // http.Server.Shutdown will do this
logger := mlog.From(ctx).WithKV(listener)
srv := http.Server{Handler: h}
mrun.OnStart(ctx, func(mctx.Context) error {
srv.Addr = listener.Addr().String()
mrun.Thread(ctx, func() error {
if err := srv.Serve(listener); err != http.ErrServerClosed {
logger.Error("error serving listener", merr.KV(err))
return err
}
return nil
})
return nil
})
mrun.OnStop(ctx, func(innerCtx mctx.Context) error {
logger.Info("shutting down server")
if err := srv.Shutdown(context.Context(innerCtx)); err != nil {
return err
}
return mrun.Wait(ctx, innerCtx.Done())
})
return &srv
}
// AddXForwardedFor populates the X-Forwarded-For header on the Request to
// convey that the request is being proxied for IP.
//
// If the IP is invalid, loopback, or otherwise part of a reserved range, this
// does nothing.
func AddXForwardedFor(r *http.Request, ipStr string) {
const xff = "X-Forwarded-For"
ip := net.ParseIP(ipStr)
if ip == nil || mnet.IsReservedIP(ip) { // IsReservedIP includes loopback
return
}
prev, _ := r.Header[xff]
r.Header.Set(xff, strings.Join(append(prev, ip.String()), ", "))
}
// ReverseProxy returns an httputil.ReverseProxy which will send requests to the
// given URL and copy their responses back without modification.
//
// Only the Scheme and Host of the given URL are used.
//
// Any http.ResponseWriters passed into the ServeHTTP call of the returned
// instance should not be modified afterwards.
func ReverseProxy(u *url.URL) *httputil.ReverseProxy {
rp := new(httputil.ReverseProxy)
rp.Director = func(req *http.Request) {
if ipStr, _, err := net.SplitHostPort(req.RemoteAddr); err != nil {
AddXForwardedFor(req, ipStr)
}
req.URL.Scheme = u.Scheme
req.URL.Host = u.Host
}
// TODO when this package has a function for creating a Client use that for
// the default here
return rp
}