mediocre-go-lib/mhttp/mhttp.go
2018-08-09 14:02:11 -06:00

83 lines
2.4 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/m"
"github.com/mediocregopher/mediocre-go-lib/mcfg"
"github.com/mediocregopher/mediocre-go-lib/mlog"
"github.com/mediocregopher/mediocre-go-lib/mnet"
)
// CfgServer initializes and returns an *http.Server which will initialize on
// the Start hook. This also sets up config params for configuring the address
// being listened on.
func CfgServer(cfg *mcfg.Cfg, h http.Handler) *http.Server {
cfg = cfg.Child("http")
addr := cfg.ParamString("addr", ":0", "Address to listen on. Default is any open port")
srv := http.Server{Handler: h}
cfg.Start.Then(func(ctx context.Context) error {
srv.Addr = *addr
kv := mlog.KV{"addr": *addr}
log := m.Log(cfg, kv)
log.Info("listening")
go func() {
err := srv.ListenAndServe()
// TODO the listening log should happen here, somehow, now that we
// know the actual address being listened on
log.Fatal("http server fataled", mlog.ErrKV(err))
}()
return nil
})
// TODO shutdown logic
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
}