Fix wonky brackets

mark.george / httpcat

Browse code Fix wonky brackets master
1 parent 75f344c commit 3bb44389467831e5a49d8f12750c3cbe19ae703a Mark George authored on 2 Aug 2022

Patch

Showing 1 changed file

Ignore Space Show notes View src/proxy.go
/** Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License / package main import ( "fmt" "net/http" "net/http/httputil" "net/url" "strconv" "strings" ) var ( proxyOpts ProxyCommand ) type ProxyCommand struct { Port int `short:"p" long:"port" description:"The port that the proxy listens on." required:"true"` Target string `short:"t" long:"target" description:"The URL for the target web server that the proxy forwards requests to." required:"true"` } func (opts ProxyCommand) Execute(args []string) error { fmt.Println("Proxying port " + strconv.Itoa(opts.Port) + " to " + opts.Target) proxyOpts = opts proxy, err := CreateProxy(opts.Target) if err != nil { panic(err) } http.HandleFunc("/", RequestHandler(proxy)) if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil { panic(err) } return nil } func CreateProxy(target string) (httputil.ReverseProxy, error) { url, err := url.Parse(target) // bad target URL if err != nil { return nil, err } proxy := httputil.NewSingleHostReverseProxy(url) OriginalDirector := proxy.Director proxy.Director = func(req http.Request) { FixHeaders(url, req) showRequest(req) // send request to target OriginalDirector(req) } proxy.ModifyResponse = func(rsp http.Response) error { // rewrite the port for redirect responses switch rsp.StatusCode { case 301, 302, 303, 307, 308: url, _ := url.Parse(rsp.Header["Location"][0]) newUrl := RewritePort(url, strconv.Itoa(proxyOpts.Port)) rsp.Header["Location"][0] = newUrl.String() } showResponse(rsp) return nil } proxy.ErrorHandler = func(rsp http.ResponseWriter, req http.Request, err error) { fmt.Println("Error sending request to target server:") fmt.Println(" " + err.Error()) } return proxy, nil } func FixHeaders(url url.URL, req http.Request) { // TODO this may be necessary for proxying HTTPS (need to test) req.URL.Host = url.Host req.URL.Scheme = url.Scheme req.Host = url.Host } func RewritePort(url url.URL, newPort string) url.URL { var newUrl string if url.Port() != "" { // port exists, so replace :port with :newport newUrl = strings.Replace(url.String(), ":"+url.Port(), ":"+newPort, 1) } else { // no port, so replace hostname with hostname:port newUrl = strings.Replace(url.String(), url.Hostname(), url.Hostname()+":"+newPort, 1) } rewrittenUrl, _ := url.Parse(newUrl) return rewrittenUrl } func RequestHandler(proxy httputil.ReverseProxy) func(http.ResponseWriter, http.Request) { return func(w http.ResponseWriter, r http.Request) { proxy.ServeHTTP(w, r) } } /** Author: Mark George <mark.george@otago.ac.nz> License: Zero-Clause BSD License / package main import ( "fmt" "net/http" "net/http/httputil" "net/url" "strconv" "strings" ) var ( proxyOpts ProxyCommand ) type ProxyCommand struct { Port int `short:"p" long:"port" description:"The port that the proxy listens on." required:"true"` Target string `short:"t" long:"target" description:"The URL for the target web server that the proxy forwards requests to." required:"true"` } func (opts ProxyCommand) Execute(args []string) error { fmt.Println("Proxying port " + strconv.Itoa(opts.Port) + " to " + opts.Target) proxyOpts = opts proxy, err := CreateProxy(opts.Target) if err != nil { panic(err) } http.HandleFunc("/", RequestHandler(proxy)) if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil { panic(err) } return nil } func CreateProxy(target string) (httputil.ReverseProxy, error) { url, err := url.Parse(target) // bad target URL if err != nil { return nil, err } proxy := httputil.NewSingleHostReverseProxy(url) OriginalDirector := proxy.Director proxy.Director = func(req http.Request) { FixHeaders(url, req) showRequest(req) // send request to target OriginalDirector(req) } proxy.ModifyResponse = func(rsp http.Response) error { // rewrite the port for redirect responses switch rsp.StatusCode { case 301, 302, 303, 307, 308: { url, _ := url.Parse(rsp.Header["Location"][0]) newUrl := RewritePort(url, strconv.Itoa(proxyOpts.Port)) rsp.Header["Location"][0] = newUrl.String() } } showResponse(rsp) return nil } proxy.ErrorHandler = func(rsp http.ResponseWriter, req http.Request, err error) { fmt.Println("Error sending request to target server:") fmt.Println(" " + err.Error()) } return proxy, nil } func FixHeaders(url url.URL, req http.Request) { // TODO this may be necessary for proxying HTTPS (need to test) req.URL.Host = url.Host req.URL.Scheme = url.Scheme req.Host = url.Host } func RewritePort(url url.URL, newPort string) url.URL { var newUrl string if url.Port() != "" { // port exists, so replace :port with :newport newUrl = strings.Replace(url.String(), ":"+url.Port(), ":"+newPort, 1) } else { // no port, so replace hostname with hostname:port newUrl = strings.Replace(url.String(), url.Hostname(), url.Hostname()+":"+newPort, 1) } rewrittenUrl, _ := url.Parse(newUrl) return rewrittenUrl } func RequestHandler(proxy httputil.ReverseProxy) func(http.ResponseWriter, http.Request) { return func(w http.ResponseWriter, r http.Request) { proxy.ServeHTTP(w, r) } }

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src/proxy.go

/**
  Author: Mark George <mark.george@otago.ac.nz>
  License: Zero-Clause BSD License
*/

package main

import (
	"fmt"
	"net/http"
	"net/http/httputil"
	"net/url"
	"strconv"
	"strings"
)

var (
	proxyOpts *ProxyCommand
)

type ProxyCommand struct {
	Port   int    `short:"p" long:"port" description:"The port that the proxy listens on." required:"true"`
	Target string `short:"t" long:"target" description:"The URL for the target web server that the proxy forwards requests to." required:"true"`
}

func (opts *ProxyCommand) Execute(args []string) error {
	fmt.Println("Proxying port " + strconv.Itoa(opts.Port) + " to " + opts.Target)

proxyOpts = opts

proxy, err := CreateProxy(opts.Target)

if err != nil {
		panic(err)
	}

http.HandleFunc("/", RequestHandler(proxy))
	if err := http.ListenAndServe(":"+strconv.Itoa(opts.Port), nil); err != nil {
		panic(err)
	}

return nil
}

func CreateProxy(target string) (*httputil.ReverseProxy, error) {

url, err := url.Parse(target)

// bad target URL
	if err != nil {
		return nil, err
	}

proxy := httputil.NewSingleHostReverseProxy(url)

OriginalDirector := proxy.Director

proxy.Director = func(req *http.Request) {
		FixHeaders(url, req)

showRequest(req)

// send request to target
		OriginalDirector(req)
	}

proxy.ModifyResponse = func(rsp *http.Response) error {
		// rewrite the port for redirect responses
		switch rsp.StatusCode {
		case 301, 302, 303, 307, 308:
			url, _ := url.Parse(rsp.Header["Location"][0])
			newUrl := RewritePort(url, strconv.Itoa(proxyOpts.Port))
			rsp.Header["Location"][0] = newUrl.String()
		}

showResponse(rsp)
		return nil
	}

proxy.ErrorHandler = func(rsp http.ResponseWriter, req *http.Request, err error) {
		fmt.Println("Error sending request to target server:")
		fmt.Println("   " + err.Error())
	}

return proxy, nil
}

func FixHeaders(url *url.URL, req *http.Request) {
	// TODO this may be necessary for proxying HTTPS (need to test)
	req.URL.Host = url.Host
	req.URL.Scheme = url.Scheme
	req.Host = url.Host
}

func RewritePort(url *url.URL, newPort string) url.URL {
	var newUrl string

if url.Port() != "" {
		// port exists, so replace :port with :newport
		newUrl = strings.Replace(url.String(), ":"+url.Port(), ":"+newPort, 1)
	} else {
		// no port, so replace hostname with hostname:port
		newUrl = strings.Replace(url.String(), url.Hostname(), url.Hostname()+":"+newPort, 1)
	}
	rewrittenUrl, _ := url.Parse(newUrl)
	return *rewrittenUrl
}

func RequestHandler(proxy *httputil.ReverseProxy) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		proxy.ServeHTTP(w, r)
	}
}