output_http.go

package main

import (
	"bufio"
	"bytes"
	"io"
	"log"
	"net/http"
	"net/url"
	"strconv"
	"strings"
)

type RedirectNotAllowed struct{}

func (e *RedirectNotAllowed) Error() string {
	return "Redirects not allowed"
}

// customCheckRedirect disables redirects https://github.com/buger/gor/pull/15
func customCheckRedirect(req *http.Request, via []*http.Request) error {
	if len(via) >= 0 {
		return new(RedirectNotAllowed)
	}
	return nil
}

// ParseRequest in []byte returns a http request or an error
func ParseRequest(data []byte) (request *http.Request, err error) {
	buf := bytes.NewBuffer(data)
	reader := bufio.NewReader(buf)

	request, err = http.ReadRequest(reader)

	return
}

type HTTPOutput struct {
	address string
	limit   int

	urlRegexp         HTTPUrlRegexp
	headerFilters     HTTPHeaderFilters
	headerHashFilters HTTPHeaderHashFilters

	buf chan []byte

	headers HTTPHeaders
	methods HTTPMethods

	bufStats *GorStat
}

func NewHTTPOutput(options string, headers HTTPHeaders, methods HTTPMethods, urlRegexp HTTPUrlRegexp, headerFilters HTTPHeaderFilters, headerHashFilters HTTPHeaderHashFilters) io.Writer {
	o := new(HTTPOutput)

	optionsArr := strings.Split(options, "|")
	address := optionsArr[0]

	if !strings.HasPrefix(address, "http") {
		address = "http://" + address
	}

	o.address = address
	o.headers = headers
	o.methods = methods

	o.urlRegexp = urlRegexp
	o.headerFilters = headerFilters
	o.headerHashFilters = headerHashFilters

	o.buf = make(chan []byte, 100)
	o.bufStats = NewGorStat("output_http")

	if len(optionsArr) > 1 {
		o.limit, _ = strconv.Atoi(optionsArr[1])
	}

	for i := 0; i < 10; i++ {
		go o.worker(i)
	}

	if o.limit > 0 {
		return NewLimiter(o, o.limit)
	} else {
		return o
	}
}

func (o *HTTPOutput) worker(n int) {
	client := &http.Client{
		CheckRedirect: customCheckRedirect,
	}

	for {
		data := <-o.buf
		o.sendRequest(client, data)
	}
}

func (o *HTTPOutput) Write(data []byte) (n int, err error) {
	buf := make([]byte, len(data))
	copy(buf, data)

	o.buf <- buf
	o.bufStats.Write(len(o.buf))

	return len(data), nil
}

func (o *HTTPOutput) sendRequest(client *http.Client, data []byte) {
	request, err := ParseRequest(data)

	if err != nil {
		log.Println("Cannot parse request", string(data), err)
		return
	}

	if len(o.methods) > 0 && !o.methods.Contains(request.Method) {
		return
	}

	if !(o.urlRegexp.Good(request) && o.headerFilters.Good(request) && o.headerHashFilters.Good(request)) {
		return
	}

	// Change HOST of original request
	URL := o.address + request.URL.Path + "?" + request.URL.RawQuery

	request.RequestURI = ""
	request.URL, _ = url.ParseRequestURI(URL)

	for _, header := range o.headers {
		SetHeader(request, header.Name, header.Value)
	}

	resp, err := client.Do(request)

	// We should not count Redirect as errors
	if urlErr, ok := err.(*url.Error); ok {
		if _, ok := urlErr.Err.(*RedirectNotAllowed); ok {
			err = nil
		}
	}

	if err == nil {
		defer resp.Body.Close()
	} else {
		log.Println("Request error:", err)
	}

}

func SetHeader(request *http.Request, name string, value string) {

	// Need to check here for the Host header as it needs to be set on the request and not as a separate header
	// http.ReadRequest sets it by default to the URL Host of the request being read
	if name == "Host" {
		request.Host = value
	} else {
		request.Header.Set(name, value)
	}

	return

}

func (o *HTTPOutput) String() string {
	return "HTTP output: " + o.address
}