helpers.go

// Adapted from https://code.csdn.net/flycutter/git-http-backend.
package git

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path"
	"strconv"
	"strings"
	"time"
)

// General helpers

func sendFile(contentType string, hr handlerReq) {
	w, r := hr.w, hr.r
	reqFile := path.Join(hr.Dir, hr.File)

	f, err := os.Stat(reqFile)
	if os.IsNotExist(err) {
		renderNotFound(w)
		return
	} else {
		log.Print("err stating file:", err)
	}

	w.Header().Set("Content-Type", contentType)
	w.Header().Set("Content-Length", fmt.Sprintf("%d", f.Size()))
	w.Header().Set("Last-Modified", f.ModTime().Format(http.TimeFormat))
	http.ServeFile(w, r, reqFile)
}

func getGitDir(filePath string) (string, error) {
	f := path.Join(config.ProjectRoot, filePath)
	if _, err := os.Stat(f); os.IsNotExist(err) {
		return "", err
	}

	return f, nil
}

func getServiceType(r *http.Request) string {
	serviceType := r.FormValue("service")

	if s := strings.HasPrefix(serviceType, "git-"); !s {
		return ""
	}

	return strings.Replace(serviceType, "git-", "", 1)
}

func hasAccess(r *http.Request, dir string, rpc string, checkContentType bool) bool {
	if checkContentType {
		if r.Header.Get("Content-Type") != fmt.Sprintf("application/x-git-%s-request", rpc) {
			return false
		}
	}

	if !(rpc == "upload-pack" || rpc == "receive-pack") {
		return false
	}
	if rpc == "receive-pack" {
		return config.ReceivePack
	}
	if rpc == "upload-pack" {
		return config.UploadPack
	}

	return getConfigSetting(rpc, dir)
}

func updateServerInfo(dir string) []byte {
	args := []string{"update-server-info"}
	return gitCommand(dir, args...)
}

func getConfigSetting(serviceName string, dir string) bool {
	serviceName = strings.Replace(serviceName, "-", "", -1)
	setting := getGitConfig("http."+serviceName, dir)

	if serviceName == "uploadpack" {
		return setting != "false"
	}

	return setting == "true"
}

func getGitConfig(configName string, dir string) string {
	args := []string{"config", configName}
	out := string(gitCommand(dir, args...))
	return out[0 : len(out)-1]
}

func gitCommand(dir string, args ...string) []byte {
	command := exec.Command(config.GitBinPath, args...)
	command.Dir = dir
	out, err := command.Output()

	if err != nil {
		// TODO: Properly handle error
		log.Print(err)
	}

	return out
}

// HTTP error response functions

func renderMethodNotAllowed(w http.ResponseWriter, r *http.Request) {
	if r.Proto == "HTTP/1.1" {
		w.WriteHeader(http.StatusMethodNotAllowed)
		w.Write([]byte("Method Not Allowed"))
	} else {
		w.WriteHeader(http.StatusBadRequest)
		w.Write([]byte("Bad Request"))
	}
}

func renderNotFound(w http.ResponseWriter) {
	w.WriteHeader(http.StatusNotFound)
	w.Write([]byte("Not Found"))
}

func renderNoAccess(w http.ResponseWriter) {
	w.WriteHeader(http.StatusForbidden)
	w.Write([]byte("Forbidden"))
}

// Packet-line helpers

func packetFlush() []byte {
	return []byte("0000")
}

func packetWrite(str string) []byte {
	s := strconv.FormatInt(int64(len(str)+4), 16)

	if len(s)%4 != 0 {
		s = strings.Repeat("0", 4-len(s)%4) + s
	}

	return []byte(s + str)
}

// Header writing helpers

func hdrNoCache(w http.ResponseWriter) {
	w.Header().Set("Expires", "Fri, 01 Jan 1980 00:00:00 GMT")
	w.Header().Set("Pragma", "no-cache")
	w.Header().Set("Cache-Control", "no-cache, max-age=0, must-revalidate")
}

func hdrCacheForever(w http.ResponseWriter) {
	now := time.Now().Unix()
	expires := now + 31536000
	w.Header().Set("Date", fmt.Sprintf("%d", now))
	w.Header().Set("Expires", fmt.Sprintf("%d", expires))
	w.Header().Set("Cache-Control", "public, max-age=31536000")
}