gosora/router_gen/main.go
Azareal bf851bd9fc We now use Go 1.11 modules. This should help with build times, deployment and development, although it does mean that the minimum requirement for Gosora has been bumped up from Go 1.10 to Go 1.11
Added support for dyntmpl to the template system.
The Account Dashboard now sort of uses dyntmpl, more work needed here.
Renamed the pre_render_view_topic hook to pre_render_topic.
Added the GetCurrentLangPack() function.
Added the alerts_no_new_alerts phrase.
Added the account_level_list phrase.

Refactored the route rename logic in the patcher to cut down on the amount of boilerplate.
Added more route renames to the patcher. You will need to run the patcher / updater in this commit.
2018-10-27 13:40:36 +10:00

759 lines
22 KiB
Go

/* WIP Under Construction */
package main
import (
"bytes"
"log"
"os"
"strconv"
"text/template"
)
var routeList []*RouteImpl
var routeGroups []*RouteGroup
type TmplVars struct {
RouteList []*RouteImpl
RouteGroups []*RouteGroup
AllRouteNames []string
AllRouteMap map[string]int
AllAgentNames []string
AllAgentMap map[string]int
AllOSNames []string
AllOSMap map[string]int
}
func main() {
log.Println("Generating the router...")
// Load all the routes...
routes()
var tmplVars = TmplVars{
RouteList: routeList,
RouteGroups: routeGroups,
}
var allRouteNames []string
var allRouteMap = make(map[string]int)
var out string
var mapIt = func(name string) {
allRouteNames = append(allRouteNames, name)
allRouteMap[name] = len(allRouteNames) - 1
}
var countToIndents = func(indent int) (indentor string) {
for i := 0; i < indent; i++ {
indentor += "\t"
}
return indentor
}
var runBefore = func(runnables []Runnable, indent int) (out string) {
var indentor = countToIndents(indent)
if len(runnables) > 0 {
for _, runnable := range runnables {
if runnable.Literal {
out += "\n\t" + indentor + runnable.Contents
} else {
out += "\n" + indentor + "err = common." + runnable.Contents + "(w,req,user)\n" +
indentor + "if err != nil {\n" +
indentor + "\trouter.handleError(err,w,req,user)\n" +
indentor + "\treturn\n" +
indentor + "}\n" + indentor
}
}
}
return out
}
for _, route := range routeList {
mapIt(route.Name)
var end = len(route.Path) - 1
out += "\n\t\tcase \"" + route.Path[0:end] + "\":"
out += runBefore(route.RunBefore, 4)
out += "\n\t\t\tcounters.RouteViewCounter.Bump(" + strconv.Itoa(allRouteMap[route.Name]) + ")"
out += "\n\t\t\terr = " + route.Name + "(w,req,user"
for _, item := range route.Vars {
out += "," + item
}
out += `)`
}
for _, group := range routeGroups {
var end = len(group.Path) - 1
out += "\n\t\tcase \"" + group.Path[0:end] + "\":"
out += runBefore(group.RunBefore, 3)
out += "\n\t\t\tswitch(req.URL.Path) {"
var defaultRoute = blankRoute()
for _, route := range group.RouteList {
if group.Path == route.Path {
defaultRoute = route
continue
}
mapIt(route.Name)
out += "\n\t\t\t\tcase \"" + route.Path + "\":"
if len(route.RunBefore) > 0 {
skipRunnable:
for _, runnable := range route.RunBefore {
for _, gRunnable := range group.RunBefore {
if gRunnable.Contents == runnable.Contents {
continue
}
// TODO: Stop hard-coding these
if gRunnable.Contents == "AdminOnly" && runnable.Contents == "MemberOnly" {
continue skipRunnable
}
if gRunnable.Contents == "AdminOnly" && runnable.Contents == "SuperModOnly" {
continue skipRunnable
}
if gRunnable.Contents == "SuperModOnly" && runnable.Contents == "MemberOnly" {
continue skipRunnable
}
}
if runnable.Literal {
out += "\n\t\t\t\t\t" + runnable.Contents
} else {
out += `
err = common.` + runnable.Contents + `(w,req,user)
if err != nil {
router.handleError(err,w,req,user)
return
}
`
}
}
}
out += "\n\t\t\t\t\tcounters.RouteViewCounter.Bump(" + strconv.Itoa(allRouteMap[route.Name]) + ")"
out += "\n\t\t\t\t\terr = " + route.Name + "(w,req,user"
for _, item := range route.Vars {
out += "," + item
}
out += ")"
}
if defaultRoute.Name != "" {
mapIt(defaultRoute.Name)
out += "\n\t\t\t\tdefault:"
out += runBefore(defaultRoute.RunBefore, 4)
out += "\n\t\t\t\t\tcounters.RouteViewCounter.Bump(" + strconv.Itoa(allRouteMap[defaultRoute.Name]) + ")"
out += "\n\t\t\t\t\terr = " + defaultRoute.Name + "(w,req,user"
for _, item := range defaultRoute.Vars {
out += ", " + item
}
out += ")"
}
out += `
}`
}
// Stubs for us to refer to these routes through
mapIt("routes.DynamicRoute")
mapIt("routes.UploadedFile")
mapIt("routes.StaticFile")
mapIt("routes.RobotsTxt")
mapIt("routes.SitemapXml")
mapIt("routes.BadRoute")
tmplVars.AllRouteNames = allRouteNames
tmplVars.AllRouteMap = allRouteMap
tmplVars.AllOSNames = []string{
"unknown",
"windows",
"linux",
"mac",
"android",
"iphone",
}
tmplVars.AllOSMap = make(map[string]int)
for id, os := range tmplVars.AllOSNames {
tmplVars.AllOSMap[os] = id
}
tmplVars.AllAgentNames = []string{
"unknown",
"firefox",
"chrome",
"opera",
"safari",
"edge",
"internetexplorer",
"trident", // Hack to support IE11
"androidchrome",
"mobilesafari",
"samsung",
"ucbrowser",
"googlebot",
"yandex",
"bing",
"baidu",
"duckduckgo",
"seznambot",
"discord",
"twitter",
"cloudflare",
"uptimebot",
"slackbot",
"discourse",
"lynx",
"blank",
"malformed",
"suspicious",
"zgrab",
}
tmplVars.AllAgentMap = make(map[string]int)
for id, agent := range tmplVars.AllAgentNames {
tmplVars.AllAgentMap[agent] = id
}
var fileData = `// Code generated by Gosora's Router Generator. DO NOT EDIT.
/* This file was automatically generated by the software. Please don't edit it as your changes may be overwritten at any moment. */
package main
import (
"log"
"strings"
"strconv"
"compress/gzip"
"sync"
"sync/atomic"
"errors"
"io"
"os"
"net/http"
"github.com/Azareal/Gosora/common"
"github.com/Azareal/Gosora/common/counters"
"github.com/Azareal/Gosora/routes"
"github.com/Azareal/Gosora/routes/panel"
)
var ErrNoRoute = errors.New("That route doesn't exist.")
// TODO: What about the /uploads/ route? x.x
var RouteMap = map[string]interface{}{ {{range .AllRouteNames}}
"{{.}}": {{.}},{{end}}
}
// ! NEVER RELY ON THESE REMAINING THE SAME BETWEEN COMMITS
var routeMapEnum = map[string]int{ {{range $index, $element := .AllRouteNames}}
"{{$element}}": {{$index}},{{end}}
}
var reverseRouteMapEnum = map[int]string{ {{range $index, $element := .AllRouteNames}}
{{$index}}: "{{$element}}",{{end}}
}
var osMapEnum = map[string]int{ {{range $index, $element := .AllOSNames}}
"{{$element}}": {{$index}},{{end}}
}
var reverseOSMapEnum = map[int]string{ {{range $index, $element := .AllOSNames}}
{{$index}}: "{{$element}}",{{end}}
}
var agentMapEnum = map[string]int{ {{range $index, $element := .AllAgentNames}}
"{{$element}}": {{$index}},{{end}}
}
var reverseAgentMapEnum = map[int]string{ {{range $index, $element := .AllAgentNames}}
{{$index}}: "{{$element}}",{{end}}
}
var markToAgent = map[string]string{
"OPR":"opera",
"Chrome":"chrome",
"Firefox":"firefox",
"MSIE":"internetexplorer",
"Trident":"trident", // Hack to support IE11
"Edge":"edge",
"Lynx":"lynx", // There's a rare android variant of lynx which isn't covered by this
"SamsungBrowser":"samsung",
"UCBrowser":"ucbrowser",
"Google":"googlebot",
"Googlebot":"googlebot",
"yandex": "yandex", // from the URL
"DuckDuckBot":"duckduckgo",
"Baiduspider":"baidu",
"bingbot":"bing",
"BingPreview":"bing",
"SeznamBot":"seznambot",
"CloudFlare":"cloudflare", // Track alwayson specifically in case there are other bots?
"Uptimebot":"uptimebot",
"Slackbot":"slackbot",
"Discordbot":"discord",
"Twitterbot":"twitter",
"Discourse":"discourse",
"zgrab":"zgrab",
}
/*var agentRank = map[string]int{
"opera":9,
"chrome":8,
"safari":1,
}*/
// TODO: Stop spilling these into the package scope?
func init() {
counters.SetRouteMapEnum(routeMapEnum)
counters.SetReverseRouteMapEnum(reverseRouteMapEnum)
counters.SetAgentMapEnum(agentMapEnum)
counters.SetReverseAgentMapEnum(reverseAgentMapEnum)
counters.SetOSMapEnum(osMapEnum)
counters.SetReverseOSMapEnum(reverseOSMapEnum)
}
type gzipResponseWriter struct {
io.Writer
http.ResponseWriter
}
func (w gzipResponseWriter) Write(b []byte) (int, error) {
return w.Writer.Write(b)
}
type WriterIntercept struct {
http.ResponseWriter
}
func NewWriterIntercept(w http.ResponseWriter) *WriterIntercept {
return &WriterIntercept{w}
}
func (writ *WriterIntercept) WriteHeader(code int) {
if code == 200 {
writ.ResponseWriter.Header().Set("Cache-Control", "max-age=" + strconv.Itoa(int(common.Day)))
writ.ResponseWriter.Header().Set("Vary", "Accept-Encoding")
}
writ.ResponseWriter.WriteHeader(code)
}
type GenRouter struct {
UploadHandler func(http.ResponseWriter, *http.Request)
extraRoutes map[string]func(http.ResponseWriter, *http.Request, common.User) common.RouteError
requestLogger *log.Logger
sync.RWMutex
}
func NewGenRouter(uploads http.Handler) (*GenRouter, error) {
f, err := os.OpenFile("./logs/requests.log", os.O_WRONLY|os.O_APPEND|os.O_CREATE, 0755)
if err != nil {
return nil, err
}
return &GenRouter{
UploadHandler: func(w http.ResponseWriter, req *http.Request) {
writ := NewWriterIntercept(w)
http.StripPrefix("/uploads/",uploads).ServeHTTP(writ,req)
},
extraRoutes: make(map[string]func(http.ResponseWriter, *http.Request, common.User) common.RouteError),
requestLogger: log.New(f, "", log.LstdFlags),
}, nil
}
func (router *GenRouter) handleError(err common.RouteError, w http.ResponseWriter, r *http.Request, user common.User) {
if err.Handled() {
return
}
if err.Type() == "system" {
common.InternalErrorJSQ(err, w, r, err.JSON())
return
}
common.LocalErrorJSQ(err.Error(), w, r, user,err.JSON())
}
func (router *GenRouter) Handle(_ string, _ http.Handler) {
}
func (router *GenRouter) HandleFunc(pattern string, handle func(http.ResponseWriter, *http.Request, common.User) common.RouteError) {
router.Lock()
defer router.Unlock()
router.extraRoutes[pattern] = handle
}
func (router *GenRouter) RemoveFunc(pattern string) error {
router.Lock()
defer router.Unlock()
_, ok := router.extraRoutes[pattern]
if !ok {
return ErrNoRoute
}
delete(router.extraRoutes, pattern)
return nil
}
func (router *GenRouter) DumpRequest(req *http.Request, prepend string) {
var heads string
for key, value := range req.Header {
for _, vvalue := range value {
heads += "Header '" + common.SanitiseSingleLine(key) + "': " + common.SanitiseSingleLine(vvalue) + "!!\n"
}
}
router.requestLogger.Print(prepend +
"\nUA: " + common.SanitiseSingleLine(req.UserAgent()) + "\n" +
"Method: " + common.SanitiseSingleLine(req.Method) + "\n" + heads +
"req.Host: " + common.SanitiseSingleLine(req.Host) + "\n" +
"req.URL.Path: " + common.SanitiseSingleLine(req.URL.Path) + "\n" +
"req.URL.RawQuery: " + common.SanitiseSingleLine(req.URL.RawQuery) + "\n" +
"req.Referer(): " + common.SanitiseSingleLine(req.Referer()) + "\n" +
"req.RemoteAddr: " + req.RemoteAddr + "\n")
}
func (router *GenRouter) SuspiciousRequest(req *http.Request, prepend string) {
if prepend != "" {
prepend += "\n"
}
router.DumpRequest(req,prepend+"Suspicious Request")
counters.AgentViewCounter.Bump({{.AllAgentMap.suspicious}})
}
// TODO: Pass the default path or config struct to the router rather than accessing it via a package global
// TODO: SetDefaultPath
// TODO: GetDefaultPath
func (router *GenRouter) ServeHTTP(w http.ResponseWriter, req *http.Request) {
// Redirect www. requests to the right place
if req.Host == "www." + common.Site.Host {
w.Header().Set("Connection", "close")
var s string
if common.Site.EnableSsl {
s = "s"
}
dest := "http"+s+"://" + req.Host + req.URL.Path
if len(req.URL.RawQuery) > 0 {
dest += "?" + req.URL.RawQuery
}
http.Redirect(w, req, dest, http.StatusMovedPermanently)
return
}
// Deflect malformed requests
if len(req.URL.Path) == 0 || req.URL.Path[0] != '/' || req.Host != common.Site.Host {
w.WriteHeader(200) // 400
w.Write([]byte(""))
router.DumpRequest(req,"Malformed Request")
counters.AgentViewCounter.Bump({{.AllAgentMap.malformed}})
return
}
// TODO: Cover more suspicious strings and at a lower layer than this
for _, char := range req.URL.Path {
if char != '&' && !(char > 44 && char < 58) && char != '=' && char != '?' && !(char > 64 && char < 91) && char != '\\' && char != '_' && !(char > 96 && char < 123) {
router.SuspiciousRequest(req,"Bad char in path")
break
}
}
lowerPath := strings.ToLower(req.URL.Path)
// TODO: Flag any requests which has a dot with anything but a number after that
if strings.Contains(req.URL.Path,"..") || strings.Contains(req.URL.Path,"--") || strings.Contains(lowerPath,".php") || strings.Contains(lowerPath,".asp") || strings.Contains(lowerPath,".cgi") || strings.Contains(lowerPath,".py") || strings.Contains(lowerPath,".sql") || strings.Contains(lowerPath,".action") {
router.SuspiciousRequest(req,"Bad snippet in path")
}
// Indirect the default route onto a different one
if req.URL.Path == "/" {
req.URL.Path = common.Config.DefaultPath
}
var prefix, extraData string
prefix = req.URL.Path[0:strings.IndexByte(req.URL.Path[1:],'/') + 1]
if req.URL.Path[len(req.URL.Path) - 1] != '/' {
extraData = req.URL.Path[strings.LastIndexByte(req.URL.Path,'/') + 1:]
req.URL.Path = req.URL.Path[:strings.LastIndexByte(req.URL.Path,'/') + 1]
}
if prefix != "/ws" {
h := w.Header()
h.Set("X-Frame-Options", "deny")
h.Set("X-XSS-Protection", "1; mode=block") // TODO: Remove when we add a CSP? CSP's are horrendously glitchy things, tread with caution before removing
// TODO: Set the content policy header
h.Set("X-Content-Type-Options", "nosniff")
}
if common.Dev.SuperDebug {
router.DumpRequest(req,"before routes.StaticFile")
}
// Increment the request counter
counters.GlobalViewCounter.Bump()
if prefix == "/static" {
counters.RouteViewCounter.Bump({{ index .AllRouteMap "routes.StaticFile" }})
req.URL.Path += extraData
routes.StaticFile(w, req)
return
}
if atomic.LoadInt32(&common.IsDBDown) == 1 {
common.DatabaseError(w, req)
return
}
if common.Dev.SuperDebug {
router.requestLogger.Print("before PreRoute")
}
// Track the user agents. Unfortunately, everyone pretends to be Mozilla, so this'll be a little less efficient than I would like.
// TODO: Add a setting to disable this?
// TODO: Use a more efficient detector instead of smashing every possible combination in
ua := strings.TrimSpace(strings.Replace(strings.TrimPrefix(req.UserAgent(),"Mozilla/5.0 ")," Safari/537.36","",-1)) // Noise, no one's going to be running this and it would require some sort of agent ranking system to determine which identifier should be prioritised over another
if ua == "" {
counters.AgentViewCounter.Bump({{.AllAgentMap.blank}})
if common.Dev.DebugMode {
var prepend string
for _, char := range req.UserAgent() {
prepend += strconv.Itoa(int(char)) + " "
}
router.DumpRequest(req,"Blank UA: " + prepend)
}
} else {
var runeEquals = func(a []rune, b []rune) bool {
if len(a) != len(b) {
return false
}
for i, item := range a {
if item != b[i] {
return false
}
}
return true
}
// WIP UA Parser
var indices []int
var items []string
var buffer []rune
for index, item := range ua {
if (item > 64 && item < 91) || (item > 96 && item < 123) {
buffer = append(buffer, item)
} else if item == ' ' || item == '(' || item == ')' || item == '-' || (item > 47 && item < 58) || item == '_' || item == ';' || item == '.' || item == '+' || (item == ':' && (runeEquals(buffer,[]rune("http")) || runeEquals(buffer,[]rune("rv")))) || item == ',' || item == '/' {
if len(buffer) != 0 {
items = append(items, string(buffer))
indices = append(indices, index - 1)
buffer = buffer[:0]
}
} else {
// TODO: Test this
items = items[:0]
indices = indices[:0]
router.SuspiciousRequest(req,"Illegal char in UA")
router.requestLogger.Print("UA Buffer: ", buffer)
router.requestLogger.Print("UA Buffer String: ", string(buffer))
break
}
}
// Iterate over this in reverse as the real UA tends to be on the right side
var agent string
for i := len(items) - 1; i >= 0; i-- {
fAgent, ok := markToAgent[items[i]]
if ok {
agent = fAgent
if agent != "safari" {
break
}
}
}
if common.Dev.SuperDebug {
router.requestLogger.Print("parsed agent: ", agent)
}
var os string
for _, mark := range items {
switch(mark) {
case "Windows":
os = "windows"
case "Linux":
os = "linux"
case "Mac":
os = "mac"
case "iPhone":
os = "iphone"
case "Android":
os = "android"
}
}
if os == "" {
os = "unknown"
}
if common.Dev.SuperDebug {
router.requestLogger.Print("os: ", os)
router.requestLogger.Printf("items: %+v\n",items)
}
// Special handling
switch(agent) {
case "chrome":
if os == "android" {
agent = "androidchrome"
}
case "safari":
if os == "iphone" {
agent = "mobilesafari"
}
case "trident":
// Hack to support IE11, change this after we start logging versions
if strings.Contains(ua,"rv:11") {
agent = "internetexplorer"
}
case "zgrab":
router.SuspiciousRequest(req,"Vulnerability Scanner")
}
if agent == "" {
counters.AgentViewCounter.Bump({{.AllAgentMap.unknown}})
if common.Dev.DebugMode {
var prepend string
for _, char := range req.UserAgent() {
prepend += strconv.Itoa(int(char)) + " "
}
router.DumpRequest(req,"Blank UA: " + prepend)
}
} else {
counters.AgentViewCounter.Bump(agentMapEnum[agent])
}
counters.OSViewCounter.Bump(osMapEnum[os])
}
// TODO: Do we want to track missing language headers too? Maybe as it's own type, e.g. "noheader"?
lang := req.Header.Get("Accept-Language")
if lang != "" {
lang = strings.TrimSpace(lang)
lLang := strings.Split(lang,"-")
common.DebugDetail("lLang:", lLang)
counters.LangViewCounter.Bump(lLang[0])
} else {
counters.LangViewCounter.Bump("none")
}
referrer := req.Header.Get("Referer") // Check the 'referrer' header too? :P
if referrer != "" {
// ? Optimise this a little?
referrer = strings.TrimPrefix(strings.TrimPrefix(referrer,"http://"),"https://")
referrer = strings.Split(referrer,"/")[0]
portless := strings.Split(referrer,":")[0]
if portless != "localhost" && portless != "127.0.0.1" && portless != common.Site.Host {
counters.ReferrerTracker.Bump(referrer)
}
}
// Deal with the session stuff, etc.
user, ok := common.PreRoute(w, req)
if !ok {
return
}
if common.Dev.SuperDebug {
router.requestLogger.Print(
"after PreRoute\n" +
"routeMapEnum: ", routeMapEnum)
}
// Disable Gzip when SSL is disabled for security reasons?
if prefix != "/ws" && strings.Contains(req.Header.Get("Accept-Encoding"), "gzip") {
w.Header().Set("Content-Encoding", "gzip")
w.Header().Set("Content-Type", "text/html; charset=utf-8")
gz := gzip.NewWriter(w)
defer func() {
if w.Header().Get("Content-Encoding") == "gzip" {
gz.Close()
}
}()
w = gzipResponseWriter{Writer: gz, ResponseWriter: w}
}
router.routeSwitch(w, req, user, prefix, extraData)
}
func (router *GenRouter) routeSwitch(w http.ResponseWriter, req *http.Request, user common.User, prefix string, extraData string) {
var err common.RouteError
switch(prefix) {` + out + `
/*case "/sitemaps": // TODO: Count these views
req.URL.Path += extraData
err = sitemapSwitch(w,req)*/
case "/uploads":
if extraData == "" {
common.NotFound(w,req,nil)
return
}
gzw, ok := w.(gzipResponseWriter)
if ok {
w = gzw.ResponseWriter
w.Header().Del("Content-Type")
w.Header().Del("Content-Encoding")
}
counters.RouteViewCounter.Bump({{index .AllRouteMap "routes.UploadedFile" }})
req.URL.Path += extraData
// TODO: Find a way to propagate errors up from this?
router.UploadHandler(w,req) // TODO: Count these views
return
case "":
// Stop the favicons, robots.txt file, etc. resolving to the topics list
// TODO: Add support for favicons and robots.txt files
switch(extraData) {
case "robots.txt":
counters.RouteViewCounter.Bump({{index .AllRouteMap "routes.RobotsTxt"}})
err = routes.RobotsTxt(w,req)
if err != nil {
router.handleError(err,w,req,user)
}
return
/*case "sitemap.xml":
counters.RouteViewCounter.Bump({{index .AllRouteMap "routes.SitemapXml"}})
err = routes.SitemapXml(w,req)
if err != nil {
router.handleError(err,w,req,user)
}
return*/
}
common.NotFound(w,req,nil)
return
default:
// A fallback for the routes which haven't been converted to the new router yet or plugins
router.RLock()
handle, ok := router.extraRoutes[req.URL.Path]
router.RUnlock()
if ok {
counters.RouteViewCounter.Bump({{index .AllRouteMap "routes.DynamicRoute" }}) // TODO: Be more specific about *which* dynamic route it is
req.URL.Path += extraData
err = handle(w,req,user)
if err != nil {
router.handleError(err,w,req,user)
}
return
}
lowerPath := strings.ToLower(req.URL.Path)
if strings.Contains(lowerPath,"admin") || strings.Contains(lowerPath,"sql") || strings.Contains(lowerPath,"manage") || strings.Contains(lowerPath,"//") || strings.Contains(lowerPath,"\\\\") || strings.Contains(lowerPath,"wp") || strings.Contains(lowerPath,"wordpress") || strings.Contains(lowerPath,"config") || strings.Contains(lowerPath,"setup") || strings.Contains(lowerPath,"install") || strings.Contains(lowerPath,"update") || strings.Contains(lowerPath,"php") {
router.SuspiciousRequest(req,"Bad Route")
} else {
router.DumpRequest(req,"Bad Route")
}
counters.RouteViewCounter.Bump({{index .AllRouteMap "routes.BadRoute" }})
common.NotFound(w,req,nil)
return
}
if err != nil {
router.handleError(err,w,req,user)
}
}
`
var tmpl = template.Must(template.New("router").Parse(fileData))
var b bytes.Buffer
err := tmpl.Execute(&b, tmplVars)
if err != nil {
log.Fatal(err)
}
writeFile("./gen_router.go", string(b.Bytes()))
log.Println("Successfully generated the router")
}
func writeFile(name string, content string) {
f, err := os.Create(name)
if err != nil {
log.Fatal(err)
}
_, err = f.WriteString(content)
if err != nil {
log.Fatal(err)
}
f.Sync()
f.Close()
}