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#golang . latihan uintptr : https://golang.org/pkg/builtin/#uintptr
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| package main | |
| import ( | |
| "crypto/rand" | |
| "fmt" | |
| "net/http" | |
| "unsafe" | |
| "github.com/cespare/xxhash" | |
| ) | |
| var _kode = []byte("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-") | |
| func UInt64ToBase64(d uint64) (s [11]byte) { | |
| copy(s[:], "+++++++++++") | |
| i := 0 | |
| for d > 0 { | |
| s[i] = _kode[d&63] | |
| i++ | |
| d = d >> 6 | |
| } | |
| return | |
| } | |
| var kode_ = func() (kode [123]byte) { | |
| for i := 0; i < 123; i++ { | |
| kode[i] = 64 | |
| } | |
| for i := byte(48); i < 58; i++ { | |
| kode[i] = i - 48 //'0' - '9' -> 0 - 9 | |
| } | |
| for i := byte(97); i < 123; i++ { | |
| kode[i] = i - 87 //'a' - 'z' -> 10 - 35 | |
| } | |
| for i := byte(65); i < 91; i++ { | |
| kode[i] = i - 29 //'A' - 'Z' -> 36 - 61 | |
| } | |
| kode[95] = 62 //'_' -> 62 | |
| kode[45] = 63 //'-' -> 63 | |
| return | |
| }() | |
| func Base64ToUInt64(s string) (d uint64, err error) { | |
| i := 10 | |
| for i >= 0 && s[i] == ' ' { | |
| i-- | |
| } | |
| for i >= 0 && s[i] < 123 { | |
| d = d << 6 | |
| mod := kode_[s[i]] | |
| if mod == 64 { | |
| break | |
| } | |
| d = d | uint64(mod) | |
| i-- | |
| } | |
| if i >= 0 { | |
| return 0, fmt.Errorf("Invalid character: '%c'", s[i]) | |
| } | |
| return | |
| } | |
| func PutUint64(bfr *[8]byte, data uint64) { | |
| for i := 0; data > 0; i++ { | |
| (*bfr)[i] = byte(data) | |
| data = data >> 8 | |
| } | |
| } | |
| func Uint64(bfr [8]byte) (ret uint64) { | |
| for i := 7; i >= 0; i-- { | |
| if bfr[i] == 0 { | |
| continue | |
| } | |
| ret = (ret << 8) | uint64(bfr[i]) | |
| } | |
| return | |
| } | |
| func HashBase64(data uint64) [11]byte { | |
| bfr := [8]byte{} | |
| PutUint64(&bfr, data) | |
| return UInt64ToBase64(xxhash.Sum64(bfr[:])) | |
| } | |
| func HashVerify(data, hash string, s3cr3t uint64) (uint64, bool) { | |
| v, err1 := Base64ToUInt64(data) | |
| if err1 != nil { | |
| return 0, true | |
| } | |
| bfr := [8]byte{} | |
| PutUint64(&bfr, v^s3cr3t) | |
| vHash, err2 := Base64ToUInt64(hash) | |
| return v, err2 != nil && xxhash.Sum64(bfr[:]) != vHash | |
| } | |
| type RW struct { | |
| http.ResponseWriter | |
| Msg string | |
| } | |
| type Handler struct { | |
| Next *http.ServeMux | |
| S3cr3t uint64 | |
| } | |
| func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) { | |
| hndlr := r.FormValue("hndlr") | |
| hash := r.FormValue("hash") | |
| if hndlr != "" && hash != "" { | |
| hndlr_, rqErr := HashVerify(hndlr, hash, h.S3cr3t) | |
| if rqErr { | |
| http.Error(w, "bad request", http.StatusBadRequest) | |
| return | |
| } | |
| hndlrPtr := (*func(http.ResponseWriter, *http.Request))(unsafe.Pointer(uintptr(hndlr_))) | |
| (*hndlrPtr)(RW{w, "direct handler call"}, r) | |
| } else { | |
| h.Next.ServeHTTP(RW{w, "via routing"}, r) | |
| } | |
| } | |
| func root(w http.ResponseWriter, r *http.Request) { | |
| w.WriteHeader(200) | |
| w.Write([]byte(` | |
| <html> | |
| <head></head> | |
| <body> | |
| <a href="javascript:GET('/page1', putResponse)">/page1</a> | <a href="javascript:GET('/page2', putResponse)">/page2</a><br> | |
| <div id="responsePlaceHolder"></div> | |
| <script> | |
| var path = { | |
| "/page1": "", | |
| "/page2": "" | |
| } | |
| function GET(url, cb){ | |
| var xhr = new XMLHttpRequest() | |
| if(!xhr){ | |
| return alert('Giving up : Cannot create an XMLHTTP instance') | |
| } | |
| xhr.onreadystatechange = function(){ | |
| if(xhr.readyState == 4 && xhr.status == 200) { | |
| alert(xhr.responseText) | |
| try { | |
| var res = JSON.parse(xhr.responseText) | |
| path[url] = '&hndlr=' + res.hndlr +'&hash=' + res.hash | |
| cb(res.content) | |
| }catch(e){alert(e)} | |
| } | |
| } | |
| xhr.open('GET', url + '?now=' + (new Date).getTime() + path[url]) | |
| xhr.send() | |
| } | |
| function putResponse(response){ | |
| responsePlaceHolder.innerHTML = 'response:<br>' + response | |
| } | |
| </script> | |
| </body> | |
| </html> | |
| `)) | |
| } | |
| func page1(hndlr *func(http.ResponseWriter, *http.Request), s3cr3t uint64) { | |
| hndlrUInt64 := uint64(uintptr(unsafe.Pointer(hndlr))) | |
| hndlrBase64 := UInt64ToBase64(hndlrUInt64) //sent to client | |
| hndlrHash := HashBase64(hndlrUInt64 ^ s3cr3t) //sent to Client | |
| *hndlr = func(w http.ResponseWriter, r *http.Request) { | |
| fmt.Fprintf(w, `{"hndlr": "%s", "hash": "%s", "content": "content for /page1<br>%s"}`, hndlrBase64, hndlrHash, w.(RW).Msg) | |
| } | |
| } | |
| func page2(hndlr *func(http.ResponseWriter, *http.Request), s3cr3t uint64) { | |
| hndlrUInt64 := uint64(uintptr(unsafe.Pointer(hndlr))) | |
| hndlrBase64 := UInt64ToBase64(hndlrUInt64) //sent to client | |
| hndlrHash := HashBase64(hndlrUInt64 ^ s3cr3t) //sent to Client | |
| *hndlr = func(w http.ResponseWriter, r *http.Request) { | |
| fmt.Fprintf(w, `{"hndlr": "%s", "hash": "%s", "content": "content for /page2<br>%s"}`, hndlrBase64, hndlrHash, w.(RW).Msg) | |
| } | |
| } | |
| func main() { | |
| s3cr3t := func() uint64 { | |
| bfr := [8]byte{} | |
| rand.Read(bfr[:]) | |
| return Uint64(bfr) | |
| }() | |
| var page1Hndlr, page2Hndlr func(http.ResponseWriter, *http.Request) | |
| page1(&page1Hndlr, s3cr3t) | |
| page2(&page2Hndlr, s3cr3t) | |
| mux := http.NewServeMux() | |
| mux.HandleFunc("/", root) | |
| mux.HandleFunc("/page1", page1Hndlr) | |
| mux.HandleFunc("/page2", page2Hndlr) | |
| http.ListenAndServe(":8080", &Handler{mux, s3cr3t}) | |
| } |
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