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interceptor.go
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interceptor.go
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package main
import (
"bytes"
"encoding/base64"
"encoding/json"
"fmt"
"globe-and-citizen/layer8-interceptor/internals"
"os"
"time"
"net/http"
"net/url"
"strings"
"syscall/js"
utils "github.com/globe-and-citizen/layer8-utils"
uuid "github.com/google/uuid"
)
// Declare global constants
type IndexedDBName string
const (
INTERCEPTOR_VERSION = "0.0.14"
// IndexedDB constants
INDEXEDDB_CACHE IndexedDBName = "_layer8cache"
INDEXEDDB_CACHE_TTL time.Duration = time.Hour * 24 * 2 // 2 days
)
// Declare global variables
var (
Layer8LightsailURL string
Counter int
EncryptedTunnelFlag bool
privJWK_ecdh *utils.JWK
pubJWK_ecdh *utils.JWK
userSymmetricKey *utils.JWK
UpJWT string
UUID string
staticPath string
L8Clients map[string]internals.ClientImpl = make(map[string]internals.ClientImpl)
// IndexedDBs is a map of the IndexedDBs that the interceptor uses
IndexedDBs = map[IndexedDBName]map[string]interface{}{
INDEXEDDB_CACHE: map[string]interface{}{
"store": "static",
"keyPath": "url",
"indexes": map[string]interface{}{
"url": map[string]interface{}{
"unique": true,
},
"_exp": map[string]interface{}{
"unique": false,
},
},
},
}
)
func OpenDB(dbName IndexedDBName, reject js.Value) js.Value {
indb, ok := IndexedDBs[dbName]
if !ok {
msg := fmt.Sprintf("The IndexedDB %s does not exist.", dbName)
if reject.IsUndefined() || reject.IsNull() {
js.Global().Get("console").Call("error", msg)
} else {
reject.Invoke(js.Global().Get("Error").New(msg))
}
return js.ValueOf(nil)
}
db := js.Global().Get("indexedDB").Call("open", string(dbName))
db.Set("onerror", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
msg := fmt.Sprintf(
"Please enable IndexedDB in your browser or update your browser to the latest version.")
if reject.IsUndefined() || reject.IsNull() {
js.Global().Get("console").Call("error", msg)
} else {
reject.Invoke(js.Global().Get("Error").New(msg))
}
return nil
}))
db.Set("onupgradeneeded", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
db := args[0].Get("target").Get("result")
store := db.Call("createObjectStore", indb["store"].(string), js.ValueOf(map[string]interface{}{
"keyPath": indb["keyPath"].(string),
}))
for index, indexConfig := range indb["indexes"].(map[string]interface{}) {
store.Call("createIndex", index, index, js.ValueOf(indexConfig.(map[string]interface{})))
}
return nil
}))
return db
}
func ClearExpiredCache() {
// open the cache
db := OpenDB(INDEXEDDB_CACHE, js.ValueOf(nil))
db.Set("onsuccess", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
tx := args[0].Get("target").Get("result").Call("transaction", "static", "readwrite")
store := tx.Call("objectStore", "static")
index := store.Call("index", "_exp")
// get all the expired items
bound := js.Global().Get("IDBKeyRange").Call("upperBound", js.ValueOf(time.Now().Unix()))
index.Call("openCursor", bound).Set("onsuccess", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
cursor := args[0].Get("target").Get("result")
if cursor.IsUndefined() || cursor.IsNull() {
return nil
}
store.Call("delete", cursor.Get("value").Get("url"))
cursor.Call("continue")
return nil
}))
return nil
}))
}
/*
//var L8Client = internals.NewClient(Layer8Scheme, Layer8Host, Layer8Port) // Ravi TODO this should probably be revisited
*/
func main() {
// Create channel to keep the Go thread alive
c := make(chan struct{})
EncryptedTunnelFlag = false
// Expose layer8 functionality to the front end Javascript
js.Global().Set("layer8", js.ValueOf(map[string]interface{}{
"testWASM": js.FuncOf(testWASM),
"persistenceCheck": js.FuncOf(persistenceCheck),
"initEncryptedTunnel": js.FuncOf(initializeECDHTunnel),
"checkEncryptedTunnel": js.FuncOf(checkEncryptedTunnel),
"fetch": js.FuncOf(fetch),
"static": js.FuncOf(getStatic),
// TODO: add a function here that returns the state of the tunnel
}))
// Developer Warnings:
fmt.Println("WARNING: wasm_exec.js is versioned and has some breaking changes. Ensure you are using the correct version.")
// Wait indefinitely
<-c
}
// Utility function to test promise resolution / rejection from the console.
func testWASM(this js.Value, args []js.Value) interface{} {
var promise_logic = func(this js.Value, resolve_reject []js.Value) interface{} {
resolve := resolve_reject[0]
reject := resolve_reject[1]
if len(args) == 0 {
reject.Invoke(js.ValueOf("Promise rejection occurs if not arguments are passed. Pass an argument."))
return nil
}
go func() {
resolve.Invoke(js.ValueOf(fmt.Sprintf("WASM Interceptor version %s successfully loaded. Argument passed: %v. To test promise rejection, call with no argument.", INTERCEPTOR_VERSION, args[0])))
}()
return nil
}
promiseConstructor := js.Global().Get("Promise")
promise := promiseConstructor.New(js.FuncOf(promise_logic))
return promise
}
func persistenceCheck(this js.Value, args []js.Value) interface{} {
var promise_logic = func(this js.Value, resolve_reject []js.Value) interface{} {
resolve := resolve_reject[0]
go func() {
Counter++
fmt.Println("WASM Counter: ", Counter)
resolve.Invoke(js.ValueOf(Counter))
}()
return nil
}
promiseConstructor := js.Global().Get("Promise")
promise := promiseConstructor.New(js.FuncOf(promise_logic))
return promise
}
func getHost(u string) (string, error) {
p, err := url.Parse(u)
if err != nil {
return "", err
}
res := p.Scheme + "://" + p.Hostname()
if p.Port() != "" {
res = res + ":" + p.Port()
}
return res, nil
}
func initializeECDHTunnel(this js.Value, args []js.Value) interface{} {
// Convert JS values into useable Golang variables
var (
providers []string
proxy string = "https://layer8devproxy.net" // set LAYER8_PROXY in the environment to override
mode string = "prod"
)
if len(args) > 1 {
mode = args[1].String()
}
ErrorDestructuringConfigObject := false
// clean up cache
go ClearExpiredCache()
js.Global().Get("Object").Call("entries", args[0]).Call("forEach", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
key := args[0].Index(0).String()
switch key {
case "providers":
providers = make([]string, args[0].Index(1).Length())
for i := 0; i < args[0].Index(1).Get("length").Int(); i++ {
providers[i] = args[0].Index(1).Index(i).String()
}
case "proxy":
if mode == "dev" {
proxy = args[0].Index(1).String()
} else {
if os.Getenv("LAYER8_PROXY") != "" {
proxy = os.Getenv("LAYER8_PROXY")
}
}
case "staticPath":
staticPath = args[0].Index(1).String()
default:
ErrorDestructuringConfigObject = true
}
return nil
}))
if ErrorDestructuringConfigObject {
return js.Global().Get("Promise").New(js.FuncOf(func(this js.Value, args []js.Value) interface{} {
// resolve := args[0]
reject := args[1]
reject.Invoke(js.Global().Get("Error").New("Unable to destructure the Layer8 encrypted tunnel config object. "))
return nil
}))
}
return js.Global().Get("Promise").New(js.FuncOf(func(this js.Value, args []js.Value) interface{} {
resolve := args[0]
reject := args[1]
initTunnel := func(provider string) {
// parse the provider URL to maintain a pattern of scheme://host:port
// in the L8Clients map
provider, err := getHost(provider)
if err != nil {
fmt.Println("[Interceptor]", err.Error())
EncryptedTunnelFlag = false
reject.Invoke(js.Global().Get("Error").New("Unable to parse the provider URL. "))
return
}
privJWK_ecdh, pubJWK_ecdh, err = utils.GenerateKeyPair(utils.ECDH)
if err != nil {
fmt.Println("[Interceptor]", err.Error())
EncryptedTunnelFlag = false
reject.Invoke(js.Global().Get("Error").New("Unable to generate client key pair"))
return
}
b64PubJWK, err := pubJWK_ecdh.ExportAsBase64()
if err != nil {
fmt.Println("[Interceptor]", err.Error())
EncryptedTunnelFlag = false
reject.Invoke(js.Global().Get("Error").New("Failed to Export publicJWK_ecdh"))
return
}
proxy = fmt.Sprintf("%s/init-tunnel?backend=%s", proxy, provider)
client := &http.Client{}
req, err := http.NewRequest("POST", proxy, bytes.NewBuffer([]byte(b64PubJWK)))
if err != nil {
fmt.Println(err.Error())
EncryptedTunnelFlag = false
reject.Invoke(js.Global().Get("Error").New("Creation of initialization POST request failed. "))
return
}
uuid := uuid.New()
UUID = uuid.String()
req.Header.Add("x-ecdh-init", b64PubJWK)
req.Header.Add("x-client-uuid", uuid.String())
// send request
resp, err := client.Do(req)
if err != nil {
fmt.Println(err.Error())
reject.Invoke(js.Global().Get("Error").New("Initialization POST request to Proxy failed. "))
EncryptedTunnelFlag = false
return
}
if resp.StatusCode == 401 {
reject.Invoke(js.Global().Get("Error").New("401 response from proxy, user is not authorized. "))
EncryptedTunnelFlag = false
return
}
Respbody := utils.ReadResponseBody(resp.Body)
data := map[string]interface{}{}
err = json.Unmarshal(Respbody, &data)
if err != nil {
reject.Invoke(js.Global().Get("Error").New("The data received from the proxy could not be unmarshalled: ", err.Error()))
EncryptedTunnelFlag = false
return
}
UpJWT = data["up-JWT"].(string)
server_pubKeyECDH, err := utils.JWKFromMap(data)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
EncryptedTunnelFlag = false
return
}
userSymmetricKey, err = privJWK_ecdh.GetECDHSharedSecret(server_pubKeyECDH)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
EncryptedTunnelFlag = false
return
}
// fmt.Println("[Interceptor] UpJWT: ", UpJWT)
// TODO: Send an encrypted ping / confirmation to the server using the shared secret
// just like the 1. Syn 2. Syn/Ack 3. Ack flow in a TCP handshake
EncryptedTunnelFlag = true
proxyURL, err := url.Parse(proxy)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
EncryptedTunnelFlag = false
return
}
port := proxyURL.Port()
if port == "" {
if proxyURL.Scheme == "https" {
port = "443"
} else {
port = "80"
}
}
L8Clients[provider], err = internals.NewClient(proxyURL.Scheme, proxyURL.Hostname(), port)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
EncryptedTunnelFlag = false
return
}
fmt.Printf("[%s] Encrypted tunnel successfully established.\n", provider)
resolve.Invoke(true)
return
}
for _, provider := range providers {
go initTunnel(provider)
}
return nil
}))
}
func checkEncryptedTunnel(this js.Value, args []js.Value) interface{} {
return js.Global().Get("Promise").New(js.FuncOf(func(this js.Value, resolve_reject []js.Value) interface{} {
resolve := resolve_reject[0]
//reject := resolve_reject[1]
if EncryptedTunnelFlag {
resolve.Invoke(true)
} else {
resolve.Invoke(false)
}
return nil
}))
}
func fetch(this js.Value, args []js.Value) interface{} {
var promise_logic = func(this js.Value, resolve_reject []js.Value) interface{} {
resolve := resolve_reject[0]
reject := resolve_reject[1]
if !EncryptedTunnelFlag {
reject.Invoke(js.Global().Get("Error").New("The Encrypted tunnel is closed. Reload page."))
return nil
}
if len(args) == 0 {
reject.Invoke(js.Global().Get("Error").New("No URL provided to fetch call."))
return nil
}
spURL := args[0].String()
if len(spURL) <= 0 {
reject.Invoke(js.Global().Get("Error").New("Invalid URL provided to fetch call."))
return nil
}
options := js.ValueOf(map[string]interface{}{
"method": "GET", // Set HTTP "GET" request to be the default
"headers": js.ValueOf(map[string]interface{}{}),
"body": js.ValueOf("<undefined>"),
})
if len(args) > 1 {
options = args[1]
}
method := options.Get("method").String()
if method == "" {
method = "GET"
}
// Set headers to an empty object if it is 'undefined' or 'null'
userAddedHeaders := options.Get("headers")
if userAddedHeaders.String() == "<undefined>" || userAddedHeaders.String() == "null" {
userAddedHeaders = js.ValueOf(map[string]interface{}{})
}
userHeaderMap := make(map[string]string)
js.Global().Get("Object").Call("entries", userAddedHeaders).Call("forEach", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
userHeaderMap[args[0].Index(0).String()] = args[0].Index(1).String()
return nil
}))
// set the content-type to application/json if it's undefined
// TODO: If it's a GET request, is this still necessary / appropriate?
// In the switch statement below, all GET requests are given a body of '{}'. On arrival in the sever, this should actually be `undefined`.
if _, ok := userHeaderMap["Content-Type"]; !ok {
body := options.Get("body")
if body.String() != "<undefined>" && body.Get("constructor").Get("name").String() == "FormData" {
userHeaderMap["Content-Type"] = "multipart/form-data"
} else {
userHeaderMap["Content-Type"] = "application/json"
}
}
host, err := getHost(spURL)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return nil
}
client := L8Clients[host]
go func() {
var res *utils.Response
switch strings.ToLower(userHeaderMap["Content-Type"]) {
case "application/json": // Note this is the default that GET requests travel through
// Converting the body to Golag or setting it as null/nil
urlPath := strings.Replace(spURL, host, "", 1)
bodyMap := map[string]interface{}{
"__url_path": urlPath,
}
body := options.Get("body")
if body.String() == "<undefined>" {
// body = js.ValueOf(map[string]interface{}{}) <= this will err out as "Uncaught (in promise) Error: invalid character '<' looking for beginning of value"
body = js.ValueOf("{}")
} else {
err := json.Unmarshal([]byte(body.String()), &bodyMap)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return
}
}
// encode the body to json
bodyByte, err := json.Marshal(bodyMap)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return
}
// forward request to the layer8 proxy server
res = client.Do(
spURL, utils.NewRequest(method, userHeaderMap, bodyByte),
userSymmetricKey, false, UpJWT, UUID)
case "multipart/form-data":
userHeaderMap["Content-Type"] = "application/layer8.buffer+json"
body := options.Get("body")
if body.String() == "<undefined>" || body.String() == "null" {
reject.Invoke(js.Global().Get("Error").New("No body provided to fetch call."))
return
}
// get data from formdata
var (
dataLength = js.Global().Get("Array").Call("from", body.Call("keys")).Get("length").Int()
formdata = make(map[string]interface{}, dataLength)
)
urlPath := strings.Replace(spURL, host, "", 1)
dataToAdd := map[string]interface{}{
"_type": "String",
"value": urlPath,
}
if _, ok := formdata["__url_path"]; !ok {
formdata["__url_path"] = []map[string]interface{}{dataToAdd}
}
js.Global().Get("Array").Call("from", body.Call("keys")).Call("forEach", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
var (
key = args[0].String()
value = body.Call("get", key)
valueType = value.Get("constructor").Get("name").String()
)
switch valueType {
case "File":
value.Call("arrayBuffer").Call("then", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
buff := make([]byte, value.Get("size").Int())
js.CopyBytesToGo(buff, js.Global().Get("Uint8Array").New(args[0]))
data := map[string]interface{}{
"_type": "File",
"name": value.Get("name").String(),
"size": value.Get("size").Int(),
"type": value.Get("type").String(),
"buff": base64.StdEncoding.EncodeToString(buff),
}
// because formdata can have multiple entries for the same key
// each key is an array of maps
if val, ok := formdata[key]; !ok {
formdata[key] = []map[string]interface{}{data}
} else {
formdata[key] = append(val.([]map[string]interface{}), data)
}
return nil
}))
case "String":
data := map[string]interface{}{
"_type": "String",
"value": value.String(),
}
if val, ok := formdata[key]; !ok {
formdata[key] = []map[string]interface{}{data}
} else {
formdata[key] = append(val.([]map[string]interface{}), data)
}
case "Number":
data := map[string]interface{}{
"_type": "Number",
"value": value.Float(),
}
if val, ok := formdata[key]; !ok {
formdata[key] = []map[string]interface{}{data}
} else {
formdata[key] = append(val.([]map[string]interface{}), data)
}
case "Boolean":
data := map[string]interface{}{
"_type": "Boolean",
"value": value.Bool(),
}
if val, ok := formdata[key]; !ok {
formdata[key] = []map[string]interface{}{data}
} else {
formdata[key] = append(val.([]map[string]interface{}), data)
}
default:
reject.Invoke(js.Global().Get("Error").New(fmt.Sprintf("Unsupported type: %s", valueType)))
return nil
}
return nil
}))
// wait for the formdata to be populated, this is a hacky way to do it, but it works for now
// having tried using a channel, it fails with a "fatal error: all goroutines are asleep - deadlock!"
// TODO: find a better way to do this
time.Sleep(100 * time.Millisecond)
// encode the body to json
bodyByte, err := json.Marshal(formdata)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return
}
// forward request to the layer8 proxy server
res = client.Do( // RAVI TODO: Get a single client working again.
spURL, utils.NewRequest(method, userHeaderMap, bodyByte),
userSymmetricKey, false, UpJWT, UUID)
default:
res = &utils.Response{
Status: 400,
StatusText: "Content-Type not supported",
}
}
if res.Status >= 100 && res.Status < 300 { // Handle Success & Default Rejection
resHeaders := js.Global().Get("Headers").New()
for k, v := range res.Headers {
//fmt.Println("Encrypted Headers from the SP: ", k, v)
resHeaders.Call("append", js.ValueOf(k), js.ValueOf(v))
}
resolve.Invoke(js.Global().Get("Response").New(string(res.Body), js.ValueOf(map[string]interface{}{
"status": res.Status,
"statusText": res.StatusText,
"headers": resHeaders,
})))
return
}
reject.Invoke(js.Global().Get("Error").New(res.StatusText))
fmt.Printf("[interceptor] fetch status %d. Error txt: %s", res.Status, res.StatusText)
return
}()
return nil
}
promiseConstructor := js.Global().Get("Promise")
promise := promiseConstructor.New(js.FuncOf(promise_logic))
return promise
}
func getStatic(this js.Value, args []js.Value) interface{} {
spURL := args[0].String()
return js.Global().Get("Promise").New(js.FuncOf(func(this js.Value, args []js.Value) interface{} {
resolve := args[0]
reject := args[1]
pURL, err := url.Parse(spURL)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return nil
}
client := L8Clients[pURL.Scheme+"://"+pURL.Host]
host, err := getHost(spURL)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return nil
}
host = host + staticPath
urlPath := strings.Replace(spURL, host, "", 1)
bodyMap := map[string]interface{}{
"__url_path": urlPath,
}
bodyByte, err := json.Marshal(bodyMap)
if err != nil {
reject.Invoke(js.Global().Get("Error").New(err.Error()))
return nil
}
// fetch the static file from the server and store it in the cache
fetchStatic := func() {
resp := client.Do(
host, utils.NewRequest("GET", make(map[string]string), bodyByte),
userSymmetricKey, true, UpJWT, UUID)
// convert response body to js arraybuffer
jsBody := js.Global().Get("Uint8Array").New(len(resp.Body))
js.CopyBytesToJS(jsBody, resp.Body)
// create a map of the response headers
resHeaders := js.Global().Get("Headers").New()
for k, v := range resp.Headers {
resHeaders.Call("append", js.ValueOf(k), js.ValueOf(v))
}
fileType := resHeaders.Call("get", js.ValueOf("content-type"))
// store the file in the cache
db := OpenDB(INDEXEDDB_CACHE, reject)
db.Set("onsuccess", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
db := args[0].Get("target").Get("result")
tx := db.Call("transaction", "static", "readwrite")
store := tx.Call("objectStore", "static")
store.Call("put", js.ValueOf(map[string]interface{}{
"url": spURL,
"body": jsBody,
"type": fileType,
"_exp": time.Now().Add(INDEXEDDB_CACHE_TTL).Unix(),
}))
return nil
}))
// convert the response body to a blob and resolve the promise
blob := js.Global().Get("Blob").New([]interface{}{jsBody}, js.ValueOf(map[string]interface{}{
"type": fileType,
}))
objURL := js.Global().Get("URL").Call("createObjectURL", blob)
resolve.Invoke(objURL)
}
// check if the file is in the cache
db := OpenDB(INDEXEDDB_CACHE, reject)
db.Set("onsuccess", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
db := args[0].Get("target").Get("result")
tx := db.Call("transaction", "static", "readonly")
store := tx.Call("objectStore", "static")
index := store.Call("index", "url")
req := index.Call("get", spURL)
req.Set("onsuccess", js.FuncOf(func(this js.Value, args []js.Value) interface{} {
if req.Get("result").IsUndefined() {
// if the file is not in the cache, fetch it from the server
go fetchStatic()
} else {
data := req.Get("result")
blob := js.Global().Get("Blob").New([]interface{}{js.ValueOf(data.Get("body"))}, js.ValueOf(map[string]interface{}{
"type": data.Get("type"),
}))
objURL := js.Global().Get("URL").Call("createObjectURL", blob)
resolve.Invoke(objURL)
}
return nil
}))
return nil
}))
return nil
}))
}