/
server.go
195 lines (173 loc) · 4.35 KB
/
server.go
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package server
import (
"context"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"encoding/base64"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"time"
logging "github.com/ipfs/go-log"
)
var log = logging.Logger("agent")
// agent is the agent in the system.
type agent struct {
ctx context.Context
key []byte
server *http.Server
handlers map[byte]func(data []byte) (byte, []byte, error)
peerIDs []string
}
// Message type
const (
GetID = 1
SetID = 2
Check = 3
Publish = 4
Lookup = 5
Clean = 6
Disconnect = 7
)
// NewServer creates a new server.
func NewServer(ctx context.Context, listenAddr string, keyStr string) error {
key, err := base64.RawStdEncoding.DecodeString(keyStr)
if err != nil {
return err
}
if len(key) != 32 {
return fmt.Errorf("Wrong key size, expect 32, got: %v", len(key))
}
a := &agent{
ctx: ctx,
key: key,
handlers: make(map[byte]func(data []byte) (byte, []byte, error)),
peerIDs: make([]string, 0),
}
a.server = &http.Server{
Addr: listenAddr,
Handler: a,
ReadTimeout: 60 * time.Second,
WriteTimeout: 60 * time.Second,
MaxHeaderBytes: 1 << 20,
}
// Add handlers
a.handlers[GetID] = handleGetID
a.handlers[SetID] = a.handleSetID
a.handlers[Check] = handleCheck
a.handlers[Publish] = handlePublish
a.handlers[Lookup] = handleLookup
a.handlers[Clean] = handleClean
a.handlers[Disconnect] = a.handleDisonnect
// Start server
log.Infof("Start listening at %v", listenAddr)
if err = a.server.ListenAndServe(); err != nil {
return err
}
return nil
}
// ServeHTTP serves http.
func (a *agent) ServeHTTP(w http.ResponseWriter, r *http.Request) {
content, err := ioutil.ReadAll(r.Body)
if closeErr := r.Body.Close(); closeErr != nil {
log.Warn("HTTP can't close request body")
}
if err != nil {
log.Error("Error reading request %v", err.Error())
WriteError(w, 400, fmt.Sprintf("Invalid Request: %v.", err.Error()))
return
}
if len(content) <= 1 {
log.Error("Received content with empty request %v", content)
WriteError(w, 400, "Content body is empty")
return
}
plain, err := decrypt(content, a.key)
if err != nil {
log.Error("Request fails to verify")
WriteError(w, 400, "Request fails to verify")
return
}
msgType := plain[0]
msgData := plain[1:]
handler, ok := a.handlers[msgType]
if !ok {
log.Error("Unsupported message type: %v", msgType)
WriteError(w, 400, fmt.Sprintf("Unsupported method: %v", msgType))
return
}
respType, respData, err := handler(msgData)
if err != nil {
log.Error("Error handling request: %v", err.Error())
WriteError(w, 400, fmt.Sprintf("Error handling request: %v", err.Error()))
return
}
respEnc, err := encrypt(append([]byte{respType}, respData...), a.key)
if err != nil {
log.Error("Internal Error in encryption: %v", err.Error())
WriteError(w, 500, "Internal Error")
return
}
w.WriteHeader(200)
_, err = w.Write(respEnc)
if err != nil {
log.Error("Error responding to client: %v", err.Error())
}
}
// WriteError writes an error.
func WriteError(w http.ResponseWriter, header int, msg string) {
w.WriteHeader(header)
resp, err := json.Marshal(map[string]string{"Error": msg})
if err == nil {
w.Write(resp)
}
}
func encrypt(plain []byte, key []byte) ([]byte, error) {
//Create a new Cipher Block from the key
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
//Create a new GCM
aesGCM, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
//Create a nonce. Nonce should be from GCM
nonce := make([]byte, aesGCM.NonceSize())
if _, err = io.ReadFull(rand.Reader, nonce); err != nil {
return nil, err
}
enc := aesGCM.Seal(nonce, nonce, plain, nil)
return enc, nil
}
func decrypt(enc []byte, key []byte) ([]byte, error) {
// Create a new Cipher Block from the key
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
// Create a new GCM
aesGCM, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
// Get the nonce size
nonceSize := aesGCM.NonceSize()
// Extract the nonce from the encrypted data
nonce, ciphertext := enc[:nonceSize], enc[nonceSize:]
// Decrypt the data
plain, err := aesGCM.Open(nil, nonce, ciphertext, nil)
if err != nil {
return nil, err
}
return plain, nil
}
// shutdownRoutine shuts down the server.
func (a *agent) shutdownRoutine() {
<-a.ctx.Done()
a.server.Close()
}