// RemoteConnHandler continuously reads an encrypted message from a remote user
// (sent from his/her LanChat client), decrypts it, then prints it to the
// terminal. Called by RemoteTCPServer, which is used when *ActAsServer == true,
// and TCPBridge, which is used when *ActAsServer == false.
func RemoteConnHandler(conn net.Conn) {
// New user connected; add their connection to routing table
connList.AddRemote <- conn
// Close conn and remove it from the routing table when we're done
// here
defer func() {
connList.DeleteRemote <- conn
conn.Close()
}()
// Create new cipher.Block
decBlock, err := aes.NewCipher([]byte(SharedSecret))
if err != nil {
log.Fatalf("Error creating AES cipher for decryption: %v\n", err)
}
ciphertext := make([]byte, MAX_MESSAGE_SIZE)
for {
n, err := conn.Read(ciphertext)
if err != nil {
if err == io.EOF {
break
// TODO: os.Exit(1) when disconnecting from _the_ server
}
log.Printf("Error reading message from remote conn %s: %v\n",
conn.RemoteAddr(), err)
continue
}
if DEBUG {
log.Printf("ciphertext[:n] == %v\n", ciphertext[:n])
}
// Send message to other remote users
go func() {
connList.WriteToRemotes <- &types.Cipherstore{conn, ciphertext[:n]}
}()
// Decrypt
plaintext, err := crypt.AESDecryptBytes(decBlock, ciphertext[:n])
if err != nil {
log.Printf("Error decrypting '%v' ('%s'): %v\n",
ciphertext[:n], ciphertext[:n], err)
continue
}
// Print to screen of the form `[timestamp] remoteIP: Message`
now := time.Now().Format(time.Kitchen)
fmt.Printf("[%s] %s: %s\n", now, conn.RemoteAddr(), plaintext)
}
}
func main() {
msg := []byte("This is 18+ chars!")
fmt.Printf("msg == %s\n", msg)
// Encrypt
encBlock, err := aes.NewCipher(PASSPHRASE)
fun.MaybeFatalAt("aes.NewCipher", err)
// See https://github.com/thecloakproject/utils/blob/master/crypt/aes.go
cipher, err := crypt.AESEncryptBytes(encBlock, msg)
fun.MaybeFatalAt("AESEncryptBytes", err)
fmt.Printf("cipher == %v\n", cipher)
// Decrypt
decBlock, err := aes.NewCipher(PASSPHRASE)
fun.MaybeFatalAt("aes.NewCipher", err)
// See https://github.com/thecloakproject/utils/blob/master/crypt/aes.go
plain, err := crypt.AESDecryptBytes(decBlock, cipher)
fun.MaybeFatalAt("AESDecryptBytes", err)
fmt.Printf("plain == %s\n", plain)
msgPadded := utils.PadBytes(msg, decBlock.BlockSize())
// Check for equality
fmt.Printf("\nThey match? %v!\n", bytes.Equal(msgPadded, plain))
// Check for equality in other ways
msgUnpadded := strings.TrimSpace(string(msgPadded))
match := (msgUnpadded == string(plain))
fmt.Printf("\nDo their trimmed versions match? %v!\n", match)
if match {
fmt.Printf("They both equal '%s'\n", msgUnpadded)
}
// Here's how to remove those ugly trailing nulls
fmt.Printf("Cleanest-looking version: '%s'\n",
strings.TrimRight(string(plain), "\x00"))
}