Fix n2n v2 connection with empty encryption key

When an empty encryption key is set, hin2n disables the encryption

Hin2n_android/app/src/main/cpp/edge_jni/edge_android_v2.c

@@ -353,20 +353,21 @@ int start_edge_v2(n2n_edge_status_t* status)
  conf.transop_id = N2N_TRANSFORM_ID_TWOFISH;
  conf.encrypt_key = strdup(cmd->enc_key);
  traceEvent(TRACE_DEBUG, "encrypt_key = '%s'\n", encrypt_key);
- }
 
- if(cmd->encryption_mode[0]) {
- if(!strcmp(cmd->encryption_mode, "Twofish"))
- conf.transop_id = N2N_TRANSFORM_ID_TWOFISH;
- else if(!strcmp(cmd->encryption_mode, "AES-CBC"))
- conf.transop_id = N2N_TRANSFORM_ID_AESCBC;
- else if(!strcmp(cmd->encryption_mode, "Speck-CTR"))
- conf.transop_id = N2N_TRANSFORM_ID_SPECK;
- else if(!strcmp(cmd->encryption_mode, "ChaCha20"))
- conf.transop_id = N2N_TRANSFORM_ID_CHACHA20;
- else
- traceEvent(TRACE_WARNING, "unknown encryption mode:'%s'\n", cmd->encryption_mode);
- }
+ if(cmd->encryption_mode[0]) {
+ if(!strcmp(cmd->encryption_mode, "Twofish"))
+ conf.transop_id = N2N_TRANSFORM_ID_TWOFISH;
+ else if(!strcmp(cmd->encryption_mode, "AES-CBC"))
+ conf.transop_id = N2N_TRANSFORM_ID_AESCBC;
+ else if(!strcmp(cmd->encryption_mode, "Speck-CTR"))
+ conf.transop_id = N2N_TRANSFORM_ID_SPECK;
+ else if(!strcmp(cmd->encryption_mode, "ChaCha20"))
+ conf.transop_id = N2N_TRANSFORM_ID_CHACHA20;
+ else
+ traceEvent(TRACE_WARNING, "unknown encryption mode:'%s'\n", cmd->encryption_mode);
+ }
+ } else
+ conf.transop_id = N2N_TRANSFORM_ID_NULL;
 
  scan_address(ip_addr, N2N_NETMASK_STR_SIZE,
  ip_mode, N2N_IF_MODE_SIZE,