C++/CLI HTTP Proxy problems - proxy

I'm trying(very hard) to make a small HTTP Proxy server which I can use to save all communications to a file. Seeing as I dont really have any experience in the area, I used a class from codeproject.com and some associated code to get started (It was made in the old CLI syntax, so I converted it). I couldn't get it working, so I added lots more code to make it work (threads etc), and now it sort of works. Basically, it recieves something from a client (I just configured Mozilla Firefox to route its connections through this proxy) and then routes it to google.com. After it sends Firefox's data to google, recieves a responce, and sends that to Firefox. This works fine, but then the proxy fails to recieve any data from Firefox. It just loops in the Sleep(50) section. Anyway, heres the code:
ProxyTest.cpp:
#include "stdafx.h"
#include "windows.h"
#include "CHTTPProxy.h"
public ref class ClientThread {
public:
System::Net::Sockets::TcpClient ^ pClient;
CHttpProxy ^ pProxy;
System::Int32 ^ pRecieveBufferSize;
System::Threading::Thread ^ Thread;
ClientThread(System::Net::Sockets::TcpClient ^ sClient,
CHttpProxy ^ sProxy,
System::Int32 ^ sRecieveBufferSize) {
pClient = sClient;
pProxy = sProxy;
pRecieveBufferSize = sRecieveBufferSize;
};
void StartReading() {
Thread = gcnew System::Threading::Thread(gcnew System::Threading::ThreadStart(this,&ClientThread::ThreadEntryPoint));
Thread->Start();
};
void ThreadEntryPoint() {
char * bytess;
bytess = new char[(int)pRecieveBufferSize];
memset(bytess, 0, (int)pRecieveBufferSize);
array<unsigned char> ^ bytes = gcnew array<unsigned char>((int)pRecieveBufferSize);
array<unsigned char> ^ sendbytes;
do {
if (pClient->GetStream()->DataAvailable) {
try {
do {
Sleep(100); //Lets wait for whole packet to get cached (If it even does...)
unsigned int k = pClient->GetStream()->Read(bytes, 0, (int)pRecieveBufferSize); //Read it
for (unsigned int i=0; i<(int)pRecieveBufferSize; i++) bytess[i] = bytes[i];
Console::WriteLine("Packet Received:\n"+gcnew System::String(bytess));
pProxy->SendToServer(bytes,pClient->GetStream()); //Now send it to google!
} while (pClient->GetStream()->DataAvailable);
} catch (Exception ^ e) {
break;
}
} else {
Sleep(50);
if (!(pClient->Connected)) break;
};
} while (pClient->GetStream()->CanRead);
delete [] bytess;
pClient->Close();
};
};
int main(array<System::String ^> ^args)
{
System::Collections::Generic::Stack<ClientThread ^> ^ Clients =
gcnew System::Collections::Generic::Stack<ClientThread ^>();
System::Net::Sockets::TcpListener ^ pTcpListener = gcnew System::Net::Sockets::TcpListener(8080);
pTcpListener->Start();
System::Net::Sockets::TcpClient ^ pTcpClient;
while (1) {
pTcpClient = pTcpListener->AcceptTcpClient(); //Wait for client
ClientThread ^ Client = gcnew ClientThread(pTcpClient,
gcnew CHttpProxy("www.google.com.au", 80),
pTcpClient->ReceiveBufferSize); //Make a new object for this client
Client->StartReading(); //Start the thread
Clients->Push(Client); //Add it to the list
};
pTcpListener->Stop();
return 0;
}
CHTTPProxy.h, from http://www.codeproject.com/KB/IP/howtoproxy.aspx with a lot of modifications:
#using <mscorlib.dll>
#using <SYSTEM.DLL>
using namespace System;
using System::Net::Sockets::TcpClient;
using System::String;
using System::Exception;
using System::Net::Sockets::NetworkStream;
#include <stdio.h>
ref class CHttpProxy
{
public:
CHttpProxy(System::String ^ szHost, int port);
System::String ^ m_host;
int m_port;
void SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr);
};
CHttpProxy::CHttpProxy(System::String ^ szHost, int port)
{
m_host = gcnew System::String(szHost);
m_port = port;
}
void CHttpProxy::SendToServer(array<unsigned char> ^ Packet, System::Net::Sockets::NetworkStream ^ sendstr)
{
TcpClient ^ tcpclnt = gcnew TcpClient();
try
{
tcpclnt->Connect(m_host,m_port);
}
catch (Exception ^ e )
{
Console::WriteLine(e->ToString());
return;
}
// Send it
if ( tcpclnt )
{
NetworkStream ^ networkStream;
networkStream = tcpclnt->GetStream();
int size = Packet->Length;
networkStream->Write(Packet, 0, size);
array<unsigned char> ^ bytes = gcnew array<unsigned char>(tcpclnt->ReceiveBufferSize);
char * bytess = new char[tcpclnt->ReceiveBufferSize];
Sleep(500); //Wait for responce
do {
unsigned int k = networkStream->Read(bytes, 0, (int)tcpclnt->ReceiveBufferSize); //Read from google
for(unsigned int i=0; i<k; i++) {
bytess[i] = bytes[i];
if (bytess[i] == 0) bytess[i] = ' '; //Dont terminate the string
if (bytess[i] < 8) bytess[i] = ' '; //Somethings making the computer beep, and its not 7?!?!
};
Console::WriteLine("\n\nAbove packet sent to google. Google Packet Received:\n"+gcnew System::String(bytess));
sendstr->Write(bytes,0,k); //Send it to mozilla
Console::WriteLine("\n\nAbove packet sent to client...");
//Sleep(1000);
} while(networkStream->DataAvailable);
delete [] bytess;
}
return;
}
Any help would be much appreciated, I've tried for hours. (Sorry about the indents nobugz, its fixed now)

Related

ESP32-C3-DevKitC-02 Getting Junk Data on UART for AT commands

I am interfacing A7672S 4G module with ESP32-C3-DevKitC-02 over Uart0
The problem i am facing is for any AT command published,i am getting lot of junk data
I have tried publising AT to the same 4G module using arduino ,i am able to get the correct response only with this ESP module i am seeing such issues
void uart_init(void)
{
const uart_config_t uart_config = {
.baud_rate = 115200,
.data_bits = UART_DATA_8_BITS,
.parity = UART_PARITY_DISABLE,
.stop_bits = UART_STOP_BITS_1,
.flow_ctrl = UART_HW_FLOWCTRL_DISABLE,
.source_clk = UART_SCLK_DEFAULT,
};
// We won't use a buffer for sending data.
uart_driver_install(UART_NUM_0, RX_BUF_SIZE * 2, 0, 0, NULL, 0);
uart_param_config(UART_NUM_0, &uart_config);
uart_set_pin(UART_NUM_0, TXD_PIN, RXD_PIN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
}
#define RX_BUF_SIZE 1024
int sendData( const char *data)
{
static const char *TX_TASK_TAG = "TX_TASK";
esp_log_level_set(TX_TASK_TAG, ESP_LOG_VERBOSE);
const int len = strlen(data);
const int txBytes = uart_write_bytes(UART_NUM_0, data, len);
ESP_LOGI(TX_TASK_TAG, "Wrote %d bytes", txBytes);
return txBytes;
}
static uint8_t receiveData(uint8_t *data,unsigned int delay_ms)
{
uint8_t rxBytes = 0;
static const char *RX_TASK_TAG = "RX_TASK";
esp_log_level_set(RX_TASK_TAG, ESP_LOG_VERBOSE);
rxBytes = uart_read_bytes(UART_NUM_0, data,RX_BUF_SIZE, delay_ms / portTICK_PERIOD_MS);
data[rxBytes]='\0';
ESP_LOGI(RX_TASK_TAG, "Received %d bytes:\nRxData:%s\n", rxBytes,data);
return rxBytes;
}
uint8_t *data = (uint8_t *)malloc(RX_BUF_SIZE + 1);
uint8_t len=0;
static const char *MAIN_TAG = "MAIN_FUNCTION";
esp_log_level_set(MAIN_TAG, ESP_LOG_VERBOSE);
memset(data, 0, RX_BUF_SIZE + 1);
uart_init();
vTaskDelay(20);
uart_flush(UART_NUM_0);
sendData("AT+CGMI\r\n");
len = receiveData(data,2000);
if(OK == check_response(data,(unsigned char*)"OK"))
{
ESP_LOGI(MAIN_TAG,"Incorporated AT Response Received");
}
else
{
ESP_LOGI(MAIN_TAG,"AT Response Not Received");
}

How to recieve a Direct Method on the ESP32 with azure-sdk-for-c-arduino

For a school project I am using IoT Hub to connect between different devices (ESP32), The intention is to use a web application to retrieve data from a device. I want to do this by using a Direct Method.
Now I have seen in the past some direct methods using python and how I can use this in Azure Functions but not yet on an ESP32. By the way, I am programming in C on the ESP32.
Does anyone have an example code for this? I am not finding really much info about direct methods in C with the library "azure-sdk-for-c-arduino".
Thanks in advance
My code at the moment (This is test code):
// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT
/*
This is an Arduino-based Azure IoT Hub sample for ESPRESSIF ESP32 boards.
It uses our Azure Embedded SDK for C to help interact with Azure IoT.
For reference, please visit https://github.com/azure/azure-sdk-for-c.
To connect and work with Azure IoT Hub you need an MQTT client, connecting, subscribing
and publishing to specific topics to use the messaging features of the hub.
Our azure-sdk-for-c is an MQTT client support library, helping composing and parsing the
MQTT topic names and messages exchanged with the Azure IoT Hub.
This sample performs the following tasks:
- Synchronize the device clock with a NTP server;
- Initialize our "az_iot_hub_client" (struct for data, part of our azure-sdk-for-c);
- Initialize the MQTT client (here we use ESPRESSIF's esp_mqtt_client, which also handle the tcp connection and TLS);
- Connect the MQTT client (using server-certificate validation, SAS-tokens for client authentication);
- Periodically send telemetry data to the Azure IoT Hub.
To properly connect to your Azure IoT Hub, please fill the information in the `iot_configs.h` file.
*/
//Variabeles for drukknop
const int PushButton = 35;
//Variables for weight sensor;
double weight = 5.0;
// C99 libraries
#include <cstdlib>
#include <string.h>
#include <time.h>
// Libraries for MQTT client and WiFi connection
#include <WiFi.h>
#include <mqtt_client.h>
// Azure IoT SDK for C includes
#include <az_core.h>
#include <az_iot.h>
#include <azure_ca.h>
// Libraries for SendingJson
#include <ArduinoJson.h>
// Additional sample headers
#include "AzIoTSasToken.h"
#include "SerialLogger.h"
#include "iot_configs.h"
// When developing for your own Arduino-based platform,
// please follow the format '(ard;<platform>)'.
#define AZURE_SDK_CLIENT_USER_AGENT "c/" AZ_SDK_VERSION_STRING "(ard;esp32)"
// Utility macros and defines
#define sizeofarray(a) (sizeof(a) / sizeof(a[0]))
#define NTP_SERVERS "pool.ntp.org", "time.nist.gov"
#define MQTT_QOS1 1
#define DO_NOT_RETAIN_MSG 0
#define SAS_TOKEN_DURATION_IN_MINUTES 60
#define UNIX_TIME_NOV_13_2017 1510592825
#define PST_TIME_ZONE -8
#define PST_TIME_ZONE_DAYLIGHT_SAVINGS_DIFF 1
#define GMT_OFFSET_SECS (PST_TIME_ZONE * 3600)
#define GMT_OFFSET_SECS_DST ((PST_TIME_ZONE + PST_TIME_ZONE_DAYLIGHT_SAVINGS_DIFF) * 3600)
// Translate iot_configs.h defines into variables used by the sample
static const char* ssid = IOT_CONFIG_WIFI_SSID;
static const char* password = IOT_CONFIG_WIFI_PASSWORD;
static const char* host = IOT_CONFIG_IOTHUB_FQDN;
static const char* mqtt_broker_uri = "mqtts://" IOT_CONFIG_IOTHUB_FQDN;
static const char* device_id = IOT_CONFIG_DEVICE_ID;
static const int mqtt_port = AZ_IOT_DEFAULT_MQTT_CONNECT_PORT;
// Memory allocated for the sample's variables and structures.
static esp_mqtt_client_handle_t mqtt_client;
static az_iot_hub_client client;
static char mqtt_client_id[128];
static char mqtt_username[128];
static char mqtt_password[200];
static uint8_t sas_signature_buffer[256];
static unsigned long next_telemetry_send_time_ms = 0;
static char telemetry_topic[128];
static uint8_t telemetry_payload[100];
static uint32_t telemetry_send_count = 0;
#define INCOMING_DATA_BUFFER_SIZE 128
static char incoming_data[INCOMING_DATA_BUFFER_SIZE];
// Auxiliary functions
#ifndef IOT_CONFIG_USE_X509_CERT
static AzIoTSasToken sasToken(
&client,
AZ_SPAN_FROM_STR(IOT_CONFIG_DEVICE_KEY),
AZ_SPAN_FROM_BUFFER(sas_signature_buffer),
AZ_SPAN_FROM_BUFFER(mqtt_password));
#endif // IOT_CONFIG_USE_X509_CERT
static void connectToWiFi()
{
Logger.Info("Connecting to WIFI SSID " + String(ssid));
WiFi.mode(WIFI_STA);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED)
{
delay(500);
Serial.print(".");
}
Serial.println("");
Logger.Info("WiFi connected, IP address: " + WiFi.localIP().toString());
}
static void initializeTime()
{
Logger.Info("Setting time using SNTP");
configTime(GMT_OFFSET_SECS, GMT_OFFSET_SECS_DST, NTP_SERVERS);
time_t now = time(NULL);
while (now < UNIX_TIME_NOV_13_2017)
{
delay(500);
Serial.print(".");
now = time(nullptr);
}
Serial.println("");
Logger.Info("Time initialized!");
}
void receivedCallback(char* topic, byte* payload, unsigned int length)
{
Logger.Info("Received [");
Logger.Info(topic);
Logger.Info("]: ");
for (int i = 0; i < length; i++)
{
Serial.print((char)payload[i]);
}
Serial.println("");
}
static esp_err_t mqtt_event_handler(esp_mqtt_event_handle_t event)
{
switch (event->event_id)
{
int i, r;
case MQTT_EVENT_ERROR:
Logger.Info("MQTT event MQTT_EVENT_ERROR");
break;
case MQTT_EVENT_CONNECTED:
Logger.Info("MQTT event MQTT_EVENT_CONNECTED");
r = esp_mqtt_client_subscribe(mqtt_client, AZ_IOT_HUB_CLIENT_C2D_SUBSCRIBE_TOPIC, 1);
if (r == -1)
{
Logger.Error("Could not subscribe for cloud-to-device messages.");
}
else
{
Logger.Info("Subscribed for cloud-to-device messages; message id:" + String(r));
}
break;
case MQTT_EVENT_DISCONNECTED:
Logger.Info("MQTT event MQTT_EVENT_DISCONNECTED");
break;
case MQTT_EVENT_SUBSCRIBED:
Logger.Info("MQTT event MQTT_EVENT_SUBSCRIBED");
break;
case MQTT_EVENT_UNSUBSCRIBED:
Logger.Info("MQTT event MQTT_EVENT_UNSUBSCRIBED");
break;
case MQTT_EVENT_PUBLISHED:
Logger.Info("MQTT event MQTT_EVENT_PUBLISHED");
break;
case MQTT_EVENT_DATA:
Logger.Info("MQTT event MQTT_EVENT_DATA");
for (i = 0; i < (INCOMING_DATA_BUFFER_SIZE - 1) && i < event->topic_len; i++)
{
incoming_data[i] = event->topic[i];
}
incoming_data[i] = '\0';
Logger.Info("Topic: " + String(incoming_data));
for (i = 0; i < (INCOMING_DATA_BUFFER_SIZE - 1) && i < event->data_len; i++)
{
incoming_data[i] = event->data[i];
}
incoming_data[i] = '\0';
if (String(incoming_data) == "GETWEIGHT")
{
Logger.Info("Send Data To The Cloud ");
sendTelemetry();
}
else
{
Logger.Info("Data: " + String(incoming_data));
}
break;
case MQTT_EVENT_BEFORE_CONNECT:
Logger.Info("MQTT event MQTT_EVENT_BEFORE_CONNECT");
break;
default:
Logger.Error("MQTT event UNKNOWN");
break;
}
return ESP_OK;
}
static void initializeIoTHubClient()
{
az_iot_hub_client_options options = az_iot_hub_client_options_default();
options.user_agent = AZ_SPAN_FROM_STR(AZURE_SDK_CLIENT_USER_AGENT);
if (az_result_failed(az_iot_hub_client_init(
&client,
az_span_create((uint8_t*)host, strlen(host)),
az_span_create((uint8_t*)device_id, strlen(device_id)),
&options)))
{
Logger.Error("Failed initializing Azure IoT Hub client");
return;
}
size_t client_id_length;
if (az_result_failed(az_iot_hub_client_get_client_id(
&client, mqtt_client_id, sizeof(mqtt_client_id) - 1, &client_id_length)))
{
Logger.Error("Failed getting client id");
return;
}
if (az_result_failed(az_iot_hub_client_get_user_name(
&client, mqtt_username, sizeofarray(mqtt_username), NULL)))
{
Logger.Error("Failed to get MQTT clientId, return code");
return;
}
Logger.Info("Client ID: " + String(mqtt_client_id));
Logger.Info("Username: " + String(mqtt_username));
}
static int initializeMqttClient()
{
#ifndef IOT_CONFIG_USE_X509_CERT
if (sasToken.Generate(SAS_TOKEN_DURATION_IN_MINUTES) != 0)
{
Logger.Error("Failed generating SAS token");
return 1;
}
#endif
esp_mqtt_client_config_t mqtt_config;
memset(&mqtt_config, 0, sizeof(mqtt_config));
mqtt_config.uri = mqtt_broker_uri;
mqtt_config.port = mqtt_port;
mqtt_config.client_id = mqtt_client_id;
mqtt_config.username = mqtt_username;
#ifdef IOT_CONFIG_USE_X509_CERT
Logger.Info("MQTT client using X509 Certificate authentication");
mqtt_config.client_cert_pem = IOT_CONFIG_DEVICE_CERT;
mqtt_config.client_key_pem = IOT_CONFIG_DEVICE_CERT_PRIVATE_KEY;
#else // Using SAS key
mqtt_config.password = (const char*)az_span_ptr(sasToken.Get());
#endif
mqtt_config.keepalive = 30;
mqtt_config.disable_clean_session = 0;
mqtt_config.disable_auto_reconnect = false;
mqtt_config.event_handle = mqtt_event_handler;
mqtt_config.user_context = NULL;
mqtt_config.cert_pem = (const char*)ca_pem;
mqtt_client = esp_mqtt_client_init(&mqtt_config);
if (mqtt_client == NULL)
{
Logger.Error("Failed creating mqtt client");
return 1;
}
esp_err_t start_result = esp_mqtt_client_start(mqtt_client);
if (start_result != ESP_OK)
{
Logger.Error("Could not start mqtt client; error code:" + start_result);
return 1;
}
else
{
Logger.Info("MQTT client started");
return 0;
}
}
/*
#brief Gets the number of seconds since UNIX epoch until now.
#return uint32_t Number of seconds.
*/
static uint32_t getEpochTimeInSecs()
{
return (uint32_t)time(NULL);
}
static void establishConnection()
{
connectToWiFi();
initializeTime();
initializeIoTHubClient();
(void)initializeMqttClient();
}
static void getTelemetryPayload(az_span payload, az_span* out_payload)
{
az_span original_payload = payload;
payload = az_span_copy(
payload, AZ_SPAN_FROM_STR("{ \"deviceId\": "));
payload = az_span_copy(payload, AZ_SPAN_FROM_STR( IOT_CONFIG_DEVICE_ID ));
payload = az_span_copy(payload, AZ_SPAN_FROM_STR( "," ));
payload = az_span_copy(payload, AZ_SPAN_FROM_STR( "\" weight\": "));
(void)az_span_u32toa(payload, weight , &payload);
payload = az_span_copy(payload, AZ_SPAN_FROM_STR(" }"));
payload = az_span_copy_u8(payload, '\0');
*out_payload = az_span_slice(original_payload, 0, az_span_size(original_payload) - az_span_size(payload) - 1);
}
static void sendTelemetry()
{
az_span telemetry = AZ_SPAN_FROM_BUFFER(telemetry_payload);
Logger.Info("Sending telemetry ...");
// The topic could be obtained just once during setup,
// however if properties are used the topic need to be generated again to reflect the
// current values of the properties.
if (az_result_failed(az_iot_hub_client_telemetry_get_publish_topic(
&client, NULL, telemetry_topic, sizeof(telemetry_topic), NULL)))
{
Logger.Error("Failed az_iot_hub_client_telemetry_get_publish_topic");
return;
}
getTelemetryPayload(telemetry, &telemetry);
if (esp_mqtt_client_publish(
mqtt_client,
telemetry_topic,
(const char*)az_span_ptr(telemetry),
az_span_size(telemetry),
MQTT_QOS1,
DO_NOT_RETAIN_MSG)
== 0)
{
Logger.Error("Failed publishing");
}
else
{
Logger.Info("Message published successfully");
}
}
// Arduino setup and loop main functions.
void setup()
{
establishConnection();
pinMode(PushButton, INPUT);
}
void loop()
{
if (WiFi.status() != WL_CONNECTED)
{
connectToWiFi();
}
#ifndef IOT_CONFIG_USE_X509_CERT
else if (sasToken.IsExpired())
{
Logger.Info("SAS token expired; reconnecting with a new one.");
(void)esp_mqtt_client_destroy(mqtt_client);
initializeMqttClient();
}
#endif
int Push_button_state = digitalRead(PushButton);
// if condition checks if push button is pressed
if ( Push_button_state == HIGH )
{
Serial.println("De Button Is ingedrukt");
sendTelemetry();
delay(500);
}
}
The idea is that when I send a Direct Method "GETWEIGHT" I get a json value back.
In your initializeMqttClient method, you can add the following line.
mqtt_client.setCallback(receivedCallback);
Your receivedCallback method can have the following definition (code from a Microsoft sample)
void receivedCallback(char* topic, byte* payload, unsigned int length)
{
Logger.Info("Received [");
Logger.Info(topic);
Logger.Info("]: ");
for (int i = 0; i < length; i++)
{
Serial.print((char)payload[i]);
}
Serial.println("");
}
You mentioned you want to retrieve data from the device, so you probably want to respond to the message. This is done by sending a message on the right topic. You need to include the status (for instance a 200 indicating 'OK') and the ID of the direct method. This id is included when you receive the direct method. For instance, if you receive a direct method with ID 42, you can respond to it by publishing:
void RespondToDirectMethod()
{
mqtt_client.publish("$iothub/methods/res/200/?$rid=42", "", false);
}

Error: NED type 'myApp' could not be fully resolved due to a missing base type or interface?

In my project,
I implement a new class called myApp which inherits from ApplicationBase and UdpSocket classes. When I build my project I get no error, but when I debug C/C++ application with the IDE, it displays the first error in errors section. And the command line display the second error when I run make :
Code of myApp.ned, myApp.h and myApp.cc in what follows :
I did include inet library in project references, and I tried the solution posted in The following NED types could not be fully resolved, due to a missing base type or interface.
import inet.applications.contract.IApp;
simple myApp like IApp
{
parameters:
int localPort = default(-1); // local UDP port number (-1: use ephemeral port)
int destPort; // remote UDP port number
string packetName = default("myApp");
string interfaceTableModule; // The path to the InterfaceTable module
double helloInterval #unit(s) = default(5s); // how often hello messages should be sent out
volatile double sendInterval #unit(s); // should usually be a random value, e.g. exponential(1)
double startTime #unit(s) = default(this.sendInterval); // application start time (start of the first packet)
double stopTime #unit(s) = default(-1s); // time of finishing sending, -1s means forever
double maxVariance = default(1); // This is the maximum of a random value to determine when the first hello message will be sent out
volatile double broadcastDelay #unit(s) = default(uniform(0s,0.01s));
int timeToLive = default(-1); // if not -1, set the TTL (IPv4) or Hop Limit (IPv6) field of sent packets to this value
bool dontFragment = default(false); // if true, asks IP to not fragment the message during routing
int typeOfService = default(-1); // if not -1, set the ToS (IPv4) or Traffic Class (IPv6) field of sent packets to this value
string multicastInterface = default(""); // if not empty, set the multicast output interface option on the socket (interface name expected)
bool receiveBroadcast = default(false); // if true, makes the socket receive broadcast packets
bool joinLocalMulticastGroups = default(false); // if true, makes the socket receive packets from all multicast groups set on local interfaces
#class(myApp);
gates:
input socketIn #labels(UdpControlInfo/up);
output socketOut #labels(UdpControlInfo/down);
}
#ifndef MYAPP_H_
#define MYAPP_H_
#include "inet/common/INETDefs.h"
#include "inet/applications/base/ApplicationBase.h"
#include "inet/transportlayer/contract/udp/UdpSocket.h"
#include "inet/transportlayer/contract/udp/UdpControlInfo_m.h"
#include "inet/common/ModuleAccess.h"
#include "inet/common/TimeTag_m.h"
#include "inet/common/packet/Packet.h"
#include "inet/common/lifecycle/ModuleOperations.h"
#include "inet/common/IProtocolRegistrationListener.h"
#include "inet/common/ProtocolTag_m.h"
#include "inet/linklayer/common/InterfaceTag_m.h"
#include "inet/networklayer/contract/IInterfaceTable.h"
#include "inet/networklayer/contract/ipv4/Ipv4Address.h"
#include "inet/networklayer/ipv4/IIpv4RoutingTable.h"
#include "inet/networklayer/ipv4/Ipv4Header_m.h"
#include "inet/networklayer/ipv4/Ipv4InterfaceData.h"
#include "inet/networklayer/common/FragmentationTag_m.h"
#include "inet/networklayer/common/L3AddressResolver.h"
#include "HelloMsg_m.h"
#include "XedMsg_m.h"
#include <omnetpp.h>
#include <vector>
#include <random>
#include <algorithm>
using namespace omnetpp;
using namespace inet;
using namespace std;
class myApp : public ApplicationBase, public UdpSocket::ICallback
{
protected:
//enum SelfMsgKinds { START = 1, SEND, STOP };
int localPort = -1, destPort = -1;
bool dontFragment = false;
const char *packetName = nullptr;
simtime_t startTime;
simtime_t stopTime;
// state
UdpSocket socket;
cMessage *selfMsg = nullptr;
cModule *host = nullptr;
cMessage *event = nullptr;
cPar *broadcastDelay = nullptr;
unsigned int sequencenumber = 0;
simtime_t helloInterval;
IInterfaceTable *ift = nullptr;
InterfaceEntry *interface80211ptr = nullptr;
int interfaceId = -1;
list<L3Address> neighbors;
Ipv4Address source;
/********** XED **********/
class XED
{
public:
L3Address originatorAddr, destinationAddr;
unsigned int random;
XED(const L3Address& originatorAddr, const L3Address& destinationAddr, unsigned int random)
: originatorAddr(originatorAddr), destinationAddr(destinationAddr), random(random) {};
bool operator==(const XED& other) const
{
return this->originatorAddr == other.originatorAddr && this->destinationAddr == other.destinationAddr
&& this->random == other.random;
}
};
list<XED> lr,ls;
/********** MTLSD **********/
class MTLSD
{
public:
L3Address originatorAddr, destinationAddr;
char *position;
simtime_t time;
MTLSD(const L3Address& originatorAddr, const L3Address& destinationAddr, char *position, simtime_t time)
: originatorAddr(originatorAddr), destinationAddr(destinationAddr), position(position), time(time) {};
bool operator==(const MTLSD& other) const
{
return this->originatorAddr == other.originatorAddr && this->destinationAddr == other.destinationAddr
&& this->position == other.position && this->time == time;
}
};
protected:
virtual int numInitStages() const override { return NUM_INIT_STAGES; }
virtual void initialize(int stage) override;
virtual void handleMessageWhenUp(cMessage *msg) override;
void handleSelfMessage(cMessage *msg);
/*virtual void processStart();
virtual void processSend();
virtual void processStop();*/
// lifecycle
virtual void handleStartOperation(LifecycleOperation *operation) override { start(); }
virtual void handleStopOperation(LifecycleOperation *operation) override { stop(); }
virtual void handleCrashOperation(LifecycleOperation *operation) override { stop(); }
void start();
void stop();
virtual void socketDataArrived(UdpSocket *socket, Packet *packet) override;
virtual void socketErrorArrived(UdpSocket *socket, Indication *indication) override;
virtual void socketClosed(UdpSocket *socket) override;
//virtual void generateMTLSDPacket();
//virtual Packet *generateXEDPacket();
virtual double generateRandom();
public:
myApp() {}
~myApp();
};
#endif /* MYAPP_H_ */
#include "myApp.h"
#include "inet/applications/base/ApplicationPacket_m.h"
#include "inet/applications/udpapp/UdpBasicApp.h"
#include "inet/common/TagBase_m.h"
#include "inet/networklayer/common/L3AddressTag_m.h"
#include <iterator>
using namespace std;
Define_Module(myApp);
myApp::~myApp()
{
EV << "App destructor" << endl;
cancelAndDelete(selfMsg);
}
void myApp::initialize(int stage)
{
ApplicationBase::initialize(stage);
if (stage == INITSTAGE_LOCAL)
{
sequencenumber = 0;
ift = getModuleFromPar<IInterfaceTable>(par("interfaceTableModule"), this);
event = new cMessage("event");
broadcastDelay = &par("broadcastDelay");
helloInterval = par("helloInterval");
localPort = par("localPort");
destPort = par("destPort");
packetName = par("packetName");
startTime = par("startTime");
stopTime = par("stopTime");
}
else if (stage == INITSTAGE_ROUTING_PROTOCOLS)
{
registerService(Protocol::manet, nullptr, gate("socketIn"));
registerProtocol(Protocol::manet, gate("socketOut"), nullptr);
}
}
void myApp::handleSelfMessage(cMessage *msg)
{
if (msg == event)
{
auto hello = makeShared<HelloMsg>();
Ipv4Address source = (interface80211ptr->getProtocolData<Ipv4InterfaceData>()->getIPAddress());
hello->setChunkLength(b(128));
hello->setSrcAddress(source);
sequencenumber += 2;
hello->setSequencenumber(sequencenumber);
hello->setNextAddress(source);
hello->setHopdistance(1);
auto packet = new Packet("Hello", hello);
packet->addTagIfAbsent<L3AddressReq>()->setDestAddress(Ipv4Address(255, 255, 255, 255));
packet->addTagIfAbsent<L3AddressReq>()->setSrcAddress(source);
packet->addTagIfAbsent<InterfaceReq>()->setInterfaceId(interface80211ptr->getInterfaceId());
packet->addTagIfAbsent<PacketProtocolTag>()->setProtocol(&Protocol::manet);
packet->addTagIfAbsent<DispatchProtocolReq>()->setProtocol(&Protocol::ipv4);
send(packet, "socketOut");
packet = nullptr;
hello = nullptr;
scheduleAt(simTime()+helloInterval+broadcastDelay->doubleValue(), event);
}
}
void myApp::handleMessageWhenUp(cMessage *msg)
{
if (msg->isSelfMessage())
{
handleSelfMessage(msg);
}
else if (check_and_cast<Packet *>(msg)->getTag<PacketProtocolTag>()->getProtocol() == &Protocol::manet)
{
auto recHello = staticPtrCast<HelloMsg>(check_and_cast<Packet *>(msg)->peekData<HelloMsg>()->dupShared());
if (msg->arrivedOn("socketIn"))
{
bubble("Received hello message");
Ipv4Address source = interface80211ptr->getProtocolData<Ipv4InterfaceData>()->getIPAddress();
Ipv4Address src;
unsigned int msgsequencenumber;
int numHops;
Ipv4Address next;
src = recHello->getSrcAddress();
msgsequencenumber = recHello->getSequencenumber();
next = recHello->getNextAddress();
numHops = recHello->getHopdistance();
if (src == source)
{
EV_INFO << "Hello msg dropped. This message returned to the original creator.\n";
delete msg;
return;
}
else
{
neighbors.push_back(src);
/*list<XED>::iterator findIter = find(ls.begin()->destinationAddr, ls.end()->destinationAddr, src);
if (findIter != ls.end()->destinationAddr)
{
}*/
source = (interface80211ptr->getProtocolData<Ipv4InterfaceData>()->getIPAddress());
//socket.bind(source, localPort);
auto xed = makeShared<XedMsg>();
xed->setChunkLength(b(128)); ///size of XED message in bits
xed->setSrcAddress(source);
xed->setDstAddress(src);
double random = generateRandom();
xed->setRandom(random);
//XED item = XED(source, src, random);
//ls.push_back(item);
auto packet = new Packet("XED", xed);
packet->addTagIfAbsent<L3AddressReq>()->setDestAddress(src);
packet->addTagIfAbsent<L3AddressReq>()->setSrcAddress(source);
packet->addTagIfAbsent<InterfaceReq>()->setInterfaceId(interfaceId);
packet->addTagIfAbsent<PacketProtocolTag>()->setProtocol(&Protocol::ipv4);
packet->addTagIfAbsent<DispatchProtocolReq>()->setProtocol(&Protocol::ipv4);
socket.setOutputGate(gate("socketOut"));
socket.setCallback(this);
socket.bind(source, localPort);
//emit(packetSentSignal, packet);
socket.sendTo(packet, src, destPort);
//send(packet, "socketOut");
packet = nullptr;
xed = nullptr;
/*Ipv4Address source = (interface80211ptr->getProtocolData<Ipv4InterfaceData>()->getIPAddress());
EV << "I am node " << source << ", my neighbors are : " << endl;
list<L3Address>::iterator it;
for (it = neighbors.begin(); it != neighbors.end(); ++it)
{
EV << it. << endl;
}
for (auto const& i : neighbors)
{
EV << i.str() << endl;
}*/
EV << "I am your neighbor " << src.str();
}
delete msg;
}
else if (check_and_cast<Packet *>(msg)->getTag<PacketProtocolTag>()->getProtocol() == &Protocol::ipv4)
{
EV << "Xed message received" << endl;
//auto recXed = staticPtrCast<XedMsg>(check_and_cast<Packet *>(msg)->peekData<XedMsg>()->dupShared());
}
else
throw cRuntimeError("Message arrived on unknown gate %s", msg->getArrivalGate()->getName());
}
}
void myApp::start()
{
/*socket.setOutputGate(gate("socketOut"));
socket.setCallback(this);*/
int num_80211 = 0;
InterfaceEntry *ie;
InterfaceEntry *i_face;
const char *name;
for (int i = 0; i < ift->getNumInterfaces(); i++)
{
ie = ift->getInterface(i);
name = ie->getInterfaceName();
if (strstr(name, "wlan") != nullptr)
{
i_face = ie;
num_80211++;
interfaceId = i;
}
}
if (num_80211 == 1)
{
interface80211ptr = i_face;
interfaceId = interface80211ptr->getInterfaceId();
}
else
throw cRuntimeError("Node has found %i 80211 interfaces", num_80211);
scheduleAt(simTime() + uniform(0.0, par("maxVariance").doubleValue()), event);
}
double myApp::generateRandom()
{
double lower_bound = 10000;
double upper_bound = 100000;
uniform_real_distribution<double> unif(lower_bound,upper_bound);
default_random_engine re;
double a_random_double = unif(re);
return a_random_double;
}
void myApp::stop()
{
cancelEvent(event);
socket.close();
delayActiveOperationFinish(par("stopOperationTimeout"));
}
void myApp::socketDataArrived(UdpSocket *socket, Packet *packet)
{
emit(packetReceivedSignal, packet);
EV_INFO << "Received packet: " << UdpSocket::getReceivedPacketInfo(packet) << endl;
}
void myApp::socketErrorArrived(UdpSocket *socket, Indication *indication)
{
EV_WARN << "Ignoring UDP error report " << indication->getName() << endl;
delete indication;
}
void myApp::socketClosed(UdpSocket *socket)
{
if (operationalState == State::STOPPING_OPERATION)
startActiveOperationExtraTimeOrFinish(par("stopOperationExtraTime"));
}
Error: NED type 'myApp' could not be fully resolved due to a missing base type or interface, at /home/bocuhra/Downloads/omnetpp-5.4.1/samples/SaaS/myApp.ned:18
myApp.cc
HelloMsg_m.cc
XedMsg_m.cc
Creating executable: out/gcc-release//SaaS
/usr/bin/ld: cannot find -lINET
collect2: error: ld returned 1 exit status
Makefile:104: recipe for target 'out/gcc-release//SaaS' failed
make: *** [out/gcc-release//SaaS] Error 1
I did solve the problem by adding all ned files in my .ini file.
ned-path = .;../inet/src/inet

boost asio io_context.run() segmentation error

I am trying to make simple server that remembers and operates some variables with receive short instructions.
I didn't complete this server, and I am trying to test connecting to the server.
But when I try to connect the server, it occurs segmentation fault.
It seems that be occured at io_context.run() function.
I don't know exact cause of this error in spite of reading asio's reference page.
Please help me..
I think that you don't have to read code of data(data.hpp).
This is server code.
//server.cpp
#include <iostream>
#include "network/sc_network.hpp"
int main(int argc, char *argv[])
{
try
{
if(argc != 2)
{
std::cerr << "Usage: server <port>\n";
return 1;
}
boost::asio::io_context io_context;
tcp::endpoint endpoint(tcp::v4(), std::atoi(argv[1]));
server server(io_context, endpoint);
io_context.run();
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}
This is client code.
//client.cpp
#include <iostream>
#include <thread>
#include <cstdlib>
#include <boost/asio.hpp>
#include "network/data/data.hpp"
using boost::asio::ip::tcp;
class client{
private:
boost::asio::io_context& io_context_;
tcp::socket socket_;
oper_data *data_;
void do_connect(const tcp::resolver::results_type& endpoints)
{
boost::asio::async_connect(socket_, endpoints,
[this](boost::system::error_code ec, tcp::endpoint)
{
if(!ec)
{
boost::asio::async_read(socket_,
boost::asio::buffer(data_, sizeof(oper_data)),
[this](boost::system::error_code ec, std::size_t)
{
if(!ec)
{
boost::asio::async_write(socket_,
boost::asio::buffer(data_,sizeof(oper_data)),
[this](boost::system::error_code ec, std::size_t)
{
});
}
else
{
socket_.close();
}
});
}
else
{
socket_.close();
}
});
}
public:
client(boost::asio::io_context& io_context,
const tcp::resolver::results_type& endpoints)
: io_context_(io_context),
socket_(io_context)
{
do_connect(endpoints);
}
void write(const oper_data& data)
{
boost::asio::post(io_context_,
[this, data]()
{
});
}
};
int main(int argc, char *argv[])
{
try
{
if(argc != 3)
{
std::cerr << "Usage: client <host> <port>\n";
return 1;
}
boost::asio::io_context io_context;
tcp::resolver resolver(io_context);
auto endpoints = resolver.resolve(argv[1], argv[2]);
client c(io_context, endpoints);
std::thread t([&io_context](){ io_context.run(); });
char line[128];
while (std::cin.getline(line, 128))
{
oper_data data;
//processing the line with deviding in 3 words.
}
}
catch (std::exception& e)
{
std::cerr << "Exception: " << e.what() << "\n";
}
return 0;
}
this is sc_network.hpp
//sc_network.hpp
#include <boost/asio.hpp>
#include <memory>
#include <utility>
#include "data/data.hpp"
using boost::asio::ip::tcp;
class session
: public std::enable_shared_from_this<session>
{
private:
tcp::socket socket_;
data_proc data_proc_;
public:
session(tcp::socket socket)
: socket_(std::move(socket)){}
void start()
{
oper_data *input_data;
boost::asio::async_read(socket_,
boost::asio::buffer(input_data, sizeof(oper_data)),
[this, input_data](boost::system::error_code ec, std::size_t)
{
if(!ec)
{
data_proc_.set_data(*input_data);
data_proc_.oper_process();
start();
}
else
{
return;
}
});
}
};
class server
{
private:
tcp::acceptor acceptor_;
void do_accept()
{
acceptor_.async_accept(
[this](boost::system::error_code ec, tcp::socket socket)
{
if(!ec)
{
session ex_session(std::move(socket));
}
do_accept();
});
}
public:
server(boost::asio::io_context& io_context,
const tcp::endpoint& endpoint)
: acceptor_(io_context, endpoint)
{
do_accept();
}
};
this is data.hpp.
//data.hpp
#include <deque>
#include <cstring>
#include "favdew_utility.hpp"
#define max_oper_size 5
#define max_oper_buf max_oper_size + 1
struct oper_data {
char oper_[max_oper_buf] = "\0";
char *operand_;
char *oper_num_;
};
typedef struct oper_data oper_data;
class data_store {
private:
char *var_name_;
char *var_value_;
public:
data_store()
: var_name_(NULL), var_value_(NULL) {}
data_store(const char *var_name, const char *var_value)
{
std::size_t var_name_size = strlen(var_name) + 1;
var_name_ = new char[var_name_size];
strncpy(var_name_, var_name, strlen(var_name));
std::size_t var_value_size = strlen(var_value) + 1;
var_value_ = new char[var_value_size];
strncpy(var_value_, var_value, strlen(var_value));
}
char *var_name() { return var_name_; }
char *var_value() { return var_value_; }
void set_value(const char *var_value) {
var_value_ = new char[strlen(var_value) + 1];
strncpy(var_value_, var_value, strlen(var_value));
}
};
typedef std::deque<data_store> data_queue;
class data_proc {
private:
oper_data data_;
data_queue proc_queue;
void var()
{
if (data_store *var = this->get_var(data_.operand_)) {
var->set_value(data_.oper_num_);
}
else {
data_store input_data(data_.operand_, data_.oper_num_);
this->proc_queue.push_back(input_data);
}
}
bool sum()
{
data_store *var = this->get_var(data_.operand_);
if ( (var) && isNumber(var->var_value()))
{
const int input_data = std::atoi(var->var_value()) +
std::atoi(this->data_.oper_num_);
var->set_value(std::to_string(input_data).c_str());
return true;
}
else
return false;
}
bool dif()
{
data_store *var = this->get_var(data_.operand_);
if ((var) && isNumber(var->var_value()))
{
const int input_data = std::atoi(var->var_value()) -
std::atoi(this->data_.oper_num_);
var->set_value(std::to_string(input_data).c_str());
return true;
}
else
return false;
}
public:
data_proc()
{
oper_data input_data;
//<input_data.oper_> is already initialized with "\0"
std::memset(input_data.operand_, 0, sizeof(char *));
std::memset(input_data.oper_num_, 0, sizeof(char *));
}
data_proc(const char *oper, const char *operand, const char *oper_num)
{
strncpy(data_.oper_, oper, max_oper_size);
std::size_t operand_size = strlen(operand) + 1;
data_.operand_ = new char[operand_size];
strncpy(data_.operand_, operand, strlen(operand));
std::size_t oper_num_size = strlen(oper_num) + 1;
data_.oper_num_ = new char[oper_num_size];
strncpy(data_.oper_num_, oper_num, strlen(oper_num));
}
inline void set_data(oper_data data)
{
this->data_ = data;
}
void set_data(const char *oper, const char *operand, const char *oper_num)
{
strncpy(data_.oper_, oper, max_oper_size);
std::size_t operand_size = strlen(operand) + 1;
data_.operand_ = new char[operand_size];
strncpy(data_.operand_, operand, strlen(operand));
std::size_t oper_num_size = strlen(oper_num) + 1;
data_.oper_num_ = new char[oper_num_size];
strncpy(data_.oper_num_, oper_num, strlen(oper_num));
}
data_store *get_var(const char *var_name)
{
const std::size_t queue_size = this->proc_queue.size();
for (std::size_t i=0; i < queue_size; i++) {
if (!strcmp(this->proc_queue[i].var_name(), var_name)) {
return &proc_queue[i];
}
}
return NULL;
}
bool oper_process()
{
const char *oper = this->data_.oper_;
if (!strcmp(oper, "var")) {
var();
return true;
}
else if (!strcmp(oper, "sum")) {
sum();
return true;
}
else if (!strcmp(oper, "dif")) {
dif();
return true;
}
else {
return false;
}
}
};
this is favdew_utility.hpp
#include <string>
#include <cstdlib>
bool isNumber(const char *str)
{
std::size_t length = strlen(str);
for (std::size_t i = 0; i < length; i++)
{
if (!('0' < str[i] && str[i] < '9'))
return false;
continue;
}
return true;
}
bool isEmpty(void *buffer)
{
if (!buffer || *(char *)buffer == '\0')
return true;
else
return false;
}
There are many issues, just pointing out a few:
The declaration
session ex_session(std::move(socket));
This creates a local (stack) variable that inherits from enable_shared_from_this. Using shared_from_this will be Undefined Behaviour
Session gets immediately destructed and start() appears to be never called
If session::start() were called, it would fail because it starts an async operation without guarding the lifetime of the session instance:
boost::asio::async_read(socket_,
boost::asio::buffer(input_data, sizeof(oper_data)),
[this, input_data](boost::system::error_code ec, std::size_t) { ....
At the very least you need to capture the shared pointer to the session:
auto self = shared_from_this();
boost::asio::async_read(socket_,
boost::asio::buffer(input_data, sizeof(oper_data)),
[this, self, input_data](boost::system::error_code ec, std::size_t)
Even worse, input_data is never initialized. Again: Undefined Behaviour. Even if you did initialize it, you'd have to manage lifetime; why not make it a member of the session, instead of dynamically allocating (or forgetting to, as you have now)?
Caution: No, you cannot stack-allocate inside start() not even if you capture it in the lambda, because the async operations will not complete before start() exits.
Same in client: data_ is never initialized. Boom.
Even if you had it correctly allocated, using it as an asio::buffer() treats it as a POD.
Since, however, data_proc happily aggregates a data_queue which is std::deque<> it obviously IS NOT POD. More Undefined Behaviour.
What you probably need is to serialize your datastructures, instead of hoping that copying some bytes of memory is going to magically "work". It won't!
See e.g. sending/receiving a struct in boost::asio
Note While you're at is, use C++ instead of C? All the raw pointers and char* are complexity that you don't need, and it is handing your dozens of footguns or ends or rope that you're gonna hurt yourself more with.
In client.cpp you have:
std::thread t([&io_context](){ io_context.run(); });
char line[128];
while (std::cin.getline(line, 128))
{
oper_data data;
//processing the line with deviding in 3 words.
}
Soooo many things...
use std::getline, not std::istream::getline
the thread needs to be joined (https://en.cppreference.com/w/cpp/thread/thread/~thread)
if all you do is block for input, why have the thread?
io_context.run(); // replaces all of the above
data_store is also not POD, but it is also a living memory-leak. All the new-ed memory is never freed.
Note that, the way it's written, the struct might APPEAR to be POD, but logically it isn't (Rule Of Three). Basically, you wrote it in C, not C++. This foregoes all abstractions that C++ has, and now the compiler cannot tell that the struct refers to non-owned resources.
Mind you, this gives me the impression that oper_data might have similar issues (though at first I assumed that operand_ and _oper_num are supposed to point inside the fixed-size buffer oper_[])
Summarizing:
You're way ahead of yourself. Start much simpler. Use C++ (std::string, never use new/delete, actually use std::make_shared if you want to enable_shared_from_this).
You'll be much happier. Feel free to come back with simpler questions when you get stuck, ideally the SSCCE would be a (few) dozen or so lines.

Why i am not able to read multiple strings in the server file?

While working in client-server programming, I have passed 3 strings in client, which will be received by server and it should be printed in there 3 times. (i.e I have used a 'for' loop which will do the read & write operations in client & server side respectively.), but in server only the 1st string is getting printed.
Please explain,
Here is my code
server.c
#include "head.h"
void readstr(int connfd ,char [][20]);
//void writestr(char * ,int);
int main(int c ,char *v[])
{
// socket declarations,etc
sd =socket( AF_INET ,SOCK_STREAM ,0);
// Binding socket
retbind =bind(sd ,(struct sockaddr*)&serveraddress ,sizeof(serveraddress
));
listen(sd ,4);
for(;;)
{
printf("i am waiting for client\n");
len =sizeof(cliaddr);
connfd = accept(sd ,(struct sockaddr*)&cliaddr ,&len);
readstr(connfd ,databuf);
close(connfd);
}
return 0;
}
void readstr(int connfd ,char str[3] [20])
{
int pointer=0 ,i=0, n,pos=0;
memset(str ,'\0',sizeof(str));
for(i=0;i<3;i++)
{
while((n=read(connfd ,str[i] ,20)) >>0)
{
printf("Looping while\n");
pos =pos +n;
}
str[i][pos] ='\0';
}
for(i=0;i<3;i++)
{
printf("\n%s",str[i]);
}
}
client.c
#include "head.h"
void send1(int ,char*);
int main(int c,char*v[])
{
//Socket declarations, etc..
sd = socket(AF_INET ,SOCK_STREAM ,0);
//Connect
if(connect(sd,(struct sockaddr*)&serveraddress ,sizeof(serveraddress)) <
0)
{
printf("cannot connect to server");
exit(1);
}
for(i=0;i<3;i++)
{
memset(buf ,'\0',sizeof(buf));
printf("\n Enter the string : ");
fgets(buf[i],20,stdin);
len =strlen(buf[i]);
if(buf[i][len] =='\n')
buf[i][len]='\0';
send1(sd ,(char *)buf);
}
shutdown(sd ,SHUT_WR);
}
void send1(int sd ,char *str)
{
int n ,byteswritten =0, wr;
char buf[1024];
strcpy(buf ,str);
n =strlen(buf);
while(byteswritten < n)
{
printf("\nStarting to write in client side\n");
wr = write(sd , buf+byteswritten ,(n-byteswritten));
byteswritten+=wr;
}
printf("\n string sent %s" ,buf);
}
In server.c in readstr() you are not setting pos to zero before the next for iteration.
Also, there is strange line:
while((n=read(connfd ,str[i] ,20)) >>0)
Note ">>".

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