C :: Send Data Packet
Mar 6, 2015
how to send datapackets. When we send a data packet from device to another, say I have a "string". How Do I send it? Are data sent as a hex or binary number?If so do i first convert the "string" into hex or binary and then send it over the communication medium(say UART)??
I have two hex numbers to be sent using the UART, do i wrap it in some specific form and send it and retrieve it on the other side?Say if I have a data structure, in that case how do i send it? Sending data packets is very cruicial in an embedded system.
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Dec 26, 2014
I have Build code for sending/receiving TCP Traffic over c Socket . Now I want t add HTTP Protocol to it .
After searching out on google ,one method I found which is by GET method to send a query to a server like google.com and request a page .
But ,Suppose I saved a HTML page in my directory how can I send HTTP packet via client/server in socket using this HTML page .
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Dec 27, 2014
I have code for sending/receiving TCP traffic over C socket. Now I want to add HTTP protocol to it. After searching the web, one method I found which is by GET method to send a query to a server like google.com and request a page.
But, suppose I saved a HTML page in my directory how can I send HTTP packet via client/server in socket using this HTML page.
Server side code:
sockfd = socket(AF_INET, SOCK_STREAM, 0);
bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
listen(sockfd,5);
newsockfd = accept(sockfd, (struct sockaddr *)&cli_addr,&clilen);
while (1)
[Code] .....
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Jan 8, 2014
How can header info 'foo' be combined with data in buffer 'buff' to pass to sendto function
Code:
/* Send a single RTP packet, converting the RTP header to network byte order. */
int sendrtp(int fd, struct sockaddr_in ........ockAddr, struct rtpheader *foo, void *data, int len)
{
char *buff = alloca(len+sizeof(struct rtpheader));
foo->b.sequence = htons(foo->b.sequence);
foo->timestamp = htonl(foo->timestamp);
foo->ssrc = htonl(foo->ssrc);
}
[code]....
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Apr 16, 2015
This question is kind of a continuation of Winsock Sending X264 Nal Unit. I was finally able to solve that problem, turns out in the end I was missing a memcpy(). Now my current issue is, when I try to decode the received packets, I am shown a bunch of errors. I have attached a picture with my decoding errors. So since I am using a reliable multicast socket, which doesn't guarantee order of delivery. My initial thought is that I am getting packets out of order.
So my question is, how would I attach a packet header to my current data? Could I get away with sending the header separately? Similar to what I am doing with the nal length. If I do attach my header to the packet data, what is a good way to delimit the two?
Server:
#include <WinSock2.h>
#include <WS2tcpip.h>
#include "wsrm.h"
#include <Windows.h>
#include <stdio.h>
#include <stdint.h>
#include <iostream>
#include "x264Encoder.h"
[Code] ....
My client is just reading packets into a vector, because decoding it right away was too slow. So I thought that might have been an issue, so I decided to read in 200 packets just for testing purposes.
Attached image(s)
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Apr 26, 2014
I have a situation where I am accessing an ASP.NET Generic Handler to load data using JQuery. But since data loaded from Javascript is not visible to the search engine crawlers, I decided to load data from C# and then cache it for JQuery. My handler contains a lot of logic that I don't want to apply again on code behind. Here is my Handler code:
public void ProcessRequest(HttpContext context) {
JavascriptSerializer jsonSerializer = new JavascriptSerializer();
string jsonString = string.Empty;
context.Request.InputStream.Position = 0;
using (var inputStream = new System.IO.StreamReader(context.Request.InputStream))
[Code] ....
I can call the function : getUserControlMarkup() from C# but I will have to apply some URL based conditions while calling it. The contentType.typeOfContent is actually based on URL parameters.
If possible to send JSON data to this handler then how to do that. I am trying to access the handler like this:
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Common.host + "Handlers/SideContentLoader.ashx?typeOfContent=1&UCArgs=cdata");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
But its giving NullReferenceException in Handler code at line:
ContentType contentType = jsonSerializer.Deserialize<ContentType>(jsonString);
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Sep 3, 2014
I am writing a client-server program in C++ using C libraries. The server listens for a connection and when one is found, it is supposed to send a binary file(an image in my case) to the client. The server is sending the binary file perfectly after opening it and reading its contents into a buffer that is dynamically allocated in the SERVER file.
The problem begins when the client file is supposed to recv() the file, I do not know how I can allocate a buffer big enough for the file to be received. I know how to use malloc() and new, I prefer malloc() for executable size customization. Assuming the file being sent is 11000 bytes(note that this is an assumption and the client can not know the file size because the file size is dynamically generated by server).
How can the client generate a dynamically allocated buffer big enough to hold 11000 bytes?
OR
How can the client store the data in a buffer using recv() without knowing the file size.
Below is part of the code that does the send()'ing and recv()'ing.
SERVER
FILE *img = fopen("img.jpg", "rb");
fseek(img, 0, SEEK_END);
unsigned long filesize = ftell(img);
char *buffer = (char*)malloc(sizeof(char)*filesize);
rewind(img);
// store read data into buffer
[Code] ....
This outputs all the binary code perfectly but it is a bug because it can't be written to a file. Is there a way to dynamically increase the buffer until all filesize is received? Certainly, buffer needs to be dynamically allocated or program crashes ...
Also one more thing, when I telnet the server from command line, telnet displays all the output perfectly as well
Maybe telnet is storing data into a buffer behind the scenes, if so, how?
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Oct 26, 2014
i am making a client server application but the problem is that i cannot send data from CLIENT to SERVER , but i can receive data from SERVER to CLIENT ... Below is mt client and Server code and i also have attached both client and server files...
CLIENT CODE:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net;
using System.Net.Sockets;
namespace asynclient {
[code]....
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Sep 8, 2014
I'm trying to send a simple text string using httpsendrequest, everything works fine, the string is sent but I don't know how to retrieve it in the PHP server. Also when I use internetreadfile, the dwBytesRead is 0 meaning that there is no response from the server though the application works fine. This is the code that I have so far.
#define _WIN32_WINNT 0x600
#include <stdio.h>
#include <wininet.h>
#define BUFLEN 200
static const char *acceptTypes[] = {"application/x-www-form-urlencoded", NULL};
static const char *postData = "teststr=Hello+world&testval=42";
int main() {
HINTERNET hSession, hConnect, hFile;
[code].....
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Mar 27, 2014
I am trying to make a streambuf for a socket, which will use either WinSock or POSIX sockets depending on OS. I understand about how to send and receive data via sockets, but I don't really understand how to put that into a 'streambuf'. What functions do I need to override?
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Aug 13, 2014
private void button1_Click(object sender, EventArgs e) {
serialPort1.PortName = "COM1";
serialPort1.BaudRate = 9600;
serialPort1.DataBits = 8;
serialPort1.Parity = Parity.None;
serialPort1.StopBits = StopBits.One;
[Code]...
In my project i have a serialport control and a button, there is no error but i want to know how actually this works, i want to send and recieve the data from the serial port don't know how to do it..
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Oct 5, 2014
I found the following code in [URL] ....., that send .TXT files perfectly to php script in my server using Wininet, but when I insert a .BMP file, this file (.BMP) is correctly created and named in server side, but it is empty! I read that is necessary implement base64 encode for work properly, so how would?
PHP Code:
#include <windows.h>
#include <wininet.h>
#include <iostream>
#define ERROR_OPEN_FILE 10
#define ERROR_MEMORY 11
#define ERROR_SIZE 12
[Code] ....
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Feb 7, 2013
I'm trying to send some binary data, such as an animated gif, via an HTTP response for a simple web server.
I am having issues having the browser close the connection after receipt of the data.
I create the header such as:
"HTTP/1.1 200 OK
Content-Length: <file size>
Content-Type: <file type>
<binary data>"
This is stored in a malloc'ed char *. To add the binary data I'm using fread: fread(request + strlen(request), 1, size, fp)
I then write 'total' bits via connfd:
write(connfd, request, total)
where total = strlen(headerRequest) + size + 3 (for ending
).
The writing seems to be okay however the image doesn't load and the browser still seems to be waiting for data.
If I added "Connection: close" to the header and closed connfd myself the page loads fine. Obviously, for efficiency purposes, I'd rather only close connfd once read() returns 0.
The header creation code is below:
======= Code:
/* Try to get file */
strcat(cwd, file);
if(endsWith (cwd, ".html") || endsWith(cwd, ".htm")) {
strcpy(fileType, "text/html");
binary = 0;
} else if (endsWith(cwd, ".txt")) {
strcpy(fileType, "text/plain");
binary = 0;
[Code]...
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Mar 13, 2013
Is there any standard USB protocol which i can follow to send data to my embedded board(and vice versa). I have no clue on USB programming using c,is there any example code i could follow,
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Oct 30, 2013
I have a socket connection already set up, my thing is what would be the best way to send a packet through sockets? My teacher wants us to convert the packet to bits first before we send it. I think he wants something like this:
Code:
struct packet{
int header
int message
int flag
}clientpacket; m
My question is how do we covert this to bits, before sending it. One of my friends said we can create a char[] array the size of the struct as a buffer. will memcpy() change the struct to bits if I copy it to the buffer?
this is how is suppose to look in bits for the header field/column.
Field : header
Field size(bits): 8
data format: Unsigned int
value example: 1
Value in bits: 0000 0001
I am confused, I think I send a structure over the socket but I did not convert it to bits before I sent it .
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Aug 12, 2014
have udp server-client application written in C. On the client side packet loss is detected using recvfrom function and sequence numbers of packets. How can I now simulate dropped packet's on the client side, for example if server is sending 1000 packet I want to drop 20% of them? I want to do this in the code, not for example using ip tables or WANEM or something like that. And one more thing, I have few clients and I want that they can dropped different packets, not the same one.
Code:
while(1){
nbytes = recvfrom(socket, buffer, MAX_SIZE, 0, (struct sockaddr *) &srv_addr, &addrlen);
if (nbytes != -1) {
// packet is received
}else{
//packet is not received
}
}
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Dec 15, 2014
Questions : I am running a client Server Program whose Sender and Receiver loop is given below .I have multi threaded Sender using OMP .As per My logic Receive should receive same amount of data send by Sender ,But its receiving more packet than Sender sent .I am not able to identify the Bug !!
Code:
/*
Running As Follow :
gcc UTGen.c -o Sender
gcc UTGen.c -o Receiver
./Receiver -m 0 -p 5000 -z 256 -P t
export OMP_NUM_THREADS=4
./Sender -m 1 -s localhost -p 5000 -z 256 -T 10 -P t
*/
[Code] .....
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Aug 19, 2014
I am just getting back in to C++ after 10 years not doing any, contributing to an open source project. I'm adding in some functionality and am hitting a road block.
I need to send a multicast packet out on the network that is structured in a certain way. I have the definition, and know what data is going in each byte. I can successfully send a message using multicast, I now just need to send the right message.
I have used a char array to hold the message, as each char represents 1 byte, and I can transmit the array.
I am having trouble putting all of the data in the right place though. If my source data is a string, then I seem to be able to convert it, but if it is a short or int, then I keep getting errors when compiling. Similarly, two of the lines, (version and type) i initially tried using char arrays with a length of one.
Should I be using memcpy or a different function, or even be doing this in a totally different way altogether? This is the code that I am using, along with the packet structure:
//Construct a Zone Query packet
// 4 bytes - Signature "Ohz " = 0x6f, 0x68, 0x7a, 0x20
// 1 bytes - Version = 1
// 1 bytes - Type (0 = Zone Query, 1 = Zone Uri)
// 2 bytes - Entire message length = 12 + zone length
// 4 bytes - Length in bytes of the zone ID
// n bytes - Zone ID to query
[Code] ....
The errors that I get are:
error: invalid conversion from ‘short int’ to ‘const void*’ [-fpermissive]
memcpy(buffer + 6, packetLength, sizeof(packetLength));
^
[Code] ....
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Dec 17, 2014
I want to calculate the total some of delay pf receiving Side Packet . Code is as Follow ..
What is weird that even if i invoke a sleep of 2 sec ,than its show delay always zero. Delay will be in microsec ..Is there any problem with logic or anything else..
Code:
do
{#pragma omp parallel private(nthreads, tid) {
/* Obtain thread number */
tid = omp_get_thread_num();
if (tid == 0) {
nthreads = omp_get_num_threads();
[Code]...
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Jan 19, 2014
I am programming in c++ with 'winpcap' . I read a .pcap file and after I want to get the source and destination of packets in that file. Here is a piece of my code:
Code:
////I define the sructures here
#pragma pack(1)
struct sniff_ethernet {
u_char ether_dhost[ETHER_ADDR_LEN]; /* Destination host address */
u_char ether_shost[ETHER_ADDR_LEN]; /* Source host address */
u_short ether_type; /* IP? ARP? RARP? etc */
[Code] ....
but the result is incorrect? where is the problem?
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Feb 26, 2013
I need to send a packet of type byte:
0x00, 0x01, 0x02, 0x11, 0x00, 0x00
to a device via the serial port and then I receive and store data coming from device like this:
0x01, 0x01, 0x01 , 0x00, 0x00, 0x00, 0x01, 0x00, 0x04, 0x01, 0x00.
Writing lines of code through which:
1) I create the array
2) the sending the array to serial port
3) I'll see what I'm sending
4) I get the data
I'm using Visual Studio 2010 and C + + or VC++ language.
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Dec 2, 2014
My first time programming sth in Network. I have to use C to send a file to another PC, well COM port are useful but I didn't find how to refer to the address of my destination.
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Apr 1, 2014
i developed 2programm that the first one is in C and the second one is in c#.and now i have to send some string text from c to c#.how can i do that in c ?
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Apr 9, 2013
I'm connecting to my website through sockets, like this:
Code:
#include <stdio.h>
#include <stdlib.h>
#include <winsock2.h>
#include <string.h>
int main(int argc, char *argv[]) {
WSADATA wsadata;
if (WSAStartup(MAKEWORD(2,2), &wsadata) == -1)
[Code]...
I want to send GET to a certain web page. How can I do that?
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Jul 3, 2014
I was wondering if there was a way for me to send information, say a username and password, to a webpage via a c++ function. I was unsure how exactly to word it, but I did attempt to google it. Here is an example of what I mean.
App starts -> goes to "Https://www.my-site.com/?user=$username&password=$password" -> username/password is valid -> logs them in on desktop app
I do not know much about php, but I am assuming the ?user=$username is setting a variable, correct? I am familiar with sockets, but it seems using the above method, this could be possible without sockets, would it?
Important part:
That is the method that minecraft uses to login players, the question here is what function could I start to send the desktop app to the webpage.
EDIT:: After looking a little more I find that it is probably not possible without sockets, which is fine; however I don't know how to do it still, I would prefer to not use external libraries, such as Curl.
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Aug 4, 2014
so im just getting into network programming and im trying to make a chat server and client so i can send and receive messages. I have written both a chat and a client, with no error reporting (i know, i know). But the message that comes through on the server side is "hiiinaovH+". Ive represented this as well as i can but really they are non alphabetic symbols coming through.
client code:
#include <iostream>
#include <winsock2.h>
int main()
{
[Code]....
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