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?
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?
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.
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:
I am writing an MFC app in Visual Studio 2012 that will open a JPG file as binary and read all the contents to a CString.
I am able to read it to a std::Vector, but that doesn't work much as i need to pass all the binary content as a MFC CString to another function.
More Update:
Let me explain the problem a little more deeper.
I am trying to call a JavaScript (JS) function in a HTML page and then want to pass the binary date. The C++ function that calls the JS is given below.
The 1st argument is the JS Function Name and 2nd is the one to pass the Binary Data. 1st argument works fine as i am able to call the JS fucntion called "LoadImage" without any problem. Problem is with 2nd argument that's supposed to take the Binary data of the JPG file.
If i try to pass a std::Vector or std::string then it will give me an error.
But it's happy if i pass CString. But then with CString there's a problem with NULL characters.
Actually my plan is to pass the binary of a JPG to a JS function and let it display the JPG in the HTML page.
Can i typecast a Vector or std::string to a CComVariant*?
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.
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 {
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.
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?
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..
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,
I am writing a program where I need to read a byte of char data and convert it into a text string of binary data that represents the hex value...
i.e. The char byte is 0x42 so I need a string that has 01000010 in it. I've written the following subroutine....
------------- My Subroutine ---------------------------------------------------------------------- void charbytetostring(char input, char *output){ int i, remainder; char BASE=0x2; int DIGITS=8; char digitsArray[3] = "01";
[Code] ....
When I submitted the byte 0x42 to the subroutine, the subroutine returned to the output variable 01000010... Life is good.
The next byte that came in was 0x91. When I submit this to the subroutine I get garbage out.
I am using a debugger and stepped through the subroutine a line at a time. When I feed it 0x42 I get what I expect for all variables at all points in the execution.
When I submit 0x91 When the line remainder = input % BASE; gets executed the remainder variable gets set to 0xFFFF (I expected 1). Also, when the next line gets executed..
input = input / BASE; I get C9 where I expected to get 48.
My question is, are there data limits on what can be used with the mod (%) operator? Or am I doing something more fundamentally incorrect?
Following is the program I wrote it basically takes 9 inputs and then save them into binary file. then print out the data stored in binary data and find inverse of it then print the inverse out. but its stuck in a loop somewhere.
Code: #include <stdio.h> int main() { int a[3][3],i,j; float determinant=0; int x; FILE *fp = fopen ("file.bin", "wb");
I'm not the best at C but I'm trying to write a C function that basically opens a text file with assembler language does a syntax error check on it and then converts the binary data into hex.
This is my code so far:
Code:
#include <stdio.h> #include <string.h> int main(void) { FILE*fname; char prompt; char filename[15]; char text[100]; printf( "Please enter the name of the file you wish to open: " );
I a want to write a code to convert a string into binary data for that i wrote a code its working perfectly but there is one problem , some of the binary data is written in 7bit and i want to convert it to 8 bit by adding 0 to the last.
#include <iostream> #include <fstream> #include <string> using namespace std;
I am having problems either writing data to a binary file or reading from the file. Through the process of elimination I am posting the code where the data is written to file to see if I can eliminate that as an option. I know the data is being processed correctly because, through the use of another function, I can view the data.
I also know that fwrite must be including some padding because the file size ends up being 576 bytes after it is written instead of 540 bytes (the size it would be if no padding is used). Here is my struct:
Code:
typedef struct { char teams[25]; float wins; float losses; float pct; int runsScored; int runsAgainst; } STATISTICS;
So, if I'm right, computer store their data as binary values. So if I write int x = 5; , my computer converts the value of x from decimal (5) into binary (101) and stores it in memory as a a binary number. If I print that value on the screen that value is converted(by default) back into a decimal number before being printed on the screen.
Now, my question is if there is any way to print the value of x directly into binary(as it's stored in memory) without it being converted back into a decimal value?
I am trying to encrypt a char Array with binary data.
I think I understand the basic of Encryption / Decryption but I fail to see how to implement something.
I am trying to have a "key" that needs entered so the data can become readable executable. The program I am encrypting is a small console window with a message with the text "A secret message from your friend" (Not that it matters).
I have the binary data witch I can copy and what not. But how go about Encryption and then decrypt it and not destroying the data.
I have two std::string data items that contain binary data (so it may have the null character!). What is the proper way to concatenate them to preserve all of the data? I am guess a simple:
string string3 = string1 + string2;
Will not work, as it will terminate string3 on the first NULL character it encounters.
Note: V_hChildStd_OUT_Rd is a handle to the output of program A.
After running the program although bSuccess becomes TRUE, Buf array does not include the number (12.54) that I am expecting. If I do the same process without using the binary format it works fine and I can read the number. I know somethings wrong with the writing or reading of binary data but I do not know what it is.
