C++file transfer
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I'm currently writing a server and client app that attemps to transfer a screenshot but it's not working properly. I implemented it like this.
SOCKET sock;
char buf[4096];
DWORD WINAPI thread_function()
{
bool file_transfer = false;
bool loop = true;
while (1)
{
ZeroMemory(buf, 4096);
int bytesReceived = recv(sock, buf, 4096, 0);
if (bytesReceived > 0)
{
std::string received(buf, 0, bytesReceived);
if (received == "Sending file.")
{
file_transfer = true;
}
if (file_transfer == false)
{
std::cout << "nSERVER> " << std::string(buf, 0, bytesReceived) << std::endl;
std::cout << "> ";
}
else if (file_transfer == true)
{
loop = true;
TCHAR *szfname = "screenshot.bmp";
FILE* f = fopen(szfname, "wb");
if (NULL == f)
{
std::cerr << "Error opening file" << std::endl;
return 1;
}
while ((bytesReceived = recv(sock, buf, 4096, 0)) > 0 && loop == true)
{
received = buf;
if (received == "File transfer completed !")
{
loop = false;
std::cout << "File transfer completed !" << std::endl;
std::cout << "> ";
}
else
{
fwrite(buf, 1, bytesReceived, f);
}
}
file_transfer = false;
}
}
}
}
I call the function with this
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)thread_function, 0, 0, 0);
The thing is I believe this is not a very clean way of doing it and also it's not working perfectly. After a file is received I don't correctly receive what the server is sending.
This is the server code wich I think is fine.
send(clientSocket, TEXT("Attempting to take a screenshot."), sizeof(TEXT("Attempting to take a screenshot...")), 0);
HWND win = GetDesktopWindow();
HDC dc = GetDC(win);
if (HDCToFile("screenshot.bmp", dc, { 0, 0, 1920, 1080 }) == true)
{
send(clientSocket, TEXT("Sending file."), sizeof(TEXT("Sending file.")), 0);
FILE *fp = fopen("screenshot.bmp", "rb");
if (fp == NULL)
{
std::cerr << "Error : Cannot open file." << std::endl;
return 1;
}
while (1)
{
char buff[4096] = { 0 };
int nread = fread(buff, 1, 4096, fp);
if (nread > 0)
{
send(clientSocket, buff, sizeof(buff), 0);
}
if (nread < 4096)
{
if (feof(fp))
{
std::cout << "File transfer completed !" << std::endl;
send(clientSocket, TEXT("File transfer completed !"), sizeof(TEXT("File transfer completed !")), 0);
}
if (ferror(fp))
std::cerr << "Error reading." << std::endl;
break;
}
}
}
else
{
send(clientSocket, TEXT("Screen capture failed...."), sizeof(TEXT("Screen capture failed....")), 0);
}
Thanks for your time and help.
c++ sockets client-server file-transfer
asked 1 hour ago
programme-zero
13
add a comment |
up vote
-1
down vote
favorite
I'm currently writing a server and client app that attemps to transfer a screenshot but it's not working properly. I implemented it like this.
SOCKET sock;
char buf[4096];
DWORD WINAPI thread_function()
{
bool file_transfer = false;
bool loop = true;
while (1)
{
ZeroMemory(buf, 4096);
int bytesReceived = recv(sock, buf, 4096, 0);
if (bytesReceived > 0)
{
std::string received(buf, 0, bytesReceived);
if (received == "Sending file.")
{
file_transfer = true;
}
if (file_transfer == false)
{
std::cout << "nSERVER> " << std::string(buf, 0, bytesReceived) << std::endl;
std::cout << "> ";
}
else if (file_transfer == true)
{
loop = true;
TCHAR *szfname = "screenshot.bmp";
FILE* f = fopen(szfname, "wb");
if (NULL == f)
{
std::cerr << "Error opening file" << std::endl;
return 1;
}
while ((bytesReceived = recv(sock, buf, 4096, 0)) > 0 && loop == true)
{
received = buf;
if (received == "File transfer completed !")
{
loop = false;
std::cout << "File transfer completed !" << std::endl;
std::cout << "> ";
}
else
{
fwrite(buf, 1, bytesReceived, f);
}
}
file_transfer = false;
}
}
}
}
I call the function with this
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)thread_function, 0, 0, 0);
The thing is I believe this is not a very clean way of doing it and also it's not working perfectly. After a file is received I don't correctly receive what the server is sending.
This is the server code wich I think is fine.
send(clientSocket, TEXT("Attempting to take a screenshot."), sizeof(TEXT("Attempting to take a screenshot...")), 0);
HWND win = GetDesktopWindow();
HDC dc = GetDC(win);
if (HDCToFile("screenshot.bmp", dc, { 0, 0, 1920, 1080 }) == true)
{
send(clientSocket, TEXT("Sending file."), sizeof(TEXT("Sending file.")), 0);
FILE *fp = fopen("screenshot.bmp", "rb");
if (fp == NULL)
{
std::cerr << "Error : Cannot open file." << std::endl;
return 1;
}
while (1)
{
char buff[4096] = { 0 };
int nread = fread(buff, 1, 4096, fp);
if (nread > 0)
{
send(clientSocket, buff, sizeof(buff), 0);
}
if (nread < 4096)
{
if (feof(fp))
{
std::cout << "File transfer completed !" << std::endl;
send(clientSocket, TEXT("File transfer completed !"), sizeof(TEXT("File transfer completed !")), 0);
}
if (ferror(fp))
std::cerr << "Error reading." << std::endl;
break;
}
}
}
else
{
send(clientSocket, TEXT("Screen capture failed...."), sizeof(TEXT("Screen capture failed....")), 0);
}
Thanks for your time and help.
c++ sockets client-server file-transfer
asked 1 hour ago
programme-zero
13
1
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1
Your receive-side checkif (received == "Sending file.")is wrong. Assuming TCP, the stringreceivedcan be a full 4Kb buffer, because boundaries betweensendcalls are not preserved when callingrecv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).
– Useless
50 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago
add a comment |
up vote
-1
down vote
favorite
up vote
-1
down vote
favorite
I'm currently writing a server and client app that attemps to transfer a screenshot but it's not working properly. I implemented it like this.
SOCKET sock;
char buf[4096];
DWORD WINAPI thread_function()
{
bool file_transfer = false;
bool loop = true;
while (1)
{
ZeroMemory(buf, 4096);
int bytesReceived = recv(sock, buf, 4096, 0);
if (bytesReceived > 0)
{
std::string received(buf, 0, bytesReceived);
if (received == "Sending file.")
{
file_transfer = true;
}
if (file_transfer == false)
{
std::cout << "nSERVER> " << std::string(buf, 0, bytesReceived) << std::endl;
std::cout << "> ";
}
else if (file_transfer == true)
{
loop = true;
TCHAR *szfname = "screenshot.bmp";
FILE* f = fopen(szfname, "wb");
if (NULL == f)
{
std::cerr << "Error opening file" << std::endl;
return 1;
}
while ((bytesReceived = recv(sock, buf, 4096, 0)) > 0 && loop == true)
{
received = buf;
if (received == "File transfer completed !")
{
loop = false;
std::cout << "File transfer completed !" << std::endl;
std::cout << "> ";
}
else
{
fwrite(buf, 1, bytesReceived, f);
}
}
file_transfer = false;
}
}
}
}
I call the function with this
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)thread_function, 0, 0, 0);
The thing is I believe this is not a very clean way of doing it and also it's not working perfectly. After a file is received I don't correctly receive what the server is sending.
This is the server code wich I think is fine.
send(clientSocket, TEXT("Attempting to take a screenshot."), sizeof(TEXT("Attempting to take a screenshot...")), 0);
HWND win = GetDesktopWindow();
HDC dc = GetDC(win);
if (HDCToFile("screenshot.bmp", dc, { 0, 0, 1920, 1080 }) == true)
{
send(clientSocket, TEXT("Sending file."), sizeof(TEXT("Sending file.")), 0);
FILE *fp = fopen("screenshot.bmp", "rb");
if (fp == NULL)
{
std::cerr << "Error : Cannot open file." << std::endl;
return 1;
}
while (1)
{
char buff[4096] = { 0 };
int nread = fread(buff, 1, 4096, fp);
if (nread > 0)
{
send(clientSocket, buff, sizeof(buff), 0);
}
if (nread < 4096)
{
if (feof(fp))
{
std::cout << "File transfer completed !" << std::endl;
send(clientSocket, TEXT("File transfer completed !"), sizeof(TEXT("File transfer completed !")), 0);
}
if (ferror(fp))
std::cerr << "Error reading." << std::endl;
break;
}
}
}
else
{
send(clientSocket, TEXT("Screen capture failed...."), sizeof(TEXT("Screen capture failed....")), 0);
}
Thanks for your time and help.
c++ sockets client-server file-transfer
asked 1 hour ago
programme-zero
13
I'm currently writing a server and client app that attemps to transfer a screenshot but it's not working properly. I implemented it like this.
SOCKET sock;
char buf[4096];
DWORD WINAPI thread_function()
{
bool file_transfer = false;
bool loop = true;
while (1)
{
ZeroMemory(buf, 4096);
int bytesReceived = recv(sock, buf, 4096, 0);
if (bytesReceived > 0)
{
std::string received(buf, 0, bytesReceived);
if (received == "Sending file.")
{
file_transfer = true;
}
if (file_transfer == false)
{
std::cout << "nSERVER> " << std::string(buf, 0, bytesReceived) << std::endl;
std::cout << "> ";
}
else if (file_transfer == true)
{
loop = true;
TCHAR *szfname = "screenshot.bmp";
FILE* f = fopen(szfname, "wb");
if (NULL == f)
{
std::cerr << "Error opening file" << std::endl;
return 1;
}
while ((bytesReceived = recv(sock, buf, 4096, 0)) > 0 && loop == true)
{
received = buf;
if (received == "File transfer completed !")
{
loop = false;
std::cout << "File transfer completed !" << std::endl;
std::cout << "> ";
}
else
{
fwrite(buf, 1, bytesReceived, f);
}
}
file_transfer = false;
}
}
}
}
I call the function with this
CreateThread(0, 0, (LPTHREAD_START_ROUTINE)thread_function, 0, 0, 0);
The thing is I believe this is not a very clean way of doing it and also it's not working perfectly. After a file is received I don't correctly receive what the server is sending.
This is the server code wich I think is fine.
send(clientSocket, TEXT("Attempting to take a screenshot."), sizeof(TEXT("Attempting to take a screenshot...")), 0);
HWND win = GetDesktopWindow();
HDC dc = GetDC(win);
if (HDCToFile("screenshot.bmp", dc, { 0, 0, 1920, 1080 }) == true)
{
send(clientSocket, TEXT("Sending file."), sizeof(TEXT("Sending file.")), 0);
FILE *fp = fopen("screenshot.bmp", "rb");
if (fp == NULL)
{
std::cerr << "Error : Cannot open file." << std::endl;
return 1;
}
while (1)
{
char buff[4096] = { 0 };
int nread = fread(buff, 1, 4096, fp);
if (nread > 0)
{
send(clientSocket, buff, sizeof(buff), 0);
}
if (nread < 4096)
{
if (feof(fp))
{
std::cout << "File transfer completed !" << std::endl;
send(clientSocket, TEXT("File transfer completed !"), sizeof(TEXT("File transfer completed !")), 0);
}
if (ferror(fp))
std::cerr << "Error reading." << std::endl;
break;
}
}
}
else
{
send(clientSocket, TEXT("Screen capture failed...."), sizeof(TEXT("Screen capture failed....")), 0);
}
Thanks for your time and help.
c++ sockets client-server file-transfer
c++ sockets client-server file-transfer
asked 1 hour ago
programme-zero
13
asked 1 hour ago
programme-zero
13
asked 1 hour ago
programme-zero
13
asked 1 hour ago
programme-zero
13
asked 1 hour ago
programme-zero
13
13
1
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1
Your receive-side checkif (received == "Sending file.")is wrong. Assuming TCP, the stringreceivedcan be a full 4Kb buffer, because boundaries betweensendcalls are not preserved when callingrecv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).
– Useless
50 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago
add a comment |
1
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1
Your receive-side checkif (received == "Sending file.")is wrong. Assuming TCP, the stringreceivedcan be a full 4Kb buffer, because boundaries betweensendcalls are not preserved when callingrecv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).
– Useless
50 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago
1
1
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1
1
Your receive-side check
if (received == "Sending file.") is wrong. Assuming TCP, the string received can be a full 4Kb buffer, because boundaries between send calls are not preserved when calling recv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).– Useless
50 mins ago
Your receive-side check
if (received == "Sending file.") is wrong. Assuming TCP, the string received can be a full 4Kb buffer, because boundaries between send calls are not preserved when calling recv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).– Useless
50 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago
add a comment |
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1
1. threads add problems of their own, so start with removing that. 2. read this 3. once you have things working without the thread, you can consider adding it.
– UKMonkey
1 hour ago
1
Your receive-side check
if (received == "Sending file.")is wrong. Assuming TCP, the stringreceivedcan be a full 4Kb buffer, because boundaries betweensendcalls are not preserved when callingrecv. String comparison doesn't stop at the nul terminator if there is one. You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload).– Useless
50 mins ago
This is indeed TCP protocol. "You should consider separating your transport layer (big lumps of data received from the TCP stream) from your parsing layer (distinguishing status or control messages from the payload)." I understand what you mean but I honestly have no idea of how to implement that. For the person who linked me "How to debug small programs" if I had an idea of why this is not working I wouldn't be asking. I don't know a lot about sockets since I just started using them. My question isn't very specific because I don't know where the problem is at all.
– programme-zero
40 mins ago