Receiving binary files in socket progamming (ftp)

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April 30th, 2004, 03:13 AM

kucing

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Receiving binary files in socket progamming (ftp)

Hi, I am currently writing an FTP program. The program that I have written can get ASCII files but not binary files. I am not sure onwhat to do for binary files

. Here is part of the code that tries to get the binary file.

Code:

	string msg;
	char acceptBuffer[10000];

	...

	msg = "retr picture.jpg\n";   // Binary file
	send(sockfd, msg.c_str(), msg.size(), 0);

	int sockfd2 = socket(AF_INET, SOCK_STREAM, 0);

	target_address.sin_port = htons(dataSocket);
	connect(sockfd2, (struct sockaddr *)&target_address, sizeof(struct sockaddr));

	int lengthRecv = recv(sockfd2, acceptBuffer, MAXDATASIZE, 0);

	ofstream outFile(saveAs.c_str(), ios::out|ios::binary);
	outFile.write(acceptBuffer, lengthRecv);

Recv always receives an amount smaller than the real size of the file everytime I try to download a binary file. But for ASCII file it outputs properly. I have changed the type of transfer mode to binary by sending "type i" earlier in the program.

Does it mean that I can not use recv? What should I use instead to download binary files then? Any help is appreciated.

April 30th, 2004, 07:16 AM

mitakeet

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Have you instructed the FTP Server to send the file in binary mode? Many servers have a default value of ASCII.

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April 30th, 2004, 10:59 AM

infamous41md

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is that just an example, or the real code? why aren't u recieving in a loop?

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April 30th, 2004, 07:52 PM

kucing

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Thanks guy, I finally figure out what's wrong. Apparently it is caused by lag. And I set the lag tolerance in recv to 0. Changing it to:

Code:

int lengthRecv = recv(sockfd2, acceptBuffer, MAXDATASIZE, 1000);

makes the code work properly

Last edited by kucing : April 30th, 2004 at 08:36 PM.

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