Binary through http - c++

Question

I'm using C++ to send post-request with binary information. The code looks like:
int binary[4] = { 1, 2, 3, 4 };
std::stringstream out;
out << "POST /address HTTP/1.1\r\n";
out << "Host: localhost\r\n";
out << "Connection: Keep-Alive\r\n";
out << "Content-Type: application/octet-stream\r\n";
out << "Content-Transfer-Encoding: binary\r\n";
out << "Content-Length: " << 4*sizeof(int) << "\r\n\r\n"; // 4 elements of integer type
And sending data into opened connection in socket:
std::string headers = out.str();
socket.send(headers.c_str(), headers.size()); // Send headers first
socket.send(reinterpret_cast<char*>(&binary[0]), bufferLength*sizeof(int)); // And array of numbers
But I was told, that sending pure bytes through http-protocol is wrong. Is that right? For example, I can't send 0 (zero), it's used by protocol.
If that's right (because I can't handle that post-request and get the data I've sent) what could I use instead? Maybe, convert array into hex or base64url?
Thanks.

Answer 1

The problem people saying it's wrong are addressing is about the endianness. You can transfer binary data with http of course, but when the other end receives them, it must be able to interpret them correctly. Let's suppose your machine is a little endian machine; your integers will be, in memory, stored as (32 bit int)
01 00 00 00
02 00 00 00
03 00 00 00
04 00 00 00
and you send these 16 bytes as they "are". Now, suppose the receiving machine get the data naively disregarding who and how they are sent, and suppose that machine is a big endian machine; in such machine, the memory layout for 1, 2, 3, 4 intergers would be
00 00 00 01
00 00 00 02
00 00 00 03
00 00 00 04
This means that for the receiving machine the first integer is 0x01000000 which is not 0x00000001 as the sender wanted.
If you decide that your integers must be sent always as big endian integer, then if the sender is a little endian machine, it needs to "re-arrange" properly the integers before sending. There are functions like hton* (host to net) that "transforms" host 32/16 bit integers to the "net byte order" that is big endian (and viceversa, with ntoh* net to host)
Note that data are not scrambled, they are send as they "are", so to say. What changes is the way you store them in memory, and the way you interpret them when reading. Usually it's not an issue, since data are sent according to a format that, if needed, specifies the endianness of non-single-byte data (e.g. see PNG format spec, sec 2.1, integers byte order: PNG uses net byte order i.e. big endian)

Answer 2

But I was told, that sending pure bytes through http-protocol is
wrong. Is that right?
No, it is fine in the body, depending on the Content-Type of course. "Octet-stream" should be fine in this regard, and yes it can contain zero bytes.

Answer 3

There is nothing wrong to send binaries via HTTP.
This happens all the time with images and with file upload