I tried to parse the data which was generated by chunked transfer encoding in a Rest API ,I did see the data has value when I tried to print the value in a string and I thought it should be working,but when I tried to assign the value to the file, the file is totally unreadable, the code below I used boost library and I gonna elaborate my thoughts in the code , we gonna get started from the response portion of my code, I have no idea what wrong I have done
// Send the request.
boost::asio::write(socket, request);
// Read the response status line. The response streambuf will automatically
// grow to accommodate the entire line. The growth may be limited by passing
// a maximum size to the streambuf constructor.
boost::asio::streambuf response;
boost::asio::read_until(socket, response, "\r\n");
// Check that response is OK.
std::istream response_stream(&response);
std::string http_version;
response_stream >> http_version;
unsigned int status_code;
response_stream >> status_code;
std::string status_message;
std::getline(response_stream, status_message);
if (!response_stream || http_version.substr(0, 5) != "HTTP/")
{
//std::cout << "Invalid response\n";
return 9002;
}
if (status_code != 200)
{
//std::cout << "Response returned with status code " << status_code << "\n";
return 9003;
}
// Read the response headers, which are terminated by a blank line.
boost::asio::read_until(socket, response, "\r\n\r\n");
// Process the response headers.
//this portion of code I tried to parse the file name in the header of response which the file name is in the content-disposition of header
std::string header;
std::string fullHeader = "";
string zipfilename="", txtfilename="";
bool foundfilename = false;
while (std::getline(response_stream, header) && header != "\r")
{
fullHeader.append(header).append("\n");
std::transform(header.begin(), header.end(), header.begin(),
[](unsigned char c){ return std::tolower(c); });
string containstr = "content-disposition";
string containstr2 = "filename";
string quotestr = "\"";
if (header.find(containstr) != std::string::npos && header.find(containstr2) != std::string::npos)
{
int countquotes = 0;
bool foundquote = true;
std::size_t startpos = 0, beginpos, endpos;
while (foundquote)
{
std::size_t myfound = header.find(quotestr, startpos);
if (myfound != std::string::npos)
{
if (countquotes % 2 == 0)
beginpos = myfound;
else
{
endpos = myfound;
foundfilename = true;
}
startpos = myfound + 1;
}
else
foundquote = false;
countquotes++;
}
if (endpos > beginpos && foundfilename)
{
size_t zipfileleng = endpos - beginpos;
zipfilename = header.substr(beginpos+1, zipfileleng-1);
txtfilename = header.substr(beginpos+1, zipfileleng-5);
}
else
return 9004;
}
}
if (foundfilename == false || zipfilename.length() == 0 || txtfilename.length() == 0)
return 9005;
//when the zipfilename has been found, we gonna get the data from the body of response, due to the response was chunked transfer encoding, I tried to parse it,it's not complicated due to I saw it on the Wikipedia, it just first line was length of data,the next line was data,and it's the loop which over and over again ,all I tried to do was spliting all the data from the body of response by "\r\n" into a vector<string>, and I gonna read the data from that vector
// Write whatever content we already have to output.
std::string fullResponse = "";
if (response.size() > 0)
{
std::stringstream ss;
ss << &response;
fullResponse = ss.str();
}
//tried split the entire body of response into a vector<string>
vector<string> allresponsedata;
split_regex(allresponsedata, fullResponse, boost::regex("(\r\n)+"));
//tried to merge the data of response
string zipfiledata;
int myindex = 0;
for (auto &x : allresponsedata) {
std::cout << "Split: " << x << std::endl;// I tried to print the data, I did see the value in the variable of x
if (myindex % 2 != 0)
{
zipfiledata = zipfiledata + x;//tried to accumulate the datas
}
myindex++;
}
//tried to write the data into a file
std::ofstream zipfilestream(zipfilename, ios::out | ios::binary);
zipfilestream.write(zipfiledata.c_str(), zipfiledata.length());
zipfilestream.close();
//afterward, the zipfile was built, but it's unreadable which it's not able to open,the zip utlities software says it's a damaged zip file though
I even tried something else ways like this slow http client based on boost::asio - (Chunked Transfer) ,but this way is not working as well ,VS says
1 IntelliSense: no instance of overloaded function "boost::asio::read" matches the argument list
argument types are: (boost::asio::ip::tcp::socket, boost::asio::streambuf, boost::asio::detail::transfer_exactly_t, std::error_code)
it just NOT able to compile in the line which is
size_t n = asio::read(socket, response, asio::transfer_exactly(chunk_bytes_to_read), error);
even I have read the example of asio::transfer_exactly, there's no exactly example like this though https://www.boost.org/doc/libs/1_57_0/doc/html/boost_asio/reference/transfer_exactly.html
any idea?
