CFURL does not give full data when download - objective-c

Question

Iam trying to use CFHTTP to write a small downloader. Unfortunately I cannot use NSURL which is very easy. I basically want an async way to download the data and store it in a file. I have not yet found how to do async way but I have some code with Sync approach which not working as well. The problem is the downloader does not download the complete bytes. I see some data missing causing the final file to be corrupt. Here is the code I have so far.
#include <stdio.h>
#include <string.h>
#include <CoreFoundation/CoreFoundation.h>
#include <CFNetwork/CFNetwork.h>
#include <CFNetwork/CFHTTPStream.h>
int main(int argc, const char * argv[])
{
// insert code here...
const char *data;
FILE *fp;
CFShow(CFSTR("Hello, World!\n"));
CFURLRef cfUrl = CFURLCreateWithString(kCFAllocatorDefault, CFSTR("http://the.earth.li/~sgtatham/putty/0.62/x86/putty.zip"), NULL);
CFHTTPMessageRef cfHttpReq = CFHTTPMessageCreateRequest(kCFAllocatorDefault, CFSTR("GET"), cfUrl, kCFHTTPVersion1_1);
CFReadStreamRef readStream = CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault, cfHttpReq);
CFReadStreamOpen(readStream);
CFHTTPMessageRef cfHttpResp = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, TRUE);
CFIndex numBytesRead;
do {
const int nBuffSize = 1024;
UInt8 buff[nBuffSize];
numBytesRead = CFReadStreamRead(readStream, buff, nBuffSize);
if( numBytesRead > 0 )
{
CFHTTPMessageAppendBytes(cfHttpResp, buff, numBytesRead);
}
else if( numBytesRead < 0 )
{
CFStreamError error = CFReadStreamGetError(readStream);
printf ("Error %d", error.error);
}
} while ( numBytesRead > 0 );
CFStringRef myStatusLine = CFHTTPMessageCopyResponseStatusLine(cfHttpReq);
CFReadStreamClose(readStream);
CFDataRef cfResp = CFHTTPMessageCopyBody(cfHttpResp);
CFIndex length = CFDataGetLength(cfResp);
printf ("%lu\n", length);
CFShow(myStatusLine);
data = (const char*)CFDataGetBytePtr(cfResp);
fp = fopen("/var/tmp/Update.zip", "w");
if (fp == NULL) {
printf("ACnnot be opened\n");
} else {
fwrite(data, length, 1, fp);
fclose(fp);
}
printf ("Download done\n");
CFRelease(cfUrl);
CFRelease(cfHttpReq);
CFRelease(readStream);
CFRelease(cfHttpResp);
CFRelease(cfResp);
return 0;
}
The length I get is less than my actual file download. I dont understand whats is wrong with this code. Can someone please help me with this?

Answer 1

I still dont know what went wrong in this code. But I fixed my problem by replacing
//CFHTTPMessageRef cfHttpResp = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, TRUE);
CFMutableDataRef cfResp = CFDataCreateMutable(kCFAllocatorDefault, 0);
I now use MutableDataRef instead of CFHTTPMessageRef. I will upadte the new code here.
int main(int argc, const char * argv[])
{
// insert code here...
const char *data;
FILE *fp;
CFShow(CFSTR("Hello, World!\n"));
CFURLRef cfUrl = CFURLCreateWithString(kCFAllocatorDefault, CFSTR("http://the.earth.li/~sgtatham/putty/0.62/x86/putty.zip"), NULL);
CFHTTPMessageRef cfHttpReq = CFHTTPMessageCreateRequest(kCFAllocatorDefault, CFSTR("GET"), cfUrl, kCFHTTPVersion1_1);
CFReadStreamRef readStream = CFReadStreamCreateForHTTPRequest(kCFAllocatorDefault, cfHttpReq);
CFReadStreamOpen(readStream);
//CFHTTPMessageRef cfHttpResp = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, TRUE);
CFMutableDataRef cfResp = CFDataCreateMutable(kCFAllocatorDefault, 0);
CFIndex numBytesRead;
do {
const int nBuffSize = 1024;
UInt8 buff[nBuffSize];
numBytesRead = CFReadStreamRead(readStream, buff, nBuffSize);
if( numBytesRead > 0 )
{
CFDataAppendBytes(cfResp, buff, numBytesRead);
//CFHTTPMessageAppendBytes(cfHttpResp, buff, numBytesRead);
}
else if( numBytesRead < 0 )
{
CFStreamError error = CFReadStreamGetError(readStream);
printf ("Error %d", error.error);
}
} while ( numBytesRead > 0 );
CFReadStreamClose(readStream);
//CFDataRef cfResp = CFHTTPMessageCopyBody(cfHttpResp);
CFIndex length = CFDataGetLength(cfResp);
printf ("%lu\n", length);
data = (const char*)CFDataGetBytePtr(cfResp);
fp = fopen("/var/tmp/Update.zip", "w");
if (fp == NULL) {
printf("ACnnot be opened\n");
} else {
fwrite(data, length, 1, fp);
fclose(fp);
}
printf ("Download done\n");
CFRelease(cfUrl);
CFRelease(cfHttpReq);
CFRelease(readStream);
CFRelease(cfResp);
return 0;
}
Hope this helps. It will still be useful if someone can point out what went wrong original code.

Answer 2

I know this late, but your code really helped me out (it is surprisingly hard to find straight forward, complete, examples of getting the response body bytes using CFNetworking API).
Anyway, I think the mistake was the last parameter should be FALSE (response message), and not TRUE (request message) in CFHTTPMessageCreateEmpty line.
CFHTTPMessageRef cfHttpResp = CFHTTPMessageCreateEmpty(kCFAllocatorDefault, FALSE);