(Objective-C) Wasabi File Streaming Upload

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Demonstrates how to do a streaming upload from a file to the Wasabi storage service. The AWS authorization presents some difficulties when the REST request body is to be streamed from a file (or from some other source). The issue is that the SHA-256 hash of the file data must be calculated. There are only two possible ways to do this: (1) stream the file into memory in its entirety and calculate the SHA-256 hash prior to uploading, or (2) pre-calculate the SHA-256 in a streaming fashion, and then provide it to the AWS authentication object.

If the application does NOT pre-compute the SHA-256, then Chilkat (internally) is forced to stream into memory, calculate the SHA-256, and then upload from the in-memory copy of the file.

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#import <CkoCrypt2.h>
#import <NSString.h>
#import <CkoRest.h>
#import <CkoAuthAws.h>
#import <CkoStream.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// This first part is optional.  AWS authentication requires
// the SHA-256 hash of the request body (i.e. the contents of the file
// to be uploaded).  We can choose to pre-calculate the SHA-256 in a streaming fashion
// and then provide it to the authenticator object.  This way, if the file is
// extremely large, it never needs to completely reside in memory.
CkoCrypt2 *crypt = [[CkoCrypt2 alloc] init];
// ----------------------------------------------------
// Important: Wasabi requires a lowercase hex format.
// ----------------------------------------------------
crypt.EncodingMode = @"hex-lower";
crypt.HashAlgorithm = @"sha-256";
NSString *fileToUploadPath = @"qa_data/xml/hamlet.xml";
NSString *hashStr = [crypt HashFileENC: fileToUploadPath];

CkoRest *rest = [[CkoRest alloc] init];

// Connect to the Amazon AWS REST server.
BOOL bTls = YES;
int port = 443;
BOOL bAutoReconnect = YES;
// This example will demonstrate uploading to a bucket in the eu-west-2 region
BOOL success = [rest Connect: @"s3.eu-west-2.wasabisys.com" port: [NSNumber numberWithInt: port] tls: bTls autoReconnect: bAutoReconnect];

// Provide AWS credentials for the REST call.
CkoAuthAws *authAws = [[CkoAuthAws alloc] init];
authAws.AccessKey = @"access-key";
authAws.SecretKey = @"secret-key";
authAws.ServiceName = @"s3";
// Provide the pre-computed SHA-256 here:
authAws.PrecomputedSha256 = hashStr;

success = [rest SetAuthAws: authAws];

[rest AddHeader: @"Expect" value: @"100-continue"];
[rest AddHeader: @"Content-Type" value: @"application/xml"];

// Set the bucket name via the HOST header.
// In this case, the bucket name is "chilkat100".
rest.Host = @"chilkat100.s3.eu-west-2.wasabisys.com";

CkoStream *fileStream = [[CkoStream alloc] init];
fileStream.SourceFile = fileToUploadPath;

// Upload to the Wasabi Storage service.
// If the application provided the SHA-256 hash of the file contents (as shown above)
// then file is streamed and never has to completely reside in memory.
// If the application did NOT provide the SHA-256, then Chilkat will (internally) 
// load the entire file into memory, calculate the SHA-256, and then upload.
NSString *responseStr = [rest FullRequestStream: @"PUT" uriPath: @"/hamlet.xml" stream: fileStream];
if (rest.LastMethodSuccess != YES) {
    NSLog(@"%@",rest.LastErrorText);
    return;
}

// When successful, the Wasabi Storage service will respond with a 200 response code,
// with an XML body.  
if ([rest.ResponseStatusCode intValue] == 200) {
    NSLog(@"%@",responseStr);
    NSLog(@"%@",@"File uploaded.");
}
else {
    // Examine the request/response to see what happened.
    NSLog(@"%@%d",@"response status code = ",[rest.ResponseStatusCode intValue]);
    NSLog(@"%@%@",@"response status text = ",rest.ResponseStatusText);
    NSLog(@"%@%@",@"response header: ",rest.ResponseHeader);
    NSLog(@"%@%@",@"response body: ",responseStr);
    NSLog(@"%@",@"---");
    NSLog(@"%@%@",@"LastRequestStartLine: ",rest.LastRequestStartLine);
    NSLog(@"%@%@",@"LastRequestHeader: ",rest.LastRequestHeader);
}