C

AWS S3 File Streaming Upload

See more Amazon S3 (new) Examples

Demonstrates how to do a streaming upload from a file to the AWS S3 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.

C

#include <C_CkCrypt2.h>
#include <C_CkRest.h>
#include <C_CkAuthAws.h>
#include <C_CkStream.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkCrypt2 crypt;
    const char *fileToUploadPath;
    const char *hashStr;
    HCkRest rest;
    BOOL bTls;
    int port;
    BOOL bAutoReconnect;
    HCkAuthAws authAws;
    HCkStream fileStream;
    const char *responseStr;

    success = FALSE;

    // 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.
    crypt = CkCrypt2_Create();
    CkCrypt2_putEncodingMode(crypt,"hex");
    CkCrypt2_putHashAlgorithm(crypt,"sha-256");
    fileToUploadPath = "qa_data/xml/hamlet.xml";
    hashStr = CkCrypt2_hashFileENC(crypt,fileToUploadPath);

    rest = CkRest_Create();

    // Connect to the Amazon AWS REST server.
    bTls = TRUE;
    port = 443;
    bAutoReconnect = TRUE;
    success = CkRest_Connect(rest,"s3.amazonaws.com",port,bTls,bAutoReconnect);

    // ----------------------------------------------------------------------------
    // Important: For buckets created in regions outside us-east-1,
    // there are three important changes that need to be made.
    // See Working with S3 Buckets in Non-us-east-1 Regions for the details.
    // ----------------------------------------------------------------------------

    // Provide AWS credentials for the REST call.
    authAws = CkAuthAws_Create();
    CkAuthAws_putAccessKey(authAws,"AWS_ACCESS_KEY");
    CkAuthAws_putSecretKey(authAws,"AWS_SECRET_KEY");
    CkAuthAws_putServiceName(authAws,"s3");
    // Provide the pre-computed SHA-256 here:
    CkAuthAws_putPrecomputedSha256(authAws,hashStr);

    success = CkRest_SetAuthAws(rest,authAws);

    // Set the bucket name via the HOST header.
    // In this case, the bucket name is "chilkat100".
    CkRest_putHost(rest,"chilkat100.s3.amazonaws.com");

    fileStream = CkStream_Create();
    CkStream_putSourceFile(fileStream,fileToUploadPath);

    // Upload to the S3 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.
    responseStr = CkRest_fullRequestStream(rest,"PUT","/hamlet.xml",fileStream);
    if (CkRest_getLastMethodSuccess(rest) != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkCrypt2_Dispose(crypt);
        CkRest_Dispose(rest);
        CkAuthAws_Dispose(authAws);
        CkStream_Dispose(fileStream);
        return;
    }

    // When successful, the S3 Storage service will respond with a 200 response code,
    // with an XML body.  
    if (CkRest_getResponseStatusCode(rest) == 200) {
        printf("%s\n",responseStr);
        printf("File uploaded.\n");
    }
    else {
        // Examine the request/response to see what happened.
        printf("response status code = %d\n",CkRest_getResponseStatusCode(rest));
        printf("response status text = %s\n",CkRest_responseStatusText(rest));
        printf("response header: %s\n",CkRest_responseHeader(rest));
        printf("response body: %s\n",responseStr);
        printf("---\n");
        printf("LastRequestStartLine: %s\n",CkRest_lastRequestStartLine(rest));
        printf("LastRequestHeader: %s\n",CkRest_lastRequestHeader(rest));
    }



    CkCrypt2_Dispose(crypt);
    CkRest_Dispose(rest);
    CkAuthAws_Dispose(authAws);
    CkStream_Dispose(fileStream);

    }