(C) Generate an AWS (S3) Pre-Signed URL to Download File

Demonstrates how to generate a pre-signed URL to download a file from the Amazon S3 service.

Note: This example requires Chilkat v11.0.0 or greater.

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#include <C_CkHttp.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkHttp http;
    const char *bucketName;
    const char *objectName;
    const char *localFilePath;
    const char *awsService;
    int numSecondsValid;
    BOOL bUseHttps;
    const char *preSignedUrl;

    success = FALSE;

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

    http = CkHttp_Create();

    CkHttp_putAwsAccessKey(http,"AWS_ACCESS_KEY");
    CkHttp_putAwsSecretKey(http,"AWS_SECRET_KEY");

    // Make sure to set your AWS region correctly
    CkHttp_putAwsRegion(http,"us-east-1");

    bucketName = "chilkat100";
    objectName = "starfish/starfish.jpg";
    localFilePath = "qa_output/starfish.jpg";
    awsService = "s3";

    // The signed URL will be valid for this number of seconds:
    numSecondsValid = 86400;

    // Choose between a URL beginning with "http://" or "https://"...
    bUseHttps = FALSE;

    // Generate the pre-signed URL
    preSignedUrl = CkHttp_s3_GenPresignedUrl(http,"GET",bUseHttps,bucketName,objectName,numSecondsValid,awsService);
    if (CkHttp_getLastMethodSuccess(http) == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        return;
    }

    // The following URL can be copy-and-pasted into a browser..
    printf("Pre-Signed AWS S3 URL: %s\n",preSignedUrl);

    // Here's an example of a pre-signed URL. 
    // This URL will only work within 1 day (86400 seconds) after the time this example was published.
    // 
    //     http://chilkat100.s3.amazonaws.com/starfish/starfish.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=16QXXDGY83AJJR6RVQ02%2F20170111%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20170111T161959Z&X-Amz-Expires=86400&X-Amz-SignedHeaders=host&X-Amz-Signature=72bf4fd9a15d7bbcdd313a3318d937a778905f62a3fbff9b789d8dc28acd9232

    // Now try to do an HTTP Download using the signed URL.
    success = CkHttp_Download(http,preSignedUrl,"c:/temp/qa_output/starfish.jpg");
    if (success == FALSE) {
        printf("%s\n",CkHttp_lastErrorText(http));
        CkHttp_Dispose(http);
        return;
    }

    printf("Success.\n");


    CkHttp_Dispose(http);

    }