s3SimpleUpload.php is a standalone (no AWS SDK), intentionally verbose, upload only S3 class utilizing the AWS API, Signature Version 4.

s3SimpleUpload.php

<?php

/*
ABSTRACT

	s3SimpleUpload.php is a standalone (no AWS SDK), intentionally verbose, upload only S3 class utilizing the AWS API, Signature Version 4.
	
	Options include defining the s3_prefix path, regardless of the origination path, or using the source file's origination prefix path (default).

USAGE

	Works with remote files, e.g.:
	$file_path = 'https://www.google.com/robots.txt'
	
	Example generating remote testing images on the fly with dummyimage.com:
	$file_path = '/301.png' ; // set size of resulting image
	$file_path = '/305/999/blah.png' ; // set size/color/name of resulting image
	$file_path = 'https://dummyimage.com'.$file_path ;
	
	Works with local files, e.g.:
	$file_path = /tmp/myimage.jpg
	$file_path = /tmp/some/path/myimage.jpg
	
	S3 prefix path configuration options:
	$s3_prefix = '';		// null|empty|false: The resulting bucket s3_prefix will match its origination
	$s3_prefix - '/'		// Uploaded to defined path (root in this case), regardless of origination
	$s3_prefix = 'this/is/a/path/';	// Uploaded to defined path, regardless of origination
	
	S3 configuration example:
	s3SimpleUpload::$key='KAIATMRL6QMWQKZFXZ7U';
	s3SimpleUpload::$secret='x5QmHhEv9qTBe76sM0Uwul8joS47uFqcooxLTBgq'; 
	s3SimpleUpload::$bucket='myspecialbucket';
	s3SimpleUpload::$acl="public-read"; // public-read is default (see class config note)
	s3SimpleUpload::$print_log=true;

	$result = s3SimpleUpload::uploadFile($file_path,$s3_prefix);
	
	echo '<pre>'; echo($res); echo '</pre>';
	
	Author: Eric Pecoraro
	License: Unlicense (https://unlicense.org/)
	Comments/questions (via Gist): https://gist.github.com/EricP/a5f6e94b62d9a5efded5eb218be661a6
	
	Test cases:
	$file_path = '/250.png' ;
	$file_path = '/250/999/file.png' ;
	$file_path = 'https://dummyimage.com'.$file_path ; // Dynamically create remote file
	if ( !strstr($file_path,'//') ) {
		$file_path = sys_get_temp_dir().$file_path; // Uncomment dummyimage.com & use locally created file
	}
	$s3_prefix = '/';
	$s3_prefix = false;
	$s3_prefix = '/a/path/to/the/';
	$res = s3SimpleUpload::uploadFile($file_path,$s3_prefix);
	echo '<pre>'; echo($res); echo '</pre>';	

*/

class s3SimpleUpload {

	// Available configurations/defaults.
	public static $key = '';
	public static $secret = '';
	public static $region = 'us-east-1';
	public static $bucket = '';
	public static $host = 's3.amazonaws.com';
	// ACL: public-read|private|bucket-owner-full-control (more:https://docs.aws.amazon.com/cli/latest/reference/s3api/put-object-acl.html)
	public static $acl = 'public-read'; 
	public static $print_log = false;
	
	public static function uploadFile($file_path,$s3_prefix=null) {
		
		$log="\n";
		$default_timezone = date_default_timezone_get();
		date_default_timezone_set('UTC');
		
		$file_name = basename($file_path);
		$file_contents = file_get_contents($file_path); // Payload
		
		$remote=false;
		if ( strstr($file_path,'//') ) {
			$remote = true;
		}
		$prefix=false;
		if ( strlen($s3_prefix)>0 ) {
			$prefix = true;
		}
		if ( $s3_prefix === true ) {
			$s3_prefix = null;
		}
		
		// Upload remote file, with existing remote path.
		if ( $remote && !$prefix ) {
			$local_path = sys_get_temp_dir().parse_url($file_path,PHP_URL_PATH);
			$local_dir = dirname($local_path);
			if ( !is_dir($local_dir) ) {
				mkdir( $local_dir, 0777, true );
			}
			file_put_contents($local_path,$file_contents);
			$s3_prefix = dirname( parse_url($file_path,PHP_URL_PATH) );
			$s3_prefix = trim($s3_prefix,'/').'/'; // trailing slash
			$file_path = str_replace('//','/',$local_path); // define local
		}

		// Upload remote file with defined s3_prefix.
		if ( $remote && $prefix ) {
			$local_dir = sys_get_temp_dir().'/'.trim($s3_prefix,'/');
			if ( !is_dir($local_dir) ) {
				mkdir( $local_dir, 0777, true );
			}
			$s3_prefix = trim($s3_prefix,'/').'/';
			$file_path = str_replace('//','/',$local_dir.'/'.$file_name); // define local
			file_put_contents($file_path,$file_contents);
		}
		
		// Upload local file, with existing path.
		if ( !$remote && !$prefix ) {
			$local_dir = dirname($file_path);
			$s3_prefix = ltrim($local_dir,sys_get_temp_dir()); // Remove system tmp dir
			$s3_prefix = trim($s3_prefix,'/').'/'; // + trailing slash
		}
		
		// Upload local file, with defined s3_prefix.
		if ( !$remote && $prefix ) {
			$s3_prefix = trim($s3_prefix,'/').'/';
		}

		if ( $s3_prefix == '/' ) {
			$s3_prefix = null; // Bucket root
		}
		
		if ( !realpath($file_path) ) {
			echo "Local file does not exist ".print_r($file_path,true)."\n";
			return;
		}

		$log.= "<hr>file_path: ".print_r($file_path,true)."\n";
		$log.= "<hr>s3_prefix: ".print_r($s3_prefix,true)."\n";
		
		$hashed_payload = hash('sha256', $file_contents);
		
		$file_type = mime_content_type($file_path);
		if ( empty($file_type) ) {
			// fallback if mime_content_type() unavailable
			$file_type = exec("file -bi '".$file_path."'");
		}
		
		$log.= "<hr>file_type: ".print_r($file_type,true)."\n";

		$date_full = date('D, d M Y H:i:s \G\M\T'); // @todo don't force GMT!
		$date_time = date('Ymd\THisZ'); // @todo don't force Z!
		$date = date('Ymd');

		// Set headers.
		$headers = array(
			'Host' => self::$bucket . '.' . self::$host,
			'Content-Type' => $file_type,
			'x-amz-content-sha256' => $hashed_payload,
			'x-amz-date' => $date_full,
			'x-amz-acl' => self::$acl
		);
		ksort($headers);
		$signed_headers_string = strtolower(implode(';', array_keys($headers)));

		// Build canonical request.
		$canonical_request = "PUT\n"; // HTTP Method
		$canonical_request .= '/' . $s3_prefix.$file_name . "\n"; // Canonical uri
		$canonical_request .= "\n"; // CanonicalQueryString
		foreach ($headers as $header => $value) {
			$canonical_request .= strtolower($header) . ':' . trim($value) . "\n";
		}
		$canonical_request .= "\n";
		$canonical_request .= $signed_headers_string . "\n"; // SignedHeaders
		$canonical_request .= $hashed_payload; // HashedPayload
		$log.= "<hr>canonical_request: ".print_r($canonical_request,true)."\n";

		// Build string to sign.
		$string_to_sign = "AWS4-HMAC-SHA256\n";
		$string_to_sign .= $date_full . "\n";
		$string_to_sign .= $date . '/' . self::$region . "/s3/aws4_request\n";
		$string_to_sign .= hash('sha256', $canonical_request);
		$log.= "<hr>string_to_sign: ".print_r($string_to_sign,true)."\n";

		// Calculate signature.
		$signature_date = hash_hmac('sha256', $date, 'AWS4' . self::$secret, true);
		$signature_region = hash_hmac('sha256', self::$region, $signature_date, true);
		$signature_service = hash_hmac('sha256', 's3', $signature_region, true);
		$signature_request = hash_hmac('sha256', 'aws4_request', $signature_service, true);
		$signature = hash_hmac('sha256', $string_to_sign, $signature_request);

		// Calculate final `Authorization` header.
		$headers['Authorization'] = 'AWS4-HMAC-SHA256 Credential=' . self::$key . '/' . $date . '/' . self::$region . '/s3/aws4_request,';
		$headers['Authorization'] .= 'SignedHeaders=' . $signed_headers_string . ',';
		$headers['Authorization'] .= 'Signature=' . $signature;
		$log.= "<hr>Authorization: ".print_r($headers,true)."\n";

		// Convert headers to key:value strings.
		$curl_headers = array();
		foreach ($headers as $header => $value) {
			$curl_headers[] = "{$header}:{$value}";
		}

		// Init curl.
		$curl = curl_init();
		$url = 'https://' . self::$bucket . '.' . self::$host . '/' . $s3_prefix.$file_name ;
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 0);
		curl_setopt($curl, CURLOPT_URL, $url);
		curl_setopt($curl, CURLOPT_VERBOSE, 1);
		curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'PUT');
		curl_setopt($curl, CURLINFO_HEADER_OUT, true);
		curl_setopt($curl, CURLOPT_HEADER, true);
		curl_setopt($curl, CURLOPT_HTTPHEADER, $curl_headers);
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
		curl_setopt($curl, CURLOPT_POSTFIELDS, $file_contents);

		// Run request.
		if ($result = curl_exec($curl)) {
		
			$res = "<hr>Curl Success:"."\n";
			
			$curl_info = curl_getinfo($curl, CURLINFO_HTTP_CODE);
			$headers_sent = curl_getinfo($curl, CURLINFO_HEADER_OUT);
			
			$res.= "<hr>curl_info: ".print_r($curl_info,true)."\n";
			$res.= "<hr>result: ".print_r($result,true)."\n";
			$res.= "<hr>headers_sent: ".print_r($headers_sent,true)."\n";
			
			//$site = 'https://' . self::$bucket . '/' . $s3_prefix.$file_name; // if hosting bucket as s3 website
			$site = 'https://' . self::$bucket . '.' . self::$host . '/' . $s3_prefix.$file_name ; // direct uri link
			$site = '<br><br>Site &rarr; <a href="'.$site.'" target="_blank">'.$site.'</a><br><br>';
			
		}
		else {
			$res = "<hr>Curl Error:"."\n";
			$res.= "<hr>curl_errno: ".print_r(curl_errno($curl),true)."\n";
			$res.= "<hr>curl_errno: ".print_r(curl_error($curl),true)."\n";
		}
		
		if ( self::$print_log ) {
			echo $site;
			echo '<pre>'; echo($log); echo '</pre>';
		}
		
		return $res;
	
		@curl_close($curl);
		date_default_timezone_set($default_timezone);
	}
}