Ethereum Eth Call

eth_call executes a new message call immediately without creating a transaction on the block chain.

include_once "../libraries/vendor/autoload.php";
$hosts = [""=>"",""=>"", ""=>"", ""=>"",
$blockParams = ['pending'=>'Pending','latest'=>'Latest', 'earliest'=>'Earliest'];

	try {
		if (!in_array($_POST['host'], array_keys($hosts))) {
			throw new Exception("Please provide valid host.");
		$url = $_POST['host'] . "/" . $_POST['path'];

		$ch = curl_init();
		$requestId = time();
		$params = [];
		$params['jsonrpc']= "2.0";
		$params['method'] = 'eth_call';
		$params['params'] = [["to" => $_POST['to'],"data" => $_POST['data']],$_POST['blockparam']];
		$params['id'] = $requestId;
		$req = json_encode($params);
		curl_setopt($ch, CURLOPT_URL,$url);
		curl_setopt($ch, CURLOPT_POST, 1);
		curl_setopt($ch, CURLOPT_POSTFIELDS,$req);
		curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
		curl_setopt($ch, CURLOPT_HTTPHEADER, ["Content-Type: application/json"]);

		$resp = curl_exec($ch);
		if ($resp === false) {
			throw new Exception("curl_exec return false.");
		if (strlen($err = @curl_error($ch)) > 0) {
			$errno = @curl_errno($ch);
			throw new Exception( "{$err} ({$errno})." );
		$result = json_decode($resp,true); 
		if ($result['id'] != $requestId) {
			throw new Exception("Invalid request id.");
		$result = $result['result'];
		curl_close ($ch);
	    <div class="alert alert-success">
			<h6 class="mt-3">Host</h6>
			<textarea class="form-control" rows="1" readonly><?php echo $url;?></textarea>
			<h6 class="mt-3">JSON-RPC Request</h6>
			<textarea class="form-control" rows="5" id="comment" readonly><?php echo $req;?></textarea>
			<h6 class="mt-3">JSON-RPC Response</h6>
			<textarea class="form-control" rows="1" id="comment" readonly><?php echo $resp;?></textarea>
			<small>Result can be parse by <a href="eth_abi.php" target="_blank">Ethereum ABI decoder</a> and turn into human readable form.</small>
	} catch (Exception $e) {
		$errmsg .= "Problem found. " . $e->getMessage();

if ($errmsg) {
    <div class="alert alert-danger">
        <strong>Error!</strong> <?php echo $errmsg?>

<form id='this_form' action='?action=submit' method='post'>

	<div class="form-group">
		<label for="host">Host To Receive RPC:</label>
		<div class="input-group mb-3">
			<select id="host" name="host" class="form-control" >
			foreach($hosts as $k=>$v) {
				echo "<option value='{$k}'".($k == $_POST['host'] ? " selected": "").">{$v}</option>";
			<div class="input-group-append">
				<span class="input-group-text">
			<input class="form-control" type='text' name='path' id='path' value='<?php echo $_POST['path']?>' placeholder="Put extra path or blank if it does not.">
	<div class="form-group">
		<label for="blockparam">Block Parameter:</label>
		<select id="blockparam" name="blockparam" class="form-control" >
			foreach($blockParams as $k=>$v) {
				echo "<option value='{$k}'".($k == $_POST['blockparam'] ? " selected": "").">{$v}</option>";
    <div class="form-group">
        <label for="to">To:</label>
        <input class="form-control" type='text' name='to' id='to' value='<?php echo $_POST['to']?>' placeholder='Contract Address'>
	<div class="form-group">
        <label for="data">Data (Hex):</label>
        <input class="form-control" type='text' name='data' id='data' value='<?php echo $_POST['data']?>'>
		<small>You can get this data through <a href="eth_abi.php" target="_blank">Ethereum ABI encoder</a>.</small>
    <input type='submit' class="btn btn-success btn-block"/>

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