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40 ” cURL Extension • CURLOPT_RETURNTRANSFER is set to true in the curl_setopt_array call even though the return value of curl_exec isn’t captured. This is simply to prevent unwanted output. • CURLINFO_HEADER_OUT is set to true in the curl_setopt_array call to indicate that the request should be retained because it will be extracted after the request is made. • CURLINFO_HEADER_OUT is specified in the curl_getinfo call to limit its return value to a string containing the request that was made. Cookies H ere is a quick list of pertinent points. • After the first curl_exec call, cURL will have stored the value of the the Set-Cookie response header returned by the server in the file referenced by ’/path/to/file’ on the local filesystem as per the CURLOPT_COOKIEJAR setting. This setting value will persist through the second curl_exec call. • When the second curl_exec call takes place, the CURLOPT_COOKIEFILE setting will also point to ’/path/to/file’. This will cause cURL to read the contents of
cURL Extension ” 41 that file and use it as the value for the Cookie request header when the request is constructed. • If $cookiejar is set to an empty string, cookie data will persist in memory rather than a local file. This impro ves performance (memory access is faster than disk) and security (file storage may be more open to access by other users and processes than memory depending on the server environment). In some instances it may be desirable for the CURLOPT_COOKIEJAR value to have a different value per request, such as for debugging. In most cases, ho wever, CURLOPT_COOKIEJAR will be set for the first request to receive the initial cookie data and its value will persist for subsequent requests. In most cases, CURLOPT_COOKIEFILE will be assigned the same value as CURLOPT_COOKIEJAR after the first request. This will result in cookie data being read to include in the request, follo wed by cookie data from the response being written back (and o verwriting any existing data at that location) for use in subsequent requests. On a related note, if you want cURL to begin a new session in order to have it discard data for session cookies (i.e. cookies without an expiration date), you can set the CURLOPT_COOKIESESSION setting to true. If you want to handle cookie data manually for any reason, you can set the value of the Cookie request header via the CURLOPT_COOKIE setting. To get access to the response headers, set the CURLOPT_HEADER and CURLOPT_RETURNTRANSFER settings to true. This will cause the curl_exec call to return the entire response including the headers and the body. Recall that there is a single blank line between the headers and the body and that a colon separates each header name from its corresponding value. This information combined with the basic string handling functions in PHP should be all you need. Also , you ’ll need to set CURLOPT_FOLLOWLOCATION to false in order to prevent cURL from processing redirections automatically. N ot doing this would cause any cookies set by requests resulting in redirections to be lost. HTTP A uthentication cURL supports both Basic and Digest HTTP authentication methods, among others. The CURLOPT_HTTPAUTH setting controls the method to use and is set using constants such as CURLAUTH_BASIC or CURLAUTH_DIGEST. The CURLOPT_USERPWD setting is a string
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vi ” CONTENTS Referring URLs . .
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