You can write webbots that support cookies without using PHP/CURL, but doing so adds to the complexity of your designs. Without PHP/CURL, you'll have to read each returned HTTP header, parse the cookies, and store them for later use. You will also have to decide which cookies to send to which domains, manage expiration dates, and return everything correctly in headers of page requests. PHP/CURL does all this for you, automatically. Even with PHP/CURL, however, cookies pose challenges to webbot designers.

Fortunately, PHP/CURL does support cookies, and we can effectively use it to capture the cookies from the previous example, as shown in Listing 22-2.

include("LIB_http.php");
$target="http://www.schrenk.com/nostarch/webbots/EXAMPLE_writing_cookies.php";
http_get($target, "");

Listing 22-2: Reading cookies with PHP/CURL and the LIB_http library

LIB_http defines the file where PHP/CURL stores cookies. This declaration is done near the beginning of the file, as shown in Listing 22-3.

# Location of your cookie file (must be a fully resolved address)
define("COOKIE_FILE", "c:cookie.txt");

Listing 23-3: Cookie file declaration, as made in LIB_http

As noted in Listing 22-3, the address for a cookie file should be a fully resolved local one. Relative addresses sometimes work, but not for all PHP/CURL distributions. When you execute the scripts in Listing 22-1 (available at this book's website), PHP/CURL writes the cookies (in Netscape Cookie Format) in the file defined in the LIB_http configuration, as shown in Listing 22-4.

# Netscape HTTP Cookie File
# http://www.netscape.com/newsref/std/cookie_spec.html
# This file was generated by libcurl! Edit at your own risk.

www.schrenk.com  FALSE /nostarch/webbots/  FALSE  1159120749  PermanentCookie 88

www.schrenk.com  FALSE /nostarch/webbots/  FALSE  0  TemporaryCookie  66

Listing 22-4: The cookie file, as written by PHP/CURL