View Full Version : Problems with sessions / cookie ?- PHP

January 31st, 2008, 01:01 PM

a script I programmed is not working, I assume it has to do something with setting cookies and sessions.

For testing purposes I just created a sample script:


echo "<a href=\"index.php?".session_name()."=".session_id()."\">test</a>\n";

setcookie(session_name(), session_id(), time()+3600);

When I call the script on local host it produces:

Warning: Cannot modify header information - headers already sent by (output started at /home/ben2/public_html/sessiontest2.php:5) in /home/ben2/public_html/sessiontest2.php on line 9

Don't really know what to do now - maybe someone knows.

I have checked the php.ini - "session.auto_start = 0" should i change the value to 1 ?

; Handler used to store/retrieve data.
session.save_handler = files

; Argument passed to save_handler. In the case of files, this is the path
; where data files are stored. Note: Windows users have to change this
; variable in order to use PHP's session functions.
; As of PHP 4.0.1, you can define the path as:
; session.save_path = "N;/path"
; where N is an integer. Instead of storing all the session files in
; /path, what this will do is use subdirectories N-levels deep, and
; store the session data in those directories. This is useful if you
; or your OS have problems with lots of files in one directory, and is
; a more efficient layout for servers that handle lots of sessions.
; NOTE 1: PHP will not create this directory structure automatically.
; You can use the script in the ext/session dir for that purpose.
; NOTE 2: See the section on garbage collection below if you choose to
; use subdirectories for session storage
; The file storage module creates files using mode 600 by default.
; You can change that by using
; session.save_path = "N;MODE;/path"
; where MODE is the octal representation of the mode. Note that this
; does not overwrite the process's umask.
;session.save_path = /var/lib/php5

; Whether to use cookies.
session.use_cookies = 1

;session.cookie_secure =

; This option enables administrators to make their users invulnerable to
; attacks which involve passing session ids in URLs; defaults to 0.
; session.use_only_cookies = 1

; Name of the session (used as cookie name).
session.name = PHPSESSID

; Initialize session on request startup.
session.auto_start = 0

; Lifetime in seconds of cookie or, if 0, until browser is restarted.
session.cookie_lifetime = 0

; The path for which the cookie is valid.
session.cookie_path = /

; The domain for which the cookie is valid.
session.cookie_domain =

; Whether or not to add the httpOnly flag to the cookie, which makes it inaccessible to browser scripting languages such as JavaScript.
session.cookie_httponly =

; Handler used to serialize data. php is the standard serializer of PHP.
session.serialize_handler = php

; Define the probability that the 'garbage collection' process is started
; on every session initialization.
; The probability is calculated by using gc_probability/gc_divisor,
; e.g. 1/100 means there is a 1% chance that the GC process starts
; on each request.

; This is disabled in the Debian packages, due to the strict permissions
; on /var/lib/php5. Instead of setting this here, see the cronjob at
; /etc/cron.d/php5, which uses the session.gc_maxlifetime setting below
;session.gc_probability = 0
session.gc_divisor = 100

; After this number of seconds, stored data will be seen as 'garbage' and
; cleaned up by the garbage collection process.
session.gc_maxlifetime = 1440

; NOTE: If you are using the subdirectory option for storing session files
; (see session.save_path above), then garbage collection does *not*
; happen automatically. You will need to do your own garbage
; collection through a shell script, cron entry, or some other method.
; For example, the following script would is the equivalent of
; setting session.gc_maxlifetime to 1440 (1440 seconds = 24 minutes):
; cd /path/to/sessions; find -cmin +24 | xargs rm

; PHP 4.2 and less have an undocumented feature/bug that allows you to
; to initialize a session variable in the global scope, albeit register_globals
; is disabled. PHP 4.3 and later will warn you, if this feature is used.
; You can disable the feature and the warning separately. At this time,
; the warning is only displayed, if bug_compat_42 is enabled.

session.bug_compat_42 = 1
session.bug_compat_warn = 1

; Check HTTP Referer to invalidate externally stored URLs containing ids.
; HTTP_REFERER has to contain this substring for the session to be
; considered as valid.
session.referer_check =

; How many bytes to read from the file.
session.entropy_length = 0

; Specified here to create the session id.
session.entropy_file =

;session.entropy_length = 16

;session.entropy_file = /dev/urandom

; Set to {nocache,private,public,} to determine HTTP caching aspects
; or leave this empty to avoid sending anti-caching headers.
session.cache_limiter = nocache

; Document expires after n minutes.
session.cache_expire = 180

; trans sid support is disabled by default.
; Use of trans sid may risk your users security.
; Use this option with caution.
; - User may send URL contains active session ID
; to other person via. email/irc/etc.
; - URL that contains active session ID may be stored
; in publically accessible computer.
; - User may access your site with the same session ID
; always using URL stored in browser's history or bookmarks.
session.use_trans_sid = 0

; Select a hash function
; 0: MD5 (128 bits)
; 1: SHA-1 (160 bits)
session.hash_function = 0

; Define how many bits are stored in each character when converting
; the binary hash data to something readable.
; 4 bits: 0-9, a-f
; 5 bits: 0-9, a-v
; 6 bits: 0-9, a-z, A-Z, "-", ","
session.hash_bits_per_character = 4

; The URL rewriter will look for URLs in a defined set of HTML tags.
; form/fieldset are special; if you include them here, the rewriter will
; add a hidden <input> field with the info which is otherwise appended
; to URLs. If you want XHTML conformity, remove the form entry.
; Note that all valid entries require a "=", even if no value follows.
url_rewriter.tags = "a=href,area=href,frame=src,input=src,form=,fieldse t="

January 31st, 2008, 01:13 PM
I found out, need to post set cookie first, header information needs to be sent before any output.

January 31st, 2008, 03:08 PM
You can use output controlling (http://ch2.php.net/manual/en/ref.outcontrol.php) if you need to generate ouput before sending the headers.

January 31st, 2008, 08:35 PM
You want to set the cookie, load the cookie, check for expiry and all that stuff before you echo anything. During those checks you can decide what page to show or whether or not to redirect the user to another page (such as a logout page if they have been idle too long etc).