mirror of
https://github.com/moparisthebest/curl
synced 2024-12-23 00:28:48 -05:00
135 lines
5.1 KiB
Markdown
135 lines
5.1 KiB
Markdown
# HTTP Cookies
|
|
|
|
## Cookie overview
|
|
|
|
Cookies are `name=contents` pairs that a HTTP server tells the client to
|
|
hold and then the client sends back those to the server on subsequent
|
|
requests to the same domains and paths for which the cookies were set.
|
|
|
|
Cookies are either "session cookies" which typically are forgotten when the
|
|
session is over which is often translated to equal when browser quits, or
|
|
the cookies aren't session cookies they have expiration dates after which
|
|
the client will throw them away.
|
|
|
|
Cookies are set to the client with the Set-Cookie: header and are sent to
|
|
servers with the Cookie: header.
|
|
|
|
For a very long time, the only spec explaining how to use cookies was the
|
|
original [Netscape spec from 1994](https://curl.se/rfc/cookie_spec.html).
|
|
|
|
In 2011, [RFC6265](https://www.ietf.org/rfc/rfc6265.txt) was finally
|
|
published and details how cookies work within HTTP. In 2016, an update which
|
|
added support for prefixes was
|
|
[proposed](https://tools.ietf.org/html/draft-ietf-httpbis-cookie-prefixes-00),
|
|
and in 2017, another update was
|
|
[drafted](https://tools.ietf.org/html/draft-ietf-httpbis-cookie-alone-01)
|
|
to deprecate modification of 'secure' cookies from non-secure origins. Both
|
|
of these drafts have been incorporated into a proposal to
|
|
[replace](https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-02)
|
|
RFC6265. Cookie prefixes and secure cookie modification protection has been
|
|
implemented by curl.
|
|
|
|
## Cookies saved to disk
|
|
|
|
Netscape once created a file format for storing cookies on disk so that they
|
|
would survive browser restarts. curl adopted that file format to allow
|
|
sharing the cookies with browsers, only to see browsers move away from that
|
|
format. Modern browsers no longer use it, while curl still does.
|
|
|
|
The netscape cookie file format stores one cookie per physical line in the
|
|
file with a bunch of associated meta data, each field separated with
|
|
TAB. That file is called the cookiejar in curl terminology.
|
|
|
|
When libcurl saves a cookiejar, it creates a file header of its own in which
|
|
there is a URL mention that will link to the web version of this document.
|
|
|
|
## Cookie file format
|
|
|
|
The cookie file format is text based and stores one cookie per line. Lines
|
|
that start with `#` are treated as comments.
|
|
|
|
Each line that each specifies a single cookie consists of seven text fields
|
|
separated with TAB characters. A valid line must end with a newline
|
|
character.
|
|
|
|
### Fields in the file
|
|
|
|
Field number, what type and example data and the meaning of it:
|
|
|
|
0. string `example.com` - the domain name
|
|
1. boolean `FALSE` - include subdomains
|
|
2. string `/foobar/` - path
|
|
3. boolean `TRUE` - send/receive over HTTPS only
|
|
4. number `1462299217` - expires at - seconds since Jan 1st 1970, or 0
|
|
5. string `person` - name of the cookie
|
|
6. string `daniel` - value of the cookie
|
|
|
|
## Cookies with curl the command line tool
|
|
|
|
curl has a full cookie "engine" built in. If you just activate it, you can
|
|
have curl receive and send cookies exactly as mandated in the specs.
|
|
|
|
Command line options:
|
|
|
|
`-b, --cookie`
|
|
|
|
tell curl a file to read cookies from and start the cookie engine, or if it
|
|
isn't a file it will pass on the given string. -b name=var works and so does
|
|
-b cookiefile.
|
|
|
|
`-j, --junk-session-cookies`
|
|
|
|
when used in combination with -b, it will skip all "session cookies" on load
|
|
so as to appear to start a new cookie session.
|
|
|
|
`-c, --cookie-jar`
|
|
|
|
tell curl to start the cookie engine and write cookies to the given file
|
|
after the request(s)
|
|
|
|
## Cookies with libcurl
|
|
|
|
libcurl offers several ways to enable and interface the cookie engine. These
|
|
options are the ones provided by the native API. libcurl bindings may offer
|
|
access to them using other means.
|
|
|
|
`CURLOPT_COOKIE`
|
|
|
|
Is used when you want to specify the exact contents of a cookie header to
|
|
send to the server.
|
|
|
|
`CURLOPT_COOKIEFILE`
|
|
|
|
Tell libcurl to activate the cookie engine, and to read the initial set of
|
|
cookies from the given file. Read-only.
|
|
|
|
`CURLOPT_COOKIEJAR`
|
|
|
|
Tell libcurl to activate the cookie engine, and when the easy handle is
|
|
closed save all known cookies to the given cookiejar file. Write-only.
|
|
|
|
`CURLOPT_COOKIELIST`
|
|
|
|
Provide detailed information about a single cookie to add to the internal
|
|
storage of cookies. Pass in the cookie as a HTTP header with all the details
|
|
set, or pass in a line from a netscape cookie file. This option can also be
|
|
used to flush the cookies etc.
|
|
|
|
`CURLINFO_COOKIELIST`
|
|
|
|
Extract cookie information from the internal cookie storage as a linked
|
|
list.
|
|
|
|
## Cookies with javascript
|
|
|
|
These days a lot of the web is built up by javascript. The webbrowser loads
|
|
complete programs that render the page you see. These javascript programs
|
|
can also set and access cookies.
|
|
|
|
Since curl and libcurl are plain HTTP clients without any knowledge of or
|
|
capability to handle javascript, such cookies will not be detected or used.
|
|
|
|
Often, if you want to mimic what a browser does on such websites, you can
|
|
record web browser HTTP traffic when using such a site and then repeat the
|
|
cookie operations using curl or libcurl.
|