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5.11 How do I make libcurl not receive the whole HTTP response?
You make the write callback (or progress callback) return an error and
libcurl will then abort the transfer.
5.12 Can I make libcurl fake or hide my real IP address?
No. libcurl operates on a higher level than so. Besides, faking IP address
would imply sending IP packages with a made-up source address, and then you
normally get a problem with intercepting the packages sent back as they
would then not be routed to you!
If you use a proxy to access remote sites, the sites will not see your local
IP address but instead the address of the proxy.
Also note that on many networks NATs or other IP-munging techniques are used
that makes you see and use a different IP address locally than what the
remote server will see you coming from.
Curl and libcurl are released under a MIT/X derivate license. The license is
very liberal and should not impose a problem for your project. This section
is just a brief summary for the cases we get the most questions. (Parts of
this section was much enhanced by Bjorn Reese.)
We are not lawyers and this is not legal advice. You should probably consult
one if you want true and accurate legal insights without our prejudice.
6.1 I have a GPL program, can I use the libcurl library?
Since libcurl may be distributed under the MIT/X derivate license, it can be
used together with GPL in any software.
6.2 I have a closed-source program, can I use the libcurl library?
libcurl does not put any restrictions on the program that uses the library.
6.3 I have a BSD licensed program, can I use the libcurl library?
libcurl does not put any restrictions on the program that uses the library.
6.4 I have a program that uses LGPL libraries, can I use libcurl?
The LGPL license doesn't clash with other licenses.
6.5 Can I modify curl/libcurl for my program and keep the changes secret?
The MIT/X derivate license practically allows you to do almost anything with
the sources, on the condition that the copyright texts in the sources are
left intact.
6.6 Can you please change the curl/libcurl license to XXXX?
We have carefully picked this license after years of development and
discussions and a large amount of people have contributed with source code
knowing that this is the license we use. This license puts the restrictions
we want on curl/libcurl and it does not spread to other programs or
libraries that use it. It should be possible for everyone to use libcurl or
curl in their projects, no matter what license they already have in use.
6.7 What are my obligations when using libcurl in my commerical apps?
Next to none. All you need to adhere to is the MIT-style license (stated in
the COPYING file) which basically says you have to include the copyright
notice in "all copies" and that you may not use the copyright holder's name
when promoting your software.
You do not have to release any of your source code.
You do not have to reveal or make public any changes to the libcurl source
code.
You do not have to reveal or make public that you are using libcurl within
your app.
As can be seen here: http://curl.haxx.se/docs/companies.html and
elsewhere, more and more companies are dicovering the power
of libcurl and take advantage of it even in commercial environments.
7. PHP/CURL Issues
7.1 What is PHP/CURL?
The module for PHP that makes it possible for PHP programs to access curl-
functions from within PHP.
In the cURL project we call this module PHP/CURL to differentiate it from
curl the command line tool and libcurl the library. The PHP team however
does not refer to it like this (for unknown reasons). They call it plain
CURL (often using all caps) which causes much confusion to users which in
turn gives us a higher question load.
7.2 Who write PHP/CURL?
PHP/CURL is a module that comes with the regular PHP package. It depends and
uses libcurl, so you need to have libcurl installed properly first before
PHP/CURL can be used. PHP/CURL is written by Sterling Hughes.
7.3 Can I perform multiple requests using the same handle?
Yes - at least in PHP version 4.3.8 and later (this has been known to not
work in earlier versions, but the exact version when it started to work is
unknown to me).
After a transfer, you just set new options in the handle and make another
transfer. This will make libcurl to re-use the same connection if it can.