Path: csiph.com!usenet.pasdenom.info!weretis.net!feeder4.news.weretis.net!rt.uk.eu.org!newsfeed.xs4all.nl!newsfeed4.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Date: Sun, 28 Jul 2013 17:44:22 +0200 From: Luuk User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 Newsgroups: comp.lang.php,comp.databases.mysql Subject: Re: is mysqli_real_escape_string bullet proof with binary data? References: <874nbf6981.fsf@silissia.kaiyou.fr> <0vodca-nlt.ln1@luuk.invalid.lan> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Message-ID: Lines: 99 NNTP-Posting-Host: 2001:980:9089:1:8454:be87:7d27:4050 X-Trace: 1375026302 news.xs4all.nl 15941 [2001:980:9089:1:8454:be87:7d27:4050]:42107 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.php:10278 comp.databases.mysql:3943 On 28-07-2013 01:50, The Natural Philosopher wrote: > On 27/07/13 21:59, Luuk wrote: >> On 27-07-2013 22:25, Pierre Jaury wrote: >>> Denis McMahon writes: >>> >>>> On Sat, 27 Jul 2013 11:45:50 +0200, Luuk wrote: >>>> >>>>> On 27-07-2013 11:31, The Natural Philosopher wrote: >>>> >>>>>> The target is to create and store thumbnail PNG images in a Mysql >>>>>> table. >>>> >>>>> As far as the subject goes, i would say: >>>>> DO NOT TOUCH binary data..... >>>>> Simply store it, or not, in your database..... >>>> >>>> Is it trying to store binary data as character data, or does it >>>> think it >>>> needs to string escape binary data types? >>> >>> Escaping strings is a concept only useful when building request strings >>> that include user supplied data. It does avoid concatenating strings >>> whith special/control characters that may interfere with the original >>> language. There is no need to escape strings if you do not embed >>> them inside your request string (eg. if you use bound parameters). >>> >>> This is true when dealing with SQL (write prepared statements without >>> including any user supplied data, then bind the parameters), bash >>> commands that only require one exec (use exec* instead of system), and >>> pretty much in any case you construct interpreted code at runtime. >>> >>> Data sent to MySQL as bound parameters in prepared statements is >>> shipped as is, it not escaped or processed in any way before the >>> MySQL API structures are filled with it. Now, for your binary data >>> to be handled as is by the MySQL server (and skip the charset >>> processing), the parameter must be bound as MYSQL_TYPE_BLOB, which >>> you may control when using bind_param. >>> >>> See http://fr2.php.net/manual/fr/mysqli-stmt.bind-param.php and the >>> "b" (as in binary) flag for details. >>> >> >> Ok, the code i posted earlier in this thread is also posted here: >> http://pastebin.com/5D8ZGEhy >> >> Whn using 'bind_param' i choose to use 's' as in string, and not 'b' >> for blob/binary. >> >> The code stores an exact (binary) copy of the file in a MySQL database. >> >> When the 's' in bind_param is changed to 'b', it does not store an >> exact binary copy of the file.... >> > Why not? > >> [root@test]> select id, left(hex(image),64) from testpng where id=1; >> +----+------------------------------------------------------------------+ >> | id | left(hex(image),64) | >> +----+------------------------------------------------------------------+ >> | 1 | 89504E470D0A1A0A0000000D49484452000000090000000A0806000000660574 | >> +----+------------------------------------------------------------------+ >> 1 row in set (0.00 sec) >> >> [root@test]> \! hexdump -C upArrow.png | head -2 >> 00000000 89 50 4e 47 0d 0a 1a 0a 00 00 00 0d 49 48 44 52 >> |.PNG........IHDR| >> 00000010 00 00 00 09 00 00 00 0a 08 06 00 00 00 66 05 74 >> |.............f.t| >> [root@test]> >> >> I'm not sure how >> "Data sent to MySQL as bound parameters in prepared statements is >> shipped as is, it not escaped or processed in any way before the >> MySQL API structures are filled with it." >> and >> "Now, for your binary data to be handled as is by the MySQL server >> (and skip the charset processing), the parameter must be bound as >> MYSQL_TYPE_BLOB, which you may control when using bind_param." >> relate to each other... >> > The meaning is clear: provided you tell the API what it is to expect, it > will not be processed in ways that do not apply to the object type. > > But you contradict that, by saying that binding it as binary does in > fact get processed and only as a string will it be passed unaltered. > I was not trying to contradict anything. I was reading the post (from Pierre) and was under the impression that i SHOULD use 'b' in bind_param. I was using 's' in bind_param, and my testprog works ok These 2 lines made /me confused ;) > I'd really like to know why.. > Me likes to know why to