Using MySQL C API inside varnish

[Ken Brownfield]

mysql_fetch_row() returns NULL for no rows.  Your unused "char *limit =
row[0]" will fault immediately (row==NULL).
-- 
kb

On Tue, Jul 26, 2011 at 17:50, Roberto Moutinho
<robertomoutinho at gmail.com>wrote:

> Hello,
>
> As I said on an earlier thread... I'm trying to adapt varnish to
> authenticate users for my website API and I'm bumping into some troubles...
>
> I receive a header named x-api-key on every request made to the API and I
> need to authenticate those api keys before I start delivering cached content
> to my clients.
>
> I start with a variable that receive the value of *VRT_GetHdr(sp, HDR_REQ,
> "\012X-API-Key:")*  and I would like to consult my database to find out if
> this key is valid.
>
> So I started writing a little C code to do it...
>
> *unsigned int num_rows;
> MYSQL *conn;
> MYSQL_RES *result;
> MYSQL_ROW row;
> conn = mysql_init(NULL);
> mysql_real_connect(conn, "Server IP", "username", "password", "database",
> 0, NULL, 0);
> mysql_query(conn, query);
> result = mysql_store_result(conn);
> num_rows = mysql_num_rows(result);
> row = mysql_fetch_row(result);
> char *limit = row[0];
> if (num_rows == 0) {
>    VRT_error(sp, 403, "Forbidden");
>    VRT_done(sp, VCL_RET_ERROR);
> }
> mysql_free_result(result);
> mysql_close(conn);
> }*
>
> If the databse return no rows for the key provided on the request that
> means that the key is invalid and I should return a 403 forbidden to the
> client.
>
> The C code works perfectly when compiled with GCC on ubuntu/centos and also
> compile inside the VCL.
>
> My daemon startup options are (staging server):
>
> *varnishd -s malloc,1G -T 127.0.0.1:2000 -P /www/varnishd.pid -f
> /etc/varnish/default.vcl -p 'cc_command=exec cc -fpic -shared -Wl,-x
> -L/usr/local/include/libmemcached/memcached.h -L/usr/lib64/mysql
> -lmysqlclient -lmemcached -o %o %s' -p 'cli_timeout=10' -p
> 'thread_pool_max=5000' -p 'thread_pools=4' -p 'thread_pool_min=200' -p
> 'thread_pool_add_delay=1ms' -p 'cli_timeout=1000s' -p 'ping_interval=1' -p
> 'cli_buffer=16384' -p 'session_linger=20ms' -p 'lru_interval=360s' -p
> 'listen_depth=8192' -h 'classic,500009';*
>
>
> and this is what I get from /var/log/messages:
>
> *Jul 25 19:59:09 api varnishd[6318]: child (6319) Started
> Jul 25 19:59:09 api varnishd[6318]: Child (6319) said
> Jul 25 19:59:09 api varnishd[6318]: Child (6319) said Child starts
> Jul 25 19:59:09 api varnishd[6318]: Child (6319) said managed to mmap
> 68230176768 bytes of 68230176768
> Jul 25 16:59:16 api kernel: varnishd[6726]: segfault at 0000000000000000
> rip 0000003839e6f0f1 rsp 00002abb50cb9d90 error 6
> Jul 25 19:59:17 api varnishd[6318]: Child (6319) died signal=11
> Jul 25 19:59:17 api varnishd[6318]: child (7128) Started
> Jul 25 19:59:17 api varnishd[6318]: Child (7128) said
> Jul 25 19:59:17 api varnishd[6318]: Child (7128) said Child starts
> Jul 25 19:59:17 api varnishd[6318]: Child (7128) said managed to mmap
> 68230176768 bytes of 68230176768*
>
>
> and if I start the daemon with a "-d -d" option I get this:
>
> *Varnish on Linux,2.6.18-194.el5,x86_64,-smalloc,-hcritbit
> 200 233
> -----------------------------
> Varnish Cache CLI 1.0
> -----------------------------
> Linux,2.6.18-194.el5,x86_64,-smalloc,-hcritbit
>
> Type 'help' for command list.
> Type 'quit' to close CLI session.
> Type 'start' to launch worker process.
>
> start
> child (13163) Started
> 200 0
> Child (13184) died signal=11
> Child cleanup complete
> child (13203) Started
> Child (13203) said
> Child (13203) said Child starts*
>
> I understand that signal 11 means that the program accessed a memory
> location that was not assigned...and probably died because of it.
> Is it really a bug in my code or am I doing something wrong in trying to
> make MySQL C API work with varnish ?
>
> ps: sorry for the long message.
>
>
>
>
> _______________________________________________
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> varnish-misc at varnish-cache.org
> https://www.varnish-cache.org/lists/mailman/listinfo/varnish-misc
>
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