Cannot use environment variables in modparam() function

[mbrodala]

Description

I tried to use the $env(NAME) pseudovariable as argument for modparam() calls but evidently the result was empty.

Troubleshooting

Reproduction

Set up auth_ephemeral and add this to your configuration:

modparam("auth_ephemeral", "secret", "$env(AUTH_EPHEMERAL_SECRET)")

Now export AUTH_EPHEMERAL_SECRET=something and start Kamailio with sufficient debug output. You'll see that Kamailio literally uses $env(AUTH_EPHEMERAL_SECRET) as secret instead of inserting the value of the environment variable.

Log Messages

kamailio_1  | 17(23) DEBUG: auth_ephemeral [authorize.c:136]: do_auth(): secret: $env(AUTH_EPHEMERAL_SECRET) (27)

Should be:

kamailio_1  | 17(23) DEBUG: auth_ephemeral [authorize.c:136]: do_auth(): secret: something (9)

Possible Solutions

Replacement of environment variables should be supported in modparams(). (And possibly in all functions.)

Additional Information

• Kamailio Version - output of kamailio -v

version: kamailio 5.2.1 (x86_64/linux) 
flags: STATS: Off, USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MEM, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLACKLIST, HAVE_RESOLV_RES
ADAPTIVE_WAIT_LOOPS=1024, MAX_RECV_BUFFER_SIZE 262144 MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB
poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.
id: unknown 
compiled with gcc 5.3.1

• Operating System:

$ uname -a
Linux e2193249aa45 4.4.0-128-generic #154-Ubuntu SMP Fri May 25 14:15:18 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

(Using the Docker image kamailio/kamailio:5.2.1-xenial ATM.)

[miconda]

This should be possible via:

#substdef "/MYENVSECRET/$env(AUTH_EPHEMERAL_SECRET)/"
modparam("auth_ephemeral", "secret", "MYENVSECRET")

There is another alternative to use command line parameters to set defined values or substdef rules, see kamailio -h.

Note that you may have to use kamailio 5.3.x for some of the above.

I am going to close this one, having alternatives for it. If one wants to implement direct evaluation in modparams, then just do a pull request.

[mbrodala]

I finally got around to test this but it seems I'm doing something wrong:

#!substdef "/DBRWUSER/$env(DBRWUSER)/g"
#!substdef "/DBRWPW/$env(DBRWPW)/g"
#!substdef "/DBHOST/$env(DBHOST)/g"
#!substdef "/DBNAME/$env(DBNAME)/g"

#!define DBURL "mysql://DBRWUSER:DBRWPW@DBHOST/DBNAME"

Now trying to start Kamailio (5.3.3 as suggested) fails:

kamailio_1  |  0(1) ERROR: <core> [core/pvapi.c:923]: pv_parse_spec2(): error searching pvar "env"
kamailio_1  |  0(1) ERROR: <core> [core/pvapi.c:1126]: pv_parse_spec2(): wrong char [D/68] in [$env(DBRWUSER)/g] at [5 (5)]
kamailio_1  |  0(1) ERROR: <core> [core/re.c:170]: parse_repl(): bad specifier in replace part /$env(DBRWUSER)/g
kamailio_1  |  0(1) ERROR: <core> [core/ppcfg.c:69]: pp_subst_add(): bad subst expression: /DBRWUSER/$env(DBRWUSER)/g
kamailio_1  |  0(1) ERROR: <core> [core/ppcfg.c:96]: pp_substdef_add(): subst rule cannot be added

I also tried the following but it doesn't make a difference:

#!substdef "!DBURL!mysql://$env(DBRWUSER):$env(DBRWPW)@$env(DBHOST)/$env(DBNAME)!"

[miconda]

Try to load pv module before subsdef definitions. I haven't added this feature to know its constraints, but I see that the error is not finding $env()

[mbrodala]

This looks way better, the error is gone now. Thanks. :-)