SMPP: Don't accept password or system-id exceeding spec length

The SMPP 3.4 specification defines the password field as a
"Variable-length octet string with maximum length of 9", and according
to table 3-1 this means including the terminating NUL-byte.

However, OsmoMSC allows to configure longer passwords in the ESME
configuration. Those passwords will then never match, as libsmpp34
performs length validation and generates a parser error for anyone
trying to send a longer password via SMPP.

The same applies for system-id, where we have to permit only 15
characters with zero termination, but not 16 characters.

Change-Id: I81ef593e84bf1e15f6746386fc145495fae29354
Closes: OS#3166
1 file changed