[asterisk-users] pjsip user_eq_phone adds user=phone to anonymous user bug?

[Daniel Tryba]

With pjsip (asterisk 13.14.1) I see the problem that an anonymous from
header gets user=phone appendend to the URI if user_eq_phone=yes is
specified:

On the incoming leg:
From: anonymous <sip:anonymous at anonymous.invalid:5060>;tag=Q5zBj7BMnvI6Fe6O2866fox3ZHmn-smt
Get transformed to 
From: "Anonymous" <sip:anonymous at anonymous.invalid;user=phone>;tag=fa3cb748-6af9-485f-8a70-a2b9ad40b13a
on the outgoing leg.

Setting user_eq_phone = no will result in user=phone not being added.
The upstream provide demands user=phone in URIs if the username
resembles a phonenumber, but declines the INVITE if user=phone is
present on an anonymous username.

Looking at the code,res/res_pjsip.c function ast_sip_add_usereqphone is
the only place I see that might add user=phone:

=================================================================================
        int i = 0;
        //.....
        if (pj_strbuf(&sip_uri->user)[0] == '+') {
                i = 1;
        }

        /* Test URI user against allowed characters in AST_DIGIT_ANY */
        for (; i < pj_strlen(&sip_uri->user); i++) {
                if (!strchr(AST_DIGIT_ANYNUM, pj_strbuf(&sip_uri->user)[i])) {
                        break;
                }
        }

        if (i < pj_strlen(&sip_uri->user)) {
                return;
        }

		  //add user=phone if we get to the code below
=================================================================================

sip_uri->user should be "anonymous"
AST_DIGIT_ANY is: #define AST_DIGIT_ANYNUM "0123456789"

So in the for loop the first char of sip_uri->user should result in a
NULL from strchr. Leaving i at the value 0, which is smaller than the
length of sip_uri->user. And thus the function should return before
adding the user=phone. So why is user=phone being added?