topoh: th_mask_decode (th_mask_encode (x)) ≠ x - sr-users

3 Feb 2023


      Hello,
after receiving
INVITE sip:test-gnome-calls@bapha.be SIP/2.0
Via: SIP/2.0/WSS bapha.be;branch=z9hG4bK974100
Max-Forwards: 70
To: sip:test-gnome-calls@bapha.be
From: "Online https://sip.bapha.be" sip:online@bapha.be;tag=12q2efc423
Call-ID: fkhe8faq0fh80glmq59i
CSeq: 5622 INVITE
Contact: sip:4q5ne5no@bapha.be;transport=ws;ob
Allow: ACK,CANCEL,INVITE,MESSAGE,BYE,OPTIONS,INFO,NOTIFY,REFER
Supported: outbound
User-Agent: SIP.js/0.7.8
Content-Type: application/sdp
Content-Length: 1964
v=0
o=mozilla...THIS_IS_SDPARTA-99.0 8263261229339246488 0 IN IP4 0.0.0.0
s=-
…
kamailio calls
th_mask_encode(
char *in = "sip:test-gnome-calls@bapha.be;gr=urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562;alias=87.118.146.153~60722~2>;+sip.instance="urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562";+org.linphone.specs="conference/1.0,ephemeral/1.1,groupchat/1.1,groupchat/1.2,lime\n"\
"Content-Type: application/sdp and so on",
int ilen = 107,
str prefix = { .len = 23, .s ="sip:127.3.4.84;line=sr-" },
int *olen).
It returns olen=167, and the string "sip:127.3.4.84;line=sr-
if7s1mg7i36PNf0AbdwPpfzlbqWEpLzsSGItpLwyN39ZMY4t1mCTSd6DNo4LWdIOpfpPp5FLpUQscX63Kd47W5EPWO6sNL90pLgoW5p-1fzlSdzO25n3KoIk1vHkWXptc5wOeopsWO9-eo9*".
Then Kamailio forwards (sends):
Contact: sip:127.3.4.84;line=sr-if7s1mg7i36PNf0AbdwPpfzlbqWEpLzsSGItpLwyN39ZMY4t1mCTSd6DNo4LWdIOpfpPp5FLpUQscX63Kd47W5EPWO6sNL90pLgoW5p-
1fzlSdzO25n3KoIk1vHkWXptc5wOeopsWO9-eo9*;+sip.instance="urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562";+org.linphone.specs="conference/1.0,ephemeral/1.1,groupchat/1.1,groupchat/1.2,lime"
which at some point leads to
ACK sip:127.3.4.84;line=sr-if7s1mg7i36pnf0abdwppfzlbqweplzssgitplwyn39zmy4t1mctsd6dno4lwdiopfppp5flpuqscx63kd47w5epwo6snl90plgow5p-
1fzlsdzo25n3koik1vhkwxptc5woeopswo9-eo9* SIP/2.0
and
BYE sip:127.3.4.84;line=sr-if7s1mg7i36pnf0abdwppfzlbqweplzssgitplwyn39zmy4t1mctsd6dno4lwdiopfppp5flpuqscx63kd47w5epwo6snl90plgow5p-
1fzlsdzo25n3koik1vhkwxptc5woeopswo9-eo9* SIP/2.0
Below you can find th_test.c .  The functions th_mask_encode() and th_mask_decode() there are identical to the same functions in
src/modules/topoh/th_mask.c . main() provides some tests:
Passing «sip:test-gnome-calls@bapha.be;gr=urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562;alias=87.118.146.153~60472~2>;+sip.instance="urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562";+org.linphone.specs="conference/1.0,ephemeral/1.1,groupchat/1.1,groupchat/1.2,lime» to th_mask_encode() returns
sip:127.3.4.84;line=sr-if7s1mg7i36PNf0AbdwPpfzlbqWEpLzsSGItpLwyN39ZMY4t1mCTSd6DNo4LWdIOpfpPp5FLpUQscX63Kd47W5EPWO6sNL90pLgoW5p-
1fzlSdzO25n3KoIk1vHkWXptc5wOeopsWXi-eo9*
(this is what Kamailio does send out).  Passing the last string to th_mask_decode() returns
sip:test-gnome-calls@bapha.be;gr=urn:uuid:f2f5a3cf-a0fb-0047-be50-740fb9bdc562;alias=87.118.1
the ;alias= is incomplete, compared to the origin.
The above ACK leads to passing
"sr-if7s1mg7i36pnf0abdwppfzlbqweplzssgitplwyn39zmy4t1mctsd6dno4lwdiopfppp5flpuqscx63kd47w5epwo6snl90plgow5p-1fzlsdzo25n3koik1vhkwxptc5woeopswo9-eo9*
SIP/2.0\n"\
"Route: sip:Q+L06HX94DMPtQWQTI5OE8SQTI5O4MY=@144.76.142.78;transport=ws;r2=on;lr;nat=yes\n"\
"Route: sip:127.3.4.84;line=sr-if7s17IB5XEfVzn0WIgWwqggCTzwV5C2g5R5wCg4WwrQ5CuZ6XIQWvH3WUHkWX9tWOnyMq4RbmWsb34Q2YgoiXP-coTAboPlioPtpY6Z8dCO\n"\
to th_mask_decode() and the result is callub.p.b;rn:s.d2lQg#cfa=bA07beQ7R409bcQ62;alac=87718*1P.15#~60R22~2 with the dots being unprintable
characters. (result is garbage).
I have seen that callub.p.b in the unparsable R-URI reports from Kamailio.
That is an indication that th_mask_decode() does not decode the Contact encoded by th_mask_encode() correctly.
Valgrind does not report improper memory usage.
Greetings
  Dilyan
gcc -g -o th-test ./th-test.c && ./th-test
th-test.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define TH_EB64I \
    	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789.-"
char _th_EB64[65] = "EFvXIzGq94xKcW126gV5wCdYpNSbiM8enRUou7LmhajBlPtAsk-OQTf3H0DyrZ.J";
int _th_DB64[256];
char *_th_PD64 = "*";
struct str_ {
        char* s; /**< Pointer to the first character of the string */
        int len; /**< Length of the string */
};
typedef struct str_ str;
str prefix = { .len = 23, .s ="sip:127.3.4.84;line=sr-" };
char* th_mask_encode(char *in, int ilen, const str *prefix, int *olen);
char* th_mask_decode(char *in, int ilen, const str *prefix, int extra, int *olen);
char* th_mask_encode(char *in, int ilen, const str *prefix, int *olen)
{
    char *out;
    int  left;
    int  idx;
    int  i;
    int  r;
    char *p;
    int  block;
    *olen = (((ilen+2)/3)<<2) + ((prefix!=NULL&&prefix->len>0)?prefix->len:0);
    out = (char*)malloc((*olen+1)*sizeof(char));
    if(out==NULL)
    {
    	fprintf(stderr, "malloc error\n");
    	*olen = 0;
    	return NULL;
    }
    memset(out, 0, (*olen+1)*sizeof(char));
    if(prefix!=NULL&&prefix->len>0)
    	memcpy(out, prefix->s, prefix->len);
p = out + (int)((prefix!=NULL&&prefix->len>0)?prefix->len:0);
    for(idx=0; idx<ilen; idx+=3)
    {
    	left = ilen - idx - 1 ;
    	left = (left>1)?2:left;
block = 0;
    	for(i=0, r=16; i<=left; i++, r-=8)
    		block += ((unsigned char)in[idx+i]) << r;
*(p++) = _th_EB64[(block >> 18) & 0x3f];
    	*(p++) = _th_EB64[(block >> 12) & 0x3f];
    	*(p++) = (left>0)?_th_EB64[(block >> 6) & 0x3f]:_th_PD64[0];
    	*(p++) = (left>1)?_th_EB64[block & 0x3f]:_th_PD64[0];
    }
return out;
}
char* th_mask_decode(char *in, int ilen, const str *prefix, int extra, int *olen)
{
    char *out;
    int n;
    int block;
    int idx;
    int i;
    int j;
    int end;
    char c;
for(n=0,i=ilen-1; in[i]==_th_PD64[0]; i--)
    	n++;
*olen = (((ilen-((prefix!=NULL&&prefix->len>0)?prefix->len:0)) * 6) >> 3)
    			- n;
if (*olen<=0) {
    	return NULL;
    }
out = (char*)malloc((*olen+1+extra)*sizeof(char));
    if(out==NULL)
    {
    	fprintf(stderr, "malloc error\n");
    	*olen = 0;
    	return NULL;
    }
    memset(out, 0, (*olen+1+extra)*sizeof(char));
end = ilen - n;
    i = (prefix!=NULL&&prefix->len>0)?prefix->len:0;
    for(idx=0; i<end; idx+=3)
    {
    	block = 0;
    	for(j=0; j<4 && i<end ; j++)
    	{
    		c = _th_DB64[(int)in[i++]];
    		if(c<0)
    		{
    			free(out);
    			*olen = 0;
    			return NULL;
    		}
    		block += c << (18 - 6*j);
    	}
for(j=0, n=16; j<3 && idx+j< *olen; j++, n-=8)
    		out[idx+j] = (char)((block >> n) & 0xff);
    }
return out;
}
int main() {
  //this is from th_mask_init
  for(int i=0; i<256; i++)
    _th_DB64[i] = -1;
  for(int i=0; i<64; i++)
    _th_DB64[(int)_th_EB64[i]] = i;
  int olen, o2;
  char *end;
  char *input = "sip:test-gnome-calls@bapha.be;gr=urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562;alias=87.118.146.153~60472~2>;+sip.instance="urn:uuid:f2f5a3cf-a0fb-0047-be50-
740fb9bdc562";+org.linphone.specs="conference/1.0,ephemeral/1.1,groupchat/1.1,groupchat/1.2,lime"";
  printf("input=[%s]\n", input);
  char* middle = th_mask_encode (input, 107, &prefix, &olen);
  printf("olen = %i, middle=[%s]\n", olen, middle);
  end = th_mask_decode(middle, 147, &prefix, 0, &o2);
  printf("o2 = %i, end=[%s]\n", o2, end);
  char * b1 = "sr-if7s1mg7i36pnf0abdwppfzlbqweplzssgitplwyn39zmy4t1mctsd6dno4lwdiopfppp5flpuqscx63kd47w5epwo6snl90plgow5p-
1fzlsdzo25n3koik1vhkwxptc5woeopswo9-eo9*";
  o2 = 0;
  end = th_mask_decode(b1, 147, &prefix, 0, &o2);
  printf("o2 = %i, end=[%s]\n", o2, end);
char* b2 = 
"sr-if7s1mg7i36pnf0abdwppfzlbqweplzssgitplwyn39zmy4t1mctsd6dno4lwdiopfppp5flpuqscx63kd47w5epwo6snl90plgow5p-1fzlsdzo25n3koik1vhkwxptc5woeopswo9-eo9*
SIP/2.0\n"\
"Route: sip:Q+L06HX94DMPtQWQTI5OE8SQTI5O4MY=@144.76.142.78;transport=ws;r2=on;lr;nat=yes\n"\
"Route: sip:127.3.4.84;line=sr-if7s17IB5XEfVzn0WIgWwqggCTzwV5C2g5R5wCg4WwrQ5CuZ6XIQWvH3WUHkWX9tWOnyMq4RbmWsb34Q2YgoiXP-coTAboPlioPtpY6Z8dCO\n"\
"Via: SIP/2.0/WSS bapha.be;branch=z9hG4bK9069155\n"\
"Max-Forwards: 70\n"\
"To: sip:test-gnome-calls@bapha.be;tag=Pn4npAj\n"\
"From: "Online https://sip.bapha.be%5C" sip:online@bapha.be;tag=12q2efc423\n"\
"Call-ID: fkhe8faq0fh80glmq59i\n"\
"CSeq: 5623 ACK\n"\
"Supported: outbound\n"\
"User-Agent: SIP.js/0.7.8\n"\
"Content-Length: 0\n"\
"\n";
o2 = 0;
  end = th_mask_decode(b2, 147, &prefix, 0, &o2);
  printf("o2 = %i, end=[%s]\n", o2, end);
return 0;
}