sdp_msg: add sdp_audio_codecs_cmp(), add compare flags

A problem with SDP fmtp handling is visible in this patch: when cmp_fmtp
is true, we compare fmtp strings 1:1, which is not how things should be
done. The intention is to fix fmtp handling in a later patch.

At least there now is a flag to bypass fmtp comparison altogether.

Related: SYS#5066
Change-Id: I18d33e189674229501afec950aa1c732386455a2
changes/83/28783/3
Neels Hofmeyr 8 months ago
parent 99ab7c57da
commit c9e0ca3d1f
  1. 5
      include/osmocom/msc/sdp_msg.h
  2. 85
      src/libmsc/sdp_msg.c

@ -36,7 +36,10 @@ struct sdp_msg {
const char *sdp_msg_line_end(const char *src);
int sdp_audio_codec_cmp(const struct sdp_audio_codec *a, const struct sdp_audio_codec *b);
int sdp_audio_codec_cmp(const struct sdp_audio_codec *a, const struct sdp_audio_codec *b,
bool cmp_fmtp, bool cmp_payload_type);
int sdp_audio_codecs_cmp(const struct sdp_audio_codecs *a, const struct sdp_audio_codecs *b,
bool cmp_fmtp, bool cmp_payload_type);
struct sdp_audio_codec *sdp_audio_codec_add(struct sdp_audio_codecs *ac, unsigned int payload_type,
const char *subtype_name, unsigned int rate, const char *fmtp);

@ -31,30 +31,83 @@
#include <osmocom/msc/sdp_msg.h>
/* Compare name, rate and fmtp, returning typical cmp result: 0 on match, and -1 / 1 on mismatch.
* Do *not* compare the payload_type number.
* If cmp_fmtp is false, do *not* compare the fmtp string; if true, compare fmtp 1:1 as strings.
* If cmp_payload_type is false, do *not* compare the payload_type number.
* The fmtp is only string-compared -- e.g. if AMR parameters appear in a different order, it amounts to a mismatch even
* though all parameters are the same. */
int sdp_audio_codec_cmp(const struct sdp_audio_codec *a, const struct sdp_audio_codec *b)
int sdp_audio_codec_cmp(const struct sdp_audio_codec *a, const struct sdp_audio_codec *b,
bool cmp_fmtp, bool cmp_payload_type)
{
int rc;
int cmp;
if (a == b)
return 0;
if (!a)
return -1;
if (!b)
return 1;
rc = strncmp(a->subtype_name, b->subtype_name, sizeof(a->subtype_name));
if (rc)
return rc;
cmp = strncmp(a->subtype_name, b->subtype_name, sizeof(a->subtype_name));
if (cmp)
return cmp;
cmp = OSMO_CMP(a->rate, b->rate);
if (cmp)
return cmp;
if (cmp_fmtp) {
cmp = strncmp(a->fmtp, b->fmtp, sizeof(a->fmtp));
if (cmp)
return cmp;
}
if (cmp_payload_type) {
cmp = OSMO_CMP(a->payload_type, b->payload_type);
if (cmp)
return cmp;
}
return 0;
}
if (a->rate < b->rate)
/* Compare two lists of audio codecs, returning typical cmp result: 0 on match, and -1 / 1 on mismatch.
* The ordering in the two lists may differ, except that the first codec in 'a' must also be the first codec in 'b'.
* This is because the first codec typically expresses the preferred codec to use.
* If cmp_fmtp is false, do *not* compare the fmtp strings; if true, compare fmtp 1:1 as strings.
* If cmp_payload_type is false, do *not* compare the payload_type numbers.
* The fmtp is only string-compared -- e.g. if AMR parameters appear in a different order, it amounts to a mismatch even
* though all parameters are the same. */
int sdp_audio_codecs_cmp(const struct sdp_audio_codecs *a, const struct sdp_audio_codecs *b,
bool cmp_fmtp, bool cmp_payload_type)
{
const struct sdp_audio_codec *codec_a;
const struct sdp_audio_codec *codec_b;
int cmp;
if (a == b)
return 0;
if (!a)
return -1;
if (a->rate > b->rate)
if (!b)
return 1;
rc = strncmp(a->fmtp, b->fmtp, sizeof(a->fmtp));
if (rc)
return rc;
cmp = OSMO_CMP(a->count, b->count);
if (cmp)
return cmp;
if (!a->count)
return 0;
/* The first codec is the "chosen" codec and should match. The others may appear in different order. */
cmp = sdp_audio_codec_cmp(&a->codec[0], &b->codec[0], cmp_fmtp, cmp_payload_type);
if (cmp)
return cmp;
/* See if each codec in a is also present in b */
foreach_sdp_audio_codec(codec_a, a) {
bool match_found = false;
foreach_sdp_audio_codec(codec_b, b) {
if (!sdp_audio_codec_cmp(codec_a, codec_b, cmp_fmtp, cmp_payload_type)) {
match_found = true;
break;
}
}
if (!match_found)
return -1;
}
return 0;
}
@ -130,13 +183,13 @@ struct sdp_audio_codec *sdp_audio_codec_by_payload_type(struct sdp_audio_codecs
return codec;
}
/* Return a given sdp_msg's codec entry that matches the subtype_name, rate and fmtp of the given codec, or NULL if no
* match is found. Comparison is made by sdp_audio_codec_cmp(). */
/* Return a given sdp_msg's codec entry that matches the subtype_name and rate of the given codec, or NULL if no
* match is found. Comparison is made by sdp_audio_codec_cmp(cmp_payload_type=false). */
struct sdp_audio_codec *sdp_audio_codec_by_descr(struct sdp_audio_codecs *ac, const struct sdp_audio_codec *codec)
{
struct sdp_audio_codec *i;
foreach_sdp_audio_codec(i, ac) {
if (!sdp_audio_codec_cmp(i, codec))
if (!sdp_audio_codec_cmp(i, codec, false, false))
return i;
}
return NULL;
@ -452,8 +505,8 @@ next_line:
}
/* Leave only those codecs in 'ac_dest' that are also present in 'ac_other'.
* The matching is made by sdp_audio_codec_cmp(), i.e. payload_type numbers are not compared and fmtp parameters are
* compared 1:1 as plain strings.
* The matching is made by sdp_audio_codec_cmp(cmp_payload_type=false), i.e. payload_type numbers are not compared and
* fmtp parameters are compared 1:1 as plain strings.
* If translate_payload_type_numbers has an effect if ac_dest and ac_other have mismatching payload_type numbers for the
* same SDP codec descriptions. If translate_payload_type_numbers is true, take the payload_type numbers from ac_other.
* If false, keep payload_type numbers in ac_dest unchanged. */

Loading…
Cancel
Save