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even more gsmtap wip 

Change-Id: Icf18039117df2bf1548f8c02bccabe3c45bad99d
This commit is contained in:
Harald Welte 2022-09-06 09:19:35 +02:00
parent 07be00afd0
commit 83912d7d40
1 changed files with 64 additions and 6 deletions
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70
src/e1_gsmtap.c
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@ -109,11 +109,53 @@ enum q931_iei {
/* TODO */
};
struct q931_call_state {
struct llist_head list;
uint32_t call_ref; /* decoded call reference */
bool net2user; /* call established in Net->User direction? */
time_t create_time; /* time at which call was created */
};
/* Q.931 Section 4.3 */
static uint32_t q931_decode_callref(const uint8_t *data, uint8_t len)
{
uint8_t len_of_callref;
uint32_t callref = 0;
bool flag;
if (len < 1)
return 0;
len_of_callref = data[0] & 0x0f;
if (len_of_callref = 0)
return 0;
if (len_of_callref > 4)
return 0;
if (len - 1 < len_of_callref)
return 0;
/* first octet contains flag, needs special handling */
if (data[1] & 0x80)
flag = 1;
callref = data[1] & 0x7f;
/* all further octets ... */
for (i = 1; i < len_of_callref; i++)
callref = (callref << 8) | data[i];
if (flag)
callref |= 0x80000000;
return callref;
}
/* receive one Q.931 message for signaling analysis */
static void e1tap_q931_rx(struct e1tap_line *line, bool net2user, const uint8_t *buf, size_t len)
{
uint8_t cref_len
uint8_t cref_len;
uint32_t cref;
if (len < 2)
return;
@ -126,35 +168,50 @@ static void e1tap_q931_rx(struct e1tap_line *line, bool net2user, const uint8_t
cref_len = buf[1] & 0x0F;
if (len < 2 + cref_len)
return;
cref = q931_decode_callref(buf+1, len-1);
msg_type = buf[2+cref_len] & 0x7f;
/* TODO: dispatch by message type; look in those that contain a ChannelIndicator */
switch (msg_type) {
case Q931_MSGT_SETUP:
break;
}
}
/* trace one Q.921 / LAPD frame for signaling analysis */
static void e1tap_q921_rx(struct e1tap_line *line, bool net2user, const uint8_t *buf, size_t len)
{
uint8_t sapi, tei;
/* Parse LAPD header; Ignore anything != I frames */
/* Q.921 header: 2 bytes address; 1-2 byte control; [optional] information */
if (len < 2)
return;
/* Parse LAPD header; Ignore anything != I frames */
/* Address field: Figure 5 / Q.921 */
sapi = buf[0] >> 2;
tei = buf[1] >> 1;
/* skip unknown SAPI */
if (sapi != 0)
/* SAPI value for circuit-switched call control (Table 2/Q.921) */
if (sapi != 0) {
/* skip unknown SAPI */
return;
}
if (len < 3)
return;
/* skip frames != I-frame */
if (buf[2] & 0x01)
/* Control field: Table 4/Q.921 */
if (buf[2] & 0x01) {
/* skip frames != I-frame (which have 0 as lsb of 1st octet) */
return;
}
if (len < 4)
return;
/* skip N(R) / N(S) and go directly to Q.931 payload */
e1tap_q931_rx(buf + 4, len - 4);
}
@ -187,6 +244,7 @@ void e1tap_trace_ts(struct e1tap_ts *ts, const uint8_t *tsbuf, size_t frame_coun
gsmtap_send_ex(line->gti, GSMTAP_TYPE_E1T1, flags,
ts->num, ts->gsmtap_subtype, 0, 0, 0, 0,
ts->hdlc.state[hdlc_idx].out, rc);
/* feed D-channel into higher level analysis */
if (ts->mode == E1_TS_TRACE_MODE_ISDN_D)
e1tap_q921_rx(line, hdlc_idx, ts->hdlc.state[hdlc_idx].out, rc);
} else if (rc < 0) {