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Issue 252 - Direwolf segments large frames when sending AX.25 version 2.0 packets. 

Instead, it should simply divide the data into packets without segment headers,
on an AX.25 version 2.0 connection.
This commit is contained in:
wb2osz 2020-04-13 20:54:42 -04:00
parent e654ca46a6
commit c15903edb9
1 changed files with 45 additions and 5 deletions
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50
src/ax25_link.c
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@ -1157,6 +1157,15 @@ void dl_disconnect_request (dlq_item_t *E)
* *
* Erratum: Not sure how to interpret that. See example below for how it was implemented. * Erratum: Not sure how to interpret that. See example below for how it was implemented.
* *
* Version 1.6: Bug 252. Segmentation was occuring for a V2.0 link. From the spec:
* "The receipt of an XID response from the other station establishes that both
* stations are using AX.25 version 2.2 or higher and enables the use of the
* segmenter/reassembler and selective reject."
* "The segmenter/reassembler procedure is only enabled if both stations on the
* link are using AX.25 version 2.2 or higher."
*
* The Segmenter Ready State SDL has no decision based on protocol version.
*
*------------------------------------------------------------------------------*/ *------------------------------------------------------------------------------*/
static void data_request_good_size (ax25_dlsm_t *S, cdata_t *txdata); static void data_request_good_size (ax25_dlsm_t *S, cdata_t *txdata);
@ -1166,8 +1175,6 @@ void dl_data_request (dlq_item_t *E)
{ {
ax25_dlsm_t *S; ax25_dlsm_t *S;
int ok_to_create = 1; int ok_to_create = 1;
int nseg_to_follow;
int orig_offset, remaining_len;
S = get_link_handle (E->addrs, E->num_addr, E->chan, E->client, ok_to_create); S = get_link_handle (E->addrs, E->num_addr, E->chan, E->client, ok_to_create);
@ -1185,6 +1192,39 @@ void dl_data_request (dlq_item_t *E)
return; return;
} }
#define DIVROUNDUP(a,b) (((a)+(b)-1) / (b))
// Erratum: Don't do V2.2 segmentation for a V2.0 link.
// In this case, we can just split it into multiple frames not exceeding the specified max size.
// Hopefully the receiving end treats it like a stream and doesn't care about length of each frame.
if (S->modulo == 8) {
int num_frames = 0;
int remaining_len = E->txdata->len;
int offset = 0;
while (remaining_len > 0) {
int this_len = MIN(remaining_len, S->n1_paclen);
cdata_t *new_txdata = cdata_new(E->txdata->pid, E->txdata->data + offset, this_len);
data_request_good_size (S, new_txdata);
offset += this_len;
remaining_len -= this_len;
num_frames++;
}
if (num_frames != DIVROUNDUP(E->txdata->len, S->n1_paclen) || remaining_len != 0) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("INTERNAL ERROR, Segmentation line %d, data length = %d, N1 = %d, num frames = %d, remaining len = %d\n",
__LINE__, E->txdata->len, S->n1_paclen, num_frames, remaining_len);
}
cdata_delete (E->txdata);
E->txdata = NULL;
return;
}
// More interesting case. // More interesting case.
// It is too large to fit in one frame so we segment it. // It is too large to fit in one frame so we segment it.
@ -1251,7 +1291,7 @@ void dl_data_request (dlq_item_t *E)
// We will decrement this before putting it in the frame so the first // We will decrement this before putting it in the frame so the first
// will have one less than this number. // will have one less than this number.
nseg_to_follow = DIVROUNDUP(E->txdata->len + 1, S->n1_paclen - 1); int nseg_to_follow = DIVROUNDUP(E->txdata->len + 1, S->n1_paclen - 1);
if (nseg_to_follow < 2 || nseg_to_follow > 128) { if (nseg_to_follow < 2 || nseg_to_follow > 128) {
text_color_set(DW_COLOR_ERROR); text_color_set(DW_COLOR_ERROR);
@ -1262,8 +1302,8 @@ void dl_data_request (dlq_item_t *E)
return; return;
} }
orig_offset = 0; int orig_offset = 0;
remaining_len = E->txdata->len; int remaining_len = E->txdata->len;
// First segment. // First segment.