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Properly enforce the far end max datagram when constructing UDPTL packets

This commit is contained in:
Steve Underwood 2013-01-26 01:31:38 +08:00
parent 6cb3be7d8b
commit 063d59922b
1 changed files with 27 additions and 4 deletions
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31
src/mod/applications/mod_spandsp/udptl.c
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@ -349,6 +349,8 @@ int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int
int len; int len;
int limit; int limit;
int high_tide; int high_tide;
int len_before_entries;
int previous_len;
/* UDPTL cannot cope with zero length messages, and our buffering for redundancy limits their /* UDPTL cannot cope with zero length messages, and our buffering for redundancy limits their
maximum length. */ maximum length. */
@ -392,15 +394,26 @@ int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int
entries = s->error_correction_entries; entries = s->error_correction_entries;
else else
entries = s->tx_seq_no; entries = s->tx_seq_no;
len_before_entries = len;
/* The number of entries will always be small, so it is pointless allowing /* The number of entries will always be small, so it is pointless allowing
for the fragmented case here. */ for the fragmented case here. */
if (encode_length(buf, &len, entries) < 0) if (encode_length(buf, &len, entries) < 0)
return -1; return -1;
/* Encode the elements */ /* Encode the elements */
for (i = 0; i < entries; i++) { for (m = 0; m < entries; m++) {
j = (entry - i - 1) & UDPTL_BUF_MASK; previous_len = len;
j = (entry - m - 1) & UDPTL_BUF_MASK;
if (encode_open_type(buf, &len, s->tx[j].buf, s->tx[j].buf_len) < 0) if (encode_open_type(buf, &len, s->tx[j].buf, s->tx[j].buf_len) < 0)
return -1; return -1;
/* If we have exceeded the far end's max datagram size, don't include this last chunk,
and stop trying to add more. */
if (len > s->far_max_datagram_size) {
len = previous_len;
if (encode_length(buf, &len_before_entries, m) < 0)
return -1;
break;
}
} }
break; break;
case UDPTL_ERROR_CORRECTION_FEC: case UDPTL_ERROR_CORRECTION_FEC:
@ -417,11 +430,13 @@ int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int
/* Span is defined as an inconstrained integer, which it dumb. It will only /* Span is defined as an inconstrained integer, which it dumb. It will only
ever be a small value. Treat it as such. */ ever be a small value. Treat it as such. */
buf[len++] = 1; buf[len++] = 1;
buf[len++] = (uint8_t)span; buf[len++] = (uint8_t) span;
len_before_entries = len;
/* The number of entries is defined as a length, but will only ever be a small /* The number of entries is defined as a length, but will only ever be a small
value. Treat it as such. */ value. Treat it as such. */
buf[len++] = (uint8_t)entries; buf[len++] = (uint8_t) entries;
for (m = 0; m < entries; m++) { for (m = 0; m < entries; m++) {
previous_len = len;
/* Make an XOR'ed entry the maximum length */ /* Make an XOR'ed entry the maximum length */
limit = (entry + m) & UDPTL_BUF_MASK; limit = (entry + m) & UDPTL_BUF_MASK;
high_tide = 0; high_tide = 0;
@ -439,6 +454,14 @@ int udptl_build_packet(udptl_state_t *s, uint8_t buf[], const uint8_t msg[], int
} }
if (encode_open_type(buf, &len, fec, high_tide) < 0) if (encode_open_type(buf, &len, fec, high_tide) < 0)
return -1; return -1;
/* If we have exceeded the far end's max datagram size, don't include this last chunk,
and stop trying to add more. */
if (len > s->far_max_datagram_size) {
len = previous_len;
buf[len_before_entries] = (uint8_t) m;
break;
}
} }
break; break;
} }