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text_import: Handle SCTP and minimum packet lengths 

Correctly handle when a minimum packet length forces fragmentation of
SCTP and we are generating dummy SCTP DATA chunk headers: mark fragmentation
in the chunk flags and set the transmission sequence number and
stream sequence number appropriately.

Port from text2pcap commit f8d48662c8
Part of #16724.
This commit is contained in:
John Thacker 2021-12-18 20:23:15 -05:00
parent 8cc527cce3
commit db10235d68
1 changed files with 42 additions and 21 deletions
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63
ui/text_import.c
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@ -176,7 +176,7 @@ static guint32 hdr_sctp_tag = 0;
/* Dummy DATA chunk header */
static gboolean hdr_data_chunk = FALSE;
static guint8 hdr_data_chunk_type = 0;
static guint8 hdr_data_chunk_bits = 3;
static guint8 hdr_data_chunk_bits = 0;
static guint32 hdr_data_chunk_tsn = 0;
static guint16 hdr_data_chunk_sid = 0;
static guint16 hdr_data_chunk_ssn = 0;
@ -197,7 +197,7 @@ static guint8 *packet_buf;
static guint32 curr_offset = 0;
static guint32 max_offset = WTAP_MAX_PACKET_SIZE_STANDARD;
static guint32 packet_start = 0;
static void start_new_packet (void);
static void start_new_packet(gboolean);
/* This buffer contains strings present before the packet offset 0 */
#define PACKET_PREAMBLE_MAX_LEN 2048
@ -385,7 +385,7 @@ write_byte (const char *str)
packet_buf[curr_offset] = (guint8) num;
curr_offset ++;
if (curr_offset >= max_offset) /* packet full */
start_new_packet();
start_new_packet(TRUE);
}
/*----------------------------------------------------------------------
@ -415,9 +415,14 @@ number_of_padding_bytes (guint32 length)
/*----------------------------------------------------------------------
* Write current packet out
*
* @param cont [IN] TRUE if a packet is being written because the max frame
* length was reached, and the original packet from the input file is
* continued in a later frame. Used to set fragmentation fields in dummy
* headers (currently only implemented for SCTP; IPv4 could be added later.)
*/
static void
write_current_packet (void)
write_current_packet(gboolean cont)
{
int prefix_length = 0;
int proto_length = 0;
@ -558,6 +563,13 @@ write_current_packet (void)
/* Compute DATA chunk header and append padding */
if (hdr_data_chunk) {
hdr_data_chunk_bits = 0;
if (packet_start == 0) {
hdr_data_chunk_bits |= 0x02;
}
if (!cont) {
hdr_data_chunk_bits |= 0x01;
}
HDR_DATA_CHUNK.type = hdr_data_chunk_type;
HDR_DATA_CHUNK.bits = hdr_data_chunk_bits;
HDR_DATA_CHUNK.length = g_htons(curr_offset + sizeof(HDR_DATA_CHUNK));
@ -565,7 +577,10 @@ write_current_packet (void)
HDR_DATA_CHUNK.sid = g_htons(hdr_data_chunk_sid);
HDR_DATA_CHUNK.ssn = g_htons(hdr_data_chunk_ssn);
HDR_DATA_CHUNK.ppid = g_htonl(hdr_data_chunk_ppid);
hdr_data_chunk_tsn++;
if (!cont) {
hdr_data_chunk_ssn++;
}
padding_length = number_of_padding_bytes(curr_offset);
for (i=0; i<padding_length; i++)
packet_buf[prefix_length+curr_offset+i] = 0;
@ -901,7 +916,7 @@ void parse_data(guchar* start_field, guchar* end_field, enum data_encoding encod
parse_plain_data(&start_field, end_field, &dest, dest_end, table, NULL);
curr_offset = (int) (dest - packet_buf);
if (curr_offset == max_offset) {
write_current_packet();
write_current_packet(TRUE);
dest = &packet_buf[curr_offset];
} else
break;
@ -1047,7 +1062,7 @@ void parse_seqno(const guchar* start_field, const guchar* end_field) {
}
void flush_packet(void) {
write_current_packet();
write_current_packet(FALSE);
}
/*----------------------------------------------------------------------
@ -1106,15 +1121,21 @@ parse_preamble (void)
/*----------------------------------------------------------------------
* Start a new packet
*
* @param cont [IN] TRUE if a new packet is starting because the max frame
* length was reached on the current packet, and the original packet from the
* input file is continued in a later frame. Passed to write_current_packet,
* where it is used to set fragmentation fields in dummy headers (currently
* only implemented for SCTP; IPv4 could be added later.)
*/
static void
start_new_packet (void)
start_new_packet(gboolean cont)
{
if (debug>=1)
fprintf(stderr, "Start new packet\n");
fprintf(stderr, "Start new packet (cont = %s).\n", cont ? "TRUE" : "FALSE");
/* Write out the current packet, if required */
write_current_packet();
write_current_packet(cont);
/* Ensure we parse the packet preamble as it may contain the time */
/* THIS IMPLIES A STATE TRANSITION OUTSIDE THE STATE MACHINE */
@ -1167,21 +1188,21 @@ parse_token (token_t token, char *str)
break;
case T_OFFSET:
num = parse_num(str, TRUE);
if (num==0) {
if (num == 0) {
/* New packet starts here */
start_new_packet();
start_new_packet(FALSE);
state = READ_OFFSET;
}
break;
case T_BYTE:
if (offset_base == 0) {
start_new_packet();
start_new_packet(FALSE);
write_byte(str);
state = READ_BYTE;
}
break;
case T_EOF:
write_current_packet();
write_current_packet(FALSE);
break;
default:
break;
@ -1199,9 +1220,9 @@ parse_token (token_t token, char *str)
break;
case T_OFFSET:
num = parse_num(str, TRUE);
if (num==0) {
if (num == 0) {
/* New packet starts here */
start_new_packet();
start_new_packet(FALSE);
packet_start = 0;
state = READ_OFFSET;
} else if ((num - packet_start) != curr_offset) {
@ -1222,7 +1243,7 @@ parse_token (token_t token, char *str)
if (debug>=1)
fprintf(stderr, "Inconsistent offset. Expecting %0X, got %0X. Ignoring rest of packet\n",
curr_offset, num);
write_current_packet();
write_current_packet(FALSE);
state = INIT;
}
} else
@ -1235,7 +1256,7 @@ parse_token (token_t token, char *str)
}
break;
case T_EOF:
write_current_packet();
write_current_packet(FALSE);
break;
default:
break;
@ -1259,7 +1280,7 @@ parse_token (token_t token, char *str)
state = START_OF_LINE;
break;
case T_EOF:
write_current_packet();
write_current_packet(FALSE);
break;
default:
break;
@ -1282,7 +1303,7 @@ parse_token (token_t token, char *str)
state = START_OF_LINE;
break;
case T_EOF:
write_current_packet();
write_current_packet(FALSE);
break;
default:
break;
@ -1296,7 +1317,7 @@ parse_token (token_t token, char *str)
state = START_OF_LINE;
break;
case T_EOF:
write_current_packet();
write_current_packet(FALSE);
break;
default:
break;