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#include <stdio.h>
#include <inttypes.h>
#include <dlfcn.h>
#include "libpacketdump.h"
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <assert.h>
/* SCTP decoding by Sam Jansen, 31/08/2004
*
* Based on RFC 2960 - Stream Control Transmission Protocol
*/
struct sctp_common_hdr
{
uint16_t src_port, dst_port;
uint32_t verification_tag;
uint32_t checksum;
} __attribute__((__packed__));
struct sctp_chunk_hdr
{
uint8_t type;
uint8_t flags;
uint16_t length;
} __attribute__((__packed__));
struct sctp_data
{
uint32_t tsn;
uint16_t stream_id;
uint16_t stream_seqno;
uint32_t payload_proto_id;
} __attribute__((__packed__));
/* The following works for INIT and INIT ACK packets */
struct sctp_init_ack
{
uint32_t init_tag;
uint32_t rcv_wnd_credit;
uint16_t outbound_streams;
uint16_t inbound_streams;
uint32_t init_tsn;
} __attribute__((__packed__));
struct sctp_sack
{
uint32_t tsn_ack;
uint32_t a_wnd;
uint16_t num_gap_blocks;
uint16_t num_dup_tsns;
} __attribute__((__packed__));
struct sctp_var_param_hdr
{
uint16_t type;
uint16_t length;
} __attribute__((__packed__));
static char *sctp_type_to_str(uint8_t type)
{
switch(type)
{
case 0: return "DATA";
case 1: return "INIT";
case 2: return "INIT ACK";
case 3: return "SACK";
case 4: return "HEARTBEAT";
case 5: return "HEARTBEAT ACK";
case 6: return "ABORT";
case 7: return "SHUTDOWN";
case 8: return "SHUTDOWN ACK";
case 9: return "ERROR";
case 10: return "COOKIE ECHO";
case 11: return "COOKIE ACK";
case 12: return "Reserved for ECNE";
case 13: return "Reserved for CWR";
case 14: return "SHUTDOWN COMPLETE";
case 63:
case 127:
case 191:
case 255: return "IETF-defined Chunk Extensions";
};
return "reserved by IETF";
}
static void parse_options(char *offset, int vlen)
{
while(vlen > 0) {
struct sctp_var_param_hdr *ph = (struct sctp_var_param_hdr *)(offset);
char *data = (char *)(ph + 1);
switch(ntohs(ph->type)) {
case 5:
{
struct in_addr *ia = (struct in_addr *)data;
printf(" SCTP: Option IP address %s\n", inet_ntoa(*ia));
}
break;
case 6:
{
printf(" SCTP: Option IPv6 address (TODO)\n");
}
break;
case 7:
{
printf(" SCTP: Option State cookie\n");
/* // Prolly don't want to print this out :)
for(int i = 0; i < ntohs(ph->length) - 8; i++)
printf("%02x", data[i]);
printf("'\n");*/
}
break;
case 9:
{
printf(" SCTP: Option Cookie preservative (TODO)\n");
}
break;
case 11:
{
printf(" SCTP: Option Host name %s\n", data);
}
break;
case 12:
{
uint16_t *p = (uint16_t *)data;
int len = ntohs(ph->length) -
sizeof(struct sctp_var_param_hdr);
printf(" SCTP: Option Supported address types ");
while(len) {
printf("%hu ", ntohs(*p));
p++;
len -= sizeof(*p);
}
printf("\n");
}
break;
default:
printf(" SCTP: Option Unknown type=%hu len=%hu\n",
ntohs(ph->type), ntohs(ph->length));
}
vlen -= ntohs(ph->length);
offset += ntohs(ph->length);
}
}
DLLEXPORT void decode(int link_type UNUSED,const char *packet,unsigned len)
{
struct sctp_common_hdr *hdr;
struct sctp_chunk_hdr *chunk;
int chunk_num = 1;
int vlen;
if(len < (signed)sizeof(struct sctp_common_hdr)) {
printf(" SCTP: packet too short!\n");
return;
}
hdr = (struct sctp_common_hdr *)packet;
printf(" SCTP: Header Src port %hu Dst port %hu Tag %u Csum %u\n",
ntohs(hdr->src_port), ntohs(hdr->dst_port),
ntohl(hdr->verification_tag), ntohl(hdr->checksum));
len -= sizeof(struct sctp_common_hdr);
packet += sizeof(struct sctp_common_hdr);
while(len > 0) {
chunk = (struct sctp_chunk_hdr *)packet;
chunk->length = ntohs(chunk->length);
printf(" SCTP: Chunk %d Type %s Flags %u Len %u\n",
chunk_num++,
sctp_type_to_str(chunk->type), chunk->flags, chunk->length);
if(chunk->length == 0) {
printf(" SCTP: Invalid chunk length, aborting.\n\n");
break;
}
switch(chunk->type) {
case 0: /* DATA */
{
struct sctp_data *data = (struct sctp_data *)(chunk + 1);
printf(" SCTP: TSN %u Stream ID %hu Stream Seqno %hu "
"Payload ID %u\n",
ntohl(data->tsn), ntohs(data->stream_id),
ntohs(data->stream_seqno),
ntohl(data->payload_proto_id));
}
break;
case 1: /* INIT and */
case 2: /* INIT ACK packets have the same structure */
{
/* INIT ACK */
struct sctp_init_ack *ack = (struct sctp_init_ack *)
(chunk + 1);
printf(" SCTP: Tag %u Credit %u Outbound %hu Inbound %hu "
"TSN %u\n",
ntohl(ack->init_tag),
ntohl(ack->rcv_wnd_credit),
ntohs(ack->outbound_streams),
ntohs(ack->inbound_streams),
ntohl(ack->init_tsn));
vlen = chunk->length - (sizeof(struct sctp_init_ack) +
sizeof(struct sctp_chunk_hdr) +
sizeof(struct sctp_common_hdr)
);
parse_options((char *)(ack + 1), vlen);
}
break;
case 3: /* SACK */
{
struct sctp_sack *sack = (struct sctp_sack *)(chunk + 1);
int i;
printf(" SCTP: Ack %u Wnd %u\n", ntohl(sack->tsn_ack),
ntohl(sack->a_wnd));
for(i = 0; i < ntohs(sack->num_gap_blocks); i++) {
uint16_t *p = (uint16_t *)(sack + 1);
p += i * 2;
printf(" SCTP: Gap ACK Start %hu End %hu\n",
ntohs(*p), ntohs(*(p + 1)));
}
for(i = 0; i < ntohs(sack->num_dup_tsns); i++) {
uint32_t *p = (uint32_t *)(sack + 1);
p += ntohs(sack->num_gap_blocks) + i;
printf(" SCTP: Duplicatate TSN %u\n", ntohl(*p));
}
}
break;
}
packet += chunk->length;
len -= chunk->length;
}
printf("\n");
}
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