Babel: Refactor TLV parsing code for easier reuse
In preparation for adding authentication checks, refactor the TLV walking code so it can be reused for a separate pass of the packet for authentication checks.
This commit is contained in:
Toke Høiland-Jørgensen
Ondrej Zajicek (work)
parent
589f7d1e4f
commit
69d10132a6
1 changed files with 108 additions and 65 deletions
|
|
@ -120,8 +120,19 @@ struct babel_subtlv_source_prefix {
|
|||
#define BABEL_UF_DEF_PREFIX 0x80
|
||||
#define BABEL_UF_ROUTER_ID 0x40
|
||||
|
||||
struct babel_parse_state;
|
||||
struct babel_write_state;
|
||||
|
||||
struct babel_tlv_data {
|
||||
u8 min_length;
|
||||
int (*read_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state);
|
||||
uint (*write_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state, uint max_len);
|
||||
void (*handle_tlv)(union babel_msg *m, struct babel_iface *ifa);
|
||||
};
|
||||
|
||||
struct babel_parse_state {
|
||||
const struct babel_tlv_data* (*get_tlv_data)(u8 type);
|
||||
const struct babel_tlv_data* (*get_subtlv_data)(u8 type);
|
||||
struct babel_proto *proto;
|
||||
struct babel_iface *ifa;
|
||||
ip_addr saddr;
|
||||
|
|
@ -167,6 +178,37 @@ struct babel_write_state {
|
|||
|
||||
#define NET_SIZE(n) BYTES(net_pxlen(n))
|
||||
|
||||
|
||||
/* Helper macros to loop over a series of TLVs.
|
||||
* @start pointer to first TLV (void * or struct babel_tlv *)
|
||||
* @end byte * pointer to TLV stream end
|
||||
* @tlv struct babel_tlv pointer used as iterator
|
||||
* @frame_err boolean (u8) that will be set to 1 if a frame error occurred
|
||||
* @saddr source addr for use in log output
|
||||
* @ifname ifname for use in log output
|
||||
*/
|
||||
#define WALK_TLVS(start, end, tlv, frame_err, saddr, ifname) \
|
||||
for (tlv = start; \
|
||||
(byte *)tlv < end; \
|
||||
tlv = NEXT_TLV(tlv)) \
|
||||
{ \
|
||||
byte *loop_pos; \
|
||||
/* Ugly special case */ \
|
||||
if (tlv->type == BABEL_TLV_PAD1) \
|
||||
continue; \
|
||||
\
|
||||
/* The end of the common TLV header */ \
|
||||
loop_pos = (byte *)tlv + sizeof(struct babel_tlv); \
|
||||
if ((loop_pos > end) || (loop_pos + tlv->length > end)) \
|
||||
{ \
|
||||
LOG_PKT("Bad TLV from %I via %s type %d pos %d - framing error", \
|
||||
saddr, ifname, tlv->type, (byte *)tlv - (byte *)start); \
|
||||
frame_err = 1; \
|
||||
break; \
|
||||
}
|
||||
|
||||
#define WALK_TLVS_END }
|
||||
|
||||
static inline uint
|
||||
bytes_equal(u8 *b1, u8 *b2, uint maxlen)
|
||||
{
|
||||
|
|
@ -255,13 +297,6 @@ static uint babel_write_route_request(struct babel_tlv *hdr, union babel_msg *ms
|
|||
static uint babel_write_seqno_request(struct babel_tlv *hdr, union babel_msg *msg, struct babel_write_state *state, uint max_len);
|
||||
static int babel_write_source_prefix(struct babel_tlv *hdr, net_addr *net, uint max_len);
|
||||
|
||||
struct babel_tlv_data {
|
||||
u8 min_length;
|
||||
int (*read_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_parse_state *state);
|
||||
uint (*write_tlv)(struct babel_tlv *hdr, union babel_msg *m, struct babel_write_state *state, uint max_len);
|
||||
void (*handle_tlv)(union babel_msg *m, struct babel_iface *ifa);
|
||||
};
|
||||
|
||||
static const struct babel_tlv_data tlv_data[BABEL_TLV_MAX] = {
|
||||
[BABEL_TLV_ACK_REQ] = {
|
||||
sizeof(struct babel_tlv_ack_req),
|
||||
|
|
@ -319,6 +354,30 @@ static const struct babel_tlv_data tlv_data[BABEL_TLV_MAX] = {
|
|||
},
|
||||
};
|
||||
|
||||
static const struct babel_tlv_data *get_packet_tlv_data(u8 type)
|
||||
{
|
||||
return type < sizeof(tlv_data) / sizeof(*tlv_data) ? &tlv_data[type] : NULL;
|
||||
}
|
||||
|
||||
static const struct babel_tlv_data source_prefix_tlv_data = {
|
||||
sizeof(struct babel_subtlv_source_prefix),
|
||||
babel_read_source_prefix,
|
||||
NULL,
|
||||
NULL
|
||||
};
|
||||
|
||||
static const struct babel_tlv_data *get_packet_subtlv_data(u8 type)
|
||||
{
|
||||
switch(type)
|
||||
{
|
||||
case BABEL_SUBTLV_SOURCE_PREFIX:
|
||||
return &source_prefix_tlv_data;
|
||||
|
||||
default:
|
||||
return NULL;
|
||||
}
|
||||
}
|
||||
|
||||
static int
|
||||
babel_read_ack_req(struct babel_tlv *hdr, union babel_msg *m,
|
||||
struct babel_parse_state *state)
|
||||
|
|
@ -1083,69 +1142,65 @@ babel_write_source_prefix(struct babel_tlv *hdr, net_addr *n, uint max_len)
|
|||
return len;
|
||||
}
|
||||
|
||||
|
||||
static inline int
|
||||
babel_read_subtlvs(struct babel_tlv *hdr,
|
||||
union babel_msg *msg,
|
||||
struct babel_parse_state *state)
|
||||
{
|
||||
const struct babel_tlv_data *tlv_data;
|
||||
struct babel_proto *p = state->proto;
|
||||
struct babel_tlv *tlv;
|
||||
byte *pos, *end = (byte *) hdr + TLV_LENGTH(hdr);
|
||||
byte *end = (byte *) hdr + TLV_LENGTH(hdr);
|
||||
u8 frame_err = 0;
|
||||
int res;
|
||||
|
||||
for (tlv = (void *) hdr + state->current_tlv_endpos;
|
||||
(byte *) tlv < end;
|
||||
tlv = NEXT_TLV(tlv))
|
||||
WALK_TLVS((void *)hdr + state->current_tlv_endpos, end, tlv, frame_err,
|
||||
state->saddr, state->ifa->ifname)
|
||||
{
|
||||
/* Ugly special case */
|
||||
if (tlv->type == BABEL_TLV_PAD1)
|
||||
if (tlv->type == BABEL_SUBTLV_PADN)
|
||||
continue;
|
||||
|
||||
/* The end of the common TLV header */
|
||||
pos = (byte *)tlv + sizeof(struct babel_tlv);
|
||||
if ((pos > end) || (pos + tlv->length > end))
|
||||
return PARSE_ERROR;
|
||||
|
||||
/*
|
||||
* The subtlv type space is non-contiguous (due to the mandatory bit), so
|
||||
* use a switch for dispatch instead of the mapping array we use for TLVs
|
||||
*/
|
||||
switch (tlv->type)
|
||||
if (!state->get_subtlv_data ||
|
||||
!(tlv_data = state->get_subtlv_data(tlv->type)) ||
|
||||
!tlv_data->read_tlv)
|
||||
{
|
||||
case BABEL_SUBTLV_SOURCE_PREFIX:
|
||||
res = babel_read_source_prefix(tlv, msg, state);
|
||||
if (res != PARSE_SUCCESS)
|
||||
return res;
|
||||
break;
|
||||
|
||||
case BABEL_SUBTLV_PADN:
|
||||
default:
|
||||
/* Unknown mandatory subtlv; PARSE_IGNORE ignores the whole TLV */
|
||||
if (tlv->type >= 128)
|
||||
return PARSE_IGNORE;
|
||||
break;
|
||||
return PARSE_IGNORE;
|
||||
continue;
|
||||
}
|
||||
}
|
||||
|
||||
return PARSE_SUCCESS;
|
||||
res = tlv_data->read_tlv(tlv, msg, state);
|
||||
if (res != PARSE_SUCCESS)
|
||||
return res;
|
||||
}
|
||||
WALK_TLVS_END;
|
||||
|
||||
return frame_err ? PARSE_ERROR : PARSE_SUCCESS;
|
||||
}
|
||||
|
||||
static inline int
|
||||
static int
|
||||
babel_read_tlv(struct babel_tlv *hdr,
|
||||
union babel_msg *msg,
|
||||
struct babel_parse_state *state)
|
||||
{
|
||||
const struct babel_tlv_data *tlv_data;
|
||||
|
||||
if ((hdr->type <= BABEL_TLV_PADN) ||
|
||||
(hdr->type >= BABEL_TLV_MAX) ||
|
||||
!tlv_data[hdr->type].read_tlv)
|
||||
(hdr->type >= BABEL_TLV_MAX))
|
||||
return PARSE_IGNORE;
|
||||
|
||||
if (TLV_LENGTH(hdr) < tlv_data[hdr->type].min_length)
|
||||
tlv_data = state->get_tlv_data(hdr->type);
|
||||
|
||||
if (!tlv_data || !tlv_data->read_tlv)
|
||||
return PARSE_IGNORE;
|
||||
|
||||
if (TLV_LENGTH(hdr) < tlv_data->min_length)
|
||||
return PARSE_ERROR;
|
||||
|
||||
state->current_tlv_endpos = tlv_data[hdr->type].min_length;
|
||||
state->current_tlv_endpos = tlv_data->min_length;
|
||||
|
||||
int res = tlv_data[hdr->type].read_tlv(hdr, msg, state);
|
||||
int res = tlv_data->read_tlv(hdr, msg, state);
|
||||
if (res != PARSE_SUCCESS)
|
||||
return res;
|
||||
|
||||
|
|
@ -1330,6 +1385,7 @@ static void
|
|||
babel_process_packet(struct babel_pkt_header *pkt, int len,
|
||||
ip_addr saddr, struct babel_iface *ifa)
|
||||
{
|
||||
u8 frame_err UNUSED = 0;
|
||||
struct babel_proto *p = ifa->proto;
|
||||
struct babel_tlv *tlv;
|
||||
struct babel_msg_node *msg;
|
||||
|
|
@ -1337,15 +1393,16 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
|
|||
int res;
|
||||
|
||||
int plen = sizeof(struct babel_pkt_header) + get_u16(&pkt->length);
|
||||
byte *pos;
|
||||
byte *end = (byte *)pkt + plen;
|
||||
|
||||
struct babel_parse_state state = {
|
||||
.proto = p,
|
||||
.ifa = ifa,
|
||||
.saddr = saddr,
|
||||
.next_hop_ip6 = saddr,
|
||||
.sadr_enabled = babel_sadr_enabled(p),
|
||||
.get_tlv_data = &get_packet_tlv_data,
|
||||
.get_subtlv_data = &get_packet_subtlv_data,
|
||||
.proto = p,
|
||||
.ifa = ifa,
|
||||
.saddr = saddr,
|
||||
.next_hop_ip6 = saddr,
|
||||
.sadr_enabled = babel_sadr_enabled(p),
|
||||
};
|
||||
|
||||
if ((pkt->magic != BABEL_MAGIC) || (pkt->version != BABEL_VERSION))
|
||||
|
|
@ -1369,23 +1426,8 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
|
|||
|
||||
/* First pass through the packet TLV by TLV, parsing each into internal data
|
||||
structures. */
|
||||
for (tlv = FIRST_TLV(pkt);
|
||||
(byte *)tlv < end;
|
||||
tlv = NEXT_TLV(tlv))
|
||||
WALK_TLVS(FIRST_TLV(pkt), end, tlv, frame_err, saddr, ifa->iface->name)
|
||||
{
|
||||
/* Ugly special case */
|
||||
if (tlv->type == BABEL_TLV_PAD1)
|
||||
continue;
|
||||
|
||||
/* The end of the common TLV header */
|
||||
pos = (byte *)tlv + sizeof(struct babel_tlv);
|
||||
if ((pos > end) || (pos + tlv->length > end))
|
||||
{
|
||||
LOG_PKT("Bad TLV from %I via %s type %d pos %d - framing error",
|
||||
saddr, ifa->iface->name, tlv->type, (byte *)tlv - (byte *)pkt);
|
||||
break;
|
||||
}
|
||||
|
||||
msg = sl_allocz(p->msg_slab);
|
||||
res = babel_read_tlv(tlv, &msg->msg, &state);
|
||||
if (res == PARSE_SUCCESS)
|
||||
|
|
@ -1405,8 +1447,9 @@ babel_process_packet(struct babel_pkt_header *pkt, int len,
|
|||
break;
|
||||
}
|
||||
}
|
||||
WALK_TLVS_END;
|
||||
|
||||
/* Parsing done, handle all parsed TLVs */
|
||||
/* Parsing done, handle all parsed TLVs, regardless of any errors */
|
||||
WALK_LIST_FIRST(msg, msgs)
|
||||
{
|
||||
if (tlv_data[msg->msg.type].handle_tlv)
|
||||
|
|
|
|||
Loading…
Reference in a new issue