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lightningd: check amt_to_forward and outgoing_cltv_value 

These must be checked whether we're the final hop or not.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
ppa-0.6.1
Rusty Russell 8 years ago
committed by Christian Decker
parent
d35bf90009
commit
8016dbbc91
3 changed files with 127 additions and 20 deletions
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  1. 2
      lightningd/dev_newhtlc.c
  2. 141
      lightningd/peer_control.c
  3. 4
      wire/gen_onion_wire_csv

2
lightningd/dev_newhtlc.c
View File

@ -116,6 +116,8 @@ static void json_dev_newhtlc(struct command *cmd,
tal_arr(cmd, struct pubkey, 1);
hoppayloads = tal_arrz(cmd, struct hoppayload, 1);
hoppayloads[0].amt_to_forward = msatoshi;
hoppayloads[0].outgoing_cltv_value = expiry;
path[0] = *peer->id;
randombytes_buf(&sessionkey, sizeof(sessionkey));
packet = create_onionpacket(cmd, path, hoppayloads, sessionkey,

141
lightningd/peer_control.c
View File

@ -656,19 +656,104 @@ static void fail_htlc(struct peer *peer, u64 htlc_id, const u8 *msg)
tal_free(msg);
}
/* BOLT #4:
*
* * `amt_to_forward` - The amount in milli-satoshi to forward to the next
* (outgoing) hop specified within the routing information.
*
* This value MUST factor in the computed fee for this particular hop. When
* processing an incoming Sphinx packet along with the HTLC message it's
* encapsulated within, if the following inequality doesn't hold, then the
* HTLC should be rejected as it indicates a prior node in the path has
* deviated from the specified paramters:
*
* incoming_htlc_amt - fee >= amt_to_forward
*
* Where `fee` is calculated according to the receving node's advertised fee
* schema as described in [BOLT 7](https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md#htlc-fees), or 0 if this node is the
* final hop.
*/
static bool check_amount(struct htlc_end *hend,
u64 amt_to_forward, u64 amt_in_htlc, u64 fee)
{
if (amt_in_htlc - fee >= amt_to_forward)
return true;
log_debug(hend->peer->ld->log, "HTLC %"PRIu64" incorrect amount:"
" %"PRIu64" in, %"PRIu64" out, fee reqd %"PRIu64,
hend->htlc_id, amt_in_htlc, amt_to_forward, fee);
return false;
}
/* BOLT #4:
*
* * `outgoing_cltv_value` - The CLTV value that the _outgoing_ HTLC carrying
* the packet should have.
*
* cltv-expiry - cltv-expiry-delta = outgoing_cltv_value
*
* Inclusion of this field allows a node to both authenticate the information
* specified by the original sender and the paramaters of the HTLC forwarded,
* and ensure the original sender is using the current `cltv-expiry-delta` value.
* If there is no next hop, `cltv-expiry-delta` is zero.
* If the values don't correspond, then the HTLC should be failed+rejected as
* this indicates the incoming node has tampered with the intended HTLC
* values, or the origin has an obsolete `cltv-expiry-delta` value.
* The node MUST be consistent in responding to an unexpected
* `outgoing_cltv_value` whether it is the final hop or not, to avoid
* leaking that information.
*/
static bool check_ctlv(struct htlc_end *hend,
u32 ctlv_expiry, u32 outgoing_cltv_value, u32 delta)
{
if (ctlv_expiry - delta == outgoing_cltv_value)
return true;
log_debug(hend->peer->ld->log, "HTLC %"PRIu64" incorrect CLTV:"
" %u in, %u out, delta reqd %u",
hend->htlc_id, ctlv_expiry, outgoing_cltv_value, delta);
return false;
}
static void handle_localpay(struct htlc_end *hend,
u32 cltv_expiry,
const struct sha256 *payment_hash)
const struct sha256 *payment_hash,
u64 amt_to_forward,
u32 outgoing_cltv_value)
{
u8 *msg;
struct invoice *invoice = find_unpaid(hend->peer->ld->dstate.invoices,
payment_hash);
u8 *msg, *err;
struct invoice *invoice;
/* BOLT #4:
*
* If the `amt_to_forward` does not match the `incoming_htlc_amt` of
* the HTLC at the final hop:
*
* 1. type: 19 (`final_incorrect_htlc_amount`)
* 2. data:
* * [4:incoming-htlc-amt]
*/
if (!check_amount(hend, amt_to_forward, hend->msatoshis, 0)) {
err = towire_final_incorrect_htlc_amount(hend, hend->msatoshis);
goto fail;
}
/* BOLT #4:
*
* If the `outgoing_cltv_value` does not match the `ctlv-expiry` of
* the HTLC at the final hop:
*
* 1. type: 18 (`final_incorrect_cltv_expiry`)
* 2. data:
* * [4:cltv-expiry]
*/
if (!check_ctlv(hend, cltv_expiry, outgoing_cltv_value, 0)) {
err = towire_final_incorrect_cltv_expiry(hend, cltv_expiry);
goto fail;
}
invoice = find_unpaid(hend->peer->ld->dstate.invoices, payment_hash);
if (!invoice) {
fail_htlc(hend->peer, hend->htlc_id,
take(towire_unknown_payment_hash(hend)));
tal_free(hend);
return;
err = towire_unknown_payment_hash(hend);
goto fail;
}
/* BOLT #4:
@ -682,13 +767,11 @@ static void handle_localpay(struct htlc_end *hend,
* 1. type: PERM|16 (`incorrect_payment_amount`)
*/
if (hend->msatoshis < invoice->msatoshi) {
fail_htlc(hend->peer, hend->htlc_id,
take(towire_incorrect_payment_amount(hend)));
return;
err = towire_incorrect_payment_amount(hend);
goto fail;
} else if (hend->msatoshis > invoice->msatoshi * 2) {
fail_htlc(hend->peer, hend->htlc_id,
take(towire_incorrect_payment_amount(hend)));
return;
err = towire_incorrect_payment_amount(hend);
goto fail;
}
/* BOLT #4:
@ -702,10 +785,8 @@ static void handle_localpay(struct htlc_end *hend,
cltv_expiry,
get_block_height(hend->peer->ld->topology),
hend->peer->ld->dstate.config.deadline_blocks);
fail_htlc(hend->peer, hend->htlc_id,
take(towire_final_expiry_too_soon(hend)));
tal_free(hend);
return;
err = towire_final_expiry_too_soon(hend);
goto fail;
}
/* FIXME: fail the peer if it doesn't tell us that htlc fulfill is
@ -722,6 +803,22 @@ static void handle_localpay(struct htlc_end *hend,
msg = towire_channel_fulfill_htlc(hend->peer, hend->htlc_id, &invoice->r);
subd_send_msg(hend->peer->owner, take(msg));
resolve_invoice(&hend->peer->ld->dstate, invoice);
return;
fail:
fail_htlc(hend->peer, hend->htlc_id, take(err));
tal_free(hend);
}
static void forward_htlc(struct htlc_end *hend,
u32 cltv_expiry,
const struct sha256 *payment_hash,
u64 amt_to_forward,
u32 outgoing_cltv_value,
const u8 next_hop[20],
const u8 next_onion[TOTAL_PACKET_SIZE])
{
log_broken(hend->peer->log, "FIXME: Implement forwarding!");
}
static int peer_accepted_htlc(struct peer *peer, const u8 *msg)
@ -730,6 +827,7 @@ static int peer_accepted_htlc(struct peer *peer, const u8 *msg)
u32 cltv_expiry, amount_msat;
struct sha256 payment_hash;
u8 next_onion[TOTAL_PACKET_SIZE];
u8 next_hop[20];
bool forward;
u64 amt_to_forward;
u32 outgoing_cltv_value;
@ -754,9 +852,12 @@ static int peer_accepted_htlc(struct peer *peer, const u8 *msg)
hend->msatoshis = amount_msat;
if (forward)
log_broken(peer->log, "FIXME: Implement forwarding!");
forward_htlc(hend, cltv_expiry, &payment_hash,
amt_to_forward, outgoing_cltv_value,
next_hop, next_onion);
else
handle_localpay(hend, cltv_expiry, &payment_hash);
handle_localpay(hend, cltv_expiry, &payment_hash,
amt_to_forward, outgoing_cltv_value);
return 0;
}

4
wire/gen_onion_wire_csv
View File

@ -31,3 +31,7 @@ expiry_too_soon,2,channel_update,len
unknown_payment_hash,PERM|15
incorrect_payment_amount,PERM|16
final_expiry_too_soon,17
final_incorrect_cltv_expiry,18
final_incorrect_cltv_expiry,0,cltv-expiry,4
final_incorrect_htlc_amount,19
final_incorrect_htlc_amount,0,incoming-htlc-amt,4

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