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[or-cvs] r16156: Implement most of proposal 110. (in tor/trunk: . doc doc/spec/proposals src/or)
Author: nickm
Date: 2008-07-23 11:58:38 -0400 (Wed, 23 Jul 2008)
New Revision: 16156
Modified:
tor/trunk/
tor/trunk/ChangeLog
tor/trunk/doc/TODO
tor/trunk/doc/spec/proposals/110-avoid-infinite-circuits.txt
tor/trunk/src/or/circuitlist.c
tor/trunk/src/or/command.c
tor/trunk/src/or/or.h
tor/trunk/src/or/relay.c
Log:
r17323@aud-055: nickm | 2008-07-23 17:58:25 +0200
Implement most of proposal 110.
/home/or/svnrepo/hooks/commit-email.pl: `/usr/bin/svnlook diff /home/or/svnrepo -r 16156' failed with this output:
Property changes on: tor/trunk
___________________________________________________________________
svk:merge ticket from /tor/trunk [r17323] on 49666b30-7950-49c5-bedf-9dc8f3168102
Modified: tor/trunk/ChangeLog
===================================================================
--- tor/trunk/ChangeLog 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/ChangeLog 2008-07-23 15:58:38 UTC (rev 16156)
@@ -3,6 +3,13 @@
- Send a bootstrap problem "warn" event on the first problem if the
reason is NO_ROUTE (that is, our network is down).
+ o Major features:
+ - Implements most of proposal 110: The first K cells to be send
+ along a circuit are marked as special "early" cells; only K
+ "early" cells will be allowed. Once this code is universal, we
+ can block certain kinds of DOS attack by only allowing EXTEND
+ commands in these cells.
+
o Major bugfixes:
- Try to attach connections immediately upon receiving a RENDEZVOUS2
or RENDEZVOUS_ESTABLISHED cell. This can save a second or two
Modified: tor/trunk/doc/TODO
===================================================================
--- tor/trunk/doc/TODO 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/doc/TODO 2008-07-23 15:58:38 UTC (rev 16156)
@@ -214,7 +214,7 @@
For 0.2.1.x:
- Proposals to do:
- - 110: avoid infinite-length circuits
+ o 110: avoid infinite-length circuits
R d 128: families of private bridges
- 134: handle authority fragmentation.
Modified: tor/trunk/doc/spec/proposals/110-avoid-infinite-circuits.txt
===================================================================
--- tor/trunk/doc/spec/proposals/110-avoid-infinite-circuits.txt 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/doc/spec/proposals/110-avoid-infinite-circuits.txt 2008-07-23 15:58:38 UTC (rev 16156)
@@ -6,9 +6,11 @@
Created: 13-Mar-2007
Status: Accepted
Target: 0.2.1.x
+Implemented-In: 0.2.1.3-alpha
History:
+ Revised 28 July 2008 by nickm: set K.
Revised 3 July 2008 by nickm: rename from relay_extend to
relay_early. Revise to current migration plan. Allow K cells
over circuit lifetime, not just at start.
@@ -85,17 +87,22 @@
is not speaking the v2 link protocol, the server relays the cell as
a RELAY cell.
- In 0.2.1.x, clients begin using RELAY_EARLY cells on v2 connections.
- This functionality can be safely backported to 0.2.0.x. Clients
- should pick a random number betweeen (say) 8 and 10 to send.
+ In 0.2.1.3-alpha, clients begin using RELAY_EARLY cells on v2
+ connections. This functionality can be safely backported to
+ 0.2.0.x. Clients should pick a random number betweeen (say) K and
+ K-2 to send.
- In 0.2.1.x, servers close any circuit in which more than K
+ In 0.2.1.3-alpha, servers close any circuit in which more than K
relay_early cells are sent.
Once all versions the do not send RELAY_EARLY cells are obsolete,
servers can begin to reject any EXTEND requests not sent in a
RELAY_EARLY cell.
+Parameters:
+
+ Let K = 8, for no terribly good reason.
+
Spec:
[We can formalize this part once we think the design is a good one.]
Modified: tor/trunk/src/or/circuitlist.c
===================================================================
--- tor/trunk/src/or/circuitlist.c 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/src/or/circuitlist.c 2008-07-23 15:58:38 UTC (rev 16156)
@@ -347,6 +347,8 @@
circ->next_stream_id = crypto_rand_int(1<<16);
circ->global_identifier = n_circuits_allocated++;
+ circ->remaining_relay_early_cells = MAX_RELAY_EARLY_CELLS_PER_CIRCUIT;
+ circ->remaining_relay_early_cells -= crypto_rand_int(2);
init_circuit_base(TO_CIRCUIT(circ));
@@ -367,6 +369,8 @@
if (p_conn)
circuit_set_p_circid_orconn(circ, p_circ_id, p_conn);
+ circ->remaining_relay_early_cells = MAX_RELAY_EARLY_CELLS_PER_CIRCUIT;
+
init_circuit_base(TO_CIRCUIT(circ));
return circ;
Modified: tor/trunk/src/or/command.c
===================================================================
--- tor/trunk/src/or/command.c 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/src/or/command.c 2008-07-23 15:58:38 UTC (rev 16156)
@@ -353,8 +353,8 @@
}
}
-/** Process a 'relay' <b>cell</b> that just arrived from <b>conn</b>. Make sure
- * it came in with a recognized circ_id. Pass it on to
+/** Process a 'relay' or 'relay_early' <b>cell</b> that just arrived from
+ * <b>conn</b>. Make sure it came in with a recognized circ_id. Pass it on to
* circuit_receive_relay_cell() for actual processing.
*/
static void
@@ -390,6 +390,30 @@
else
direction = CELL_DIRECTION_IN;
+ /* If we have a relay_early cell, make sure that it's outbound, and we've
+ * gotten no more than MAX_RELAY_EARLY_CELLS_PER_CIRCUIT of them. */
+ if (cell->command == CELL_RELAY_EARLY) {
+ if (direction == CELL_DIRECTION_IN) {
+ log_fn(LOG_PROTOCOL_WARN, LD_OR,
+ "Received an inbound RELAY_EARLY cell on circuit %d from %s:%d."
+ " Closing circuit.",
+ cell->circ_id, conn->_base.address, conn->_base.port);
+ circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
+ return;
+ } else {
+ or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
+ if (or_circ->remaining_relay_early_cells == 0) {
+ log_fn(LOG_PROTOCOL_WARN, LD_OR,
+ "Received too many RELAY_EARLY cells on circ %d from %s:%d."
+ " Closing circuit.",
+ cell->circ_id, safe_str(conn->_base.address), conn->_base.port);
+ circuit_mark_for_close(circ, END_CIRC_REASON_TORPROTOCOL);
+ return;
+ }
+ --or_circ->remaining_relay_early_cells;
+ }
+ }
+
if ((reason = circuit_receive_relay_cell(cell, circ, direction)) < 0) {
log_fn(LOG_PROTOCOL_WARN,LD_PROTOCOL,"circuit_receive_relay_cell "
"(%s) failed. Closing.",
Modified: tor/trunk/src/or/or.h
===================================================================
--- tor/trunk/src/or/or.h 2008-07-23 15:58:30 UTC (rev 16155)
+++ tor/trunk/src/or/or.h 2008-07-23 15:58:38 UTC (rev 16156)
@@ -1828,6 +1828,10 @@
struct circuit_t *next; /**< Next circuit in linked list of all circuits. */
} circuit_t;
+/** Largest number of relay_early cells that we can send on a given
+ * circuit. */
+#define MAX_RELAY_EARLY_CELLS_PER_CIRCUIT 8
+
/** An origin_circuit_t holds data necessary to build and use a circuit.
*/
typedef struct origin_circuit_t {
@@ -1870,15 +1874,19 @@
*/
uint8_t rend_desc_version;
+ /** How many more relay_early cells can we send on this circuit, according
+ * to the specification? */
+ unsigned int remaining_relay_early_cells : 4;
+
+ /** The next stream_id that will be tried when we're attempting to
+ * construct a new AP stream originating at this circuit. */
+ streamid_t next_stream_id;
+
/* The intro key replaces the hidden service's public key if purpose is
* S_ESTABLISH_INTRO or S_INTRO, provided that no unversioned rendezvous
* descriptor is used. */
crypto_pk_env_t *intro_key;
- /** The next stream_id that will be tried when we're attempting to
- * construct a new AP stream originating at this circuit. */
- streamid_t next_stream_id;
-
/** Quasi-global identifier for this circuit; used for control.c */
/* XXXX NM This can get re-used after 2**32 circuits. */
uint32_t global_identifier;
@@ -1946,6 +1954,10 @@
/* ???? move to a subtype or adjunct structure? Wastes 20 bytes -NM */
char handshake_digest[DIGEST_LEN]; /**< Stores KH for the handshake. */
+ /** How many more relay_early cells can we send on this circuit, according
+ * to the specification? */
+ unsigned int remaining_relay_early_cells : 4;
+
/** True iff this circuit was made with a CREATE_FAST cell. */
unsigned int is_first_hop : 1;
} or_circuit_t;
Modified: tor/trunk/src/or/relay.c
===================================================================