[or-cvs] Implement midpoint functionality for rendezvous points.
Nick Mathewson
nickm at seul.org
Fri Apr 2 21:56:54 UTC 2004
Update of /home/or/cvsroot/src/or
In directory moria.mit.edu:/tmp/cvs-serv27068/src/or
Modified Files:
circuit.c or.h rendmid.c rendservice.c
Log Message:
Implement midpoint functionality for rendezvous points.
Index: circuit.c
===================================================================
RCS file: /home/or/cvsroot/src/or/circuit.c,v
retrieving revision 1.168
retrieving revision 1.169
diff -u -d -r1.168 -r1.169
--- circuit.c 1 Apr 2004 22:21:01 -0000 1.168
+++ circuit.c 2 Apr 2004 21:56:52 -0000 1.169
@@ -88,7 +88,6 @@
}
}
-
circuit_t *circuit_new(uint16_t p_circ_id, connection_t *p_conn) {
circuit_t *circ;
@@ -307,14 +306,21 @@
return NULL;
}
-/* Return the first circuit in global_circuitlist whose rend_service
- * field is servid and whose purpose is purpose. Returns NULL if no circuit
- * is found.
+/* Return the first circuit in global_circuitlist after 'start' whose
+ * rend_service field is servid and whose purpose is purpose. Returns
+ * NULL if no circuit is found. If 'start' is null, begin at the start of
+ * the list.
*/
-circuit_t *circuit_get_by_service_and_purpose(const char *servid, int purpose)
+circuit_t *circuit_get_next_by_service_and_purpose(circuit_t *start,
+ const char *servid, int purpose)
{
circuit_t *circ;
- for(circ=global_circuitlist; circ; circ = circ->next) {
+ if (start == NULL)
+ circ = global_circuitlist;
+ else
+ circ = start->next;
+
+ for( ; circ; circ = circ->next) {
if (circ->marked_for_close)
continue;
if (circ->purpose != purpose)
@@ -325,6 +331,21 @@
return NULL;
}
+/* Return the circuit waiting for a rendezvous with the provided cookie.
+ * Return NULL if no such circuit is found.
+ */
+circuit_t *circuit_get_rendezvous(const char *cookie)
+{
+ circuit_t *circ;
+ for (circ = global_circuitlist; circ; circ = circ->next) {
+ if (! circ->marked_for_close &&
+ circ->purpose == CIRCUIT_PURPOSE_REND_POINT_WAITING &&
+ ! memcmp(circ->rend_cookie, cookie, REND_COOKIE_LEN) )
+ return circ;
+ }
+ return NULL;
+}
+
#define MIN_SECONDS_BEFORE_EXPIRING_CIRC 10
/* circuits that were born at the end of their second might be expired
* after 10.1 seconds; circuits born at the beginning might be expired
@@ -516,6 +537,17 @@
}
if(!conn) {
+ if (circ->rend_splice && cell_direction == CELL_DIRECTION_OUT) {
+ assert(circ->purpose == CIRCUIT_PURPOSE_REND_ESTABLISHED);
+ assert(circ->rend_splice->purpose == CIRCUIT_PURPOSE_REND_ESTABLISHED);
+ cell->circ_id = circ->rend_splice->p_circ_id;
+ if (circuit_receive_relay_cell(cell, circ->rend_splice, CELL_DIRECTION_IN)<0) {
+ log_fn(LOG_WARN, "Error relaying cell across rendezvous; closing circuits");
+ circuit_mark_for_close(circ); /* XXXX Do this here, or just return -1? */
+ return -1;
+ }
+ return 0;
+ }
log_fn(LOG_WARN,"Didn't recognize cell, but circ stops here! Closing circ.");
return -1;
}
Index: or.h
===================================================================
RCS file: /home/or/cvsroot/src/or/or.h,v
retrieving revision 1.278
retrieving revision 1.279
diff -u -d -r1.278 -r1.279
--- or.h 1 Apr 2004 22:21:01 -0000 1.278
+++ or.h 2 Apr 2004 21:56:52 -0000 1.279
@@ -560,8 +560,8 @@
char rend_service[CRYPTO_SHA1_DIGEST_LEN];
/* Holds rendezvous cookie if purpose is REND_POINT_WAITING or
- * S_RENDEZVOUSING or C_ESTABLISH_REND. Filled with zeroes otherwise.
- */
+ * C_ESTABLISH_REND. Filled with zeroes otherwise.
+ */
char rend_cookie[REND_COOKIE_LEN];
/* Points to spliced circuit if purpose is REND_ESTABLISHED, and circuit
@@ -692,7 +692,9 @@
circuit_t *circuit_get_by_conn(connection_t *conn);
circuit_t *circuit_get_newest(connection_t *conn,
int must_be_open, int must_be_clean);
-circuit_t *circuit_get_by_service_and_purpose(const char *servid, int purpose);
+circuit_t *circuit_get_next_by_service_and_purpose(circuit_t *circuit,
+ const char *servid, int purpose);
+circuit_t *circuit_get_rendezvous(const char *cookie);
void circuit_expire_building(void);
int circuit_count_building(void);
Index: rendmid.c
===================================================================
RCS file: /home/or/cvsroot/src/or/rendmid.c,v
retrieving revision 1.1
retrieving revision 1.2
diff -u -d -r1.1 -r1.2
--- rendmid.c 1 Apr 2004 04:07:09 -0000 1.1
+++ rendmid.c 2 Apr 2004 21:56:52 -0000 1.2
@@ -4,28 +4,193 @@
#include "or.h"
+/* Respond to an ESTABLISH_INTRO cell by setting the circuit's purpose and
+ * rendevous service.
+ */
int
rend_mid_establish_intro(circuit_t *circ, char *request, int request_len)
{
+ crypto_pk_env_t *pk = NULL;
+ char buf[20+9];
+ char expected_digest[20];
+ char pk_digest[20];
+ int asn1len;
+ circuit_t *c;
+
+ if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
+ log_fn(LOG_WARN, "Rejecting ESTABLISH_INTRO on non-intermediate circuit");
+ goto err;
+ }
+ if (request_len < 22)
+ goto truncated;
+ /* First 2 bytes: length of asn1-encoded key. */
+ asn1len = get_uint16(request);
+
+ /* Next asn1len bytes: asn1-encoded key. */
+ if (request_len < 22+asn1len)
+ goto truncated;
+ pk = crypto_pk_asn1_decode(request+2, asn1len);
+ if (!pk) {
+ log_fn(LOG_WARN, "Couldn't decode public key");
+ goto err;
+ }
+
+ /* Next 20 bytes: Hash of handshake_digest | "INTRODUCE" */
+ memcpy(buf, circ->handshake_digest, 20);
+ memcpy(buf+20, "INTRODUCE", 9);
+ if (crypto_SHA_digest(buf, 29, expected_digest)<0) {
+ log_fn(LOG_WARN, "Error computing digest");
+ goto err;
+ }
+ if (memcmp(expected_digest, buf+2+asn1len, 20)) {
+ log_fn(LOG_WARN, "Hash of session info was not as expected");
+ goto err;
+ }
+
+ /* Rest of body: signature of previous data */
+ if (crypto_pk_public_checksig_digest(pk, buf, 22+asn1len,
+ buf+22+asn1len, request_len-(22+asn1len))<0) {
+ log_fn(LOG_WARN, "Incorrect signature on ESTABLISH_INTRO cell; rejecting");
+ goto err;
+ }
+
+ /* The request is valid. First, compute the hash of Bob's PK.*/
+ if (crypto_pk_get_digest(pk, pk_digest)<0) {
+ log_fn(LOG_WARN, "Couldn't hash public key.");
+ goto err;
+ }
+
+ /* Close any other intro circuits with the same pk. */
+ c = NULL;
+ while ((c = circuit_get_next_by_service_and_purpose(
+ c,pk_digest,CIRCUIT_PURPOSE_INTRO_POINT))) {
+ circuit_mark_for_close(c);
+ }
+
+ /* Now, set up this circuit. */
+ circ->purpose = CIRCUIT_PURPOSE_INTRO_POINT;
+ memcpy(circ->rend_service, pk_digest, 20);
+
return 0;
+ truncated:
+ log_fn(LOG_WARN, "Rejecting truncated ESTABLISH_INTRO cell");
+ err:
+ if (pk) crypto_free_pk_env(pk);
+ circuit_mark_for_close(circ);
+ return -1;
}
+/* Process an INTRODUCE1 cell by finding the corresponding introduction
+ * circuit, and relaying the body of the INTRODUCE1 cell inside an
+ * INTRODUCE2 cell.
+ */
int
rend_mid_introduce(circuit_t *circ, char *request, int request_len)
{
+ circuit_t *intro_circ;
+
+ if (request_len < 276) {
+ log_fn(LOG_WARN, "Impossibly short INTRODUCE2 cell; dropping.");
+ goto err;
+ }
+
+ /* The first 20 bytes are all we look at: they have a hash of Bob's PK. */
+ intro_circ = circuit_get_next_by_service_and_purpose(
+ NULL, request, CIRCUIT_PURPOSE_INTRO_POINT);
+ if (!intro_circ) {
+ log_fn(LOG_WARN,
+ "No introduction circuit matching INTRODUCE2 cell; dropping");
+ goto err;
+ }
+
+ /* Great. Now we just relay the cell down the circuit. */
+ if (connection_edge_send_command(NULL, intro_circ,
+ RELAY_COMMAND_INTRODUCE2,
+ request, request_len, NULL)) {
+ log_fn(LOG_WARN, "Unable to send INTRODUCE2 cell to OP.");
+ goto err;
+ }
+
return 0;
+ err:
+ circuit_mark_for_close(circ); /* Is this right? */
+ return -1;
}
+/* Process an ESTABLISH_RENDEZVOUS cell by settingthe circuit's purpose and
+ * rendezvous cookie.
+ */
int
rend_mid_establish_rendezvous(circuit_t *circ, char *request, int request_len)
{
+ if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
+ log_fn(LOG_WARN, "Tried to establish rendezvous on non-intermediate circuit");
+ goto err;
+ }
+
+ if (request_len != REND_COOKIE_LEN) {
+ log_fn(LOG_WARN, "Invalid length on ESTABLISH_RENDEZVOUS");
+ goto err;
+ }
+
+ if (circuit_get_rendezvous(request)) {
+ log_fn(LOG_WARN, "Duplicate rendezvous cookie in ESTABLISH_RENDEZVOUS");
+ goto err;
+ }
+
+ circ->purpose = CIRCUIT_PURPOSE_REND_POINT_WAITING;
+ memcpy(circ->rend_cookie, request, REND_COOKIE_LEN);
+
return 0;
+ err:
+ circuit_mark_for_close(circ);
+ return -1;
}
+/* Process a RENDEZVOUS1 cell by looking up the correct rendezvous circuit by its
+ * relaying the cell's body in a RENDEZVOUS2 cell, and connecting the two circuits.
+ */
int
rend_mid_rendezvous(circuit_t *circ, char *request, int request_len)
{
+ circuit_t *rend_circ;
+
+ if (circ->purpose != CIRCUIT_PURPOSE_INTERMEDIATE) {
+ log_fn(LOG_WARN, "Tried to complete rendezvous on non-intermediate circuit");
+ goto err;
+ }
+
+ if (request_len < 20+128+20) {
+ log_fn(LOG_WARN, "Rejecting impossibly short RENDEZVOUS1 cell");
+ goto err;
+ }
+
+ rend_circ = circuit_get_rendezvous(request);
+ if (!rend_circ) {
+ log_fn(LOG_WARN, "Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie");
+ goto err;
+ }
+
+ /* Send the RENDEZVOUS2 cell to Alice. */
+ if (connection_edge_send_command(NULL, rend_circ,
+ RELAY_COMMAND_RENDEZVOUS2,
+ request+20, request_len-20, NULL)) {
+ log_fn(LOG_WARN, "Unable to send RENDEZVOUS2 cell to OP.");
+ goto err;
+ }
+
+ /* Join the circuits. */
+ circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
+ rend_circ->purpose = CIRCUIT_PURPOSE_REND_ESTABLISHED;
+ memset(circ->rend_cookie, 0, 20);
+
+ rend_circ->rend_splice = circ;
+ circ->rend_splice = rend_circ;
+
return 0;
+ err:
+ circuit_mark_for_close(circ);
+ return -1;
}
/*
Index: rendservice.c
===================================================================
RCS file: /home/or/cvsroot/src/or/rendservice.c,v
retrieving revision 1.7
retrieving revision 1.8
diff -u -d -r1.7 -r1.8
--- rendservice.c 1 Apr 2004 22:21:01 -0000 1.7
+++ rendservice.c 2 Apr 2004 21:56:52 -0000 1.8
@@ -235,8 +235,7 @@
return 0;
}
-/*DOCDOC*/
-rend_service_t *
+static rend_service_t *
rend_service_get_by_pk_digest(const char* digest)
{
int i;
@@ -253,17 +252,6 @@
* Handle cells
******/
-typedef struct rend_introduction_t {
- /* Digest of the hidden service's PK. */
- char key_digest[20];
- /* Nickname of OR running rendezvous point. */
- char *rendezvous_point;
- /* Cookie that we'll use to recognize the rendezvous point. */
- char cookie[20];
- /* g^xy */
- char shared_secret[128];
-} rend_introduction_t;
-
/* Respond to an INTRODUCE2 cell by launching a circuit to the chosen
* rendezvous points.
*/
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