move cell size to 512 bytes

move length to 2 bytes, put it in the relay header
remove 4 reserved bytes in cell
add 4 bytes to relay header for the integrity check


svn:r942

6 files changed, 74 insertions, 78 deletions

diff --git a/src/or/circuit.c b/src/or/circuit.c
index fa5883ec1e..7a7cc13b63 100644
--- a/src/or/circuit.c
+++ b/src/or/circuit.c
@@ -303,24 +303,18 @@ int circuit_deliver_relay_cell(cell_t *cell, circuit_t *circ,
                                int cell_direction, crypt_path_t *layer_hint) {
   connection_t *conn=NULL;
   char recognized=0;
-  char buf[1+CELL_PAYLOAD_SIZE];
 
   assert(cell && circ);
   assert(cell_direction == CELL_DIRECTION_OUT || cell_direction == CELL_DIRECTION_IN); 
 
-  buf[0] = cell->length;
-  memcpy(buf+1, cell->payload, CELL_PAYLOAD_SIZE);
-
   log_fn(LOG_DEBUG,"direction %d, streamid %d before crypt.", cell_direction, *(int*)(cell->payload+1));
 
-  if(relay_crypt(circ, buf, 1+CELL_PAYLOAD_SIZE, cell_direction, &layer_hint, &recognized, &conn) < 0) {
+  if(relay_crypt(circ, cell->payload, CELL_PAYLOAD_SIZE, cell_direction,
+                 &layer_hint, &recognized, &conn) < 0) {
     log_fn(LOG_WARN,"relay crypt failed. Dropping connection.");
     return -1;
   }
 
-  cell->length = buf[0];
-  memcpy(cell->payload, buf+1, CELL_PAYLOAD_SIZE);
-
   if(recognized) {
     if(cell_direction == CELL_DIRECTION_OUT) {
 #if 0
@@ -374,11 +368,11 @@ int circuit_deliver_relay_cell(cell_t *cell, circuit_t *circ,
 int relay_crypt(circuit_t *circ, char *in, int inlen, char cell_direction,
                 crypt_path_t **layer_hint, char *recognized, connection_t **conn) {
   crypt_path_t *thishop;
-  char out[256];
+  char out[CELL_NETWORK_SIZE];
 
   assert(circ && in && recognized && conn);
 
-  assert(inlen < 256);
+  assert(inlen < CELL_NETWORK_SIZE);
 
   if(cell_direction == CELL_DIRECTION_IN) { 
     if(circ->cpath) { /* we're at the beginning of the circuit.
@@ -391,16 +385,16 @@ int relay_crypt(circuit_t *circ, char *in, int inlen, char cell_direction,
       do { /* Remember: cpath is in forward order, that is, first hop first. */
         assert(thishop);
 
-        log_fn(LOG_DEBUG,"before decrypt: %d",*(int*)(in+2));
+        log_fn(LOG_DEBUG,"before decrypt: %d",*(int*)(in+1));
         /* decrypt */
         if(crypto_cipher_decrypt(thishop->b_crypto, in, inlen, out)) {
           log_fn(LOG_WARN,"Error performing onion decryption: %s", crypto_perror());
           return -1;
         }
         memcpy(in,out,inlen);
-        log_fn(LOG_DEBUG,"after decrypt: %d",*(int*)(in+2));
+        log_fn(LOG_DEBUG,"after decrypt: %d",*(int*)(in+1));
 
-        if( (*recognized = relay_check_recognized(circ, cell_direction, in+2, conn))) {
+        if( (*recognized = relay_check_recognized(circ, cell_direction, in+1, conn))) {
           *layer_hint = thishop;
           return 0;
         }
@@ -411,14 +405,14 @@ int relay_crypt(circuit_t *circ, char *in, int inlen, char cell_direction,
       return 0;
     } else { /* we're in the middle. Just one crypt. */
 
-      log_fn(LOG_DEBUG,"before encrypt: %d",*(int*)(in+2));
+      log_fn(LOG_DEBUG,"before encrypt: %d",*(int*)(in+1));
       if(crypto_cipher_encrypt(circ->p_crypto, in, inlen, out)) {
         log_fn(LOG_WARN,"Onion encryption failed for circID %u: %s",
                circ->p_circ_id, crypto_perror());
         return -1;
       }
       memcpy(in,out,inlen);
-      log_fn(LOG_DEBUG,"after encrypt: %d",*(int*)(in+2));
+      log_fn(LOG_DEBUG,"after encrypt: %d",*(int*)(in+1));
 
       log_fn(LOG_DEBUG,"Skipping recognized check, because we're not the OP.");
       /* don't check for recognized. only the OP can recognize a stream on the way back. */
@@ -432,13 +426,13 @@ int relay_crypt(circuit_t *circ, char *in, int inlen, char cell_direction,
       do {
         assert(thishop);
 
-        log_fn(LOG_DEBUG,"before encrypt: %d",*(int*)(in+2));
+        log_fn(LOG_DEBUG,"before encrypt: %d",*(int*)(in+1));
         if(crypto_cipher_encrypt(thishop->f_crypto, in, inlen, out)) {
           log_fn(LOG_WARN,"Error performing encryption: %s", crypto_perror());
           return -1;
         }
         memcpy(in,out,inlen);
-        log_fn(LOG_DEBUG,"after encrypt: %d",*(int*)(in+2));
+        log_fn(LOG_DEBUG,"after encrypt: %d",*(int*)(in+1));
 
         thishop = thishop->prev;
       } while(thishop != circ->cpath->prev);
@@ -451,7 +445,7 @@ int relay_crypt(circuit_t *circ, char *in, int inlen, char cell_direction,
       }
       memcpy(in,out,inlen);
 
-      if( (*recognized = relay_check_recognized(circ, cell_direction, in+2, conn)))
+      if( (*recognized = relay_check_recognized(circ, cell_direction, in+1, conn)))
         return 0;
 
     }
@@ -556,8 +550,8 @@ int circuit_consider_sending_sendme(circuit_t *circ, int edge_type, crypt_path_t
   cell.command = CELL_RELAY;
   SET_CELL_RELAY_COMMAND(cell, RELAY_COMMAND_SENDME);
   SET_CELL_STREAM_ID(cell, ZERO_STREAM);
+  SET_CELL_RELAY_LENGTH(cell, 0);
 
-  cell.length = RELAY_HEADER_SIZE;
   if(edge_type == EDGE_AP) { /* i'm the AP */
     cell.circ_id = circ->n_circ_id;
     while(layer_hint->deliver_window < CIRCWINDOW_START-CIRCWINDOW_INCREMENT) {
@@ -862,7 +856,6 @@ int circuit_send_next_onion_skin(circuit_t *circ) {
     memset(&cell, 0, sizeof(cell_t));
     cell.command = CELL_CREATE;
     cell.circ_id = circ->n_circ_id;
-    cell.length = ONIONSKIN_CHALLENGE_LEN;
 
     if(onion_skin_create(circ->n_conn->onion_pkey, &(circ->cpath->handshake_state), cell.payload) < 0) {
       log_fn(LOG_WARN,"onion_skin_create (first hop) failed.");
@@ -899,11 +892,12 @@ int circuit_send_next_onion_skin(circuit_t *circ) {
     cell.circ_id = circ->n_circ_id;
     SET_CELL_RELAY_COMMAND(cell, RELAY_COMMAND_EXTEND);
     SET_CELL_STREAM_ID(cell, ZERO_STREAM);
+    SET_CELL_RELAY_LENGTH(cell, 6+ONIONSKIN_CHALLENGE_LEN);
 
-    cell.length = RELAY_HEADER_SIZE + 6 + ONIONSKIN_CHALLENGE_LEN;
     *(uint32_t*)(cell.payload+RELAY_HEADER_SIZE) = htonl(hop->addr);
     *(uint16_t*)(cell.payload+RELAY_HEADER_SIZE+4) = htons(hop->port);
-    if(onion_skin_create(router->onion_pkey, &(hop->handshake_state), cell.payload+RELAY_HEADER_SIZE+6) < 0) {
+    if(onion_skin_create(router->onion_pkey, &(hop->handshake_state),
+                         cell.payload+RELAY_HEADER_SIZE+6) < 0) {
       log_fn(LOG_WARN,"onion_skin_create failed.");
       return -1;
     }
@@ -971,7 +965,6 @@ int circuit_extend(cell_t *cell, circuit_t *circ) {
   memset(&newcell, 0, sizeof(cell_t));
   newcell.command = CELL_CREATE;
   newcell.circ_id = circ->n_circ_id;
-  newcell.length = ONIONSKIN_CHALLENGE_LEN;
 
   memcpy(newcell.payload, cell->payload+RELAY_HEADER_SIZE+6,
          ONIONSKIN_CHALLENGE_LEN);
diff --git a/src/or/command.c b/src/or/command.c
index ed0a8d04d0..8935fcb082 100644
--- a/src/or/command.c
+++ b/src/or/command.c
@@ -103,13 +103,8 @@ static void command_process_create_cell(cell_t *cell, connection_t *conn) {
 
   circ = circuit_new(cell->circ_id, conn);
   circ->state = CIRCUIT_STATE_ONIONSKIN_PENDING;
-  if(cell->length != ONIONSKIN_CHALLENGE_LEN) {
-    log_fn(LOG_WARN,"Bad cell length %d. Dropping.", cell->length);
-    circuit_close(circ);
-    return;
-  }
 
-  memcpy(circ->onionskin,cell->payload,cell->length);
+  memcpy(circ->onionskin, cell->payload, ONIONSKIN_CHALLENGE_LEN);
 
   /* hand it off to the cpuworkers, and then return */
   if(assign_to_cpuworker(NULL, CPUWORKER_TASK_ONION, circ) < 0) {
@@ -135,7 +130,6 @@ static void command_process_created_cell(cell_t *cell, connection_t *conn) {
     circuit_close(circ);
     return;
   }
-  assert(cell->length == ONIONSKIN_REPLY_LEN);
 
   if(circ->cpath) { /* we're the OP. Handshake this. */
     log_fn(LOG_DEBUG,"at OP. Finishing handshake.");
@@ -153,7 +147,7 @@ static void command_process_created_cell(cell_t *cell, connection_t *conn) {
   } else { /* pack it into an extended relay cell, and send it. */
     log_fn(LOG_INFO,"Converting created cell to extended relay cell, sending.");
     connection_edge_send_command(NULL, circ, RELAY_COMMAND_EXTENDED,
-                                 cell->payload, cell->length, NULL);
+                                 cell->payload, ONIONSKIN_REPLY_LEN, NULL);
   }
 }
 
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index 32b7c688bc..4d6be11068 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -75,7 +75,7 @@ int connection_edge_process_inbuf(connection_t *conn) {
   return 0;
 }
 
-char *connection_edge_end_reason(char *payload, unsigned char length) {
+static char *connection_edge_end_reason(char *payload, uint16_t length) {
   if(length < 1) {
     log_fn(LOG_WARN,"End cell arrived with length 0. Should be at least 1.");
     return "MALFORMED";
@@ -155,7 +155,7 @@ int connection_edge_send_command(connection_t *fromconn, circuit_t *circ, int re
   else
     SET_CELL_STREAM_ID(cell, fromconn->stream_id);
 
-  cell.length = RELAY_HEADER_SIZE + payload_len;
+  SET_CELL_RELAY_LENGTH(cell, payload_len);
   if(payload_len) {
     memcpy(cell.payload+RELAY_HEADER_SIZE,payload,payload_len);
   }
@@ -191,7 +191,7 @@ int connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ, connection
   if(conn && conn->state != AP_CONN_STATE_OPEN && conn->state != EXIT_CONN_STATE_OPEN) {
     if(conn->type == CONN_TYPE_EXIT && relay_command == RELAY_COMMAND_END) {
       log_fn(LOG_INFO,"Exit got end (%s) before we're connected. Marking for close.",
-        connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, cell->length));
+        connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, CELL_RELAY_LENGTH(*cell)));
       if(conn->state == EXIT_CONN_STATE_RESOLVING) {
         log_fn(LOG_INFO,"...and informing resolver we don't want the answer anymore.");
         dns_cancel_pending_resolve(conn->address, conn);
@@ -248,19 +248,19 @@ int connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ, connection
       }
 
 //      printf("New text for buf (%d bytes): '%s'", cell->length - RELAY_HEADER_SIZE, cell->payload + RELAY_HEADER_SIZE);
-      stats_n_data_bytes_received += (cell->length - RELAY_HEADER_SIZE);
+      stats_n_data_bytes_received += CELL_RELAY_LENGTH(*cell);
       connection_write_to_buf(cell->payload + RELAY_HEADER_SIZE,
-                              cell->length - RELAY_HEADER_SIZE, conn);
+                              CELL_RELAY_LENGTH(*cell), conn);
       connection_edge_consider_sending_sendme(conn);
       return 0;
     case RELAY_COMMAND_END:
       if(!conn) {
         log_fn(LOG_INFO,"end cell (%s) dropped, unknown stream %d.",
-          connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, cell->length),
+          connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, CELL_RELAY_LENGTH(*cell)),
           *(int*)conn->stream_id);
         return 0;
       }
-      if(cell->length-RELAY_HEADER_SIZE >= 5 &&
+      if(CELL_RELAY_LENGTH(*cell) >= 5 &&
          *(cell->payload+RELAY_HEADER_SIZE) == END_STREAM_REASON_EXITPOLICY) {
         /* No need to close the connection. We'll hold it open while
          * we try a new exit node.
@@ -281,7 +281,7 @@ int connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ, connection
         }
       }
       log_fn(LOG_INFO,"end cell (%s) for stream %d. Removing stream.",
-        connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, cell->length),
+        connection_edge_end_reason(cell->payload+RELAY_HEADER_SIZE, CELL_RELAY_LENGTH(*cell)),
         *(int*)conn->stream_id);
 
 #ifdef HALF_OPEN
@@ -347,7 +347,7 @@ int connection_edge_process_relay_cell(cell_t *cell, circuit_t *circ, connection
         return 0;
       }
       log_fn(LOG_INFO,"Connected! Notifying application.");
-      if (cell->length-RELAY_HEADER_SIZE == 4) {
+      if (CELL_RELAY_LENGTH(*cell) >= 4) {
         addr = ntohl(*(uint32_t*)(cell->payload + RELAY_HEADER_SIZE));
         client_dns_set_entry(conn->socks_request->address, addr);
       }
@@ -444,45 +444,45 @@ int connection_edge_package_raw_inbuf(connection_t *conn) {
   int amount_to_process, length;
   char payload[CELL_PAYLOAD_SIZE];
   circuit_t *circ;
- 
+
   assert(conn);
   assert(!connection_speaks_cells(conn));
- 
+
 repeat_connection_edge_package_raw_inbuf:
- 
+
   circ = circuit_get_by_conn(conn);
   if(!circ) {
     log_fn(LOG_INFO,"conn has no circuits! Closing.");
     return -1;
   }
- 
+
   if(circuit_consider_stop_edge_reading(circ, conn->type, conn->cpath_layer))
     return 0;
- 
+
   if(conn->package_window <= 0) {
     log_fn(LOG_WARN,"called with package_window %d. Tell Roger.", conn->package_window);
     connection_stop_reading(conn);
     return 0;
   }
- 
+
   amount_to_process = buf_datalen(conn->inbuf);
- 
+
   if(!amount_to_process)
     return 0;
- 
-  if(amount_to_process > CELL_PAYLOAD_SIZE - RELAY_HEADER_SIZE) {
-    length = CELL_PAYLOAD_SIZE - RELAY_HEADER_SIZE;
+
+  if(amount_to_process > RELAY_PAYLOAD_SIZE) {
+    length = RELAY_PAYLOAD_SIZE;
   } else {
     length = amount_to_process;
   }
   stats_n_data_bytes_packaged += length;
   stats_n_data_cells_packaged += 1;
- 
+
   connection_fetch_from_buf(payload, length, conn);
 
-  log_fn(LOG_DEBUG,"(%d) Packaging %d bytes (%d waiting).",conn->s,length,
+  log_fn(LOG_DEBUG,"(%d) Packaging %d bytes (%d waiting).", conn->s, length,
          (int)buf_datalen(conn->inbuf));
- 
+
   if(connection_edge_send_command(conn, circ, RELAY_COMMAND_DATA,
                                payload, length, conn->cpath_layer) < 0)
     return 0; /* circuit is closed, don't continue */
@@ -495,7 +495,7 @@ repeat_connection_edge_package_raw_inbuf:
     assert(conn->cpath_layer->package_window > 0);
     conn->cpath_layer->package_window--;
   }
- 
+
   if(--conn->package_window <= 0) { /* is it 0 after decrement? */
     connection_stop_reading(conn);
     log_fn(LOG_DEBUG,"conn->package_window reached 0.");
@@ -503,7 +503,7 @@ repeat_connection_edge_package_raw_inbuf:
     return 0; /* don't process the inbuf any more */
   }
   log_fn(LOG_DEBUG,"conn->package_window is now %d",conn->package_window);
- 
+
   /* handle more if there's more, or return 0 if there isn't */
   goto repeat_connection_edge_package_raw_inbuf;
 }
@@ -740,7 +740,7 @@ static int connection_exit_begin_conn(cell_t *cell, circuit_t *circ) {
    */
 
   if(!memchr(cell->payload+RELAY_HEADER_SIZE+STREAM_ID_SIZE,0,
-             cell->length-RELAY_HEADER_SIZE-STREAM_ID_SIZE)) {
+             CELL_RELAY_LENGTH(*cell)-STREAM_ID_SIZE)) {
     log_fn(LOG_WARN,"relay begin cell has no \\0. Dropping.");
     return 0;
   }
diff --git a/src/or/connection_or.c b/src/or/connection_or.c
index 212453411b..e516913877 100644
--- a/src/or/connection_or.c
+++ b/src/or/connection_or.c
@@ -14,17 +14,13 @@ static int connection_or_process_cell_from_inbuf(connection_t *conn);
 static void cell_pack(char *dest, const cell_t *src) {
   *(uint16_t*)dest     = htons(src->circ_id);
   *(uint8_t*)(dest+2)  = src->command;
-  *(uint8_t*)(dest+3)  = src->length;
-  *(uint32_t*)(dest+4) = 0; /* Reserved */
-  memcpy(dest+8, src->payload, CELL_PAYLOAD_SIZE);
+  memcpy(dest+3, src->payload, CELL_PAYLOAD_SIZE);
 }
 
 static void cell_unpack(cell_t *dest, const char *src) {
   dest->circ_id = ntohs(*(uint16_t*)(src));
   dest->command = *(uint8_t*)(src+2);
-  dest->length  = *(uint8_t*)(src+3);
-  dest->seq     = ntohl(*(uint32_t*)(src+4));
-  memcpy(dest->payload, src+8, CELL_PAYLOAD_SIZE);
+  memcpy(dest->payload, src+3, CELL_PAYLOAD_SIZE);
 }
 
 /**************************************************************/
diff --git a/src/or/onion.c b/src/or/onion.c
index 0923741d92..5c52dd6295 100644
--- a/src/or/onion.c
+++ b/src/or/onion.c
@@ -124,7 +124,6 @@ int onionskin_answer(circuit_t *circ, unsigned char *payload, unsigned char *key
   memset(&cell, 0, sizeof(cell_t));
   cell.command = CELL_CREATED;
   cell.circ_id = circ->p_circ_id;
-  cell.length = ONIONSKIN_REPLY_LEN;
 
   circ->state = CIRCUIT_STATE_OPEN;
 
diff --git a/src/or/or.h b/src/or/or.h
index 7cab9f17be..0b63ccf286 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -190,8 +190,6 @@
 #define RELAY_COMMAND_TRUNCATED 9
 #define RELAY_COMMAND_DROP 10
 
-#define RELAY_HEADER_SIZE 8
-
 #define END_STREAM_REASON_MISC 1
 #define END_STREAM_REASON_RESOLVEFAILED 2
 #define END_STREAM_REASON_CONNECTFAILED 3
@@ -225,9 +223,6 @@
 #define CELL_RELAY 3
 #define CELL_DESTROY 4
 
-#define CELL_PAYLOAD_SIZE 248
-#define CELL_NETWORK_SIZE 256
-
 /* legal characters in a filename */
 #define CONFIG_LEGAL_FILENAME_CHARACTERS "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-_/"
 /* legal characters in a nickname */
@@ -237,27 +232,45 @@
 
 typedef uint16_t circ_id_t;
 
-/* cell definition */
-typedef struct { 
-  circ_id_t circ_id;
-  unsigned char command;
-  unsigned char length; /* of payload if relay cell */
-  uint32_t seq; /* sequence number */
+/*
+ * Relay payload:
+ *         Relay command           [1 byte]
+ *         Stream ID               [7 bytes]
+ *         Partial SHA-1           [4 bytes]
+ *         Length                  [2 bytes]
+ *         Relay payload           [495 bytes]
+ */
 
-  unsigned char payload[CELL_PAYLOAD_SIZE];
-} cell_t;
 #define CELL_RELAY_COMMAND(c)         (*(uint8_t*)((c).payload))
 #define SET_CELL_RELAY_COMMAND(c,cmd) (*(uint8_t*)((c).payload) = (cmd))
+
 #define STREAM_ID_SIZE 7
 #define SET_CELL_STREAM_ID(c,id)      memcpy((c).payload+1,(id),STREAM_ID_SIZE)
+#define ZERO_STREAM "\0\0\0\0\0\0\0"
+
 #define CELL_RELAY_COMMAND_END_REASON(c) (*(uint8_t)((c).payload+1))
 
-#define ZERO_STREAM "\0\0\0\0\0\0\0\0"
+/* relay length is how many bytes are used in the cell payload past relay_header_size */
+#define CELL_RELAY_LENGTH(c)         (*(uint16_t*)((c).payload+1+STREAM_ID_SIZE+4))
+#define SET_CELL_RELAY_LENGTH(c,len) (*(uint16_t*)((c).payload+1+STREAM_ID_SIZE+4) = (len))
+
+#define CELL_PAYLOAD_SIZE 509
+#define CELL_NETWORK_SIZE 512
+
+/* cell definition */
+typedef struct {
+  circ_id_t circ_id;
+  unsigned char command;
+  unsigned char payload[CELL_PAYLOAD_SIZE];
+} cell_t;
+
+#define RELAY_HEADER_SIZE (1+STREAM_ID_SIZE+4+2)
+#define RELAY_PAYLOAD_SIZE (CELL_PAYLOAD_SIZE-RELAY_HEADER_SIZE)
 
 typedef struct buf_t buf_t;
 typedef struct socks_request_t socks_request_t;
 
-struct connection_t { 
+struct connection_t {
 
   uint8_t type;
   uint8_t state;
@@ -476,6 +489,7 @@ typedef struct {
   int loglevel;
 } or_options_t;
 
+/* XXX are these good enough defaults? */
 #define MAX_SOCKS_REPLY_LEN 256
 /* Not 256; addresses must fit in a begin cell. */
 #define MAX_SOCKS_ADDR_LEN 200