comment the functions in connection_or.c

svn:r1818

src/or/connection_or.c

@@ -11,12 +11,19 @@ static int connection_or_process_cells_from_inbuf(connection_t *conn);
 
 /**************************************************************/
 
+/* Pack the cell_t host-order structure 'src' into network-order
+ * in the buffer 'dest'. See tor-spec.txt for details about the
+ * wire format.
+ */
 static void cell_pack(char *dest, const cell_t *src) {
   *(uint16_t*)dest     = htons(src->circ_id);
   *(uint8_t*)(dest+2)  = src->command;
   memcpy(dest+3, src->payload, CELL_PAYLOAD_SIZE);
 }
 
+/* Unpack the network-order buffer 'src' into a host-order
+ * cell_t structure 'dest'.
+ */
 static void cell_unpack(cell_t *dest, const char *src) {
   dest->circ_id = ntohs(*(uint16_t*)(src));
   dest->command = *(uint8_t*)(src+2);
@@ -25,6 +32,11 @@ static void cell_unpack(cell_t *dest, const char *src) {
 
 /**************************************************************/
 
+/* Handle any new bytes that have come in on connection 'conn'.
+ * If conn is in 'open' state, hand it to
+ * connection_or_process_cells_from_inbuf()
+ * (else do nothing).
+ */
 int connection_or_process_inbuf(connection_t *conn) {
 
   tor_assert(conn && conn->type == CONN_TYPE_OR);
@@ -40,6 +52,14 @@ int connection_or_process_inbuf(connection_t *conn) {
   return connection_or_process_cells_from_inbuf(conn);
 }
 
+/* Connection 'conn' has finished writing and has no bytes left on
+ * its outbuf.
+ *
+ * If it's in state 'connecting', then take a look at the socket, and
+ * begin the tls handshake if the connect succeeded.
+ *
+ * Otherwise it's in state 'open': stop writing and return.
+ */
 int connection_or_finished_flushing(connection_t *conn) {
   int e, len=sizeof(e);
 
@@ -79,7 +99,13 @@ int connection_or_finished_flushing(connection_t *conn) {
 
 /*********************/
 
-void connection_or_init_conn_from_router(connection_t *conn, routerinfo_t *router) {
+/* Initialize conn to include all the relevant data from router.
+ * This function is called either from connection_or_connect(), if
+ * we initiated the connect, or from connection_tls_finish_handshake()
+ * if the other side initiated it.
+ */
+static void
+connection_or_init_conn_from_router(connection_t *conn, routerinfo_t *router) {
   conn->addr = router->addr;
   conn->port = router->or_port;
   conn->receiver_bucket = conn->bandwidth = router->bandwidthburst;
@@ -89,6 +115,19 @@ void connection_or_init_conn_from_router(connection_t *conn, routerinfo_t *route
   conn->address = tor_strdup(router->address);
 }
 
+/* Launch a new OR connection to 'router'.
+ *
+ * If router is me, do nothing. If we're already connected to router,
+ * return that connection. If the connect is in progress, set conn's
+ * state to 'connecting' and return. If connect to router succeeds, call
+ * connection_tls_start_handshake() on it.
+ *
+ * This function is called from router_retry_connections() , for
+ * ORs connecting to ORs, and circuit_establish_circuit(), for
+ * OPs connecting to ORs.
+ *
+ * Return the launched conn, or NULL if it failed.
+ */
 connection_t *connection_or_connect(routerinfo_t *router) {
   connection_t *conn;
 
@@ -131,8 +170,14 @@ connection_t *connection_or_connect(routerinfo_t *router) {
   return NULL;
 }
 
-/* ********************************** */
-
+/* Begin the tls handshake with conn. 'receiving' is 0 if we initiated
+ * the connection, else it's 1.
+ *
+ * Assign a new tls object to conn->tls, begin reading on conn, and pass
+ * conn to connection_tls_continue_handshake().
+ *
+ * Return -1 if conn is broken, else return 0.
+ */
 int connection_tls_start_handshake(connection_t *conn, int receiving) {
   conn->state = OR_CONN_STATE_HANDSHAKING;
   conn->tls = tor_tls_new(conn->s, receiving);
@@ -148,6 +193,11 @@ int connection_tls_start_handshake(connection_t *conn, int receiving) {
   return 0;
 }
 
+/* Move forward with ths tls handshake. If it finishes, hand
+ * conn to connection_tls_finish_handshake().
+ *
+ * Return -1 if conn is broken, else return 0.
+ */
 int connection_tls_continue_handshake(connection_t *conn) {
   switch(tor_tls_handshake(conn->tls)) {
     case TOR_TLS_ERROR:
@@ -167,13 +217,32 @@ int connection_tls_continue_handshake(connection_t *conn) {
   return 0;
 }
 
-static int connection_tls_finish_handshake(connection_t *conn) {
+/* The tls handshake is finished.
+ *
+ * Make sure we are happy with the person we just handshaked with:
+ * If it's an OP (that is, it has no certificate), make sure I'm an OR.
+ * If it's an OR (is has a certificate), make sure it has a recognized
+ * nickname, its cert is signed by the identity key of that nickname;
+ * if I initiated the connection, make sure it's the right guy, and if
+ * he initiated the connection, make sure he's not already connected.
+ *
+ * If he initiated the conn, also initialize conn from the information
+ * in router.
+ *
+ * If either of us is an OP, set bandwidth to the default OP bandwidth.
+ *
+ * If all is successful and he's an OR, then call circuit_n_conn_open()
+ * to handle events that have been pending on the tls handshake
+ * completion, and set the directory to be dirty (only matters if I'm
+ * a dirserver).
+ */
+static int
+connection_tls_finish_handshake(connection_t *conn) {
   routerinfo_t *router;
   char nickname[MAX_NICKNAME_LEN+1];
   connection_t *c;
 
   conn->state = OR_CONN_STATE_OPEN;
-  directory_set_dirty();
   connection_watch_events(conn, POLLIN);
   log_fn(LOG_DEBUG,"tls handshake done. verifying.");
   if (! tor_tls_peer_has_cert(conn->tls)) { /* It's an OP. */
@@ -225,14 +294,14 @@ static int connection_tls_finish_handshake(connection_t *conn) {
   if (!options.ORPort) { /* If I'm an OP... */
     conn->receiver_bucket = conn->bandwidth = DEFAULT_BANDWIDTH_OP;
   }
+  directory_set_dirty();
   circuit_n_conn_open(conn); /* send the pending creates, if any. */
   /* Note the success */
   rep_hist_note_connect_succeeded(nickname, time(NULL));
   return 0;
 }
 
-/* ********************************** */
-
+/* Pack 'cell' into wire-format, and write it onto conn's outbuf. */
 void connection_or_write_cell_to_buf(const cell_t *cell, connection_t *conn) {
   char networkcell[CELL_NETWORK_SIZE];
   char *n = networkcell;
@@ -245,7 +314,10 @@ void connection_or_write_cell_to_buf(const cell_t *cell, connection_t *conn) {
   connection_write_to_buf(n, CELL_NETWORK_SIZE, conn);
 }
 
-/* if there's a whole cell there, pull it off and process it. */
+/* Process cells from conn's inbuf. Loop: while inbuf contains a cell, pull
+ * it off the inbuf, unpack it, and hand it to command_process_cell().
+ * Always return 0.
+ */
 static int connection_or_process_cells_from_inbuf(connection_t *conn) {
   char buf[CELL_NETWORK_SIZE];
   cell_t cell;