commit e0ade2128ee7b21cede4b2477b5f00f0f2f8d51c Author: Zack Weinberg zackw@cmu.edu Date: Wed Jun 13 15:06:13 2012 -0400

Fix that race condition in connection setup again. This time for sure! --- src/protocol/chop.cc | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/src/protocol/chop.cc b/src/protocol/chop.cc index 67ed2b3..20ba563 100644 --- a/src/protocol/chop.cc +++ b/src/protocol/chop.cc @@ -903,11 +903,22 @@ chop_circuit_t::pick_connection(size_t desired, size_t *blocksize) for (unordered_set<chop_conn_t *>::iterator i = downstreams.begin(); i != downstreams.end(); i++) { chop_conn_t *conn = *i; + + // We cannot transmit on a connection whose steganography module has + // not yet been instantiated. (This only ever happens server-side.) if (!conn->steg) { log_debug(conn, "offers 0 bytes (no steg)"); continue; }

+ // We must not transmit on a connection that has not completed its + // TCP handshake. (This only ever happens client-side. If we try + // it anyway, the transmission gets silently dropped on the floor.) + if (!conn->connected) { + log_debug(conn, "offers 0 bytes (not connected)"); + continue; + } + size_t shake = conn->sent_handshake ? 0 : HANDSHAKE_LEN; size_t room = conn->steg->transmit_room(desired + shake, lo + shake, MAX_BLOCK_SIZE + shake);