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59 lines
2.7 KiB
59 lines
2.7 KiB
13 years ago
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commit cc4f9d5679278ce41cd5480fab3f5e71dba163ed
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Author: Matthew Booth <mbooth@redhat.com>
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Date: Fri Mar 16 16:29:00 2012 +0100
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transport_send: Finish in-progress key exchange before sending data
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_libssh2_channel_write() first reads outstanding packets before writing
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new data. If it reads a key exchange request, it will immediately start
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key re-exchange, which will require sending a response. If the output
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socket is full, this will result in a return from
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_libssh2_transport_read() of LIBSSH2_ERROR_EAGAIN. In order not to block
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a write because there is no data to read, this error is explicitly
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ignored and the code continues marshalling a packet for sending. When it
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is sent, the remote end immediately drops the connection because it was
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expecting a continuation of the key exchange, but got a data packet.
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This change adds the same check for key exchange to
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_libssh2_transport_send() that is in _libssh2_transport_read(). This
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ensures that key exchange is completed before any data packet is sent.
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diff --git a/src/transport.c b/src/transport.c
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index 057dcf5..95b9a3a 100644
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--- a/src/transport.c
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+++ b/src/transport.c
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@@ -296,7 +296,7 @@ int _libssh2_transport_read(LIBSSH2_SESSION * session)
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* is done!
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*/
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_libssh2_debug(session, LIBSSH2_TRACE_TRANS, "Redirecting into the"
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- " key re-exchange");
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+ " key re-exchange from _libssh2_transport_read");
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rc = _libssh2_kex_exchange(session, 1, &session->startup_key_state);
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if (rc)
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return rc;
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@@ -687,6 +687,24 @@ int _libssh2_transport_send(LIBSSH2_SESSION *session,
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const unsigned char *orgdata = data;
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size_t orgdata_len = data_len;
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+ /*
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+ * If the last read operation was interrupted in the middle of a key
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+ * exchange, we must complete that key exchange before continuing to write
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+ * further data.
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+ *
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+ * See the similar block in _libssh2_transport_read for more details.
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+ */
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+ if (session->state & LIBSSH2_STATE_EXCHANGING_KEYS &&
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+ !(session->state & LIBSSH2_STATE_KEX_ACTIVE)) {
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+ /* Don't write any new packets if we're still in the middle of a key
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+ * exchange. */
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+ _libssh2_debug(session, LIBSSH2_TRACE_TRANS, "Redirecting into the"
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+ " key re-exchange from _libssh2_transport_send");
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+ rc = _libssh2_kex_exchange(session, 1, &session->startup_key_state);
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+ if (rc)
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+ return rc;
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+ }
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+
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debugdump(session, "libssh2_transport_write plain", data, data_len);
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if(data2)
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debugdump(session, "libssh2_transport_write plain2", data2, data2_len);
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