On Thu, Feb 18, 2021 at 09:08:23AM +0300, Arseny Krasnov wrote:
Signed-off-by: Arseny Krasnov <arseny.krasnov@xxxxxxxxxxxxx>
---
virtio-vsock.tex | 40 +++++++++++++++++++++++++++++++++++++---
1 file changed, 37 insertions(+), 3 deletions(-)
diff --git a/virtio-vsock.tex b/virtio-vsock.tex
index da7e641..1ee8f99 100644
--- a/virtio-vsock.tex
+++ b/virtio-vsock.tex
@@ -102,6 +102,11 @@ \subsection{Device Operation}\label{sec:Device Types / Socket Device / Device Op
VIRTIO_VSOCK_OP_CREDIT_UPDATE = 6,
/* Request the peer to send the credit info to us */
VIRTIO_VSOCK_OP_CREDIT_REQUEST = 7,
+
+ /* Message begin for SOCK_SEQPACKET */
+ VIRTIO_VSOCK_OP_SEQ_BEGIN = 8,
+ /* Message end for SOCK_SEQPACKET */
+ VIRTIO_VSOCK_OP_SEQ_END = 9,
};
\end{lstlisting}
@@ -140,11 +145,11 @@ \subsubsection{Addressing}\label{sec:Device Types / Socket Device / Device Opera
consists of a (cid, port number) tuple. The header fields used for this are
\field{src_cid}, \field{src_port}, \field{dst_cid}, and \field{dst_port}.
-Currently only stream sockets are supported. \field{type} is 1 for stream
-socket types.
+Currently stream and seqpacket sockets are supported. \field{type} is 1 for
+stream socket types. \field{type} is 2 for seqpacket socket types.
Stream sockets provide in-order, guaranteed, connection-oriented delivery
-without message boundaries.
+without message boundaries. Seqpacket sockets also provide message boundaries.
\subsubsection{Buffer Space Management}\label{sec:Device Types / Socket Device / Device Operation / Buffer Space Management}
\field{buf_alloc} and \field{fwd_cnt} are used for buffer space management of
@@ -240,6 +245,35 @@ \subsubsection{Stream Sockets}\label{sec:Device Types / Socket Device / Device O
destination) address tuple for a new connection while the other peer is still
processing the old connection.
+\subsubsection{Seqpacket Sockets}\label{sec:Device Types / Socket Device / Device Operation / Seqpacket Sockets}
+
+Seqpacket sockets differ from stream sockets only in data transmission way: in
+stream sockets all data is sent using only VIRTIO_VSOCK_OP_RW packets. In
+seqpacket sockets, to provide message boundaries, every sequence of
+VIRTIO_VSOCK_OP_RW packets of each message is headed with
^
Since this is a spec, I think we should use MUST when something must be
respected by the peer, for example here we can say "MUST be headed"
+VIRTIO_VSOCK_OP_SEQ_BEGIN and tailed with VIRTIO_VSOCK_OP_SEQ_END packets.
+Both VIRTIO_VSOCK_OP_SEQ_BEGIN and VIRTIO_VSOCK_OP_SEQ_END packets carry
^
Same here "MUST carry" and in the rest of the patch.
+special header in payload:
+
+\begin{lstlisting}
+struct virtio_vsock_seq_hdr {
+ __le32 msg_cnt;
+ __le32 msg_len;
+};
+\end{lstlisting}
+
+\field{msg_cnt} is per socket and incremented by 1 on every send of
+VIRTIO_VSOCK_OP_SEQ_BEGIN or VIRTIO_VSOCK_OP_SEQ_END. \field{msg_len} contains
+message length. This header is used to check integrity of each message: message
+is valid if length of data in VIRTIO_VSOCK_OP_RW packets is equal to
+\field{msg_len} of prepending VIRTIO_VSOCK_OP_SEQ_BEGIN and \field{msg_cnt} of
+VIRTIO_VSOCK_OP_SEQ_END differs from \field{msg_cnt} of
+VIRTIO_VSOCK_OP_SEQ_BEGIN by 1.
If we replace msg_cnt with msg_id, I think we should have the same
'msg_id' for VIRTIO_VSOCK_OP_SEQ_BEGIN or VIRTIO_VSOCK_OP_SEQ_END. If
you want to use 'msg_cnt' and you increment it between BEGIN and END, we
should consider the overflow case.
+
+POSIX MSG_EOR flag is supported by special value of \field{flags} in packet's
+header. If this flag is set for message, then all VIRTIO_VSOCK_OP_RW packets
+of this message have bit 0 is set to 1 in \field{flags}.
Maybe we need to define what MSG_EOR means.
Thanks,
Stefano
+
\subsubsection{Device Events}\label{sec:Device Types / Socket Device / Device Operation / Device Events}
Certain events are communicated by the device to the driver using the event
--
2.25.1
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