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diff --git a/src/ceph/doc/dev/network-protocol.rst b/src/ceph/doc/dev/network-protocol.rst deleted file mode 100644 index 3a59b80..0000000 --- a/src/ceph/doc/dev/network-protocol.rst +++ /dev/null @@ -1,197 +0,0 @@ -================== - Network Protocol -================== - -This file describes the network protocol used by Ceph. In order to understand -the way the structures are defined it is recommended to read the introduction -of :doc:`/dev/network-encoding` first. - -Hello -===== - -The protocol starts with a handshake that confirms that both nodes are talking -ceph and shares some basic information. - -Banner ------- - -The first action is the server sending banner to the client. The banner is -defined in ``CEPH_BANNER`` from ``src/include/msgr.h``. This is followed by -the server's then client's address each encoded as a ``entity_addr_t``. - -Once the client verifies that the servers banner matches its own it replies with -its banner and its address. - -Connect -------- - -Once the banners have been verified and the addresses exchanged the connection -negotiation begins. First the client sends a ``ceph_msg_connect`` structure -with its information. - -:: - - // From src/include/msgr.h - struct ceph_msg_connect { - u64le features; // Supported features (CEPH_FEATURE_*) - u32le host_type; // CEPH_ENTITY_TYPE_* - u32le global_seq; // Number of connections initiated by this host. - u32le connect_seq; // Number of connections initiated in this session. - u32le protocol_version; - u32le authorizer_protocol; - u32le authorizer_len; - u8 flags; // CEPH_MSG_CONNECT_* - u8 authorizer[authorizer_len]; - } - -Connect Reply -------------- - -Once the connect has been sent the connection has effectively been opened, -however the first message the server sends must be a connect reply message. - -:: - - struct ceph_msg_connect_reply { - u8 tag; // Tag indicating response code. - u64le features; - u32le global_seq; - u32le connect_seq; - u32le protocol_version; - u32le authorizer_len; - u8 flags; - u8 authorizer[authorizer_len]; - } - -MSGR Protocol -============= - -This is a low level protocol over which messages are delivered. The messages -at this level consist of a tag byte, identifying the type of message, followed -by the message data. - -:: - - // Virtual structure. - struct { - u8 tag; // CEPH_MSGR_TAG_* - u8 data[]; // Length depends on tag and data. - } - -The length of ``data`` is determined by the tag byte and depending on the -message type via information in the ``data`` array itself. - -.. note:: - There is no way to determine the length of the message if you do not - understand the type of message. - -The message tags are defined in ``src/include/msgr.h`` and the current ones -are listed below along with the data they include. Note that the defined -structures don't exist in the source and are merely for representing the -protocol. - -CEPH_MSGR_TAG_CLOSE (0x06) --------------------------- - -:: - - struct ceph_msgr_close { - u8 tag = 0x06; - u8 data[0]; // No data. - } - -The close message indicates that the connection is being closed. - -CEPH_MSGR_TAG_MSG (0x07) ------------------------- - -:: - - struct ceph_msgr_msg { - u8 tag = 0x07; - ceph_msg_header header; - u8 front [header.front_len ]; - u8 middle[header.middle_len]; - u8 data [header.data_len ]; - ceph_msg_footer footer; - } - - // From src/include/msgr.h - struct ceph_msg_header { - u64le seq; // Sequence number. - u64le tid; // Transaction ID. - u16le type; // Message type (CEPH_MSG_* or MSG_*). - u16le priority; // Priority (higher is more important). - u16le version; // Version of message encoding. - - u32le front_len; // The size of the front section. - u32le middle_len; // The size of the middle section. - u32le data_len; // The size of the data section. - u16le data_off; // The way data should be aligned by the reciever. - - ceph_entity_name src; // Information about the sender. - - u16le compat_version; // Oldest compatible encoding version. - u16le reserved; // Unused. - u32le crc; // CRC of header. - } - - // From src/include/msgr.h - struct ceph_msg_footer { - u32le front_crc; // Checksums of the various sections. - u32le middle_crc; // - u32le data_crc; // - u64le sig; // Crypographic signature. - u8 flags; - } - -Messages are the business logic of Ceph. They are what is used to send data and -requests between nodes. The message header contains the length of the message -so unknown messages can be handled gracefully. - -There are two names for the message type constants ``CEPH_MSG_*`` and ``MSG_*``. -The only difference between the two is that the first are considered "public" -while the second is for internal use only. There is no protocol-level -difference. - -CEPH_MSGR_TAG_ACK (0x08) ------------------------- - -:: - - struct ceph_msgr_ack { - u8 tag = 0x08; - u64le seq; // The sequence number of the message being acknowledged. - } - -CEPH_MSGR_TAG_KEEPALIVE (0x09) ------------------------------- - -:: - - struct ceph_msgr_keepalive { - u8 tag = 0x09; - u8 data[0]; // No data. - } - -CEPH_MSGR_TAG_KEEPALIVE2 (0x0E) -------------------------------- - -:: - - struct ceph_msgr_keepalive2 { - u8 tag = 0x0E; - utime_t timestamp; - } - -CEPH_MSGR_TAG_KEEPALIVE2_ACK (0x0F) ------------------------------------ - -:: - - struct ceph_msgr_keepalive2_ack { - u8 tag = 0x0F; - utime_t timestamp; - } - -.. vi: textwidth=80 noexpandtab |