linux/fs/ceph/msgr.h

#ifndef __MSGR_H
#define __MSGR_H

/*
 * Data types for message passing layer used by Ceph.
 */

#define CEPH_MON_PORT    6789  /* default monitor port */

/*
 * client-side processes will try to bind to ports in this
 * range, simply for the benefit of tools like nmap or wireshark
 * that would like to identify the protocol.
 */
#define CEPH_PORT_FIRST  6789
#define CEPH_PORT_START  6800  /* non-monitors start here */
#define CEPH_PORT_LAST   6900

/*
 * tcp connection banner.  include a protocol version. and adjust
 * whenever the wire protocol changes.  try to keep this string length
 * constant.
 */
#define CEPH_BANNER "ceph v021"
#define CEPH_BANNER_MAX_LEN 30


/*
 * Rollover-safe type and comparator for 32-bit sequence numbers.
 * Comparator returns -1, 0, or 1.
 */
typedef __u32 ceph_seq_t;

static inline __s32 ceph_seq_cmp(__u32 a, __u32 b)
{
       return (__s32)a - (__s32)b;
}


/*
 * entity_name -- logical name for a process participating in the
 * network, e.g. 'mds0' or 'osd3'.
 */
struct ceph_entity_name {
	__u8 type;      /* CEPH_ENTITY_TYPE_* */
	__le64 num;
} __attribute__ ((packed));

#define CEPH_ENTITY_TYPE_MON    1
#define CEPH_ENTITY_TYPE_MDS    2
#define CEPH_ENTITY_TYPE_OSD    3
#define CEPH_ENTITY_TYPE_CLIENT 4
#define CEPH_ENTITY_TYPE_ADMIN  5

/*
 * entity_addr -- network address
 */
struct ceph_entity_addr {
	__le32 erank;  /* entity's rank in process */
	__le32 nonce;  /* unique id for process (e.g. pid) */
	struct sockaddr_storage in_addr;
} __attribute__ ((packed));

static inline bool ceph_entity_addr_is_local(const struct ceph_entity_addr *a,
					     const struct ceph_entity_addr *b)
{
	return a->nonce == b->nonce &&
		memcmp(&a->in_addr, &b->in_addr, sizeof(a->in_addr)) == 0;
}

static inline bool ceph_entity_addr_equal(const struct ceph_entity_addr *a,
					  const struct ceph_entity_addr *b)
{
	return memcmp(a, b, sizeof(*a)) == 0;
}

struct ceph_entity_inst {
	struct ceph_entity_name name;
	struct ceph_entity_addr addr;
} __attribute__ ((packed));


/* used by message exchange protocol */
#define CEPH_MSGR_TAG_READY         1  /* server->client: ready for messages */
#define CEPH_MSGR_TAG_RESETSESSION  2  /* server->client: reset, try again */
#define CEPH_MSGR_TAG_WAIT          3  /* server->client: wait for racing
					  incoming connection */
#define CEPH_MSGR_TAG_RETRY_SESSION 4  /* server->client + cseq: try again
					  with higher cseq */
#define CEPH_MSGR_TAG_RETRY_GLOBAL  5  /* server->client + gseq: try again
					  with higher gseq */
#define CEPH_MSGR_TAG_CLOSE         6  /* closing pipe */
#define CEPH_MSGR_TAG_MSG           7  /* message */
#define CEPH_MSGR_TAG_ACK           8  /* message ack */
#define CEPH_MSGR_TAG_KEEPALIVE     9  /* just a keepalive byte! */
#define CEPH_MSGR_TAG_BADPROTOVER  10  /* bad protocol version */


/*
 * connection negotiation
 */
struct ceph_msg_connect {
	__le32 host_type;    /* CEPH_ENTITY_TYPE_* */
	__le32 global_seq;   /* count connections initiated by this host */
	__le32 connect_seq;  /* count connections initiated in this session */
	__le32 protocol_version;
	__u8  flags;         /* CEPH_MSG_CONNECT_* */
} __attribute__ ((packed));

struct ceph_msg_connect_reply {
	__u8 tag;
	__le32 global_seq;
	__le32 connect_seq;
	__le32 protocol_version;
	__u8 flags;
} __attribute__ ((packed));

#define CEPH_MSG_CONNECT_LOSSY  1  /* messages i send may be safely dropped */


/*
 * message header
 */
struct ceph_msg_header {
	__le64 seq;       /* message seq# for this session */
	__le16 type;      /* message type */
	__le16 priority;  /* priority.  higher value == higher priority */

	__le32 front_len; /* bytes in main payload */
	__le32 middle_len;/* bytes in middle payload */
	__le32 data_len;  /* bytes of data payload */
	__le16 data_off;  /* sender: include full offset;
			     receiver: mask against ~PAGE_MASK */

	struct ceph_entity_inst src, orig_src;
	__le32 dst_erank;
	__le32 crc;       /* header crc32c */
} __attribute__ ((packed));

#define CEPH_MSG_PRIO_LOW     64
#define CEPH_MSG_PRIO_DEFAULT 127
#define CEPH_MSG_PRIO_HIGH    196
#define CEPH_MSG_PRIO_HIGHEST 255

/*
 * follows data payload
 */
struct ceph_msg_footer {
	__le32 front_crc, middle_crc, data_crc;
	__u8 flags;
} __attribute__ ((packed));

#define CEPH_MSG_FOOTER_COMPLETE  (1<<0)   /* msg wasn't aborted */
#define CEPH_MSG_FOOTER_NOCRC     (1<<1)   /* no data crc */


#endif