f2b/src/cmsg.h

#ifndef F2B_CMSG_H_
#define F2B_CMSG_H_

/**
 * @file
 * This header contains definitions of control messages format and routines
 */

/**
 * @def DATA_LEN_MAX
 * Maximum length of data in packet
 */
#define DATA_LEN_MAX 1476 /* 1500 - (16 bytes of cmsg header + 8 bytes of udp) */
/**
 * @def DATA_ARGS_MAX
 * Maximum count of data pieces in packet
 */
#define DATA_ARGS_MAX 6  /* number of args in data */
/**
 * @def F2B_PROTO_VER
 * Protocol version of control message
 */
#define F2B_PROTO_VER 1

/**
 * @def CMSG_FLAG_NEED_REPLY
 * Server should reply to this control message
 */
#define CMSG_FLAG_NEED_REPLY 0x01
/**
 * @def CMSG_FLAG_AUTH_PASS
 * This control message contains password
 */
#define CMSG_FLAG_AUTH_PASS  0x02

/**
 * f2b control message
 * @note Use sendmsg/recvmsg and iovec structs to pack/unpack
 */
typedef struct f2b_cmsg_t {
  char magic[3];   /**< magic string "F2B" */
  uint8_t version; /**< protocol version */
  /* 4 bytes */
  uint8_t type;    /**< command type, cast from enum f2b_cmd_type */
  uint8_t flags;   /**< CMSG_FLAG_* */
  uint16_t size;   /**< payload length */
  /* 8 bytes */
  char pass[8];    /**< auth data */
  /* 16 bytes */
  /* end of header */
  char data[DATA_LEN_MAX];      /**< set of "\n"-terminated strings */
  /* end of data */
} f2b_cmsg_t;

/**
 * @brief Convert every '\n' in data to '\0'
 * @param msg Pointer to control message
 */
void f2b_cmsg_convert_args(f2b_cmsg_t *msg);
/**
 * @brief Fill @a argv array with pointers to found data pieces
 * @param msg Pointer to control message
 * @param argv Array of pointers
 * @returns Number of found args
 */
int  f2b_cmsg_extract_args(const f2b_cmsg_t *msg, const char **argv);

#endif /* F2B_CMSG_H_ */