1 /*
2  * Copyright © 2010-2012 Stéphane Raimbault <stephane.raimbault@gmail.com>
3  *
4  * SPDX-License-Identifier: LGPL-2.1+
5  */
6 
7 #ifndef MODBUS_PRIVATE_H
8 #define MODBUS_PRIVATE_H
9 
10 #ifndef _MSC_VER
11 # include <stdint.h>
12 # include <sys/time.h>
13 #else
14 # include "stdint.h"
15 # include <time.h>
16 typedef int ssize_t;
17 #endif
18 #include <sys/types.h>
19 #include <config.h>
20 
21 #include "modbus.h"
22 
23 MODBUS_BEGIN_DECLS
24 
25 /* It's not really the minimal length (the real one is report slave ID
26  * in RTU (4 bytes)) but it's a convenient size to use in RTU or TCP
27  * communications to read many values or write a single one.
28  * Maximum between :
29  * - HEADER_LENGTH_TCP (7) + function (1) + address (2) + number (2)
30  * - HEADER_LENGTH_RTU (1) + function (1) + address (2) + number (2) + CRC (2)
31  */
32 #define _MIN_REQ_LENGTH 12
33 
34 #define _REPORT_SLAVE_ID 180
35 
36 #define _MODBUS_EXCEPTION_RSP_LENGTH 5
37 
38 /* Timeouts in microsecond (0.5 s) */
39 #define _RESPONSE_TIMEOUT    500000
40 #define _BYTE_TIMEOUT        500000
41 
42 typedef enum {
43     _MODBUS_BACKEND_TYPE_RTU=0,
44     _MODBUS_BACKEND_TYPE_TCP
45 } modbus_backend_type_t;
46 
47 /*
48  *  ---------- Request     Indication ----------
49  *  | Client | ---------------------->| Server |
50  *  ---------- Confirmation  Response ----------
51  */
52 typedef enum {
53     /* Request message on the server side */
54     MSG_INDICATION,
55     /* Request message on the client side */
56     MSG_CONFIRMATION
57 } msg_type_t;
58 
59 /* This structure reduces the number of params in functions and so
60  * optimizes the speed of execution (~ 37%). */
61 typedef struct _sft {
62     int slave;
63     int function;
64     int t_id;
65 } sft_t;
66 
67 typedef struct _modbus_backend {
68     unsigned int backend_type;
69     unsigned int header_length;
70     unsigned int checksum_length;
71     unsigned int max_adu_length;
72     int (*set_slave) (modbus_t *ctx, int slave);
73     int (*build_request_basis) (modbus_t *ctx, int function, int addr,
74                                 int nb, uint8_t *req);
75     int (*build_response_basis) (sft_t *sft, uint8_t *rsp);
76     int (*prepare_response_tid) (const uint8_t *req, int *req_length);
77     int (*send_msg_pre) (uint8_t *req, int req_length);
78     ssize_t (*send) (modbus_t *ctx, const uint8_t *req, int req_length);
79     int (*receive) (modbus_t *ctx, uint8_t *req);
80     ssize_t (*recv) (modbus_t *ctx, uint8_t *rsp, int rsp_length);
81     int (*check_integrity) (modbus_t *ctx, uint8_t *msg,
82                             const int msg_length);
83     int (*pre_check_confirmation) (modbus_t *ctx, const uint8_t *req,
84                                    const uint8_t *rsp, int rsp_length);
85     int (*connect) (modbus_t *ctx);
86     void (*close) (modbus_t *ctx);
87     int (*flush) (modbus_t *ctx);
88     int (*select) (modbus_t *ctx, fd_set *rset, struct timeval *tv, int msg_length);
89     void (*free) (modbus_t *ctx);
90 } modbus_backend_t;
91 
92 struct _modbus {
93     /* Slave address */
94     int slave;
95     /* Socket or file descriptor */
96     int s;
97     int debug;
98     int error_recovery;
99     struct timeval response_timeout;
100     struct timeval byte_timeout;
101     struct timeval indication_timeout;
102     const modbus_backend_t *backend;
103     void *backend_data;
104 };
105 
106 void _modbus_init_common(modbus_t *ctx);
107 void _error_print(modbus_t *ctx, const char *context);
108 int _modbus_receive_msg(modbus_t *ctx, uint8_t *msg, msg_type_t msg_type);
109 
110 #ifndef HAVE_STRLCPY
111 size_t strlcpy(char *dest, const char *src, size_t dest_size);
112 #endif
113 
114 MODBUS_END_DECLS
115 
116 #endif  /* MODBUS_PRIVATE_H */
117