mb.h File Reference

modbus daemon API(Interface) More...

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <stdbool.h>
#include <modbus.h>
#include "uthash.h"
#include "log.h"
#include "json.h"

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Data Structures
struct	mbtcp_key_s
	`structure key` for modbus tcp hash table More...
struct	mbtcp_handle_s
	hashable mbtcp handle type More...

Typedefs
typedef char *(*	mbtcp_fc )(uint8_t fc, mbtcp_handle_s *handle, cJSON *req)
	Function pointer of modbus tcp function code. More...

Functions
char *	set_modbus_success_resp_str_with_data (char *tid, cJSON *json_arr)
	Set modbusd success response string with data (i.e., read func) More...
char *	set_modbus_success_resp_str (char *tid)
	Set modbusd success response string without data (i.e., write func) More...
char *	set_modbus_fail_resp_str (char *tid, const char *reason)
	Set modbusd fail response string. More...
char *	set_modbus_fail_resp_str_with_errno (char *tid, mbtcp_handle_s *handle, int errnum)
	Set modbusd fail response string with error number. More...
bool	mbtcp_init_handle (mbtcp_handle_s **ptr_handle, char *ip, char *port)
	Init mbtcp handle (to hashtable) and try to connect. More...
bool	mbtcp_get_handle (mbtcp_handle_s **ptr_handle, char *ip, char *port)
	Get mbtcp handle from hashtable. More...
void	mbtcp_list_handles ()
	List all handles in mbtcp hash table. More...
bool	mbtcp_do_connect (mbtcp_handle_s *handle, char **reason)
	Connect to mbtcp slave via mbtcp hashed handle. More...
bool	mbtcp_get_connection_status (mbtcp_handle_s *handle)
	Get mbtcp handle's connection status. More...
char *	mbtcp_cmd_hanlder (uint8_t fc, cJSON *req, mbtcp_fc ptr_handler)
	Generic mbtcp command handler. More...
char *	mbtcp_set_response_timeout (char *tid, long timeout)
	Set mbtcp response timeout in usec. More...
char *	mbtcp_get_response_timeout (char *tid)
	Get mbtcp response timeout. More...
char *	mbtcp_read_bit_req_fn (uint8_t fc, mbtcp_handle_s *handle, cJSON *req)
	Help function. More...
char *	mbtcp_read_reg_req_fn (uint8_t fc, mbtcp_handle_s *handle, cJSON *req)
	Help function. More...
char *	mbtcp_single_write_req_fn (uint8_t fc, mbtcp_handle_s *handle, cJSON *req)
	Help function. More...
char *	mbtcp_multi_write_req_fn (uint8_t fc, mbtcp_handle_s *handle, cJSON *req)
	Help function. More...

Detailed Description

modbus daemon API(Interface)

Author

Taka Wang

Typedef Documentation

typedef char*(* mbtcp_fc)(uint8_t fc, mbtcp_handle_s *handle, cJSON *req)

Function pointer of modbus tcp function code.

Function pointer to `modbus tcp function code request` for `generic command handle`.

Parameters

fc	function code
handle	Mbtcp handle.
req	cJSON request object.

Returns

Modbus response string in JSON format.

Function Documentation

char* mbtcp_cmd_hanlder	(	uint8_t	fc,
		cJSON *	req,
		mbtcp_fc	ptr_handler
	)

Generic mbtcp command handler.

Parameters

fc	function code
req	cJSON request object.
ptr_handler	Function pointer to modbus tcp fc handler.

Returns

Modbus response string in JSON format.

References BEGIN, mbtcp_handle_s::ctx, enable_syslog, json_get_char(), json_get_int(), LOG, and set_modbus_fail_resp_str().

Referenced by main().

{
    BEGIN (enable_syslog);

    char * tid = json_get_char (req, "tid");
    mbtcp_handle_s *handle = NULL;
    
    if (lazy_init_mbtcp_handle (&handle, req))
    {
        char * reason = NULL;
        if (lazy_mbtcp_connect (handle, &reason))
        {
            // set slave id
            int slave = json_get_int (req, "slave");
            LOG (enable_syslog, "slave id: %d", slave);
            modbus_set_slave (handle->ctx, slave);
            return ptr_handler (fc, handle, req);
        }
        else
        {
            // [enhance]: get reason from modbus response
            return set_modbus_fail_resp_str (tid, reason);
        }
    }
    else
    {
        return set_modbus_fail_resp_str (tid, "Fail to init modbus tcp handle");
    }
}

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bool mbtcp_do_connect	(	mbtcp_handle_s *	handle,
		char **	reason
	)

Connect to mbtcp slave via mbtcp hashed handle.

Parameters

handle	Mbtcp handle.
reason	Fail reason string.

Returns

Success or not.

References BEGIN, mbtcp_handle_s::connected, mbtcp_handle_s::ctx, enable_syslog, ERR, mbtcp_key_s::ip, mbtcp_handle_s::key, LOG, and mbtcp_key_s::port.

Referenced by mbtcp_init_handle(), and test_init_tcp_handle_and_connect().

{
    BEGIN (enable_syslog);
    
    if (handle != NULL)
    {
        if (modbus_connect (handle->ctx) == -1) 
        {
            ERR (enable_syslog, "Connection failed: %s", modbus_strerror (errno));
            handle->connected = false;
            *reason = (char *) modbus_strerror (errno);
            return false;
        }
        else
        {
            LOG (enable_syslog, "%s:%s connected", handle->key.ip, handle->key.port);
            handle->connected = true;
            return true;
        }
    }
    else
    {
        ERR (enable_syslog, "NULL handle");
        *reason = "NULL handle";
        return false;
    }
}

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bool mbtcp_get_connection_status

(

mbtcp_handle_s *

handle

)

Get mbtcp handle's connection status.

Parameters

handle

Mbtcp handle.

Returns

Success or not.

References BEGIN, mbtcp_handle_s::connected, enable_syslog, ERR, mbtcp_key_s::ip, mbtcp_handle_s::key, LOG, and mbtcp_key_s::port.

Referenced by test_init_tcp_handle_and_connect().

{
    BEGIN (enable_syslog);
    
    if (handle != NULL)
    {
        LOG (enable_syslog, "%s:%s connected: %s",  handle->key.ip, 
                                                    handle->key.port, 
                                                    handle->connected ? "true" : "false");
        return handle->connected;
    }
    else
    {
        ERR (enable_syslog, "NULL handle");
        return false;
    }
}

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bool mbtcp_get_handle	(	mbtcp_handle_s **	ptr_handle,
		char *	ip,
		char *	port
	)

Get mbtcp handle from hashtable.

Parameters

ptr_handle	Pointer to mbtcp handle.
ip	IP address string.
port	Modbus TCP server port string or service name.

Returns

Success or not.

References BEGIN, enable_syslog, ERR, HASH_FIND, mbtcp_key_s::ip, mbtcp_handle_s::key, LOG, and mbtcp_key_s::port.

Referenced by test_init_tcp_handle_and_connect().

{
    BEGIN(enable_syslog);
    
    mbtcp_handle_s query, *hash_ctx;
    memset (&query, 0, sizeof (mbtcp_handle_s));
    strcpy (query.key.ip, ip);
    strcpy (query.key.port, port);
    // get handle from hash table
    HASH_FIND (hh, mbtcp_htable, &query.key, sizeof (mbtcp_key_s), hash_ctx);
    
    if (hash_ctx != NULL)
    {
        LOG (enable_syslog, "tcp server %s:%s found", hash_ctx->key.ip, hash_ctx->key.port);
        // call by reference to `mbtcp handle address`
        *ptr_handle = hash_ctx; 
        return true;
    }
    else
    {
        ERR (enable_syslog, "tcp server %s:%s not found", query.key.ip, query.key.port);
        *ptr_handle = NULL; 
        return false; // not found
    }
}

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char* mbtcp_get_response_timeout

(

char *

tid

)

Get mbtcp response timeout.

Parameters

tid	Transaction ID.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_AddNumberToObject, cJSON_AddStringToObject, cJSON_CreateObject(), cJSON_Delete(), cJSON_PrintUnformatted(), enable_syslog, END, LOG, and tcp_conn_timeout_usec.

Referenced by main().

{
    BEGIN (enable_syslog);

    cJSON *resp_root;
    resp_root = cJSON_CreateObject();
    cJSON_AddStringToObject (resp_root, "tid", tid);
    cJSON_AddNumberToObject (resp_root, "timeout", tcp_conn_timeout_usec);
    cJSON_AddStringToObject (resp_root, "status", "ok");
    char * resp_json_string = cJSON_PrintUnformatted (resp_root);
    LOG (enable_syslog, "resp: %s", resp_json_string);
    
    // clean up
    cJSON_Delete (resp_root);
    END (enable_syslog);
    return resp_json_string;
}

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bool mbtcp_init_handle	(	mbtcp_handle_s **	ptr_handle,
		char *	ip,
		char *	port
	)

Init mbtcp handle (to hashtable) and try to connect.

Parameters

ptr_handle	Pointer to mbtcp handle.
ip	IP address string.
port	Modbus TCP server port string.

Returns

Success or not.

References BEGIN, mbtcp_handle_s::connected, mbtcp_handle_s::ctx, enable_syslog, ERR, HASH_ADD, mbtcp_key_s::ip, mbtcp_handle_s::key, LOG, mbtcp_do_connect(), mbtcp_key_s::port, and tcp_conn_timeout_usec.

Referenced by test_init_tcp_handle_and_connect().

{
    BEGIN (enable_syslog);

    // create a mbtcp context
    modbus_t *ctx = modbus_new_tcp_pi (ip, port);
    
    if (ctx == NULL)
    {
        ERR (enable_syslog, "Unable to allocate mbtcp context");
        return false; // fail to allocate context
    }
        
    // set tcp connection timeout
    modbus_set_response_timeout (ctx, 0, tcp_conn_timeout_usec);
    LOG (enable_syslog, "set response timeout: %ld", tcp_conn_timeout_usec);
    
    // @add context to mbtcp hashtable
    mbtcp_handle_s *handle = (mbtcp_handle_s*) malloc (sizeof (mbtcp_handle_s));
    if (handle != NULL)
    {
        // let alignment bytes being set to zero-value!!
        memset (handle, 0, sizeof (mbtcp_handle_s));
        handle->connected = false;
        strcpy (handle->key.ip, ip);
        strcpy (handle->key.port, port);
        handle->ctx = ctx;

        HASH_ADD(hh, mbtcp_htable, key, sizeof (mbtcp_key_s), handle);
        LOG (enable_syslog, "Add %s: %s to mbtcp hashtable", handle->key.ip, mbtcp_htable->key.port);

        // call by reference to `mbtcp handle address`
        *ptr_handle = handle;

        // @connect to server
        char * reason = NULL;
        mbtcp_do_connect (handle, &reason);
        return true;
    }
    else
    {
        ERR (enable_syslog, "Unable to allocate mbtcp handle");
        return false;
    }
}

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void mbtcp_list_handles

(

)

List all handles in mbtcp hash table.

Returns

Void.

References BEGIN, enable_syslog, END, mbtcp_handle_s::hh, mbtcp_key_s::ip, mbtcp_handle_s::key, LOG, UT_hash_handle::next, and mbtcp_key_s::port.

{
    BEGIN (enable_syslog);

    mbtcp_handle_s * handle;
    for (handle = mbtcp_htable; handle != NULL; handle = handle->hh.next)
    {
        LOG (enable_syslog, "ip:%s, port:%s", handle->key.ip, handle->key.port);
    }

    END (enable_syslog);
}

char* mbtcp_multi_write_req_fn	(	uint8_t	fc,
		mbtcp_handle_s *	handle,
		cJSON *	req
	)

Help function.

FC15, FC16 request handler

Function code 15 and 16 only.

Parameters

handle	Mbtcp handle.
req	cJSON request object.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_GetArrayItem(), cJSON_GetArraySize(), cJSON_GetObjectItem(), mbtcp_handle_s::ctx, enable_syslog, json_get_char(), json_get_int(), LOG, set_modbus_fail_resp_str(), set_modbus_fail_resp_str_with_errno(), set_modbus_success_resp_str(), and cJSON::valueint.

Referenced by main().

{
    BEGIN (enable_syslog);

    int addr = json_get_int (req, "addr");
    int len  = json_get_int (req, "len");
    char * tid = json_get_char (req, "tid");
    cJSON * data = NULL;
    int ret = 0;
    uint8_t bits[len];  // FC15, VLAs
    uint16_t regs[len]; // FC16, VLAs

    switch (fc)
    {
        case 15:
            data = cJSON_GetObjectItem (req, "data");
            for (int i = 0 ; i < cJSON_GetArraySize (data) ; i++)
            {
                uint8_t subitem = cJSON_GetArrayItem (data, i)->valueint;
                bits[i] = subitem;
                LOG(enable_syslog, "[%d]=%d", i, bits[i]);
            }
            ret = modbus_write_bits (handle->ctx, addr, len, bits);
            break;

        case 16:
            data = cJSON_GetObjectItem (req, "data");
            for (int i = 0 ; i < cJSON_GetArraySize (data) ; i++)
            {
                uint16_t subitem = cJSON_GetArrayItem (data, i)->valueint;
                regs[i] = subitem;
                LOG(enable_syslog, "[%d]=%d", i, regs[i]);
            }
            ret = modbus_write_registers (handle->ctx, addr, len, regs);
            break;

        default:
            return set_modbus_fail_resp_str (tid, "Invalid function code");
    }

    if (ret < 0) 
    {
        return set_modbus_fail_resp_str_with_errno (tid, handle, errno);
    } 
    else
    {
        return set_modbus_success_resp_str (tid);         
    }
}

char* mbtcp_read_bit_req_fn	(	uint8_t	fc,
		mbtcp_handle_s *	handle,
		cJSON *	req
	)

Help function.

FC1, FC2 request handler

Function code 1 and 2 only.

Parameters

handle	Mbtcp handle.
req	cJSON request object.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_CreateUInt8Array(), mbtcp_handle_s::ctx, enable_syslog, json_get_char(), json_get_int(), LOG, set_modbus_fail_resp_str(), set_modbus_fail_resp_str_with_errno(), and set_modbus_success_resp_str_with_data().

Referenced by main().

{
    BEGIN (enable_syslog);

    int addr = json_get_int (req, "addr");
    int len  = json_get_int (req, "len");
    char *tid = json_get_char (req, "tid");
    uint8_t bits[len];
    int ret = 0;

    if (len > MODBUS_MAX_READ_BITS) // 2000
    {
        return set_modbus_fail_resp_str (tid, "Too many bits requested");
    }
    else
    {
        switch (fc)
        {
            case 1:
                ret = modbus_read_bits (handle->ctx, addr, len, bits);
                break;
            case 2:
                ret = modbus_read_input_bits (handle->ctx, addr, len, bits);
                break;
            default:
                return set_modbus_fail_resp_str (tid, "Invalid function code");
        }

        if (ret < 0) 
        {
            return set_modbus_fail_resp_str_with_errno (tid, handle, errno);
        } 
        else 
        {
            LOG (enable_syslog, "fc:%d, desired length: %d, read length:%d", fc, len, ret);
            
            /* debug only
            for (int ii = 0; ii < ret; ii++) 
            {
                LOG (enable_syslog, "[%d]=%d", ii, bits[ii]);
            }
            */

            // uint8_t array
            return set_modbus_success_resp_str_with_data (tid, cJSON_CreateUInt8Array (bits, len));
        }
    }    
}

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char* mbtcp_read_reg_req_fn	(	uint8_t	fc,
		mbtcp_handle_s *	handle,
		cJSON *	req
	)

Help function.

FC3, FC4 request handler

Function code 3 and 4 only.

Parameters

handle	Mbtcp handle.
req	cJSON request object.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_CreateUInt16Array(), mbtcp_handle_s::ctx, enable_syslog, json_get_char(), json_get_int(), LOG, set_modbus_fail_resp_str(), set_modbus_fail_resp_str_with_errno(), and set_modbus_success_resp_str_with_data().

Referenced by main().

{
    BEGIN (enable_syslog);

    int addr = json_get_int (req, "addr");
    int len  = json_get_int (req, "len");
    char * tid = json_get_char (req, "tid");
    uint16_t regs[len];
    int ret = 0;

    if (len > MODBUS_MAX_READ_REGISTERS) // 125
    {
        return set_modbus_fail_resp_str (tid, "Too many registers requested");
    }
    else
    {
        switch (fc)
        {
            case 3:
                ret = modbus_read_registers (handle->ctx, addr, len, regs);
                break;
            case 4:
                ret = modbus_read_input_registers (handle->ctx, addr, len, regs);
                break;
            default:
                return set_modbus_fail_resp_str (tid, "Invalid function code");
        }
        
        if (ret < 0) 
        {
            return set_modbus_fail_resp_str_with_errno (tid, handle, errno);
        } 
        else 
        {
            LOG (enable_syslog, "fc:%d, desired length: %d, read length:%d", fc, len, ret);
            
            /* debug only
            for (int ii = 0; ii < ret; ii++) 
            {
                LOG (enable_syslog, "[%d]=%d", ii, regs[ii]);
            }
            */
            
            // uint16_t array
            return set_modbus_success_resp_str_with_data (tid, cJSON_CreateUInt16Array (regs, len));
        }
    }
}

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char* mbtcp_set_response_timeout	(	char *	tid,
		long	timeout
	)

Set mbtcp response timeout in usec.

Parameters

tid	Transaction ID.
timeout	Timeout in usec.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_AddStringToObject, cJSON_CreateObject(), cJSON_Delete(), cJSON_PrintUnformatted(), enable_syslog, END, LOG, and tcp_conn_timeout_usec.

Referenced by main().

{
    BEGIN (enable_syslog);

    // set timeout
    tcp_conn_timeout_usec = timeout;
    
    cJSON *resp_root;
    resp_root = cJSON_CreateObject ();
    cJSON_AddStringToObject (resp_root, "tid", tid);
    cJSON_AddStringToObject (resp_root, "status", "ok");
    char * resp_json_string = cJSON_PrintUnformatted (resp_root);
    LOG (enable_syslog, "resp: %s", resp_json_string);
    
    // clean up
    cJSON_Delete (resp_root);
    END (enable_syslog);
    return resp_json_string;
}

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char* mbtcp_single_write_req_fn	(	uint8_t	fc,
		mbtcp_handle_s *	handle,
		cJSON *	req
	)

Help function.

FC5, FC6 request handler

Function code 5 and 6 only.

Parameters

handle	Mbtcp handle.
req	cJSON request object.

Returns

Modbus response string in JSON format.

References BEGIN, mbtcp_handle_s::ctx, enable_syslog, json_get_char(), json_get_int(), set_modbus_fail_resp_str(), set_modbus_fail_resp_str_with_errno(), and set_modbus_success_resp_str().

Referenced by main().

{
    BEGIN (enable_syslog);

    int addr = json_get_int (req, "addr");
    char * tid = json_get_char (req, "tid");
    int data = json_get_int (req, "data");
    int ret  = 0;

    switch (fc)
    {
        case 5:
            ret = modbus_write_bit (handle->ctx, addr, data);
            break;
        case 6:
            ret = modbus_write_register (handle->ctx, addr, data);
            break;
        default:
            return set_modbus_fail_resp_str (tid, "Invalid function code");
    }

    if (ret < 0) 
    {
        return set_modbus_fail_resp_str_with_errno (tid, handle, errno);
    }
    else
    {
        return set_modbus_success_resp_str (tid);   
    }
}

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char* set_modbus_fail_resp_str	(	char *	tid,
		const char *	reason
	)

Set modbusd fail response string.

Parameters

tid	Transaction ID.
reason	Fail reason string.

Returns

Modbus response string in JSON format.

References BEGIN, cJSON_AddStringToObject, cJSON_CreateObject(), cJSON_Delete(), cJSON_PrintUnformatted(), enable_syslog, ERR, and LOG.

Referenced by main(), mbtcp_cmd_hanlder(), mbtcp_multi_write_req_fn(), mbtcp_read_bit_req_fn(), mbtcp_read_reg_req_fn(), mbtcp_single_write_req_fn(), and set_modbus_fail_resp_str_with_errno().

{
    BEGIN (enable_syslog);

    ERR (enable_syslog, "Fail: %s", reason);

    cJSON *resp_root;
    resp_root = cJSON_CreateObject ();
    cJSON_AddStringToObject (resp_root, "tid", tid);
    cJSON_AddStringToObject (resp_root, "status", reason);

    char * resp_json_string = cJSON_PrintUnformatted (resp_root);
    LOG(enable_syslog, "resp: %s", resp_json_string);
    // clean up
    cJSON_Delete (resp_root);
    return resp_json_string;
}

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char* set_modbus_fail_resp_str_with_errno	(	char *	tid,
		mbtcp_handle_s *	handle,
		int	errnum
	)

Set modbusd fail response string with error number.

Parameters

tid	Transaction ID.
handle	Mbtcp handle.
errnum	Error number from modbus tcp handle.

Returns

Modbus error response string in JSON format.

References BEGIN, mbtcp_handle_s::connected, enable_syslog, ERR, and set_modbus_fail_resp_str().

Referenced by mbtcp_multi_write_req_fn(), mbtcp_read_bit_req_fn(), mbtcp_read_reg_req_fn(), and mbtcp_single_write_req_fn().

{
    BEGIN (enable_syslog);

    // [TODO][enhance] reconnect proactively?
    // ... if the request interval is very large, 
    // we should try to reconnect automatically
    
    if (errnum == 104) // Connection reset by peer (i.e, tcp connection timeout)
    {
        handle->connected = false;
    }

    ERR (enable_syslog, "%s:%d", modbus_strerror (errnum), errnum);
    return set_modbus_fail_resp_str (tid, modbus_strerror (errnum));
}

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char* set_modbus_success_resp_str

(

char *

tid

)

Set modbusd success response string without data (i.e., write func)

Parameters

tid	Transaction ID.

Returns

Modbus ok response string in JSON format.

References set_modbus_success_resp_str_with_data().

Referenced by mbtcp_multi_write_req_fn(), and mbtcp_single_write_req_fn().

{
    return set_modbus_success_resp_str_with_data (tid, NULL);
}

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char* set_modbus_success_resp_str_with_data	(	char *	tid,
		cJSON *	json_arr
	)

Set modbusd success response string with data (i.e., read func)

Parameters

tid	Transaction ID.
json_arr	cJSON pointer to data array

Returns

Modbus ok response string in JSON format.

References BEGIN, cJSON_AddItemToObject(), cJSON_AddStringToObject, cJSON_CreateObject(), cJSON_Delete(), cJSON_PrintUnformatted(), enable_syslog, and LOG.

Referenced by mbtcp_read_bit_req_fn(), mbtcp_read_reg_req_fn(), and set_modbus_success_resp_str().

{
    BEGIN (enable_syslog);

    cJSON *resp_root;
    resp_root = cJSON_CreateObject ();
    cJSON_AddStringToObject (resp_root, "tid", tid);
    
    if (json_arr != NULL) 
    {
        cJSON_AddItemToObject (resp_root, "data", json_arr);
    }
    cJSON_AddStringToObject (resp_root, "status", "ok");
    
    char * resp_json_str = cJSON_PrintUnformatted (resp_root);
    LOG (enable_syslog, "resp: %s", resp_json_str);
    // clean up
    cJSON_Delete (resp_root);
    return resp_json_str;
}

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