Make most of functions const correct (#714)

* Make most of the functions const correct

Used clang-tidy and sonarlint to help find places where const could
pretty easily applied. Also lot of hand work.

This commit does not yet touch handlers and typedefs of those.

* Fix Arduino uno handler_who_is() has extra parenthesis

For some reason there is extra parenthesis. Remove it this is more
likely buildable.

* Bugfix/bacapp: Fix uninitilized array_index

We have changed bacapp_snprintf_value() to be const correct. After that
we got

```
/home/runner/work/bacnet-stack/bacnet-stack/src/bacnet/bacapp.c:3183:27: warning: 4th function call argument is an uninitialized value [core.CallAndMessage]
                ret_val = bacapp_snprintf_weeklyschedule(
                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
```

So analyzer could now spot that we do not actually initilize array_index
at all. Fix this by setting array_index to zero. Note that I actually do
not know if zeroing is right thing to do here. I choose zero as if this
has worked before it is most likely that it will work with zero value.

* cmake: Add and ignore Wwrite-strings compiler option

Wwrite-strings helps find places where const correctness is broken.

Example it will warn about these

```C

void func1(char* str);

func("test") /* "test" is const so we should not pass it to func1().

char* func2()
{
  return "test"; /* func2() should return const char*.
}
```

We still need to ignore it as not all are fixed but let's add it already
so we remember that it should be opened at some point.

---------

Co-authored-by: Kari Argillander <kari.argillander@fidelix.com>

ports/win32/bip-init.c

@@ -317,7 +317,7 @@ void bip_get_broadcast_address(BACNET_ADDRESS *dest)
  *
  * @param addr - network IPv4 address
  */
-bool bip_set_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_addr(const BACNET_IP_ADDRESS *addr)
 {
     (void)addr;
     /* not something we do here within this application */
@@ -344,7 +344,7 @@ bool bip_get_addr(BACNET_IP_ADDRESS *addr)
  * @param addr - network IPv4 address
  * @return true if the address was set
  */
-bool bip_set_broadcast_addr(BACNET_IP_ADDRESS *addr)
+bool bip_set_broadcast_addr(const BACNET_IP_ADDRESS *addr)
 {
     (void)addr;
     /* not something we do within this application */
@@ -412,7 +412,8 @@ uint8_t bip_get_subnet_prefix(void)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip_send_mpdu(
+    const BACNET_IP_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in bip_dest = { 0 };
     int rv = 0;
@@ -432,7 +433,7 @@ int bip_send_mpdu(BACNET_IP_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     /* Send the packet */
     debug_print_ipv4(
         "Sending MPDU->", &bip_dest.sin_addr, bip_dest.sin_port, mtu_len);
-    rv = sendto(BIP_Socket, (char *)mtu, mtu_len, 0,
+    rv = sendto(BIP_Socket, (const char *)mtu, mtu_len, 0,
         (struct sockaddr *)&bip_dest, sizeof(struct sockaddr));
     if (rv == SOCKET_ERROR) {
         print_last_error("sendto");
@@ -737,7 +738,7 @@ static void set_broadcast_address(uint32_t net_address)
  * @param ifname [in] The named interface to use for the network layer.
  *        Eg, for Windows, ifname is the dotted ip address of the interface
  */
-void bip_set_interface(char *ifname)
+void bip_set_interface(const char *ifname)
 {
     /* setup local address */
     if (BIP_Address.s_addr == 0) {
@@ -754,7 +755,7 @@ void bip_set_interface(char *ifname)
     }
 }
 
-static SOCKET createSocket(struct sockaddr_in *sin)
+static SOCKET createSocket(const struct sockaddr_in *sin)
 {
     int rv = 0; /* return from socket lib calls */
     int value = 1;

ports/win32/bip6.c

@@ -290,7 +290,7 @@ void bip6_get_my_address(BACNET_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Addr, addr);
 }
@@ -312,7 +312,7 @@ bool bip6_get_addr(BACNET_IP6_ADDRESS *addr)
  *
  * @return true if the BACnet/IPv6 address matches our own address
  */
-bool bip6_address_match_self(BACNET_IP6_ADDRESS *addr)
+bool bip6_address_match_self(const BACNET_IP6_ADDRESS *addr)
 {
     return !bvlc6_address_different(addr, &BIP6_Addr);
 }
@@ -322,7 +322,7 @@ bool bip6_address_match_self(BACNET_IP6_ADDRESS *addr)
  *
  * @param addr - network IPv6 address
  */
-bool bip6_set_broadcast_addr(BACNET_IP6_ADDRESS *addr)
+bool bip6_set_broadcast_addr(const BACNET_IP6_ADDRESS *addr)
 {
     return bvlc6_address_copy(&BIP6_Broadcast_Addr, addr);
 }
@@ -348,7 +348,7 @@ bool bip6_get_broadcast_addr(BACNET_IP6_ADDRESS *addr)
  * @return Upon successful completion, returns the number of bytes sent.
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
-int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
+int bip6_send_mpdu(const BACNET_IP6_ADDRESS *dest, const uint8_t *mtu, uint16_t mtu_len)
 {
     struct sockaddr_in6 bvlc_dest = { 0 };
     uint16_t addr16[8];
@@ -375,8 +375,8 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
     debug_print_ipv6("Sending MPDU->", &bvlc_dest.sin6_addr);
     /* Send the packet */
     return sendto(
-        BIP6_Socket, (char *)mtu, mtu_len, 0, (struct sockaddr *)&bvlc_dest,
-        sizeof(bvlc_dest));
+        BIP6_Socket, (const char *)mtu, mtu_len, 0,
+        (const struct sockaddr *)&bvlc_dest, sizeof(bvlc_dest));
 }
 
 /**
@@ -392,9 +392,9 @@ int bip6_send_mpdu(BACNET_IP6_ADDRESS *dest, uint8_t *mtu, uint16_t mtu_len)
  *  Otherwise, -1 shall be returned and errno set to indicate the error.
  */
 int bip6_send_pdu(
-    BACNET_ADDRESS *dest,
-    BACNET_NPDU_DATA *npdu_data,
-    uint8_t *pdu,
+    const BACNET_ADDRESS *dest,
+    const BACNET_NPDU_DATA *npdu_data,
+    const uint8_t *pdu,
     unsigned pdu_len)
 {
     return bvlc6_send_pdu(dest, npdu_data, pdu, pdu_len);

ports/win32/datetime-init.c

@@ -101,8 +101,7 @@ int gettimeofday(struct timeval *tp, void *tzp)
  * @param utc - True for UTC sync, False for Local time
  * @return True if time is set
  */
-void datetime_timesync(
-    BACNET_DATE *bdate, BACNET_TIME *btime, bool utc)
+void datetime_timesync(BACNET_DATE *bdate, BACNET_TIME *btime, bool utc)
 {
     (void)bdate;
     (void)btime;

ports/win32/dlmstp-mm.c

@@ -291,18 +291,18 @@ uint16_t MSTP_Get_Send(
  */
 void MSTP_Send_Frame(
     struct mstp_port_struct_t *mstp_port,
-    uint8_t * buffer,
+    const uint8_t * buffer,
     uint16_t nbytes)
 {
     RS485_Send_Frame(mstp_port, buffer, nbytes);
 }
 
-bool dlmstp_compare_data_expecting_reply(uint8_t *request_pdu,
+bool dlmstp_compare_data_expecting_reply(const uint8_t *request_pdu,
     uint16_t request_pdu_len,
     uint8_t src_address,
-    uint8_t *reply_pdu,
+    const uint8_t *reply_pdu,
     uint16_t reply_pdu_len,
-    BACNET_ADDRESS *dest_address)
+    const BACNET_ADDRESS *dest_address)
 {
     uint16_t offset;
     /* One way to check the message is to compare NPDU

ports/win32/dlmstp.c

@@ -277,18 +277,18 @@ uint16_t MSTP_Get_Send(
  */
 void MSTP_Send_Frame(
     struct mstp_port_struct_t *mstp_port,
-    uint8_t * buffer,
+    const uint8_t * buffer,
     uint16_t nbytes)
 {
     RS485_Send_Frame(mstp_port, buffer, nbytes);
 }
 
-static bool dlmstp_compare_data_expecting_reply(uint8_t *request_pdu,
+static bool dlmstp_compare_data_expecting_reply(const uint8_t *request_pdu,
     uint16_t request_pdu_len,
     uint8_t src_address,
-    uint8_t *reply_pdu,
+    const uint8_t *reply_pdu,
     uint16_t reply_pdu_len,
-    BACNET_ADDRESS *dest_address)
+    const BACNET_ADDRESS *dest_address)
 {
     uint16_t offset;
     /* One way to check the message is to compare NPDU

ports/win32/ethernet.c

@@ -352,7 +352,7 @@ uint16_t ethernet_receive(
     return pdu_len;
 }
 
-void ethernet_set_my_address(BACNET_ADDRESS *my_address)
+void ethernet_set_my_address(const BACNET_ADDRESS *my_address)
 {
     int i = 0;
 
@@ -400,7 +400,7 @@ void ethernet_get_broadcast_address(BACNET_ADDRESS *dest)
     return;
 }
 
-void ethernet_debug_address(const char *info, BACNET_ADDRESS *dest)
+void ethernet_debug_address(const char *info, const BACNET_ADDRESS *dest)
 {
     int i = 0; /* counter */
     char msg[200];

ports/win32/rs485.c

@@ -397,7 +397,7 @@ bool RS485_Set_Baud_Rate(uint32_t baud)
 /* Transmits a Frame on the wire */
 void RS485_Send_Frame(
     struct mstp_port_struct_t *mstp_port, /* port specific data */
-    uint8_t *buffer, /* frame to send (up to 501 bytes of data) */
+    const uint8_t *buffer,  /* frame to send (up to 501 bytes of data) */
     uint16_t nbytes)
 { /* number of bytes of data (up to 501) */
     DWORD dwWritten = 0;

ports/win32/rs485.h

@@ -30,8 +30,8 @@ extern "C" {
     BACNET_STACK_EXPORT
     void RS485_Send_Frame(
         struct mstp_port_struct_t *mstp_port,  /* port specific data */
-        uint8_t * buffer,       /* frame to send (up to 501 bytes of data) */
-        uint16_t nbytes);       /* number of bytes of data (up to 501) */
+        const uint8_t * buffer,     /* frame to send (up to 501 bytes of data) */
+        uint16_t nbytes);           /* number of bytes of data (up to 501) */
 
     BACNET_STACK_EXPORT
     void RS485_Check_UART_Data(