Improve static and const correctness.

- Any non-externally-visible declarations should be `static`.
- Casting away the `const` qualifier from pointers-to-const is
  dangerous. All but one instance of this are now correct. The one
  instance where we can't keep `const` is one where toxav code actually
  writes to a chunk of memory marked as `const`. This code also assumes
  4 byte alignment of data packets. I don't know whether that is a valid
  assumption, but it's likely unportable, and *not* obviously correct.
- Replaced empty parameter lists with `(void)` to avoid passing
  parameters to it. Empty parameter lists are old style declarations for
  unknown number and type of arguments.
- Commented out (as `#if DHT_HARDENING` block) the hardening code that
  was never executed.
- Minor style fix: don't use `default` in enum-switches unless the number
  of enumerators in the default case is very large. In this case, it was
  2, so we want to list them both explicitly to be warned about missing
  one if we add one in the future.
- Removed the only two function declarations from nTox.h and put them
  into nTox.c. They are not used outside and nTox is not a library.

1 files changed, 4 insertions, 4 deletions

diff --git a/other/bootstrap_daemon/src/config.c b/other/bootstrap_daemon/src/config.c
index dc0a251c..a0c6045d 100644
--- a/other/bootstrap_daemon/src/config.c
+++ b/other/bootstrap_daemon/src/config.c
@@ -41,7 +41,7 @@
  *
  * Important: iff `tcp_relay_port_count` > 0, then you are responsible for freeing `tcp_relay_ports`.
  */
-void parse_tcp_relay_ports_config(config_t *cfg, uint16_t **tcp_relay_ports, int *tcp_relay_port_count)
+static void parse_tcp_relay_ports_config(config_t *cfg, uint16_t **tcp_relay_ports, int *tcp_relay_port_count)
 {
     const char *NAME_TCP_RELAY_PORTS = "tcp_relay_ports";
 
@@ -303,7 +303,7 @@ int get_general_config(const char *cfg_file_path, char **pid_file_path, char **k
  * @return binary on success,
  *         NULL on failure.
  */
-uint8_t *hex_string_to_bin(char *hex_string)
+static uint8_t *hex_string_to_bin(const char *hex_string)
 {
     if (strlen(hex_string) % 2 != 0) {
         return NULL;
@@ -312,7 +312,7 @@ uint8_t *hex_string_to_bin(char *hex_string)
     size_t len = strlen(hex_string) / 2;
     uint8_t *ret = malloc(len);
 
-    char *pos = hex_string;
+    const char *pos = hex_string;
     size_t i;
 
     for (i = 0; i < len; ++i, pos += 2) {
@@ -403,7 +403,7 @@ int bootstrap_from_config(const char *cfg_file_path, DHT *dht, int enable_ipv6)
             goto next;
         }
 
-        uint8_t *bs_public_key_bin = hex_string_to_bin((char *)bs_public_key);
+        uint8_t *bs_public_key_bin = hex_string_to_bin((const char *)bs_public_key);
         const int address_resolved = DHT_bootstrap_from_address(dht, bs_address, enable_ipv6, htons(bs_port),
                                      bs_public_key_bin);
         free(bs_public_key_bin);