Program for accessing user input and searching the positions of the entered position using linked list in C

list.c

#include <stdio.h>
#include <stdlib.h>
#include "list.h"

NODE* create_node(int value)
{
  NODE *node = malloc(sizeof(NODE));
  node->value = value;
  node->next = NULL;
  return node;
}

LIST* create_list(void)
{
  LIST* list = malloc(sizeof(LIST));
  list->first = NULL;
  list->last = NULL;
  return list;
}

void insert_node(LIST* list, int value)
{
  NODE *node = create_node(value);
  if (list->first == NULL)
  {
    list->first = node;
    list->last = node;
    return;
  }
  list->last->next = node;
  list->last = node;
}

void destroy_list(LIST* list)
{
  NODE *node_to_be_free = list->first;
  NODE *next_node = list->first->next;
  while (node_to_be_free != list->last)
  {
    free(node_to_be_free);
    node_to_be_free = next_node;
    next_node = next_node->next;
  }
  free(list->last);
  free(list);
}

int find_index_of(LIST *list, int number)
{
  int index = 0;
  NODE *p_walk = list->first;
  while (p_walk->next != NULL)
  {
    if (p_walk->value == number) return index;
    p_walk = p_walk->next;
    index++;
  }
  if (p_walk->value == number) return index;
  return -1;
}

list.h

typedef struct node
{
  int value;
  struct node *next;
} NODE;

typedef struct list
{
  NODE *first;
  NODE *last;
} LIST;

NODE* create_node(int value);
LIST* create_list(void);
void insert_node(LIST* list, int value);
void access_input(LIST *list);
void print_list(LIST *list);
void search_positions(LIST *list);
void print_position(int number, int position);
int find_index_of(LIST *list, int number);
void destroy_list(LIST *list);

main.c

#include <stdio.h>
#include <stdlib.h>
#include "list.h"

int main(void)
{
  LIST *list = create_list();
  access_input(list);
  search_positions(list);
  print_list(list);
  destroy_list(list);
  return 0;
}

search.c

#include <stdio.h>
#include <stdlib.h>
#include "list.h"

void access_input(LIST* list)
{
  int number;
  while (1)
  {
    printf("Please enter a number: ");
    scanf("%d", &number);
    if (number == -99)
    {
      return;
    }
    insert_node(list, number);
  }
}

void print_position(int number, int position)
{
  if (position == -1)
  {
    printf("%d is not present in the list\n", number);
    return;
  }
  printf("%d is present in the list at position %d\n", number, position);
}

void search_positions(LIST *list)
{
  int number;
  while (1)
  {
    printf("What number would you like to search for? ");
    scanf("%d", &number);
    if (number == -99)
    {
      return;
    }
    int index = find_index_of(list, number);
    print_position(number, index);
  }
}

void print_list(LIST* list)
{
  NODE *p_walk = list->first;
  while (p_walk->next != NULL)
  {
    printf("%d ", p_walk->value);
    p_walk = p_walk->next;
  }
  printf("%d\n", p_walk->value);
}

LIST seems like a constant not type. List is good enough for type name.

Duplication of list->last = node; in insert_node

destroy_list is complex, you need to use free on memory twice because you did not simplify your logic.

find_index_of is also not reviewed or thought through.
You are doing if (p_walk->value == number) return index; once inside loop, once outside

Why do you need <stdio.h> in list.c, there is no IO operation in it.

Why are access_input, search_positions declared inside the list.h ?

While(1) is a very poor idea, what is the point in infinite loop and an "if" inside it ?

Overall, seems like the code has not been reviewed/refactored enough.