xmodemserver.h

/* This header file should be included in your xmodemserver.c file.
 * You are welcome to add to it.
 */

/* Enumeration constants are similar to constants created with #define
 * It is a nice way of being able to give a name to a state in this case.
 * For example, you can use the enum below as follows:
 *     //first declare a variable:
 *     enum recstate state;
 *     //then give it a value (note that the value is not a string)
 *     state = check_block;
 */
#include <stdio.h>

enum recstate {
    initial,
    pre_block,
    get_block,
    check_block,
    finished
};

//Helper functions
void bindandlisten();
void newconnection();
static void removeclient(int soc);
static void addclient(int soc);

/* The client struct contains the state that the server needs for each client.
 */ 
struct client {
    int fd;               // socket descriptor for this client
    char buf[2048];       // buffer to hold data being read from client
    int inbuf;            // index into buf
    char filename[20];    // name of the file being transferred
    FILE *fp;             // file pointer for where the file is written to
    enum recstate state;  // current state of data transfer for this client
    int blocksize;        // the size of the current block
    int current_block;    // the block number of the current block
    struct client *next;  // a pointer to the next client in the list
};

#define XMODEM_KEY 0x1021


//ASCII characters
#define SOH 1
#define STX 2
#define EOT 4
#define ACK 6
#define NAK 21
#define CAN 24