PDUTransmit.h

#ifndef UDPTRANSMIT_H
#define UDPTRANSMIT_H

#include <stdint.h>

#define DataOffset 3    //subtract PDUMsg.length by this to get length of data
#define MaxIPMsgSize 1500
#define maxTextLen 200

#define maxHandleLen 100

//for ease of parsing messages. Not used in these functions, but can be used elsewhere when convenient
struct PDUMsg {
    uint16_t nw_length;  // length of entire message, including these header bytes
    uint8_t flag;     // 1 byte at offset 2
    uint8_t data[MaxIPMsgSize];   // flexible array starting at offset 3
} __attribute__((__packed__));

//list of possible flags for messages
typedef enum {
    FLAG_CLIENT_INITIAL      = 1,  // Client initial packet to the server
    FLAG_SEND_ACCEPTED     = 2,  // Server confirms good handle
    FLAG_SEND_REJECTED     = 3,  // Server rejects handle (already exists)
    FLAG_BROADCAST_MESSAGE   = 4,  // Broadcast message from client
    FLAG_DIRECT_MESSAGE      = 5,  // Direct message to another client
    FLAG_MULTICAST_MESSAGE   = 6,  // Multicast message to multiple clients
    FLAG_INVALID_HANDLE      = 7,  // Error: destination handle does not exist
    FLAG_REQUEST_HANDLE_LIST = 10, // Client requests list of handles (%L)
    FLAG_SEND_LIST_COUNT   = 11, // Server responds with number of handles
    FLAG_SEND_LIST_ENTRY   = 12, // Server sends one handle entry
    FLAG_SEND_LIST_DONE    = 13  // Server signals end of handle list
} ChatFlag;

//add PDU then send (adds 2 bytes indicating msg length)
int sendPDU(int socketNumber, uint8_t* dataBuffer, int lengthOfData);   //returns # bytes sent

//same as sendPDU, but also inserts the flag after PDU (but before dataBuffer)
int sendPDUWithFlag(int clientSocket, uint8_t flag, uint8_t* dataBuffer, int lengthOfData);

//sends a message just containing the PDU (2 bytes length, and 1 byte flag), of the corresponding flag passed in
int sendResponseFlag(int clientSocket, uint8_t flag);

int recvPDU(int clientSocket, uint8_t* dataBuffer, int bufferSize);

#endif // UDPTRANSMIT_H