protocol.h

#ifndef PROTOCOL_H
#define PROTOCOL_H

#include <stdint.h>
#include <stdio.h>

// the protocol constants
#define PROTOCOL_PREFIX 0x23107231
#define OP_FACE_DETECT 0
#define OP_FACE_REPLACE 1
#define OP_OUTPUT_IMAGE 2
#define OP_ERROR_MESSAGE 3

typedef struct {
    uint32_t prefix;
    uint8_t operation;
    uint32_t image1Size;
    unsigned char* image1Data;
    // Only used for face replacement
    uint32_t image2Size;
    // Only used for face replacement
    unsigned char* image2Data;
} ProtocolMessage;

// define the function prototypes
int receive_message(FILE* stream, ProtocolMessage* message);
void free_message(ProtocolMessage* message);
int send_message(FILE* stream, ProtocolMessage* message);
unsigned char* read_file_data(const char* filename, uint32_t* size);
unsigned char* read_stdin_data(uint32_t* size);
int write_file_data(const char* filename, unsigned char* data, uint32_t size);
int write_stdout_data(unsigned char* data, uint32_t size);

#endif