scufpong/src/common/networking.c

#include <string.h>

#include "scufeng/log.h"

#include "networking.h"

static const uint8_t fb = 0xfb;
static const uint8_t fe = 0xfe;

void PaddleChangeDirMsg_encode(const PaddleChangeDirMsg *const msg, uint8_t *buf, const size_t buf_size) {
    if (buf_size < PADDLE_CHANGE_DIR_MSG_ENCODED_SIZE) {
        LOG_FATALF("Buffer size too small (%zu), %zu required.", buf_size, PADDLE_CHANGE_DIR_MSG_ENCODED_SIZE);
    }

    memcpy(buf, &msg->dir, sizeof(msg->dir));
    buf += sizeof(msg->dir);
    memcpy(buf, &msg->player1, sizeof(msg->player1));
}

PaddleChangeDirMsg PaddleChangeDir_decode(const uint8_t *buf, const size_t buf_size) {
    if (buf_size < PADDLE_CHANGE_DIR_MSG_ENCODED_SIZE) {
        LOG_FATALF("Buffer size too small (%zu), %zu required.", buf_size, PADDLE_CHANGE_DIR_MSG_ENCODED_SIZE);
    }

    PaddleChangeDirMsg msg = {0};

    memcpy(&msg.dir, buf, sizeof(msg.dir));
    buf += sizeof(msg.dir);
    memcpy(&msg.player1, buf, sizeof(msg.player1));

    return msg;
}

void send_msg(FILE *s, const uint8_t *const buf, const size_t buf_size) {
    uint8_t *buf_cpy = (uint8_t *) malloc(sizeof(uint8_t) * buf_size);
    memcpy(buf_cpy, buf, buf_size);
    for (uint8_t *p = buf_cpy; p < buf_cpy + buf_size; p++) {
        if (*p == fb || *p == fe) {
            *p += SEND_FRAME_MANGLE;
        }
    }

    if (fwrite(&fb, sizeof(fb), 1, s) < 1) {
        LOG_FATAL("[send_msg] Failed to write fb");
    }
    if (fwrite(&buf_size, sizeof(buf_size), 1, s) < 1) {
        LOG_FATAL("[send_msg] Failed to write msg_len");
    }
    if (fwrite(buf_cpy, buf_size, 1, s) < 1) {
        LOG_FATAL("[send_msg] Failed to write msg");
    }
    if (fwrite(&fe, sizeof(fe), 1, s) < 1) {
        LOG_FATAL("[send_msg] Failed to write fe");
    }
    if (fflush(s) != 0) {
        LOG_FATAL("[send_msg] Failed to flush stream");
    }

    free(buf_cpy);
}

bool recv_msg(FILE *s, uint8_t *const buf, const size_t buf_size) {
    uint8_t _fb;
    if (fread(&_fb, sizeof(_fb), 1, s) < 1) {
        LOG_FATAL("[recv_msg] Failed to read _fb");
    }
    if (_fb != fb) {
        return false;
    }

    size_t msg_len;
    if (fread(&msg_len, sizeof(msg_len), 1, s) < 1) {
        LOG_FATAL("[recv_msg] Failed to read msg_len");
    }

    if (buf_size < msg_len) {
        LOG_FATALF("[recv_msg] Buffer too small. msg_len: %zu, buf_size: %zu", msg_len, buf_size);
    }
    if (fread(buf, buf_size, 1, s) < 1) {
        LOG_FATAL("[recv_msg] Failed to read msg");
    }
    for (uint8_t *p = buf; p < buf + buf_size; p++) {
        if (*p == fb + SEND_FRAME_MANGLE || *p == fe + SEND_FRAME_MANGLE) {
            *p += RECV_FRAME_MANGLE;
        }
    }

    uint8_t _fe;
    if (fread(&_fe, sizeof(_fe), 1, s) < 1) {
        LOG_FATAL("[recv_msg] Failed to read _fe");
    }
    if (_fe != fe) {
        return false;
    }

    return true;
}