#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void)
{
    char *buffer = "0x000x220x680x150x710xc60x420x09";
    char single_byte[4 + 1]; //4 bytes + 1 byte for NULL character
    int *pkt;
    int i = 0;

    pkt = (int *)malloc(strlen(buffer)/4); //you can take an array of desired size if you want
    if (!pkt) {
        perror("malloc failed");
        exit(1);
    }

    while (*buffer != '\0') {
        memset(single_byte, 0, sizeof(single_byte)); //create a NULL terminatied string
        strncpy_s(single_byte, sizeof(single_byte), strstr(buffer, "0x"), 4);
        buffer += 4;
        sscanf_s(single_byte, "0x%x", &pkt[i++]);
    }

    exit(0);
}