WebAssembly helper functions CTF

wasm.js

function download(data, filename, type) {
    var file = new Blob([data], {type: type});
    if (window.navigator.msSaveOrOpenBlob) // IE10+
        window.navigator.msSaveOrOpenBlob(file, filename);
    else { // Others
        var a = document.createElement("a"),
                url = URL.createObjectURL(file);
        a.href = url;
        a.download = filename;
        document.body.appendChild(a);
        a.click();
        setTimeout(function() {
            document.body.removeChild(a);
            window.URL.revokeObjectURL(url);  
        }, 0); 
    }
}

function dump_memory() {
  let mem = new Uint8Array(memory0.buffer)
  let out = "";

  mem.forEach( b => {
    let hb = b.toString(16);
    if (hb.length == 1) {
        hb = "0" + hb
    }
    out = out + hb;
  })
  
  download(out, "memory.hex", "text");
}

function toHex(b){
    let hb = b.toString(16);
    if (hb.length == 1) {
        hb = "0" + hb
    }
  
  	return hb;
}

function hexdump(init, end){
  let mem = new Uint8Array(memory0.buffer)
  let out = "";

  mem.slice(init,end).forEach( b => {
    let hb = b.toString(16);
    if (hb.length == 1) {
        hb = "0" + hb
    }

      out = out + hb;
  })
    
  return out;
}

let s = 71124
let l = 8
hexdump(s,s+l)

toHex(0)