download.py

from six.moves import urllib
import os, io, inspect

import util

retry_count = 20


path = "https://snapshot.debian.org/archive/debian-security/20200424T130133Z/pool/updates/main/o/openjdk-11/openjdk-11-jdk-headless_11.0.7+10-3~deb10u1_amd64.deb"

def download(pkg_key, path, out_file):
    res = urllib.request.urlopen(path)
    remained_size = int(res.info().getheader("Content-Length"))
    print("content-length: %d" % remained_size)
    range_access_enabled = "bytes" in res.info().getheader("Accept-Ranges")
    etag = res.info().getheader("ETag")
    offset = 0
    contents = []
    downloaded = res.read()
    contents.append(downloaded)
    remained_size -= len(downloaded)
    print("remained_size: %d" % remained_size)

    if remained_size != 0:
        if not range_access_enabled:
            raise RuntimeError("Fail to downlod %s" % pkg_key)

        offset += len(downloaded)
        count = retry_count

        while count > 0:
            count -= 1
            req = urllib.request.Request(path, headers={"Range": "bytes=%d-" % offset, "If-Range": etag})
            res = urllib.request.urlopen(req)

            if res.getcode() == 200:
                contents = []
                offset = 0
                remained_size = int(res.info().getheader("Content-Length"))
            downloaded = res.read()
            contents.append(downloaded)
            remained_size -= len(downloaded)
            print("remained_size: %d" % remained_size)
            if remained_size == 0:
                break
    with io.open(out_file, 'wb') as f:
        for content in contents:
            f.write(content)

def main():
    out_file = os.path.join("file", util.encode_package_name("penjdk-11-jdk-headless.deb"))
    download("openjdk", path, out_file)
    actual_checksum = util.sha256_checksum(out_file)
    print(actual_checksum)

if __name__ == "__main__":
    main()