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import io
import typing
from kaitaistruct import KaitaiStream
from mitmproxy.contrib.kaitaistruct import png
from mitmproxy.contrib.kaitaistruct import gif
Metadata = typing.List[typing.Tuple[str, str]]
def parse_png(data: bytes) -> Metadata:
img = png.Png(KaitaiStream(io.BytesIO(data)))
parts = [
('Format', 'Portable network graphics')
]
parts.append(('Size', "{0} x {1} px".format(img.ihdr.width, img.ihdr.height)))
for chunk in img.chunks:
if chunk.type == 'gAMA':
parts.append(('gamma', str(chunk.body.gamma_int / 100000)))
elif chunk.type == 'pHYs':
aspectx = chunk.body.pixels_per_unit_x
aspecty = chunk.body.pixels_per_unit_y
parts.append(('aspect', "{0} x {1}".format(aspectx, aspecty)))
elif chunk.type == 'tEXt':
parts.append((chunk.body.keyword, chunk.body.text))
elif chunk.type == 'iTXt':
parts.append((chunk.body.keyword, chunk.body.text))
elif chunk.type == 'zTXt':
parts.append((chunk.body.keyword, chunk.body.text_datastream.decode('iso8859-1')))
return parts
def parse_gif(data: bytes) -> Metadata:
img = gif.Gif(KaitaiStream(io.BytesIO(data)))
parts = [
('Format', 'Compuserve GIF')
]
parts.append(('version', "GIF{0}".format(img.header.version.decode('ASCII'))))
descriptor = img.logical_screen_descriptor
parts.append(('Size', "{0} x {1} px".format(descriptor.screen_width, descriptor.screen_height)))
parts.append(('background', str(descriptor.bg_color_index)))
ext_blocks = []
for block in img.blocks:
if block.block_type.name == 'extension':
ext_blocks.append(block)
comment_blocks = []
for block in ext_blocks:
if block.body.label._name_ == 'comment':
comment_blocks.append(block)
for block in comment_blocks:
entries = block.body.body.entries
for entry in entries:
comment = entry.bytes
if comment is not b'':
parts.append(('comment', str(comment)))
return parts
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