File: si.py
   1 #!/usr/bin/python3
   2 
   3 # The MIT License (MIT)
   4 #
   5 # Copyright © 2020-2025 pacman64
   6 #
   7 # Permission is hereby granted, free of charge, to any person obtaining a copy
   8 # of this software and associated documentation files (the “Software”), to deal
   9 # in the Software without restriction, including without limitation the rights
  10 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11 # copies of the Software, and to permit persons to whom the Software is
  12 # furnished to do so, subject to the following conditions:
  13 #
  14 # The above copyright notice and this permission notice shall be included in
  15 # all copies or substantial portions of the Software.
  16 #
  17 # THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  20 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  23 # SOFTWARE.
  24 
  25 
  26 from base64 import b64decode, b64encode
  27 from io import BytesIO
  28 from re import compile as compile_re, Pattern
  29 from socket import socket
  30 from sys import argv, exit, stderr, stdin
  31 from typing import Callable, Dict, List, Tuple
  32 from webbrowser import open_new_tab
  33 
  34 
  35 info = '''
  36 si [options...]
  37 
  38 
  39 Show It shows data read from standard-input, using your default web browser
  40 by auto-opening tabs, auto-detecing the data-format, and using a random port
  41 among those available.
  42 
  43 The localhost connection is available only until all data are transferred:
  44 this means refreshing your browser tab will lose your content, replacing it
  45 with a server-not-found message page.
  46 
  47 Dozens of common data-formats are recognized when piped from stdin, such as
  48 
  49   - HTML (web pages)
  50   - PDF
  51   - pictures (PNG, JPEG, SVG, WEBP, HEIC, AVIF, GIF, BMP)
  52   - audio (AAC, MP3, FLAC, WAV, AU, MIDI)
  53   - video (MP4, MOV, WEBM, MKV, AVI)
  54   - JSON
  55   - generic UTF-8 plain-text
  56 '''
  57 
  58 # handle standard help cmd-line options, quitting right away in that case
  59 if len(argv) == 2 and argv[1] in ('-h', '--h', '-help', '--help'):
  60     print(info.strip())
  61     exit(0)
  62 
  63 
  64 # hdr_dispatch groups format-description-groups by their first byte, thus
  65 # shortening total lookups for some data header: notice how the `ftyp` data
  66 # formats aren't handled here, since these can include any byte in parts of
  67 # their first few bytes
  68 hdr_dispatch: Dict[int, List[Tuple[bytes, str]]] = {
  69     0x00: [
  70         (b'\x00\x00\x01\xba', 'video/mpeg'),
  71         (b'\x00\x00\x01\xb3', 'video/mpeg'),
  72         (b'\x00\x00\x01\x00', 'image/x-icon'),
  73         (b'\x00\x00\x02\x00', 'image/vnd.microsoft.icon'),
  74         (b'\x00asm', 'application/wasm'),
  75     ],
  76     0x1a: [(b'\x1a\x45\xdf\xa3', 'video/webm')], # matches general MKV format
  77     0x1f: [(b'\x1f\x8b\x08', 'application/gzip')]
  78     0x23: [
  79         (b'#! ', 'text/plain; charset=UTF-8'),
  80         (b'#!/', 'text/plain; charset=UTF-8'),
  81     ],
  82     0x25: [
  83         (b'%PDF', 'application/pdf'),
  84         (b'%!PS', 'application/postscript'),
  85     ],
  86     0x2e: [(b'.snd', 'audio/basic')],
  87     0x47: [
  88         (b'GIF87a', 'image/gif'),
  89         (b'GIF89a', 'image/gif'),
  90     ],
  91     0x49: [
  92         # some MP3s start with an ID3 meta-data section
  93         (b'ID3\x02', 'audio/mpeg'),
  94         (b'ID3\x03', 'audio/mpeg'),
  95         (b'ID3\x04', 'audio/mpeg'),
  96         (b'II*\x00', 'image/tiff'),
  97     ],
  98     0x4d: [
  99         (b'MM\x00*', 'image/tiff'),
 100         (b'MThd', 'audio/midi'),
 101     ],
 102     0x4f: [(b'OggS', 'audio/ogg')],
 103     0x50: [(b'PK\x03\x04', 'application/zip')],
 104     0x63: [(b'caff\x00\x01\x00\x00', 'audio/x-caf')],
 105     0x66: [(b'fLaC', 'audio/x-flac')],
 106     0x7b: [(b'{\\rtf', 'application/rtf')],
 107     0x7f: [(b'\x7fELF', 'application/x-elf')],
 108     0x89: [(b'\x89PNG\x0d\x0a\x1a\x0a', 'image/png')],
 109     0xff: [
 110         (b'\xff\xd8\xff', 'image/jpeg'),
 111         # handle common ways MP3 data start
 112         (b'\xff\xf3\x48\xc4\x00', 'audio/mpeg'),
 113         (b'\xff\xfb', 'audio/mpeg'),
 114     ],
 115 }
 116 
 117 
 118 # ftyp_types helps func match_ftyp auto-detect MPEG-4-like formats
 119 ftyp_types: Tuple[Tuple[bytes, str]] = (
 120     (b'M4A ', 'audio/aac'),
 121     (b'M4A\x00', 'audio/aac'),
 122     (b'mp42', 'video/x-m4v'),
 123     (b'dash', 'audio/aac'),
 124     (b'isom', 'video/mp4'),
 125     # (b'isom', 'audio/aac'),
 126     (b'MSNV', 'video/mp4'),
 127     (b'qt  ', 'video/quicktime'),
 128     (b'heic', 'image/heic'),
 129     (b'avif', 'image/avif'),
 130 )
 131 
 132 # xmlish_heuristics helps func guess_mime auto-detect HTML, SVG, and XML
 133 xmlish_heuristics: Tuple[Tuple[bytes, str]] = (
 134     (b'<html>', 'text/html'),
 135     (b'<html ', 'text/html'),
 136     (b'<head>', 'text/html'),
 137     (b'<body>', 'text/html'),
 138     (b'<!DOCTYPE html', 'text/html'),
 139     (b'<svg>', 'image/svg+xml'),
 140     (b'<svg ', 'image/svg+xml'),
 141     (b'<?xml', 'application/xml'),
 142 )
 143 
 144 # json_heuristics helps func guess_mime auto-detect JSON via regexes:
 145 # it's not perfect, but it seems effective-enough in practice
 146 json_heuristics: Tuple[Pattern] = (
 147     compile_re(b'''^\\s*\\{\\s*"'''),
 148     compile_re(b'''^\\s*\\{\\s*\\['''),
 149     compile_re(b'''^\\s*\\[\\s*"'''),
 150     compile_re(b'''^\\s*\\[\\s*\\{'''),
 151     compile_re(b'''^\\s*\\[\\s*\\['''),
 152 )
 153 
 154 
 155 def exact_match(header: bytes, maybe: bytes) -> bool:
 156     if len(header) < len(maybe):
 157         # not enough bytes to tell if input data match
 158         return False
 159     return all(x == y for x, y in zip(header, maybe))
 160 
 161 
 162 def match_riff(header: bytes) -> str:
 163     'Handle a few special cases for func guess_mime.'
 164 
 165     if len(header) < 12 or not header.startswith(b'RIFF'):
 166         return ''
 167 
 168     if header.find(b'WEBP', 8, 12) == 8:
 169         return 'image/webp'
 170     if header.find(b'WAVE', 8, 12) == 8:
 171         return 'audio/x-wav'
 172     if header.find(b'AVI ', 8, 12) == 8:
 173         return 'video/avi'
 174     return ''
 175 
 176 
 177 def match_form(header: bytes) -> str:
 178     'Handle a few special cases for func guess_mime.'
 179 
 180     if len(header) < 12 or not header.startswith(b'FORM'):
 181         return ''
 182 
 183     if header.find(b'AIFF', 8, 12) == 8:
 184         return 'audio/aiff'
 185     if header.find(b'AIFC', 8, 12) == 8:
 186         return 'audio/aiff'
 187     return ''
 188 
 189 
 190 def match_ftyp(header: bytes) -> str:
 191     'Handle a few special cases for func guess_mime.'
 192 
 193     # first 4 bytes can be anything, next 4 bytes must be ASCII 'ftyp'
 194     if len(header) < 12 or header.find(b'ftyp', 4, 8) != 4:
 195         return ''
 196 
 197     # next 4 bytes after the ASCII 'ftyp' declare the data-format
 198     for marker, mime in ftyp_types:
 199         if header.find(marker, 8, 12) == 8:
 200             return mime
 201 
 202     # unrecognized MPEG-4-style data-format
 203     return ''
 204 
 205 
 206 def guess_mime(header: bytes, fallback: str) -> str:
 207     'Try to auto-detect common MIME-types, given the first few input bytes.'
 208 
 209     # no bytes, no match
 210     if len(header) == 0:
 211         return fallback
 212 
 213     # check the RIFF formats, AIFF audio, and MPEG-4-like formats
 214     for f in (match_riff, match_form, match_ftyp):
 215         m = f(header)
 216         if m != '':
 217             return m
 218 
 219     # maybe it's a bitmap picture, which almost always has 40 on 15th byte
 220     if header.startswith(b'BM') and header.find(b'\x28', 8, 16) == 14:
 221         return 'image/x-bmp'
 222 
 223     # check general lookup-table
 224     if header[0] in hdr_dispatch:
 225         for maybe in hdr_dispatch[header[0]]:
 226             if exact_match(header, maybe[0]):
 227                 return maybe[1]
 228 
 229     if header.find(b'<!DOCTYPE html', 0, 64) >= 0:
 230         return 'text/html'
 231 
 232     # try HTML, SVG, and even XML
 233     if header.find(b'<', 0, 8) >= 0:
 234         for marker, mime in xmlish_heuristics:
 235             if header.find(marker, 0, 64) >= 0:
 236                 return mime
 237 
 238     # try some common cases for JSON
 239     for pattern in json_heuristics:
 240         if pattern.match(header):
 241             return 'application/json'
 242 
 243     # nothing matched
 244     return fallback
 245 
 246 
 247 def show_it(conn, start: bytes, rest) -> None:
 248     'Handle both normal input and data-URIs.'
 249 
 250     # handle base64-encoded data-URIs
 251     if start.startswith(b'data:'):
 252         i = start.find(b';base64,', 0, 64)
 253         if i > 0:
 254             mime_type = str(start[len('data:'):i], encoding='utf-8')
 255             encoded = BytesIO()
 256             encoded.write(start[i + len(';base64,'):])
 257             encoded.write(rest.read())
 258             decoded = b64decode(encoded.getvalue())
 259             encoded.close()
 260 
 261             inp = BytesIO(decoded)
 262             if mime_type == '':
 263                 start = inp.read(4096)
 264                 mime_type = guess_mime(start, 'text/plain; charset=UTF-8')
 265                 show_it_as(conn, start, inp, mime_type)
 266             else:
 267                 show_it_as(conn, bytes(), inp, mime_type)
 268             return
 269 
 270     mime_type = guess_mime(start, 'text/plain; charset=UTF-8')
 271     return show_it_as(conn, start, rest, mime_type)
 272 
 273 
 274 def show_it_as(conn, start: bytes, rest, mime_type: str) -> None:
 275     'This is where the web-serving action happens.'
 276 
 277     # read-ignore all client headers
 278     while True:
 279         if conn.recv(1024).endswith(b'\r\n\r\n'):
 280             break
 281 
 282     # web-browsers insist on auto-downloads when given wave or flac audio
 283     for e in ('audio/x-wav', 'audio/x-flac'):
 284         if e == mime_type:
 285             handle_sound_workaround(conn, mime_type, start, rest)
 286             return
 287 
 288     # web-browsers insist on auto-downloads when given bitmap pictures
 289     if mime_type == 'image/x-bmp':
 290         handle_image_workaround(conn, mime_type, start, rest)
 291         return
 292 
 293     # handle all other data formats
 294     o = conn.sendall
 295 
 296     o(b'HTTP/1.1 200 OK\r\n')
 297     o(bytes(f'Content-Type: {mime_type}\r\n', encoding='utf-8'))
 298     o(b'Content-Disposition: inline\r\n')
 299     # tell browser this is the only/last request
 300     o(b'Connection: close\r\n')
 301     # payload starts right after an empty line
 302     o(b'\r\n')
 303 
 304     # send all input bytes
 305     o(start)
 306     conn.sendfile(rest)
 307 
 308 
 309 def handle_sound_workaround(conn, mime: str, start: bytes, rest) -> None:
 310     data = BytesIO()
 311     pre = f'    <audio controls autofocus src="data:{mime};base64,'
 312 
 313     def emit_inner_body() -> None:
 314         conn.sendall(bytes(pre, encoding='utf-8'))
 315         data.write(start)
 316         data.write(rest.read())
 317         conn.sendall(b64encode(data.getvalue()))
 318         conn.sendall(b'"></audio>\n')
 319 
 320     handle_workaround(conn, 'Wave-Audio Sound', emit_inner_body)
 321     data.close()
 322 
 323 
 324 def handle_image_workaround(conn, mime: str, start: bytes, rest) -> None:
 325     data = BytesIO()
 326     pre = f'    <img src="data:{mime};base64,'
 327 
 328     def emit_inner_body() -> None:
 329         conn.sendall(bytes(pre, encoding='utf-8'))
 330         data.write(start)
 331         data.write(rest.read())
 332         conn.sendall(b64encode(data.getvalue()))
 333         conn.sendall(b'">\n')
 334 
 335     handle_workaround(conn, 'Bitmap Picture', emit_inner_body)
 336     data.close()
 337 
 338 
 339 def handle_workaround(conn, title: str, handle_inner_body: Callable) -> None:
 340     'Avoid annoying auto-download web-browser behavior.'
 341 
 342     o = conn.sendall
 343 
 344     o(b'HTTP/1.1 200 OK\r\n')
 345     # auto-detect content-type, and announce it to the client
 346     o(b'Content-Type: text/html; charset=UTF-8\r\n')
 347     # discourage web-browsers' download-dialogs and/or auto-downloads
 348     o(b'Content-Disposition: inline\r\n')
 349     # tell browser this is the last request
 350     o(b'Connection: close\r\n')
 351     # payload starts right after an empty line
 352     o(b'\r\n')
 353 
 354     # emit HTML work-around
 355     o(b'<!DOCTYPE html>\n')
 356     o(b'<html lang="en">\n')
 357     o(b'<head>\n')
 358     o(b'    <meta charset="UTF-8">\n')
 359     o(b'    <link rel="icon" href="data:,">\n')
 360     o(b'    <meta name="viewport"')
 361     o(b' content="width=device-width, initial-scale=1.0">\n')
 362     o(bytes(f'    <title>{title}</title>\n', encoding='utf-8'))
 363     o(b'    <style>\n')
 364     o(b'        body { margin: auto; }\n')
 365     o(b'        audio { display: block; margin: auto; width: 90vw; }\n')
 366     o(b'        img { display: block; margin: auto; }\n')
 367     o(b'    </style>\n')
 368     o(b'</head>\n')
 369     o(b'<body>\n')
 370     handle_inner_body()
 371     o(b'</body>\n')
 372     o(b'</html>\n')
 373 
 374 
 375 try:
 376     # opening socket on port 0 randomly picks an available port
 377     sock = socket()
 378     sock.bind(('localhost', 0))
 379     port = sock.getsockname()[1]
 380     sock.settimeout(10.0)
 381     # only handle one thing at a time, since it's a one-off server
 382     sock.listen(1)
 383 
 384     open_new_tab(f'http://localhost:{port}')
 385 
 386     # handle only a single request-response cycle
 387     conn, addr = sock.accept()
 388     show_it(conn, stdin.buffer.read(4096), stdin.buffer)
 389     conn.close()
 390 
 391     sock.close()
 392 except Exception as e:
 393     print(f'\x1b[31m{e}\x1b[0m', file=stderr)
 394     exit(1)