two mime encoding schemes

Lib/base64.py

+# Conversions to/from base64 transport encoding as per RFC-MIME (Dec 1991
+# version).
+
+# Parameters set by RFX-XXXX.
+MAXLINESIZE = 76 # Excluding the CRLF
+INVAR = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
+PAD = '='
+
+# Check that I typed that string correctly...
+if len(INVAR) <> 64: raise RuntimeError, 'wrong INVAR string!?!?'
+
+# Compute the inverse table, for decode().
+inverse = {}
+for i in range(64): inverse[INVAR[i]] = i
+del i
+inverse[PAD] = 0
+
+# Encode a file.
+def encode(input, output):
+	line = ''
+	BUFSIZE = 8192
+	leftover = ''
+	while 1:
+		s = input.read(BUFSIZE)
+		if not s: break
+		s = leftover + s
+		i = 0
+		while i+3 <= len(s):
+			quad = makequad(s[i:i+3])
+			i = i+3
+			if len(line) + 4 > MAXLINESIZE:
+				output.write(line + '\n')
+				line = ''
+			line = line + quad
+		leftover = s[i:]
+	if leftover:
+		quad = makeshortquad(leftover)
+		if len(line) + 4 > MAXLINESIZE:
+			output.write(line + '\n')
+			line = ''
+		line = line + quad
+	if line:
+		output.write(line + '\n')
+
+def makequad(s): # Return the quad for a 3 character string
+	x = ord(s[0])*0x10000 + ord(s[1])*0x100 + ord(s[2])
+	x, c4 = divmod(x, 64)
+	x, c3 = divmod(x, 64)
+	c1, c2 = divmod(x, 64)
+	return INVAR[c1] + INVAR[c2] +INVAR[c3] + INVAR[c4]
+
+def makeshortquad(s): # Return the quad value for a 1 or 2 character string
+	n = len(s)
+	while len(s) < 3:
+		s = s + '\0'
+	quad = makequad(s)
+	if n == 2:
+		quad = quad[:3] + PAD
+	elif n == 1:
+		quad = quad[:2] + 2*PAD
+	return quad
+
+# Decode a file.
+def decode(input, output):
+	BUFSIZE = 8192
+	bits, n, bytes, prev = 0, 0, '', ''
+	while 1:
+		line = input.readline()
+		if not line: break
+		for c in line:
+			if inverse.has_key(c):
+				bits = bits*64 + inverse[c]
+				n = n+6
+				if n == 24:
+					triplet = decodequad(bits)
+					if c == PAD:
+						if prev == PAD:
+							triplet = triplet[:1]
+						else:
+							triplet = triplet[:2]
+					bits, n = 0, 0
+					bytes = bytes + triplet
+					if len(bytes) > BUFSIZE:
+						output.write(bytes[:BUFSIZE])
+						bytes = bytes[BUFSIZE:]
+				prev = c
+	if bytes:
+		output.write(bytes)
+
+def decodequad(bits): # Turn 24 bits into 3 characters
+	bits, c3 = divmod(bits, 256)
+	c1, c2 = divmod(bits, 256)
+	return chr(c1) + chr(c2) + chr(c3)
+
+def encodestring(s):
+	import StringIO
+	f = StringIO.StringIO(s)
+	g = StringIO.StringIO()
+	encode(f, g)
+	return g.getvalue()
+
+def decodestring(s):
+	import StringIO
+	f = StringIO.StringIO(s)
+	g = StringIO.StringIO()
+	decode(f, g)
+	return g.getvalue()
+
+# Small test program, reads stdin, writes stdout.
+# no arg: encode, any arg: decode.
+def test():
+	import sys
+	if sys.argv[1:]:
+		decode(sys.stdin, sys.stdout)
+	else:
+		encode(sys.stdin, sys.stdout)
+
+def test1():
+	s0 = "Aladdin:open sesame"
+	s1 = encodestring(s0)
+	s2 = decodestring(s1)
+	print s0, `s1`, s2
+
+if __name__ == '__main__':
+	test()

Lib/quopri.py

+# Conversions to/from quoted-printable transport encoding as per RFC-XXXX
+# (Dec 1991 version).
+
+ESCAPE = '='
+MAXLINESIZE = 76
+HEX = '0123456789ABCDEF'
+
+def needsquoting(c, quotetabs):
+	if c == '\t':
+		return not quotetabs
+	return c == ESCAPE or not(' ' <= c <= '~')
+
+def quote(c):
+	if c == ESCAPE:
+		return ESCAPE * 2
+	else:
+		i = ord(c)
+		return ESCAPE + HEX[i/16] + HEX[i%16]
+
+def encode(input, output, quotetabs):
+	while 1:
+		line = input.readline()
+		if not line: break
+		new = ''
+		last = line[-1:]
+		if last == '\n': line = line[:-1]
+		else: last = ''
+		prev = ''
+		for c in line:
+			if needsquoting(c, quotetabs):
+				c = quote(c)
+			if len(new) + len(c) >= MAXLINESIZE:
+				output.write(new + ESCAPE + '\n')
+				new = ''
+			new = new + c
+			prev = c
+		if prev in (' ', '\t'):
+			output.write(new + ESCAPE + '\n\n')
+		else:
+			output.write(new + '\n')
+
+def decode(input, output):
+	new = ''
+	while 1:
+		line = input.readline()
+		if not line: break
+		i, n = 0, len(line)
+		if n > 0 and line[n-1] == '\n':
+			partial = 0; n = n-1
+			# Strip trailing whitespace
+			while n > 0 and line[n-1] in (' ', '\t'):
+				n = n-1
+		else:
+			partial = 1
+		while i < n:
+			c = line[i]
+			if c <> ESCAPE:
+				new = new + c; i = i+1
+			elif i+1 == n and not partial:
+				partial = 1; break
+			elif i+1 < n and line[i+1] == ESCAPE:
+				new = new + ESCAPE; i = i+2
+			elif i+2 < n and ishex(line[i+1]) and ishex(line[i+2]):
+				new = new + chr(unhex(line[i+1:i+3])); i = i+3
+			else: # Bad escape sequence -- leave it in
+				new = new + c; i = i+1
+		if not partial:
+			output.write(new + '\n')
+			new = ''
+	if new:
+		output.write(new)
+
+def ishex(c):
+	return '0' <= c <= '9' or 'a' <= c <= 'f' or 'A' <= c <= 'F'
+
+def unhex(s):
+	bits = 0
+	for c in s:
+		if '0' <= c <= '9':
+			i = ord('0')
+		elif 'a' <= c <= 'f':
+			i = ord('a')-10
+		elif 'A' <= c <= 'F':
+			i = ord('A')-10
+		else:
+			break
+		bits = bits*16 + (ord(c) - i)
+	return bits
+
+def test():
+	import sys
+	if sys.argv[1:]:
+		if sys.argv[1] == '-t': # Quote tabs
+			encode(sys.stdin, sys.stdout, 1)
+		else:
+			decode(sys.stdin, sys.stdout)
+	else:
+		encode(sys.stdin, sys.stdout, 0)
+
+if __name__ == '__main__':
+	main()