1#! /usr/bin/env python3 2 3"""Conversions to/from quoted-printable transport encoding as per RFC 1521.""" 4 5# (Dec 1991 version). 6 7__all__ = ["encode", "decode", "encodestring", "decodestring"] 8 9ESCAPE = b'=' 10MAXLINESIZE = 76 11HEX = b'0123456789ABCDEF' 12EMPTYSTRING = b'' 13 14try: 15 from binascii import a2b_qp, b2a_qp 16except ImportError: 17 a2b_qp = None 18 b2a_qp = None 19 20 21def needsquoting(c, quotetabs, header): 22 """Decide whether a particular byte ordinal needs to be quoted. 23 24 The 'quotetabs' flag indicates whether embedded tabs and spaces should be 25 quoted. Note that line-ending tabs and spaces are always encoded, as per 26 RFC 1521. 27 """ 28 assert isinstance(c, bytes) 29 if c in b' \t': 30 return quotetabs 31 # if header, we have to escape _ because _ is used to escape space 32 if c == b'_': 33 return header 34 return c == ESCAPE or not (b' ' <= c <= b'~') 35 36def quote(c): 37 """Quote a single character.""" 38 assert isinstance(c, bytes) and len(c)==1 39 c = ord(c) 40 return ESCAPE + bytes((HEX[c//16], HEX[c%16])) 41 42 43 44def encode(input, output, quotetabs, header=False): 45 """Read 'input', apply quoted-printable encoding, and write to 'output'. 46 47 'input' and 'output' are binary file objects. The 'quotetabs' flag 48 indicates whether embedded tabs and spaces should be quoted. Note that 49 line-ending tabs and spaces are always encoded, as per RFC 1521. 50 The 'header' flag indicates whether we are encoding spaces as _ as per RFC 51 1522.""" 52 53 if b2a_qp is not None: 54 data = input.read() 55 odata = b2a_qp(data, quotetabs=quotetabs, header=header) 56 output.write(odata) 57 return 58 59 def write(s, output=output, lineEnd=b'\n'): 60 # RFC 1521 requires that the line ending in a space or tab must have 61 # that trailing character encoded. 62 if s and s[-1:] in b' \t': 63 output.write(s[:-1] + quote(s[-1:]) + lineEnd) 64 elif s == b'.': 65 output.write(quote(s) + lineEnd) 66 else: 67 output.write(s + lineEnd) 68 69 prevline = None 70 while line := input.readline(): 71 outline = [] 72 # Strip off any readline induced trailing newline 73 stripped = b'' 74 if line[-1:] == b'\n': 75 line = line[:-1] 76 stripped = b'\n' 77 # Calculate the un-length-limited encoded line 78 for c in line: 79 c = bytes((c,)) 80 if needsquoting(c, quotetabs, header): 81 c = quote(c) 82 if header and c == b' ': 83 outline.append(b'_') 84 else: 85 outline.append(c) 86 # First, write out the previous line 87 if prevline is not None: 88 write(prevline) 89 # Now see if we need any soft line breaks because of RFC-imposed 90 # length limitations. Then do the thisline->prevline dance. 91 thisline = EMPTYSTRING.join(outline) 92 while len(thisline) > MAXLINESIZE: 93 # Don't forget to include the soft line break `=' sign in the 94 # length calculation! 95 write(thisline[:MAXLINESIZE-1], lineEnd=b'=\n') 96 thisline = thisline[MAXLINESIZE-1:] 97 # Write out the current line 98 prevline = thisline 99 # Write out the last line, without a trailing newline 100 if prevline is not None: 101 write(prevline, lineEnd=stripped) 102 103def encodestring(s, quotetabs=False, header=False): 104 if b2a_qp is not None: 105 return b2a_qp(s, quotetabs=quotetabs, header=header) 106 from io import BytesIO 107 infp = BytesIO(s) 108 outfp = BytesIO() 109 encode(infp, outfp, quotetabs, header) 110 return outfp.getvalue() 111 112 113 114def decode(input, output, header=False): 115 """Read 'input', apply quoted-printable decoding, and write to 'output'. 116 'input' and 'output' are binary file objects. 117 If 'header' is true, decode underscore as space (per RFC 1522).""" 118 119 if a2b_qp is not None: 120 data = input.read() 121 odata = a2b_qp(data, header=header) 122 output.write(odata) 123 return 124 125 new = b'' 126 while line := input.readline(): 127 i, n = 0, len(line) 128 if n > 0 and line[n-1:n] == b'\n': 129 partial = 0; n = n-1 130 # Strip trailing whitespace 131 while n > 0 and line[n-1:n] in b" \t\r": 132 n = n-1 133 else: 134 partial = 1 135 while i < n: 136 c = line[i:i+1] 137 if c == b'_' and header: 138 new = new + b' '; i = i+1 139 elif c != ESCAPE: 140 new = new + c; i = i+1 141 elif i+1 == n and not partial: 142 partial = 1; break 143 elif i+1 < n and line[i+1:i+2] == ESCAPE: 144 new = new + ESCAPE; i = i+2 145 elif i+2 < n and ishex(line[i+1:i+2]) and ishex(line[i+2:i+3]): 146 new = new + bytes((unhex(line[i+1:i+3]),)); i = i+3 147 else: # Bad escape sequence -- leave it in 148 new = new + c; i = i+1 149 if not partial: 150 output.write(new + b'\n') 151 new = b'' 152 if new: 153 output.write(new) 154 155def decodestring(s, header=False): 156 if a2b_qp is not None: 157 return a2b_qp(s, header=header) 158 from io import BytesIO 159 infp = BytesIO(s) 160 outfp = BytesIO() 161 decode(infp, outfp, header=header) 162 return outfp.getvalue() 163 164 165 166# Other helper functions 167def ishex(c): 168 """Return true if the byte ordinal 'c' is a hexadecimal digit in ASCII.""" 169 assert isinstance(c, bytes) 170 return b'0' <= c <= b'9' or b'a' <= c <= b'f' or b'A' <= c <= b'F' 171 172def unhex(s): 173 """Get the integer value of a hexadecimal number.""" 174 bits = 0 175 for c in s: 176 c = bytes((c,)) 177 if b'0' <= c <= b'9': 178 i = ord('0') 179 elif b'a' <= c <= b'f': 180 i = ord('a')-10 181 elif b'A' <= c <= b'F': 182 i = ord(b'A')-10 183 else: 184 assert False, "non-hex digit "+repr(c) 185 bits = bits*16 + (ord(c) - i) 186 return bits 187 188 189 190def main(): 191 import sys 192 import getopt 193 try: 194 opts, args = getopt.getopt(sys.argv[1:], 'td') 195 except getopt.error as msg: 196 sys.stdout = sys.stderr 197 print(msg) 198 print("usage: quopri [-t | -d] [file] ...") 199 print("-t: quote tabs") 200 print("-d: decode; default encode") 201 sys.exit(2) 202 deco = False 203 tabs = False 204 for o, a in opts: 205 if o == '-t': tabs = True 206 if o == '-d': deco = True 207 if tabs and deco: 208 sys.stdout = sys.stderr 209 print("-t and -d are mutually exclusive") 210 sys.exit(2) 211 if not args: args = ['-'] 212 sts = 0 213 for file in args: 214 if file == '-': 215 fp = sys.stdin.buffer 216 else: 217 try: 218 fp = open(file, "rb") 219 except OSError as msg: 220 sys.stderr.write("%s: can't open (%s)\n" % (file, msg)) 221 sts = 1 222 continue 223 try: 224 if deco: 225 decode(fp, sys.stdout.buffer) 226 else: 227 encode(fp, sys.stdout.buffer, tabs) 228 finally: 229 if file != '-': 230 fp.close() 231 if sts: 232 sys.exit(sts) 233 234 235 236if __name__ == '__main__': 237 main() 238