1"""An object-oriented interface to .netrc files."""
2
3# Module and documentation by Eric S. Raymond, 21 Dec 1998
4
5import os, shlex, stat
6
7__all__ = ["netrc", "NetrcParseError"]
8
9
10class NetrcParseError(Exception):
11    """Exception raised on syntax errors in the .netrc file."""
12    def __init__(self, msg, filename=None, lineno=None):
13        self.filename = filename
14        self.lineno = lineno
15        self.msg = msg
16        Exception.__init__(self, msg)
17
18    def __str__(self):
19        return "%s (%s, line %s)" % (self.msg, self.filename, self.lineno)
20
21
22class _netrclex:
23    def __init__(self, fp):
24        self.lineno = 1
25        self.instream = fp
26        self.whitespace = "\n\t\r "
27        self.pushback = []
28
29    def _read_char(self):
30        ch = self.instream.read(1)
31        if ch == "\n":
32            self.lineno += 1
33        return ch
34
35    def get_token(self):
36        if self.pushback:
37            return self.pushback.pop(0)
38        token = ""
39        fiter = iter(self._read_char, "")
40        for ch in fiter:
41            if ch in self.whitespace:
42                continue
43            if ch == '"':
44                for ch in fiter:
45                    if ch == '"':
46                        return token
47                    elif ch == "\\":
48                        ch = self._read_char()
49                    token += ch
50            else:
51                if ch == "\\":
52                    ch = self._read_char()
53                token += ch
54                for ch in fiter:
55                    if ch in self.whitespace:
56                        return token
57                    elif ch == "\\":
58                        ch = self._read_char()
59                    token += ch
60        return token
61
62    def push_token(self, token):
63        self.pushback.append(token)
64
65
66class netrc:
67    def __init__(self, file=None):
68        default_netrc = file is None
69        if file is None:
70            file = os.path.join(os.path.expanduser("~"), ".netrc")
71        self.hosts = {}
72        self.macros = {}
73        try:
74            with open(file, encoding="utf-8") as fp:
75                self._parse(file, fp, default_netrc)
76        except UnicodeDecodeError:
77            with open(file, encoding="locale") as fp:
78                self._parse(file, fp, default_netrc)
79
80    def _parse(self, file, fp, default_netrc):
81        lexer = _netrclex(fp)
82        while 1:
83            # Look for a machine, default, or macdef top-level keyword
84            saved_lineno = lexer.lineno
85            toplevel = tt = lexer.get_token()
86            if not tt:
87                break
88            elif tt[0] == '#':
89                if lexer.lineno == saved_lineno and len(tt) == 1:
90                    lexer.instream.readline()
91                continue
92            elif tt == 'machine':
93                entryname = lexer.get_token()
94            elif tt == 'default':
95                entryname = 'default'
96            elif tt == 'macdef':
97                entryname = lexer.get_token()
98                self.macros[entryname] = []
99                while 1:
100                    line = lexer.instream.readline()
101                    if not line:
102                        raise NetrcParseError(
103                            "Macro definition missing null line terminator.",
104                            file, lexer.lineno)
105                    if line == '\n':
106                        # a macro definition finished with consecutive new-line
107                        # characters. The first \n is encountered by the
108                        # readline() method and this is the second \n.
109                        break
110                    self.macros[entryname].append(line)
111                continue
112            else:
113                raise NetrcParseError(
114                    "bad toplevel token %r" % tt, file, lexer.lineno)
115
116            if not entryname:
117                raise NetrcParseError("missing %r name" % tt, file, lexer.lineno)
118
119            # We're looking at start of an entry for a named machine or default.
120            login = account = password = ''
121            self.hosts[entryname] = {}
122            while 1:
123                prev_lineno = lexer.lineno
124                tt = lexer.get_token()
125                if tt.startswith('#'):
126                    if lexer.lineno == prev_lineno:
127                        lexer.instream.readline()
128                    continue
129                if tt in {'', 'machine', 'default', 'macdef'}:
130                    self.hosts[entryname] = (login, account, password)
131                    lexer.push_token(tt)
132                    break
133                elif tt == 'login' or tt == 'user':
134                    login = lexer.get_token()
135                elif tt == 'account':
136                    account = lexer.get_token()
137                elif tt == 'password':
138                    password = lexer.get_token()
139                else:
140                    raise NetrcParseError("bad follower token %r" % tt,
141                                          file, lexer.lineno)
142            self._security_check(fp, default_netrc, self.hosts[entryname][0])
143
144    def _security_check(self, fp, default_netrc, login):
145        if os.name == 'posix' and default_netrc and login != "anonymous":
146            prop = os.fstat(fp.fileno())
147            if prop.st_uid != os.getuid():
148                import pwd
149                try:
150                    fowner = pwd.getpwuid(prop.st_uid)[0]
151                except KeyError:
152                    fowner = 'uid %s' % prop.st_uid
153                try:
154                    user = pwd.getpwuid(os.getuid())[0]
155                except KeyError:
156                    user = 'uid %s' % os.getuid()
157                raise NetrcParseError(
158                    (f"~/.netrc file owner ({fowner}, {user}) does not match"
159                     " current user"))
160            if (prop.st_mode & (stat.S_IRWXG | stat.S_IRWXO)):
161                raise NetrcParseError(
162                    "~/.netrc access too permissive: access"
163                    " permissions must restrict access to only"
164                    " the owner")
165
166    def authenticators(self, host):
167        """Return a (user, account, password) tuple for given host."""
168        if host in self.hosts:
169            return self.hosts[host]
170        elif 'default' in self.hosts:
171            return self.hosts['default']
172        else:
173            return None
174
175    def __repr__(self):
176        """Dump the class data in the format of a .netrc file."""
177        rep = ""
178        for host in self.hosts.keys():
179            attrs = self.hosts[host]
180            rep += f"machine {host}\n\tlogin {attrs[0]}\n"
181            if attrs[1]:
182                rep += f"\taccount {attrs[1]}\n"
183            rep += f"\tpassword {attrs[2]}\n"
184        for macro in self.macros.keys():
185            rep += f"macdef {macro}\n"
186            for line in self.macros[macro]:
187                rep += line
188            rep += "\n"
189        return rep
190
191if __name__ == '__main__':
192    print(netrc())
193