|
| 1 | +import json |
| 2 | +from ctypes import * |
| 3 | +import sys |
| 4 | + |
| 5 | +class Nftables: |
| 6 | + """A class representing libnftables interface""" |
| 7 | + |
| 8 | + debug_flags = { |
| 9 | + "scanner": 0x1, |
| 10 | + "parser": 0x2, |
| 11 | + "eval": 0x4, |
| 12 | + "netlink": 0x8, |
| 13 | + "mnl": 0x10, |
| 14 | + "proto-ctx": 0x20, |
| 15 | + "segtree": 0x40, |
| 16 | + } |
| 17 | + |
| 18 | + numeric_levels = { |
| 19 | + "none": 0, |
| 20 | + "addr": 1, |
| 21 | + "port": 2, |
| 22 | + "all": 3, |
| 23 | + } |
| 24 | + |
| 25 | + def __init__(self, sofile="libnftables.so"): |
| 26 | + """Instantiate a new Nftables class object. |
| 27 | +
|
| 28 | + Accepts a shared object file to open, by default standard search path |
| 29 | + is searched for a file named 'libnftables.so'. |
| 30 | +
|
| 31 | + After loading the library using ctypes module, a new nftables context |
| 32 | + is requested from the library and buffering of output and error streams |
| 33 | + is turned on. |
| 34 | + """ |
| 35 | + lib = cdll.LoadLibrary(sofile) |
| 36 | + |
| 37 | + ### API function definitions |
| 38 | + |
| 39 | + self.nft_ctx_new = lib.nft_ctx_new |
| 40 | + self.nft_ctx_new.restype = c_void_p |
| 41 | + self.nft_ctx_new.argtypes = [c_int] |
| 42 | + |
| 43 | + self.nft_ctx_output_get_handle = lib.nft_ctx_output_get_handle |
| 44 | + self.nft_ctx_output_get_handle.restype = c_bool |
| 45 | + self.nft_ctx_output_get_handle.argtypes = [c_void_p] |
| 46 | + |
| 47 | + self.nft_ctx_output_set_handle = lib.nft_ctx_output_set_handle |
| 48 | + self.nft_ctx_output_set_handle.argtypes = [c_void_p, c_bool] |
| 49 | + |
| 50 | + self.nft_ctx_output_get_numeric = lib.nft_ctx_output_get_numeric |
| 51 | + self.nft_ctx_output_get_numeric.restype = c_int |
| 52 | + self.nft_ctx_output_get_numeric.argtypes = [c_void_p] |
| 53 | + |
| 54 | + self.nft_ctx_output_set_numeric = lib.nft_ctx_output_set_numeric |
| 55 | + self.nft_ctx_output_set_numeric.argtypes = [c_void_p, c_int] |
| 56 | + |
| 57 | + self.nft_ctx_output_get_stateless = lib.nft_ctx_output_get_stateless |
| 58 | + self.nft_ctx_output_get_stateless.restype = c_bool |
| 59 | + self.nft_ctx_output_get_stateless.argtypes = [c_void_p] |
| 60 | + |
| 61 | + self.nft_ctx_output_set_stateless = lib.nft_ctx_output_set_stateless |
| 62 | + self.nft_ctx_output_set_stateless.argtypes = [c_void_p, c_bool] |
| 63 | + |
| 64 | + self.nft_ctx_output_get_debug = lib.nft_ctx_output_get_debug |
| 65 | + self.nft_ctx_output_get_debug.restype = c_int |
| 66 | + self.nft_ctx_output_get_debug.argtypes = [c_void_p] |
| 67 | + |
| 68 | + self.nft_ctx_output_set_debug = lib.nft_ctx_output_set_debug |
| 69 | + self.nft_ctx_output_set_debug.argtypes = [c_void_p, c_int] |
| 70 | + |
| 71 | + self.nft_ctx_buffer_output = lib.nft_ctx_buffer_output |
| 72 | + self.nft_ctx_buffer_output.restype = c_int |
| 73 | + self.nft_ctx_buffer_output.argtypes = [c_void_p] |
| 74 | + |
| 75 | + self.nft_ctx_get_output_buffer = lib.nft_ctx_get_output_buffer |
| 76 | + self.nft_ctx_get_output_buffer.restype = c_char_p |
| 77 | + self.nft_ctx_get_output_buffer.argtypes = [c_void_p] |
| 78 | + |
| 79 | + self.nft_ctx_buffer_error = lib.nft_ctx_buffer_error |
| 80 | + self.nft_ctx_buffer_error.restype = c_int |
| 81 | + self.nft_ctx_buffer_error.argtypes = [c_void_p] |
| 82 | + |
| 83 | + self.nft_ctx_get_error_buffer = lib.nft_ctx_get_error_buffer |
| 84 | + self.nft_ctx_get_error_buffer.restype = c_char_p |
| 85 | + self.nft_ctx_get_error_buffer.argtypes = [c_void_p] |
| 86 | + |
| 87 | + self.nft_run_cmd_from_buffer = lib.nft_run_cmd_from_buffer |
| 88 | + self.nft_run_cmd_from_buffer.restype = c_int |
| 89 | + self.nft_run_cmd_from_buffer.argtypes = [c_void_p, c_char_p, c_int] |
| 90 | + |
| 91 | + self.nft_ctx_free = lib.nft_ctx_free |
| 92 | + lib.nft_ctx_free.argtypes = [c_void_p] |
| 93 | + |
| 94 | + # initialize libnftables context |
| 95 | + self.__ctx = self.nft_ctx_new(0) |
| 96 | + self.nft_ctx_buffer_output(self.__ctx) |
| 97 | + self.nft_ctx_buffer_error(self.__ctx) |
| 98 | + |
| 99 | + def get_handle_output(self): |
| 100 | + """Get the current state of handle output. |
| 101 | +
|
| 102 | + Returns a boolean indicating whether handle output is active or not. |
| 103 | + """ |
| 104 | + return self.nft_ctx_output_get_handle(self.__ctx) |
| 105 | + |
| 106 | + def set_handle_output(self, val): |
| 107 | + """Enable or disable handle output. |
| 108 | +
|
| 109 | + Accepts a boolean turning handle output on or off. |
| 110 | +
|
| 111 | + Returns the previous value. |
| 112 | + """ |
| 113 | + old = self.get_handle_output() |
| 114 | + self.nft_ctx_output_set_handle(self.__ctx, val) |
| 115 | + return old |
| 116 | + |
| 117 | + def get_numeric_output(self): |
| 118 | + """Get the current state of numeric output. |
| 119 | +
|
| 120 | + Returns a boolean indicating whether boolean output is active or not. |
| 121 | + """ |
| 122 | + return self.nft_ctx_output_get_numeric(self.__ctx) |
| 123 | + |
| 124 | + def set_numeric_output(self, val): |
| 125 | + """Enable or disable numeric output. |
| 126 | +
|
| 127 | + Accepts a boolean turning numeric output on or off. |
| 128 | +
|
| 129 | + Returns the previous value. |
| 130 | + """ |
| 131 | + old = self.get_numeric_output() |
| 132 | + |
| 133 | + if type(val) is str: |
| 134 | + val = self.numeric_levels[val] |
| 135 | + self.nft_ctx_output_set_numeric(self.__ctx, val) |
| 136 | + |
| 137 | + return old |
| 138 | + |
| 139 | + def get_stateless_output(self): |
| 140 | + """Get the current state of stateless output. |
| 141 | +
|
| 142 | + Returns a boolean indicating whether stateless output is active or not. |
| 143 | + """ |
| 144 | + return self.nft_ctx_output_get_stateless(self.__ctx) |
| 145 | + |
| 146 | + def set_stateless_output(self, val): |
| 147 | + """Enable or Disable stateless output. |
| 148 | +
|
| 149 | + Accepts a boolean turning stateless output either on or off. |
| 150 | +
|
| 151 | + Returns the previous value. |
| 152 | + """ |
| 153 | + old = self.get_stateless_output() |
| 154 | + self.nft_ctx_output_set_stateless(self.__ctx, val) |
| 155 | + return old |
| 156 | + |
| 157 | + def get_debug(self): |
| 158 | + """Get currently active debug flags. |
| 159 | +
|
| 160 | + Returns a set of flag names. See set_debug() for details. |
| 161 | + """ |
| 162 | + val = self.nft_ctx_output_get_debug(self.__ctx) |
| 163 | + |
| 164 | + names = [] |
| 165 | + for n,v in self.debug_flags.items(): |
| 166 | + if val & v: |
| 167 | + names.append(n) |
| 168 | + val &= ~v |
| 169 | + if val: |
| 170 | + names.append(val) |
| 171 | + |
| 172 | + return names |
| 173 | + |
| 174 | + def set_debug(self, values): |
| 175 | + """Set debug output flags. |
| 176 | +
|
| 177 | + Accepts either a single flag or a set of flags. Each flag might be |
| 178 | + given either as string or integer value as shown in the following |
| 179 | + table: |
| 180 | +
|
| 181 | + Name | Value (hex) |
| 182 | + ----------------------- |
| 183 | + scanner | 0x1 |
| 184 | + parser | 0x2 |
| 185 | + eval | 0x4 |
| 186 | + netlink | 0x8 |
| 187 | + mnl | 0x10 |
| 188 | + proto-ctx | 0x20 |
| 189 | + segtree | 0x40 |
| 190 | +
|
| 191 | + Returns a set of previously active debug flags, as returned by |
| 192 | + get_debug() method. |
| 193 | + """ |
| 194 | + old = self.get_debug() |
| 195 | + |
| 196 | + if type(values) in [str, int]: |
| 197 | + values = [values] |
| 198 | + |
| 199 | + val = 0 |
| 200 | + for v in values: |
| 201 | + if type(v) is str: |
| 202 | + v = self.debug_flags[v] |
| 203 | + val |= v |
| 204 | + |
| 205 | + self.nft_ctx_output_set_debug(self.__ctx, val) |
| 206 | + |
| 207 | + return old |
| 208 | + |
| 209 | + def cmd(self, cmdline): |
| 210 | + """Run a simple nftables command via libnftables. |
| 211 | +
|
| 212 | + Accepts a string containing an nftables command just like what one |
| 213 | + would enter into an interactive nftables (nft -i) session. |
| 214 | +
|
| 215 | + Returns a tuple (rc, output, error): |
| 216 | + rc -- return code as returned by nft_run_cmd_from_buffer() fuction |
| 217 | + output -- a string containing output written to stdout |
| 218 | + error -- a string containing output written to stderr |
| 219 | + """ |
| 220 | + rc = self.nft_run_cmd_from_buffer(self.__ctx, cmdline, len(cmdline)) |
| 221 | + output = self.nft_ctx_get_output_buffer(self.__ctx) |
| 222 | + error = self.nft_ctx_get_error_buffer(self.__ctx) |
| 223 | + |
| 224 | + return (rc, output, error) |
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