1 /* 2 * ng_parse.h 3 */ 4 5 /*- 6 * Copyright (c) 1999 Whistle Communications, Inc. 7 * All rights reserved. 8 * 9 * Subject to the following obligations and disclaimer of warranty, use and 10 * redistribution of this software, in source or object code forms, with or 11 * without modifications are expressly permitted by Whistle Communications; 12 * provided, however, that: 13 * 1. Any and all reproductions of the source or object code must include the 14 * copyright notice above and the following disclaimer of warranties; and 15 * 2. No rights are granted, in any manner or form, to use Whistle 16 * Communications, Inc. trademarks, including the mark "WHISTLE 17 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 18 * such appears in the above copyright notice or in the software. 19 * 20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 36 * OF SUCH DAMAGE. 37 * 38 * Author: Archie Cobbs <archie@freebsd.org> 39 * 40 * $Whistle: ng_parse.h,v 1.2 1999/11/29 01:43:48 archie Exp $ 41 * $FreeBSD$ 42 */ 43 44 #ifndef _NETGRAPH_NG_PARSE_H_ 45 #define _NETGRAPH_NG_PARSE_H_ 46 47 /* 48 49 This defines a library of routines for converting between various C 50 language types in binary form and ASCII strings. Types are user 51 definable. Several pre-defined types are supplied, for some common 52 C types: structures, variable and fixed length arrays, integer types, 53 variable and fixed length strings, IP addresses, etc. 54 55 A netgraph node type may provide a list of types that correspond to 56 the structures it expects to send and receive in the arguments field 57 of a control message. This allows these messages to be converted 58 between their native binary form and the corresponding ASCII form. 59 60 A future use of the ASCII form may be for inter-machine communication 61 of control messages, because the ASCII form is machine independent 62 whereas the native binary form is not. 63 64 Syntax 65 ------ 66 67 Structures: 68 69 '{' [ <name>=<value> ... ] '}' 70 71 Omitted fields have their default values by implication. 72 The order in which the fields are specified does not matter. 73 74 Arrays: 75 76 '[' [ [index=]<value> ... ] ']' 77 78 Element value may be specified with or without the "<index>=" prefix; 79 If omitted, the index after the previous element is used. 80 Omitted fields have their default values by implication. 81 82 Strings: 83 84 "foo bar blah\r\n" 85 86 That is, strings are specified just like C strings. The usual 87 backslash escapes are accepted. 88 89 Other simple types (integers, IP addresses) have their obvious forms. 90 91 Example 92 ------- 93 94 Suppose we have a netgraph command that takes as an argument 95 a 'struct foo' shown below. Here is an example of a possible 96 value for the structure, and the corresponding ASCII encoding 97 of that value: 98 99 Structure Binary value 100 --------- ------------ 101 102 struct foo { 103 struct in_addr ip; 01 02 03 04 104 int bar; 00 00 00 00 105 char label[8]; 61 62 63 0a 00 00 00 00 106 u_char alen; 03 00 107 short ary[]; 05 00 00 00 0a 00 108 }; 109 110 ASCII value 111 ----------- 112 { ip=1.2.3.4 label="abc\n" alen=3 ary=[ 5 2=10 ] } 113 114 Note that omitted fields and array elements get their default 115 values ("bar" and ary[2]), and that the alignment is handled 116 automatically (the extra 00 byte after "alen"). Also, since byte 117 order and alignment are inherently machine dependent, so is this 118 conversion process. The above example shows an x86 (little 119 endian) encoding. Also the above example is tricky because the 120 structure is variable length, depending on 'alen', the number of 121 elements in the array 'ary'. 122 123 Here is how one would define a parse type for the above structure, 124 subclassing the pre-defined types below. We construct the type in 125 a 'bottom up' fashion, defining each field's type first, then the 126 type for the whole structure ('//' comments used to avoid breakage). 127 128 // Super-type info for 'label' field 129 struct ng_parse_fixedstring_info foo_label_info = { 8 }; 130 131 // Parse type for 'label' field 132 struct ng_parse_type foo_label_type = { 133 &ng_parse_fixedstring_type // super-type 134 &foo_label_info // super-type info 135 }; 136 137 #define OFFSETOF(s, e) ((char *)&((s *)0)->e - (char *)((s *)0)) 138 139 // Function to compute the length of the array 'ary', which 140 // is variable length, depending on the previous field 'alen'. 141 // Upon entry 'buf' will be pointing at &ary[0]. 142 int 143 foo_ary_getLength(const struct ng_parse_type *type, 144 const u_char *start, const u_char *buf) 145 { 146 const struct foo *f; 147 148 f = (const struct foo *)(buf - OFFSETOF(struct foo, ary)); 149 return f->alen; 150 } 151 152 // Super-type info for 'ary' field 153 struct ng_parse_array_info foo_ary_info = { 154 &ng_parse_int16_type, // element type 155 &foo_ary_getLength // func to get array length 156 } 157 158 // Parse type for 'ary' field 159 struct ng_parse_type foo_ary_type = { 160 &ng_parse_array_type, // super-type 161 &foo_ary_info // super-type info 162 }; 163 164 // Super-type info for struct foo 165 struct ng_parse_struct_field foo_fields[] = { 166 { "ip", &ng_parse_ipaddr_type }, 167 { "bar", &ng_parse_int32_type }, 168 { "label", &foo_label_type }, 169 { "alen", &ng_parse_uint8_type }, 170 { "ary", &foo_ary_type }, 171 { NULL } 172 }; 173 174 // Parse type for struct foo 175 struct ng_parse_type foo_type = { 176 &ng_parse_struct_type, // super-type 177 &foo_fields // super-type info 178 }; 179 180 To define a type, you can define it as a sub-type of a predefined 181 type as shown above, possibly overriding some of the predefined 182 type's methods, or define an entirely new syntax, with the restriction 183 that the ASCII representation of your type's value must not contain 184 any whitespace or any of these characters: { } [ ] = " 185 186 See ng_ksocket.c for an example of how to do this for 'struct sockaddr'. 187 See ng_parse.c to see implementations of the pre-defined types below. 188 189 */ 190 191 /************************************************************************ 192 METHODS REQUIRED BY A TYPE 193 ************************************************************************/ 194 195 /* 196 * Three methods are required for a type. These may be given explicitly 197 * or, if NULL, inherited from the super-type. The 'getDefault' method 198 * is always optional; the others are required if there is no super-type. 199 */ 200 201 struct ng_parse_type; 202 203 /* 204 * Convert ASCII to binary according to the supplied type. 205 * 206 * The ASCII characters begin at offset *off in 'string'. The binary 207 * representation is put into 'buf', which has at least *buflen bytes. 208 * 'start' points to the first byte output by ng_parse() (ie, start <= buf). 209 * 210 * Upon return, *buflen contains the length of the new binary data, and 211 * *off is updated to point just past the end of the parsed range of 212 * characters, or, in the case of an error, to the offending character(s). 213 * 214 * Return values: 215 * 0 Success; *buflen holds the length of the data 216 * and *off points just past the last char parsed. 217 * EALREADY Field specified twice 218 * ENOENT Unknown field 219 * E2BIG Array or character string overflow 220 * ERANGE Output was longer than *buflen bytes 221 * EINVAL Parse failure or other invalid content 222 * ENOMEM Out of memory 223 * EOPNOTSUPP Mandatory array/structure element missing 224 */ 225 typedef int ng_parse_t(const struct ng_parse_type *type, const char *string, 226 int *off, const u_char *start, 227 u_char *buf, int *buflen); 228 229 /* 230 * Convert binary to ASCII according to the supplied type. 231 * 232 * The results are put into 'buf', which is at least buflen bytes long. 233 * *off points to the current byte in 'data' and should be updated 234 * before return to point just past the last byte unparsed. 235 * 236 * Returns: 237 * 0 Success 238 * ERANGE Output was longer than buflen bytes 239 */ 240 typedef int ng_unparse_t(const struct ng_parse_type *type, 241 const u_char *data, int *off, char *buf, int buflen); 242 243 /* 244 * Compute the default value according to the supplied type. 245 * 246 * Store the result in 'buf', which is at least *buflen bytes long. 247 * Upon return *buflen contains the length of the output. 248 * 249 * Returns: 250 * 0 Success 251 * ERANGE Output was longer than *buflen bytes 252 * EOPNOTSUPP Default value is not specified for this type 253 */ 254 typedef int ng_getDefault_t(const struct ng_parse_type *type, 255 const u_char *start, u_char *buf, int *buflen); 256 257 /* 258 * Return the alignment requirement of this type. Zero is same as one. 259 */ 260 typedef int ng_getAlign_t(const struct ng_parse_type *type); 261 262 /************************************************************************ 263 TYPE DEFINITION 264 ************************************************************************/ 265 266 /* 267 * This structure describes a type, which may be a sub-type of another 268 * type by pointing to it with 'supertype' and possibly omitting methods. 269 * Typically the super-type requires some type-specific info, which is 270 * supplied by the 'info' field. 271 * 272 * The 'private' field is ignored by all of the pre-defined types. 273 * Sub-types may use it as they see fit. 274 * 275 * The 'getDefault' method may always be omitted (even if there is no 276 * super-type), which means the value for any item of this type must 277 * always be explicitly given. 278 */ 279 struct ng_parse_type { 280 const struct ng_parse_type *supertype; /* super-type, if any */ 281 const void *info; /* type-specific info */ 282 void *private; /* client private info */ 283 ng_parse_t *parse; /* parse method */ 284 ng_unparse_t *unparse; /* unparse method */ 285 ng_getDefault_t *getDefault; /* get default value method */ 286 ng_getAlign_t *getAlign; /* get alignment */ 287 }; 288 289 /************************************************************************ 290 PRE-DEFINED TYPES 291 ************************************************************************/ 292 293 /* 294 * STRUCTURE TYPE 295 * 296 * This type supports arbitrary C structures. The normal field alignment 297 * rules for the local machine are applied. Fields are always parsed in 298 * field order, no matter what order they are listed in the ASCII string. 299 * 300 * Default value: Determined on a per-field basis 301 * Additional info: struct ng_parse_struct_field * 302 */ 303 extern const struct ng_parse_type ng_parse_struct_type; 304 305 /* Each field has a name, type, and optional alignment override. If the 306 override is non-zero, the alignment is determined from the field type. 307 Note: add an extra struct ng_parse_struct_field with name == NULL 308 to indicate the end of the list. */ 309 struct ng_parse_struct_field { 310 const char *name; /* field name */ 311 const struct ng_parse_type *type; /* field type */ 312 int alignment; /* override alignment */ 313 }; 314 315 /* 316 * FIXED LENGTH ARRAY TYPE 317 * 318 * This type supports fixed length arrays, having any element type. 319 * 320 * Default value: As returned by getDefault for each index 321 * Additional info: struct ng_parse_fixedarray_info * 322 */ 323 extern const struct ng_parse_type ng_parse_fixedarray_type; 324 325 /* 326 * Get the default value for the element at index 'index'. This method 327 * may be NULL, in which case the default value is computed from the 328 * element type. Otherwise, it should fill in the default value at *buf 329 * (having size *buflen) and update *buflen to the length of the filled-in 330 * value before return. If there is not enough routine return ERANGE. 331 */ 332 typedef int ng_parse_array_getDefault_t(const struct ng_parse_type *type, 333 int index, const u_char *start, 334 u_char *buf, int *buflen); 335 336 struct ng_parse_fixedarray_info { 337 const struct ng_parse_type *elementType; 338 int length; 339 ng_parse_array_getDefault_t *getDefault; 340 }; 341 342 /* 343 * VARIABLE LENGTH ARRAY TYPE 344 * 345 * Same as fixed length arrays, except that the length is determined 346 * by a function instead of a constant value. 347 * 348 * Default value: Same as with fixed length arrays 349 * Additional info: struct ng_parse_array_info * 350 */ 351 extern const struct ng_parse_type ng_parse_array_type; 352 353 /* 354 * Return the length of the array. If the array is a field in a structure, 355 * all prior fields are guaranteed to be filled in already. Upon entry, 356 * 'start' is equal to the first byte parsed in this run, while 'buf' points 357 * to the first element of the array to be filled in. 358 */ 359 typedef int ng_parse_array_getLength_t(const struct ng_parse_type *type, 360 const u_char *start, const u_char *buf); 361 362 struct ng_parse_array_info { 363 const struct ng_parse_type *elementType; 364 ng_parse_array_getLength_t *getLength; 365 ng_parse_array_getDefault_t *getDefault; 366 }; 367 368 /* 369 * ARBITRARY LENGTH STRING TYPE 370 * 371 * For arbirary length, NUL-terminated strings. 372 * 373 * Default value: Empty string 374 * Additional info: None required 375 */ 376 extern const struct ng_parse_type ng_parse_string_type; 377 378 /* 379 * BOUNDED LENGTH STRING TYPE 380 * 381 * These are strings that have a fixed-size buffer, and always include 382 * a terminating NUL character. 383 * 384 * Default value: Empty string 385 * Additional info: struct ng_parse_fixedstring_info * 386 */ 387 extern const struct ng_parse_type ng_parse_fixedstring_type; 388 389 struct ng_parse_fixedstring_info { 390 int bufSize; /* size of buffer (including NUL) */ 391 }; 392 393 /* 394 * EXPLICITLY SIZED STRING TYPE 395 * 396 * These are strings that have a two byte length field preceding them. 397 * Parsed strings are NOT NUL-terminated. 398 * 399 * Default value: Empty string 400 * Additional info: None 401 */ 402 extern const struct ng_parse_type ng_parse_sizedstring_type; 403 404 /* 405 * COMMONLY USED BOUNDED LENGTH STRING TYPES 406 */ 407 extern const struct ng_parse_type ng_parse_nodebuf_type; /* NG_NODESIZ */ 408 extern const struct ng_parse_type ng_parse_hookbuf_type; /* NG_HOOKSIZ */ 409 extern const struct ng_parse_type ng_parse_pathbuf_type; /* NG_PATHSIZ */ 410 extern const struct ng_parse_type ng_parse_typebuf_type; /* NG_TYPESIZ */ 411 extern const struct ng_parse_type ng_parse_cmdbuf_type; /* NG_CMDSTRSIZ */ 412 413 /* 414 * INTEGER TYPES 415 * 416 * Default value: 0 417 * Additional info: None required 418 */ 419 extern const struct ng_parse_type ng_parse_int8_type; 420 extern const struct ng_parse_type ng_parse_int16_type; 421 extern const struct ng_parse_type ng_parse_int32_type; 422 extern const struct ng_parse_type ng_parse_int64_type; 423 424 /* Same thing but unparse as unsigned quantities */ 425 extern const struct ng_parse_type ng_parse_uint8_type; 426 extern const struct ng_parse_type ng_parse_uint16_type; 427 extern const struct ng_parse_type ng_parse_uint32_type; 428 extern const struct ng_parse_type ng_parse_uint64_type; 429 430 /* Same thing but unparse as hex quantities, e.g., "0xe7" */ 431 extern const struct ng_parse_type ng_parse_hint8_type; 432 extern const struct ng_parse_type ng_parse_hint16_type; 433 extern const struct ng_parse_type ng_parse_hint32_type; 434 extern const struct ng_parse_type ng_parse_hint64_type; 435 436 /* 437 * IP ADDRESS TYPE 438 * 439 * Default value: 0.0.0.0 440 * Additional info: None required 441 */ 442 extern const struct ng_parse_type ng_parse_ipaddr_type; 443 444 /* 445 * ETHERNET ADDRESS TYPE 446 * 447 * Default value: None 448 * Additional info: None required 449 */ 450 extern const struct ng_parse_type ng_parse_enaddr_type; 451 452 /* 453 * VARIABLE LENGTH BYTE ARRAY TYPE 454 * 455 * The bytes are displayed in hex. The ASCII form may be either an 456 * array of bytes or a string constant, in which case the array is 457 * zero-filled after the string bytes. 458 * 459 * Default value: All bytes are zero 460 * Additional info: ng_parse_array_getLength_t * 461 */ 462 extern const struct ng_parse_type ng_parse_bytearray_type; 463 464 /* 465 * NETGRAPH CONTROL MESSAGE TYPE 466 * 467 * This is the parse type for a struct ng_mesg. 468 * 469 * Default value: All fields zero 470 * Additional info: None required 471 */ 472 extern const struct ng_parse_type ng_parse_ng_mesg_type; 473 474 /************************************************************************ 475 CONVERSTION AND PARSING ROUTINES 476 ************************************************************************/ 477 478 /* Tokens for parsing structs and arrays */ 479 enum ng_parse_token { 480 T_LBRACE, /* '{' */ 481 T_RBRACE, /* '}' */ 482 T_LBRACKET, /* '[' */ 483 T_RBRACKET, /* ']' */ 484 T_EQUALS, /* '=' */ 485 T_STRING, /* string in double quotes */ 486 T_ERROR, /* error parsing string in double quotes */ 487 T_WORD, /* anything else containing no whitespace */ 488 T_EOF, /* end of string reached */ 489 }; 490 491 /* 492 * See typedef ng_parse_t for definition 493 */ 494 extern int ng_parse(const struct ng_parse_type *type, const char *string, 495 int *off, u_char *buf, int *buflen); 496 497 /* 498 * See typedef ng_unparse_t for definition (*off assumed to be zero). 499 */ 500 extern int ng_unparse(const struct ng_parse_type *type, 501 const u_char *data, char *buf, int buflen); 502 503 /* 504 * See typedef ng_getDefault_t for definition 505 */ 506 extern int ng_parse_getDefault(const struct ng_parse_type *type, 507 u_char *buf, int *buflen); 508 509 /* 510 * Parse a token: '*startp' is the offset to start looking. Upon 511 * successful return, '*startp' equals the beginning of the token 512 * and '*lenp' the length. If error, '*startp' points at the 513 * offending character(s). 514 */ 515 extern enum ng_parse_token ng_parse_get_token(const char *s, 516 int *startp, int *lenp); 517 518 /* 519 * Like above, but specifically for getting a string token and returning 520 * the string value. The string token must be enclosed in double quotes 521 * and the normal C backslash escapes are recognized. The caller must 522 * eventually free() the returned result. Returns NULL if token is 523 * not a string token, or parse or other error. Otherwise, *lenp contains 524 * the number of characters parsed, and *slenp (if not NULL) contains 525 * the actual number of characters in the parsed string. 526 */ 527 extern char *ng_get_string_token(const char *s, int *startp, 528 int *lenp, int *slenp); 529 530 /* 531 * Convert a raw string into a doubly-quoted string including any 532 * necessary backslash escapes. Caller must free the result. 533 * Returns NULL if ENOMEM. Normally "slen" should equal strlen(s) 534 * unless you want to encode NUL bytes. 535 */ 536 extern char *ng_encode_string(const char *s, int slen); 537 538 #endif /* _NETGRAPH_NG_PARSE_H_ */ 539