The Tcpdump Group git mirrors - tcpdump/blob - print-resp.c

   1 /*
   2  * Copyright (c) 2015 The TCPDUMP project
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  15  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  16  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  17  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  18  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  20  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  21  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  22  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  24  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  25  * POSSIBILITY OF SUCH DAMAGE.
  26  *
  27  * Initial contribution by Andrew Darqui (andrew.darqui@gmail.com).
  28  */
  29
  30 /* \summary: REdis Serialization Protocol (RESP) printer */
  31
  32 #ifdef HAVE_CONFIG_H
  33 #include <config.h>
  34 #endif
  35
  36 #include "netdissect-stdinc.h"
  37 #include "netdissect.h"
  38 #include <limits.h>
  39 #include <string.h>
  40 #include <stdlib.h>
  41 #include <errno.h>
  42
  43 #include "extract.h"
  44
  45
  46 /*
  47  * For information regarding RESP, see: https://redis.io/topics/protocol
  48  */
  49
  50 #define RESP_SIMPLE_STRING    '+'
  51 #define RESP_ERROR            '-'
  52 #define RESP_INTEGER          ':'
  53 #define RESP_BULK_STRING      '$'
  54 #define RESP_ARRAY            '*'
  55
  56 #define resp_print_empty(ndo)            ND_PRINT(" empty")
  57 #define resp_print_null(ndo)             ND_PRINT(" null")
  58 #define resp_print_length_too_large(ndo) ND_PRINT(" length too large")
  59 #define resp_print_length_negative(ndo)  ND_PRINT(" length negative and not -1")
  60 #define resp_print_invalid(ndo)          ND_PRINT(" invalid")
  61
  62 void       resp_print(netdissect_options *, const u_char *, u_int);
  63 static int resp_parse(netdissect_options *, const u_char *, int);
  64 static int resp_print_string_error_integer(netdissect_options *, const u_char *, int);
  65 static int resp_print_simple_string(netdissect_options *, const u_char *, int);
  66 static int resp_print_integer(netdissect_options *, const u_char *, int);
  67 static int resp_print_error(netdissect_options *, const u_char *, int);
  68 static int resp_print_bulk_string(netdissect_options *, const u_char *, int);
  69 static int resp_print_bulk_array(netdissect_options *, const u_char *, int);
  70 static int resp_print_inline(netdissect_options *, const u_char *, int);
  71 static int resp_get_length(netdissect_options *, const u_char *, int, const u_char **);
  72
  73 #define LCHECK2(_tot_len, _len) \
  74     {                           \
  75         if (_tot_len < _len)    \
  76             goto trunc;         \
  77     }
  78
  79 #define LCHECK(_tot_len) LCHECK2(_tot_len, 1)
  80
  81 /*
  82  * FIND_CRLF:
  83  * Attempts to move our 'ptr' forward until a \r\n is found,
  84  * while also making sure we don't exceed the buffer '_len'
  85  * or go past the end of the captured data.
  86  * If we exceed or go past the end of the captured data,
  87  * jump to trunc.
  88  */
  89 #define FIND_CRLF(_ptr, _len)                   \
  90     for (;;) {                                  \
  91         LCHECK2(_len, 2);                       \
  92         ND_TCHECK_2(_ptr);                   \
  93         if (*_ptr == '\r' && *(_ptr+1) == '\n') \
  94             break;                              \
  95         _ptr++;                                 \
  96         _len--;                                 \
  97     }
  98
  99 /*
 100  * CONSUME_CRLF
 101  * Consume a CRLF that we've just found.
 102  */
 103 #define CONSUME_CRLF(_ptr, _len) \
 104     _ptr += 2;                   \
 105     _len -= 2;
 106
 107 /*
 108  * FIND_CR_OR_LF
 109  * Attempts to move our '_ptr' forward until a \r or \n is found,
 110  * while also making sure we don't exceed the buffer '_len'
 111  * or go past the end of the captured data.
 112  * If we exceed or go past the end of the captured data,
 113  * jump to trunc.
 114  */
 115 #define FIND_CR_OR_LF(_ptr, _len)           \
 116     for (;;) {                              \
 117         LCHECK(_len);                       \
 118         ND_TCHECK_1(_ptr);                  \
 119         if (*_ptr == '\r' || *_ptr == '\n') \
 120             break;                          \
 121         _ptr++;                             \
 122         _len--;                             \
 123     }
 124
 125 /*
 126  * CONSUME_CR_OR_LF
 127  * Consume all consecutive \r and \n bytes.
 128  * If we exceed '_len' or go past the end of the captured data,
 129  * jump to trunc.
 130  */
 131 #define CONSUME_CR_OR_LF(_ptr, _len)             \
 132     {                                            \
 133         int _found_cr_or_lf = 0;                 \
 134         for (;;) {                               \
 135             /*                                   \
 136              * Have we hit the end of data?      \
 137              */                                  \
 138             if (_len == 0 || !ND_TTEST_1(_ptr)) {\
 139                 /*                               \
 140                  * Yes.  Have we seen a \r       \
 141                  * or \n?                        \
 142                  */                              \
 143                 if (_found_cr_or_lf) {           \
 144                     /*                           \
 145                      * Yes.  Just stop.          \
 146                      */                          \
 147                     break;                       \
 148                 }                                \
 149                 /*                               \
 150                  * No.  We ran out of packet.    \
 151                  */                              \
 152                 goto trunc;                      \
 153             }                                    \
 154             if (*_ptr != '\r' && *_ptr != '\n')  \
 155                 break;                           \
 156             _found_cr_or_lf = 1;                 \
 157             _ptr++;                              \
 158             _len--;                              \
 159         }                                        \
 160     }
 161
 162 /*
 163  * SKIP_OPCODE
 164  * Skip over the opcode character.
 165  * The opcode has already been fetched, so we know it's there, and don't
 166  * need to do any checks.
 167  */
 168 #define SKIP_OPCODE(_ptr, _tot_len) \
 169     _ptr++;                         \
 170     _tot_len--;
 171
 172 /*
 173  * GET_LENGTH
 174  * Get a bulk string or array length.
 175  */
 176 #define GET_LENGTH(_ndo, _tot_len, _ptr, _len)                \
 177     {                                                         \
 178         const u_char *_endp;                                  \
 179         _len = resp_get_length(_ndo, _ptr, _tot_len, &_endp); \
 180         _tot_len -= (_endp - _ptr);                           \
 181         _ptr = _endp;                                         \
 182     }
 183
 184 /*
 185  * TEST_RET_LEN
 186  * If ret_len is < 0, jump to the trunc tag which returns (-1)
 187  * and 'bubbles up' to printing tstr. Otherwise, return ret_len.
 188  */
 189 #define TEST_RET_LEN(rl) \
 190     if (rl < 0) { goto trunc; } else { return rl; }
 191
 192 /*
 193  * TEST_RET_LEN_NORETURN
 194  * If ret_len is < 0, jump to the trunc tag which returns (-1)
 195  * and 'bubbles up' to printing tstr. Otherwise, continue onward.
 196  */
 197 #define TEST_RET_LEN_NORETURN(rl) \
 198     if (rl < 0) { goto trunc; }
 199
 200 /*
 201  * RESP_PRINT_SEGMENT
 202  * Prints a segment in the form of: ' "<stuff>"\n"
 203  * Assumes the data has already been verified as present.
 204  */
 205 #define RESP_PRINT_SEGMENT(_ndo, _bp, _len)            \
 206     ND_PRINT(" \"");                                   \
 207     if (nd_printn(_ndo, _bp, _len, _ndo->ndo_snapend)) \
 208         goto trunc;                                    \
 209     fn_print_char(_ndo, '"');
 210
 211 void
 212 resp_print(netdissect_options *ndo, const u_char *bp, u_int length)
 213 {
 214     int ret_len = 0, length_cur = length;
 215
 216     ndo->ndo_protocol = "resp";
 217     if(!bp || length <= 0)
 218         return;
 219
 220     ND_PRINT(": RESP");
 221     while (length_cur > 0) {
 222         /*
 223          * This block supports redis pipelining.
 224          * For example, multiple operations can be pipelined within the same string:
 225          * "*2\r\n\$4\r\nINCR\r\n\$1\r\nz\r\n*2\r\n\$4\r\nINCR\r\n\$1\r\nz\r\n*2\r\n\$4\r\nINCR\r\n\$1\r\nz\r\n"
 226          * or
 227          * "PING\r\nPING\r\nPING\r\n"
 228          * In order to handle this case, we must try and parse 'bp' until
 229          * 'length' bytes have been processed or we reach a trunc condition.
 230          */
 231         ret_len = resp_parse(ndo, bp, length_cur);
 232         TEST_RET_LEN_NORETURN(ret_len);
 233         bp += ret_len;
 234         length_cur -= ret_len;
 235     }
 236
 237     return;
 238
 239 trunc:
 240     nd_print_trunc(ndo);
 241 }
 242
 243 static int
 244 resp_parse(netdissect_options *ndo, const u_char *bp, int length)
 245 {
 246     u_char op;
 247     int ret_len;
 248
 249     LCHECK2(length, 1);
 250     ND_TCHECK_1(bp);
 251     op = GET_U_1(bp);
 252
 253     /* bp now points to the op, so these routines must skip it */
 254     switch(op) {
 255         case RESP_SIMPLE_STRING:  ret_len = resp_print_simple_string(ndo, bp, length);   break;
 256         case RESP_INTEGER:        ret_len = resp_print_integer(ndo, bp, length);         break;
 257         case RESP_ERROR:          ret_len = resp_print_error(ndo, bp, length);           break;
 258         case RESP_BULK_STRING:    ret_len = resp_print_bulk_string(ndo, bp, length);     break;
 259         case RESP_ARRAY:          ret_len = resp_print_bulk_array(ndo, bp, length);      break;
 260         default:                  ret_len = resp_print_inline(ndo, bp, length);          break;
 261     }
 262
 263     /*
 264      * This gives up with a "truncated" indicator for all errors,
 265      * including invalid packet errors; that's what we want, as
 266      * we have to give up on further parsing in that case.
 267      */
 268     TEST_RET_LEN(ret_len);
 269
 270 trunc:
 271     return (-1);
 272 }
 273
 274 static int
 275 resp_print_simple_string(netdissect_options *ndo, const u_char *bp, int length) {
 276     return resp_print_string_error_integer(ndo, bp, length);
 277 }
 278
 279 static int
 280 resp_print_integer(netdissect_options *ndo, const u_char *bp, int length) {
 281     return resp_print_string_error_integer(ndo, bp, length);
 282 }
 283
 284 static int
 285 resp_print_error(netdissect_options *ndo, const u_char *bp, int length) {
 286     return resp_print_string_error_integer(ndo, bp, length);
 287 }
 288
 289 static int
 290 resp_print_string_error_integer(netdissect_options *ndo, const u_char *bp, int length) {
 291     int length_cur = length, len, ret_len;
 292     const u_char *bp_ptr;
 293
 294     /* bp points to the op; skip it */
 295     SKIP_OPCODE(bp, length_cur);
 296     bp_ptr = bp;
 297
 298     /*
 299      * bp now prints past the (+-;) opcode, so it's pointing to the first
 300      * character of the string (which could be numeric).
 301      * +OK\r\n
 302      * -ERR ...\r\n
 303      * :02912309\r\n
 304      *
 305      * Find the \r\n with FIND_CRLF().
 306      */
 307     FIND_CRLF(bp_ptr, length_cur);
 308
 309     /*
 310      * bp_ptr points to the \r\n, so bp_ptr - bp is the length of text
 311      * preceding the \r\n.  That includes the opcode, so don't print
 312      * that.
 313      */
 314     len = ND_BYTES_BETWEEN(bp_ptr, bp);
 315     RESP_PRINT_SEGMENT(ndo, bp, len);
 316     ret_len = 1 /*<opcode>*/ + len /*<string>*/ + 2 /*<CRLF>*/;
 317
 318     TEST_RET_LEN(ret_len);
 319
 320 trunc:
 321     return (-1);
 322 }
 323
 324 static int
 325 resp_print_bulk_string(netdissect_options *ndo, const u_char *bp, int length) {
 326     int length_cur = length, string_len;
 327
 328     /* bp points to the op; skip it */
 329     SKIP_OPCODE(bp, length_cur);
 330
 331     /* <length>\r\n */
 332     GET_LENGTH(ndo, length_cur, bp, string_len);
 333
 334     if (string_len >= 0) {
 335         /* Byte string of length string_len, starting at bp */
 336         if (string_len == 0)
 337             resp_print_empty(ndo);
 338         else {
 339             LCHECK2(length_cur, string_len);
 340             ND_TCHECK_LEN(bp, string_len);
 341             RESP_PRINT_SEGMENT(ndo, bp, string_len);
 342             bp += string_len;
 343             length_cur -= string_len;
 344         }
 345
 346         /*
 347          * Find the \r\n at the end of the string and skip past it.
 348          * XXX - report an error if the \r\n isn't immediately after
 349          * the item?
 350          */
 351         FIND_CRLF(bp, length_cur);
 352         CONSUME_CRLF(bp, length_cur);
 353     } else {
 354         /* null, truncated, or invalid for some reason */
 355         switch(string_len) {
 356             case (-1):  resp_print_null(ndo);             break;
 357             case (-2):  goto trunc;
 358             case (-3):  resp_print_length_too_large(ndo); break;
 359             case (-4):  resp_print_length_negative(ndo);  break;
 360             default:    resp_print_invalid(ndo);          break;
 361         }
 362     }
 363
 364     return (length - length_cur);
 365
 366 trunc:
 367     return (-1);
 368 }
 369
 370 static int
 371 resp_print_bulk_array(netdissect_options *ndo, const u_char *bp, int length) {
 372     u_int length_cur = length;
 373     int array_len, i, ret_len;
 374
 375     /* bp points to the op; skip it */
 376     SKIP_OPCODE(bp, length_cur);
 377
 378     /* <array_length>\r\n */
 379     GET_LENGTH(ndo, length_cur, bp, array_len);
 380
 381     if (array_len > 0) {
 382         /* non empty array */
 383         for (i = 0; i < array_len; i++) {
 384             ret_len = resp_parse(ndo, bp, length_cur);
 385
 386             TEST_RET_LEN_NORETURN(ret_len);
 387
 388             bp += ret_len;
 389             length_cur -= ret_len;
 390         }
 391     } else {
 392         /* empty, null, truncated, or invalid */
 393         switch(array_len) {
 394             case 0:     resp_print_empty(ndo);            break;
 395             case (-1):  resp_print_null(ndo);             break;
 396             case (-2):  goto trunc;
 397             case (-3):  resp_print_length_too_large(ndo); break;
 398             case (-4):  resp_print_length_negative(ndo);  break;
 399             default:    resp_print_invalid(ndo);          break;
 400         }
 401     }
 402
 403     return (length - length_cur);
 404
 405 trunc:
 406     return (-1);
 407 }
 408
 409 static int
 410 resp_print_inline(netdissect_options *ndo, const u_char *bp, int length) {
 411     int length_cur = length;
 412     int len;
 413     const u_char *bp_ptr;
 414
 415     /*
 416      * Inline commands are simply 'strings' followed by \r or \n or both.
 417      * Redis will do its best to split/parse these strings.
 418      * This feature of redis is implemented to support the ability of
 419      * command parsing from telnet/nc sessions etc.
 420      *
 421      * <string><\r||\n||\r\n...>
 422      */
 423
 424     /*
 425      * Skip forward past any leading \r, \n, or \r\n.
 426      */
 427     CONSUME_CR_OR_LF(bp, length_cur);
 428     bp_ptr = bp;
 429
 430     /*
 431      * Scan forward looking for \r or \n.
 432      */
 433     FIND_CR_OR_LF(bp_ptr, length_cur);
 434
 435     /*
 436      * Found it; bp_ptr points to the \r or \n, so bp_ptr - bp is the
 437      * Length of the line text that precedes it.  Print it.
 438      */
 439     len = ND_BYTES_BETWEEN(bp_ptr, bp);
 440     RESP_PRINT_SEGMENT(ndo, bp, len);
 441
 442     /*
 443      * Skip forward past the \r, \n, or \r\n.
 444      */
 445     CONSUME_CR_OR_LF(bp_ptr, length_cur);
 446
 447     /*
 448      * Return the number of bytes we processed.
 449      */
 450     return (length - length_cur);
 451
 452 trunc:
 453     return (-1);
 454 }
 455
 456 static int
 457 resp_get_length(netdissect_options *ndo, const u_char *bp, int len, const u_char **endp)
 458 {
 459     int result;
 460     u_char c;
 461     int saw_digit;
 462     int neg;
 463     int too_large;
 464
 465     if (len == 0)
 466         goto trunc;
 467     ND_TCHECK_1(bp);
 468     too_large = 0;
 469     neg = 0;
 470     if (GET_U_1(bp) == '-') {
 471         neg = 1;
 472         bp++;
 473         len--;
 474     }
 475     result = 0;
 476     saw_digit = 0;
 477
 478     for (;;) {
 479         if (len == 0)
 480             goto trunc;
 481         ND_TCHECK_1(bp);
 482         c = GET_U_1(bp);
 483         if (!(c >= '0' && c <= '9')) {
 484             if (!saw_digit) {
 485                 bp++;
 486                 goto invalid;
 487             }
 488             break;
 489         }
 490         c -= '0';
 491         if (result > (INT_MAX / 10)) {
 492             /* This will overflow an int when we multiply it by 10. */
 493             too_large = 1;
 494         } else {
 495             result *= 10;
 496             if (result == ((INT_MAX / 10) * 10) && c > (INT_MAX % 10)) {
 497                 /* This will overflow an int when we add c */
 498                 too_large = 1;
 499             } else
 500                 result += c;
 501         }
 502         bp++;
 503         len--;
 504         saw_digit = 1;
 505     }
 506
 507     /*
 508      * OK, we found a non-digit character.  It should be a \r, followed
 509      * by a \n.
 510      */
 511     if (GET_U_1(bp) != '\r') {
 512         bp++;
 513         goto invalid;
 514     }
 515     bp++;
 516     len--;
 517     if (len == 0)
 518         goto trunc;
 519     ND_TCHECK_1(bp);
 520     if (GET_U_1(bp) != '\n') {
 521         bp++;
 522         goto invalid;
 523     }
 524     bp++;
 525     len--;
 526     *endp = bp;
 527     if (neg) {
 528         /* -1 means "null", anything else is invalid */
 529         if (too_large || result != 1)
 530             return (-4);
 531         result = -1;
 532     }
 533     return (too_large ? -3 : result);
 534
 535 trunc:
 536     *endp = bp;
 537     return (-2);
 538
 539 invalid:
 540     *endp = bp;
 541     return (-5);
 542 }