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

   1 /*
   2  * This file implements decoding of the REdis Serialization Protocol.
   3  *
   4  *
   5  * Copyright (c) 2015 The TCPDUMP project
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  21  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  25  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  27  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28  * POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * Initial contribution by Andrew Darqui (andrew.darqui@gmail.com).
  31  */
  32
  33 #define NETDISSECT_REWORKED
  34 #ifdef HAVE_CONFIG_H
  35 #include "config.h"
  36 #endif
  37
  38 #include <netdissect-stdinc.h>
  39 #include "netdissect.h"
  40 #include <limits.h>
  41 #include <string.h>
  42 #include <stdlib.h>
  43 #include <errno.h>
  44
  45 #include "extract.h"
  46
  47 static const char tstr[] = " [|RESP]";
  48
  49 /*
  50  * For information regarding RESP, see: http://redis.io/topics/protocol
  51  */
  52
  53 #define RESP_SIMPLE_STRING    '+'
  54 #define RESP_ERROR            '-'
  55 #define RESP_INTEGER          ':'
  56 #define RESP_BULK_STRING      '$'
  57 #define RESP_ARRAY            '*'
  58
  59 #define resp_print_empty(ndo)      ND_PRINT((ndo, " empty"))
  60 #define resp_print_null(ndo)       ND_PRINT((ndo, " null"))
  61 #define resp_print_invalid(ndo)    ND_PRINT((ndo, " invalid"))
  62
  63 void       resp_print(netdissect_options *, const u_char *, u_int);
  64 static int resp_parse(netdissect_options *, register const u_char *, int);
  65 static int resp_print_string_error_integer(netdissect_options *, register const u_char *, int);
  66 static int resp_print_simple_string(netdissect_options *, register const u_char *, int);
  67 static int resp_print_integer(netdissect_options *, register const u_char *, int);
  68 static int resp_print_error(netdissect_options *, register const u_char *, int);
  69 static int resp_print_bulk_string(netdissect_options *, register const u_char *, int);
  70 static int resp_print_bulk_array(netdissect_options *, register const u_char *, int);
  71 static int resp_print_inline(netdissect_options *, register const u_char *, int);
  72
  73 /*
  74  * MOVE_FORWARD:
  75  * Attempts to move our 'ptr' forward until a \r\n is found,
  76  * while also making sure we don't exceed the buffer 'len'.
  77  * If we exceed, jump to trunc.
  78  */
  79 #define MOVE_FORWARD(ptr, len) \
  80     while(*ptr != '\r' && *(ptr+1) != '\n') { ND_TCHECK2(*ptr, 2); ptr++; len--; }
  81
  82 /*
  83  * MOVE_FORWARD_CR_OR_LF
  84  * Attempts to move our 'ptr' forward until a \r or \n is found,
  85  * while also making sure we don't exceed the buffer 'len'.
  86  * If we exceed, jump to trunc.
  87  */
  88 #define MOVE_FORWARD_CR_OR_LF(ptr, len) \
  89     while(*ptr != '\r' && *ptr != '\n') { ND_TCHECK(*ptr); ptr++; len--; }
  90
  91 /*
  92  * CONSUME_CR_OR_LF
  93  * Consume all consecutive \r and \n bytes.
  94  * If we exceed 'len', jump to trunc.
  95  */
  96 #define CONSUME_CR_OR_LF(ptr, len) \
  97     while (*ptr == '\r' || *ptr == '\n') { ND_TCHECK(*ptr); ptr++; len--; }
  98
  99 /*
 100  * INCBY
 101  * Attempts to increment our 'ptr' by 'increment' bytes.
 102  * If our increment exceeds the buffer length (len - increment),
 103  * bail out by jumping to the trunc goto tag.
 104  */
 105 #define INCBY(ptr, increment, len) \
 106     { ND_TCHECK2(*ptr, increment); ptr+=increment; len-=increment; }
 107
 108 /*
 109  * INC1
 110  * Increment our ptr by 1 byte.
 111  * Most often used to skip an opcode (+-:*$ etc)
 112  */
 113 #define INC1(ptr, len) INCBY(ptr, 1, len)
 114
 115 /*
 116  * INC2
 117  * Increment our ptr by 2 bytes.
 118  * Most often used to skip CRLF (\r\n).
 119  */
 120 #define INC2(ptr, len) INCBY(ptr, 2, len)
 121
 122 /*
 123  * TEST_RET_LEN
 124  * If ret_len is < 0, jump to the trunc tag which returns (-1)
 125  * and 'bubbles up' to printing tstr. Otherwise, return ret_len.
 126  */
 127 #define TEST_RET_LEN(rl) \
 128     if (rl < 0) { goto trunc; } else { return rl; }
 129
 130 /*
 131  * TEST_RET_LEN_NORETURN
 132  * If ret_len is < 0, jump to the trunc tag which returns (-1)
 133  * and 'bubbles up' to printing tstr. Otherwise, continue onward.
 134  */
 135 #define TEST_RET_LEN_NORETURN(rl) \
 136     if (rl < 0) { goto trunc; }
 137
 138 /*
 139  * RESP_PRINT_SEGMENT
 140  * Prints a segment in the form of: ' "<stuff>"\n"
 141  */
 142 #define RESP_PRINT_SEGMENT(_ndo, _bp, _len)            \
 143         ND_PRINT((_ndo, " \""));                       \
 144         fn_printn(_ndo, _bp, _len, _ndo->ndo_snapend); \
 145         fn_print_char(_ndo, '"');
 146
 147 void
 148 resp_print(netdissect_options *ndo, const u_char *bp, u_int length)
 149 {
 150     int ret_len = 0, length_cur = length;
 151
 152     if(!bp || length <= 0)
 153         return;
 154
 155     ND_PRINT((ndo, ": RESP"));
 156     while (length_cur > 0) {
 157         /*
 158          * This block supports redis pipelining.
 159          * For example, multiple operations can be pipelined within the same string:
 160          * "*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"
 161          * or
 162          * "PING\r\nPING\r\nPING\r\n"
 163          * In order to handle this case, we must try and parse 'bp' until
 164          * 'length' bytes have been processed or we reach a trunc condition.
 165          */
 166         ret_len = resp_parse(ndo, bp, length_cur);
 167         TEST_RET_LEN_NORETURN(ret_len);
 168         bp += ret_len;
 169         length_cur -= ret_len;
 170     }
 171
 172     return;
 173
 174 trunc:
 175     ND_PRINT((ndo, "%s", tstr));
 176 }
 177
 178 static int
 179 resp_parse(netdissect_options *ndo, register const u_char *bp, int length)
 180 {
 181     int ret_len = 0;
 182     u_char op = *bp;
 183
 184     ND_TCHECK(*bp);
 185
 186     switch(op) {
 187         case RESP_SIMPLE_STRING:  ret_len = resp_print_simple_string(ndo, bp, length);   break;
 188         case RESP_INTEGER:        ret_len = resp_print_integer(ndo, bp, length);         break;
 189         case RESP_ERROR:          ret_len = resp_print_error(ndo, bp, length);           break;
 190         case RESP_BULK_STRING:    ret_len = resp_print_bulk_string(ndo, bp, length);     break;
 191         case RESP_ARRAY:          ret_len = resp_print_bulk_array(ndo, bp, length);      break;
 192         default:                  ret_len = resp_print_inline(ndo, bp, length);          break;
 193     }
 194
 195     TEST_RET_LEN(ret_len);
 196
 197 trunc:
 198     return (-1);
 199 }
 200
 201 static int
 202 resp_print_simple_string(netdissect_options *ndo, register const u_char *bp, int length) {
 203     return resp_print_string_error_integer(ndo, bp, length);
 204 }
 205
 206 static int
 207 resp_print_integer(netdissect_options *ndo, register const u_char *bp, int length) {
 208     return resp_print_string_error_integer(ndo, bp, length);
 209 }
 210
 211 static int
 212 resp_print_error(netdissect_options *ndo, register const u_char *bp, int length) {
 213     return resp_print_string_error_integer(ndo, bp, length);
 214 }
 215
 216 static int
 217 resp_print_string_error_integer(netdissect_options *ndo, register const u_char *bp, int length) {
 218     int length_cur = length, len, ret_len = 0;
 219     const u_char *bp_ptr = bp;
 220
 221     /*
 222      * MOVE_FORWARD moves past the string that follows the (+-;) opcodes
 223      * +OK\r\n
 224      * -ERR ...\r\n
 225      * :02912309\r\n
 226      */
 227     MOVE_FORWARD(bp_ptr, length_cur);
 228     len = (bp_ptr - bp);
 229     ND_TCHECK2(*bp, len);
 230     RESP_PRINT_SEGMENT(ndo, bp+1, len-1);
 231     ret_len = len /*<1byte>+<string>*/ + 2 /*<CRLF>*/;
 232
 233     TEST_RET_LEN(ret_len);
 234
 235 trunc:
 236     return (-1);
 237 }
 238
 239 static int
 240 resp_print_bulk_string(netdissect_options *ndo, register const u_char *bp, int length) {
 241     int length_cur = length, string_len;
 242     long strtol_ret;
 243     char *p;
 244
 245     ND_TCHECK(*bp);
 246
 247     /* opcode: '$' */
 248     INC1(bp, length_cur);
 249     ND_TCHECK(*bp);
 250
 251     /* <length> */
 252     errno = 0;
 253     strtol_ret = strtol((const char *)bp, &p, 10);
 254     if (errno != 0 || p == (const char *)bp || strtol_ret < -1 ||
 255         strtol_ret > INT_MAX)
 256         string_len = -2; /* invalid */
 257     else
 258         string_len = (int)strtol_ret;
 259
 260     /* move to \r\n */
 261     MOVE_FORWARD(bp, length_cur);
 262
 263     /* \r\n */
 264     INC2(bp, length_cur);
 265
 266     if (string_len > 0) {
 267         /* Byte string of length string_len */
 268         ND_TCHECK2(*bp, string_len);
 269         RESP_PRINT_SEGMENT(ndo, bp, string_len);
 270     } else {
 271         switch(string_len) {
 272             case 0: resp_print_empty(ndo); break;
 273             case (-1): {
 274                 /* This is the NULL response. It follows a different pattern: $-1\r\n */
 275                 resp_print_null(ndo);
 276                 TEST_RET_LEN(length - length_cur);
 277                 /* returned ret_len or jumped to trunc */
 278             }
 279             default: resp_print_invalid(ndo); break;
 280         }
 281     }
 282
 283     /* <string> */
 284     INCBY(bp, string_len, length_cur);
 285
 286     /* \r\n */
 287     INC2(bp, length_cur);
 288
 289     TEST_RET_LEN(length - length_cur);
 290
 291 trunc:
 292     return (-1);
 293 }
 294
 295 static int
 296 resp_print_bulk_array(netdissect_options *ndo, register const u_char *bp, int length) {
 297     int length_cur = length, array_len, i, ret_len = 0;
 298     long strtol_ret;
 299     char *p;
 300
 301     ND_TCHECK(*bp);
 302
 303     /* opcode: '*' */
 304     INC1(bp, length_cur);
 305     ND_TCHECK(*bp);
 306
 307     /* <array_length> */
 308     errno = 0;
 309     strtol_ret = strtol((const char *)bp, &p, 10);
 310     if (errno != 0 || p == (const char *)bp || strtol_ret < -1 ||
 311         strtol_ret > INT_MAX)
 312         array_len = -2; /* invalid */
 313     else
 314         array_len = (int)strtol_ret;
 315
 316     /* move to \r\n */
 317     MOVE_FORWARD(bp, length_cur);
 318
 319     /* \r\n */
 320     INC2(bp, length_cur);
 321
 322     if (array_len > 0) {
 323         /* non empty array */
 324         for (i = 0; i < array_len; i++) {
 325             ret_len = resp_parse(ndo, bp, length_cur);
 326
 327             TEST_RET_LEN_NORETURN(ret_len);
 328
 329             bp += ret_len;
 330             length_cur -= ret_len;
 331
 332             TEST_RET_LEN_NORETURN(length - length_cur);
 333         }
 334     } else {
 335         /* empty, null, or invalid */
 336         switch(array_len) {
 337             case 0:     resp_print_empty(ndo);   break;
 338             case (-1):  resp_print_null(ndo);    break;
 339             default:    resp_print_invalid(ndo); break;
 340         }
 341     }
 342
 343     TEST_RET_LEN(length - length_cur);
 344
 345 trunc:
 346     return (-1);
 347 }
 348
 349 static int
 350 resp_print_inline(netdissect_options *ndo, register const u_char *bp, int length) {
 351     int length_cur = length, len;
 352     const u_char *bp_ptr;
 353
 354     /*
 355      * Inline commands are simply 'strings' followed by \r or \n or both.
 356      * Redis will do it's best to split/parse these strings.
 357      * This feature of redis is implemented to support the ability of
 358      * command parsing from telnet/nc sessions etc.
 359      *
 360      * <string><\r||\n||\r\n...>
 361      */
 362     CONSUME_CR_OR_LF(bp, length_cur);
 363     bp_ptr = bp;
 364     MOVE_FORWARD_CR_OR_LF(bp_ptr, length_cur);
 365     len = (bp_ptr - bp);
 366     ND_TCHECK2(*bp, len);
 367     RESP_PRINT_SEGMENT(ndo, bp, len);
 368     CONSUME_CR_OR_LF(bp_ptr, length_cur);
 369
 370     TEST_RET_LEN(length - length_cur);
 371
 372 trunc:
 373     return (-1);
 374 }