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-rw-r--r--print-resp.c534
1 files changed, 534 insertions, 0 deletions
diff --git a/print-resp.c b/print-resp.c
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+/*
+ * Copyright (c) 2015 The TCPDUMP project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Initial contribution by Andrew Darqui (andrew.darqui@gmail.com).
+ */
+
+/* \summary: REdis Serialization Protocol (RESP) printer */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+#include "netdissect.h"
+#include <limits.h>
+
+#include "extract.h"
+
+
+/*
+ * For information regarding RESP, see: https://redis.io/topics/protocol
+ */
+
+#define RESP_SIMPLE_STRING '+'
+#define RESP_ERROR '-'
+#define RESP_INTEGER ':'
+#define RESP_BULK_STRING '$'
+#define RESP_ARRAY '*'
+
+#define resp_print_empty(ndo) ND_PRINT(" empty")
+#define resp_print_null(ndo) ND_PRINT(" null")
+#define resp_print_length_too_large(ndo) ND_PRINT(" length too large")
+#define resp_print_length_negative(ndo) ND_PRINT(" length negative and not -1")
+#define resp_print_invalid(ndo) ND_PRINT(" invalid")
+
+static int resp_parse(netdissect_options *, const u_char *, int);
+static int resp_print_string_error_integer(netdissect_options *, const u_char *, int);
+static int resp_print_simple_string(netdissect_options *, const u_char *, int);
+static int resp_print_integer(netdissect_options *, const u_char *, int);
+static int resp_print_error(netdissect_options *, const u_char *, int);
+static int resp_print_bulk_string(netdissect_options *, const u_char *, int);
+static int resp_print_bulk_array(netdissect_options *, const u_char *, int);
+static int resp_print_inline(netdissect_options *, const u_char *, int);
+static int resp_get_length(netdissect_options *, const u_char *, int, const u_char **);
+
+#define LCHECK2(_tot_len, _len) \
+ { \
+ if (_tot_len < _len) \
+ goto trunc; \
+ }
+
+#define LCHECK(_tot_len) LCHECK2(_tot_len, 1)
+
+/*
+ * FIND_CRLF:
+ * Attempts to move our 'ptr' forward until a \r\n is found,
+ * while also making sure we don't exceed the buffer '_len'
+ * or go past the end of the captured data.
+ * If we exceed or go past the end of the captured data,
+ * jump to trunc.
+ */
+#define FIND_CRLF(_ptr, _len) \
+ for (;;) { \
+ LCHECK2(_len, 2); \
+ ND_TCHECK_2(_ptr); \
+ if (GET_U_1(_ptr) == '\r' && \
+ GET_U_1(_ptr+1) == '\n') \
+ break; \
+ _ptr++; \
+ _len--; \
+ }
+
+/*
+ * CONSUME_CRLF
+ * Consume a CRLF that we've just found.
+ */
+#define CONSUME_CRLF(_ptr, _len) \
+ _ptr += 2; \
+ _len -= 2;
+
+/*
+ * FIND_CR_OR_LF
+ * Attempts to move our '_ptr' forward until a \r or \n is found,
+ * while also making sure we don't exceed the buffer '_len'
+ * or go past the end of the captured data.
+ * If we exceed or go past the end of the captured data,
+ * jump to trunc.
+ */
+#define FIND_CR_OR_LF(_ptr, _len) \
+ for (;;) { \
+ LCHECK(_len); \
+ if (GET_U_1(_ptr) == '\r' || \
+ GET_U_1(_ptr) == '\n') \
+ break; \
+ _ptr++; \
+ _len--; \
+ }
+
+/*
+ * CONSUME_CR_OR_LF
+ * Consume all consecutive \r and \n bytes.
+ * If we exceed '_len' or go past the end of the captured data,
+ * jump to trunc.
+ */
+#define CONSUME_CR_OR_LF(_ptr, _len) \
+ { \
+ int _found_cr_or_lf = 0; \
+ for (;;) { \
+ /* \
+ * Have we hit the end of data? \
+ */ \
+ if (_len == 0 || !ND_TTEST_1(_ptr)) {\
+ /* \
+ * Yes. Have we seen a \r \
+ * or \n? \
+ */ \
+ if (_found_cr_or_lf) { \
+ /* \
+ * Yes. Just stop. \
+ */ \
+ break; \
+ } \
+ /* \
+ * No. We ran out of packet. \
+ */ \
+ goto trunc; \
+ } \
+ if (GET_U_1(_ptr) != '\r' && \
+ GET_U_1(_ptr) != '\n') \
+ break; \
+ _found_cr_or_lf = 1; \
+ _ptr++; \
+ _len--; \
+ } \
+ }
+
+/*
+ * SKIP_OPCODE
+ * Skip over the opcode character.
+ * The opcode has already been fetched, so we know it's there, and don't
+ * need to do any checks.
+ */
+#define SKIP_OPCODE(_ptr, _tot_len) \
+ _ptr++; \
+ _tot_len--;
+
+/*
+ * GET_LENGTH
+ * Get a bulk string or array length.
+ */
+#define GET_LENGTH(_ndo, _tot_len, _ptr, _len) \
+ { \
+ const u_char *_endp; \
+ _len = resp_get_length(_ndo, _ptr, _tot_len, &_endp); \
+ _tot_len -= (_endp - _ptr); \
+ _ptr = _endp; \
+ }
+
+/*
+ * TEST_RET_LEN
+ * If ret_len is < 0, jump to the trunc tag which returns (-1)
+ * and 'bubbles up' to printing tstr. Otherwise, return ret_len.
+ */
+#define TEST_RET_LEN(rl) \
+ if (rl < 0) { goto trunc; } else { return rl; }
+
+/*
+ * TEST_RET_LEN_NORETURN
+ * If ret_len is < 0, jump to the trunc tag which returns (-1)
+ * and 'bubbles up' to printing tstr. Otherwise, continue onward.
+ */
+#define TEST_RET_LEN_NORETURN(rl) \
+ if (rl < 0) { goto trunc; }
+
+/*
+ * RESP_PRINT_SEGMENT
+ * Prints a segment in the form of: ' "<stuff>"\n"
+ * Assumes the data has already been verified as present.
+ */
+#define RESP_PRINT_SEGMENT(_ndo, _bp, _len) \
+ ND_PRINT(" \""); \
+ if (nd_printn(_ndo, _bp, _len, _ndo->ndo_snapend)) \
+ goto trunc; \
+ fn_print_char(_ndo, '"');
+
+void
+resp_print(netdissect_options *ndo, const u_char *bp, u_int length)
+{
+ int ret_len = 0;
+
+ ndo->ndo_protocol = "resp";
+
+ ND_PRINT(": RESP");
+ while (length > 0) {
+ /*
+ * This block supports redis pipelining.
+ * For example, multiple operations can be pipelined within the same string:
+ * "*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"
+ * or
+ * "PING\r\nPING\r\nPING\r\n"
+ * In order to handle this case, we must try and parse 'bp' until
+ * 'length' bytes have been processed or we reach a trunc condition.
+ */
+ ret_len = resp_parse(ndo, bp, length);
+ TEST_RET_LEN_NORETURN(ret_len);
+ bp += ret_len;
+ length -= ret_len;
+ }
+
+ return;
+
+trunc:
+ nd_print_trunc(ndo);
+}
+
+static int
+resp_parse(netdissect_options *ndo, const u_char *bp, int length)
+{
+ u_char op;
+ int ret_len;
+
+ LCHECK2(length, 1);
+ op = GET_U_1(bp);
+
+ /* bp now points to the op, so these routines must skip it */
+ switch(op) {
+ case RESP_SIMPLE_STRING: ret_len = resp_print_simple_string(ndo, bp, length); break;
+ case RESP_INTEGER: ret_len = resp_print_integer(ndo, bp, length); break;
+ case RESP_ERROR: ret_len = resp_print_error(ndo, bp, length); break;
+ case RESP_BULK_STRING: ret_len = resp_print_bulk_string(ndo, bp, length); break;
+ case RESP_ARRAY: ret_len = resp_print_bulk_array(ndo, bp, length); break;
+ default: ret_len = resp_print_inline(ndo, bp, length); break;
+ }
+
+ /*
+ * This gives up with a "truncated" indicator for all errors,
+ * including invalid packet errors; that's what we want, as
+ * we have to give up on further parsing in that case.
+ */
+ TEST_RET_LEN(ret_len);
+
+trunc:
+ return (-1);
+}
+
+static int
+resp_print_simple_string(netdissect_options *ndo, const u_char *bp, int length) {
+ return resp_print_string_error_integer(ndo, bp, length);
+}
+
+static int
+resp_print_integer(netdissect_options *ndo, const u_char *bp, int length) {
+ return resp_print_string_error_integer(ndo, bp, length);
+}
+
+static int
+resp_print_error(netdissect_options *ndo, const u_char *bp, int length) {
+ return resp_print_string_error_integer(ndo, bp, length);
+}
+
+static int
+resp_print_string_error_integer(netdissect_options *ndo, const u_char *bp, int length) {
+ int length_cur = length, len, ret_len;
+ const u_char *bp_ptr;
+
+ /* bp points to the op; skip it */
+ SKIP_OPCODE(bp, length_cur);
+ bp_ptr = bp;
+
+ /*
+ * bp now prints past the (+-;) opcode, so it's pointing to the first
+ * character of the string (which could be numeric).
+ * +OK\r\n
+ * -ERR ...\r\n
+ * :02912309\r\n
+ *
+ * Find the \r\n with FIND_CRLF().
+ */
+ FIND_CRLF(bp_ptr, length_cur);
+
+ /*
+ * bp_ptr points to the \r\n, so bp_ptr - bp is the length of text
+ * preceding the \r\n. That includes the opcode, so don't print
+ * that.
+ */
+ len = ND_BYTES_BETWEEN(bp_ptr, bp);
+ RESP_PRINT_SEGMENT(ndo, bp, len);
+ ret_len = 1 /*<opcode>*/ + len /*<string>*/ + 2 /*<CRLF>*/;
+
+ TEST_RET_LEN(ret_len);
+
+trunc:
+ return (-1);
+}
+
+static int
+resp_print_bulk_string(netdissect_options *ndo, const u_char *bp, int length) {
+ int length_cur = length, string_len;
+
+ /* bp points to the op; skip it */
+ SKIP_OPCODE(bp, length_cur);
+
+ /* <length>\r\n */
+ GET_LENGTH(ndo, length_cur, bp, string_len);
+
+ if (string_len >= 0) {
+ /* Byte string of length string_len, starting at bp */
+ if (string_len == 0)
+ resp_print_empty(ndo);
+ else {
+ LCHECK2(length_cur, string_len);
+ ND_TCHECK_LEN(bp, string_len);
+ RESP_PRINT_SEGMENT(ndo, bp, string_len);
+ bp += string_len;
+ length_cur -= string_len;
+ }
+
+ /*
+ * Find the \r\n at the end of the string and skip past it.
+ * XXX - report an error if the \r\n isn't immediately after
+ * the item?
+ */
+ FIND_CRLF(bp, length_cur);
+ CONSUME_CRLF(bp, length_cur);
+ } else {
+ /* null, truncated, or invalid for some reason */
+ switch(string_len) {
+ case (-1): resp_print_null(ndo); break;
+ case (-2): goto trunc;
+ case (-3): resp_print_length_too_large(ndo); break;
+ case (-4): resp_print_length_negative(ndo); break;
+ default: resp_print_invalid(ndo); break;
+ }
+ }
+
+ return (length - length_cur);
+
+trunc:
+ return (-1);
+}
+
+static int
+resp_print_bulk_array(netdissect_options *ndo, const u_char *bp, int length) {
+ u_int length_cur = length;
+ int array_len, i, ret_len;
+
+ /* bp points to the op; skip it */
+ SKIP_OPCODE(bp, length_cur);
+
+ /* <array_length>\r\n */
+ GET_LENGTH(ndo, length_cur, bp, array_len);
+
+ if (array_len > 0) {
+ /* non empty array */
+ for (i = 0; i < array_len; i++) {
+ ret_len = resp_parse(ndo, bp, length_cur);
+
+ TEST_RET_LEN_NORETURN(ret_len);
+
+ bp += ret_len;
+ length_cur -= ret_len;
+ }
+ } else {
+ /* empty, null, truncated, or invalid */
+ switch(array_len) {
+ case 0: resp_print_empty(ndo); break;
+ case (-1): resp_print_null(ndo); break;
+ case (-2): goto trunc;
+ case (-3): resp_print_length_too_large(ndo); break;
+ case (-4): resp_print_length_negative(ndo); break;
+ default: resp_print_invalid(ndo); break;
+ }
+ }
+
+ return (length - length_cur);
+
+trunc:
+ return (-1);
+}
+
+static int
+resp_print_inline(netdissect_options *ndo, const u_char *bp, int length) {
+ int length_cur = length;
+ int len;
+ const u_char *bp_ptr;
+
+ /*
+ * Inline commands are simply 'strings' followed by \r or \n or both.
+ * Redis will do its best to split/parse these strings.
+ * This feature of redis is implemented to support the ability of
+ * command parsing from telnet/nc sessions etc.
+ *
+ * <string><\r||\n||\r\n...>
+ */
+
+ /*
+ * Skip forward past any leading \r, \n, or \r\n.
+ */
+ CONSUME_CR_OR_LF(bp, length_cur);
+ bp_ptr = bp;
+
+ /*
+ * Scan forward looking for \r or \n.
+ */
+ FIND_CR_OR_LF(bp_ptr, length_cur);
+
+ /*
+ * Found it; bp_ptr points to the \r or \n, so bp_ptr - bp is the
+ * Length of the line text that precedes it. Print it.
+ */
+ len = ND_BYTES_BETWEEN(bp_ptr, bp);
+ RESP_PRINT_SEGMENT(ndo, bp, len);
+
+ /*
+ * Skip forward past the \r, \n, or \r\n.
+ */
+ CONSUME_CR_OR_LF(bp_ptr, length_cur);
+
+ /*
+ * Return the number of bytes we processed.
+ */
+ return (length - length_cur);
+
+trunc:
+ return (-1);
+}
+
+static int
+resp_get_length(netdissect_options *ndo, const u_char *bp, int len, const u_char **endp)
+{
+ int result;
+ u_char c;
+ int saw_digit;
+ int neg;
+ int too_large;
+
+ if (len == 0)
+ goto trunc;
+ too_large = 0;
+ neg = 0;
+ if (GET_U_1(bp) == '-') {
+ neg = 1;
+ bp++;
+ len--;
+ }
+ result = 0;
+ saw_digit = 0;
+
+ for (;;) {
+ if (len == 0)
+ goto trunc;
+ c = GET_U_1(bp);
+ if (!(c >= '0' && c <= '9')) {
+ if (!saw_digit) {
+ bp++;
+ goto invalid;
+ }
+ break;
+ }
+ c -= '0';
+ if (result > (INT_MAX / 10)) {
+ /* This will overflow an int when we multiply it by 10. */
+ too_large = 1;
+ } else {
+ result *= 10;
+ if (result == ((INT_MAX / 10) * 10) && c > (INT_MAX % 10)) {
+ /* This will overflow an int when we add c */
+ too_large = 1;
+ } else
+ result += c;
+ }
+ bp++;
+ len--;
+ saw_digit = 1;
+ }
+
+ /*
+ * OK, we found a non-digit character. It should be a \r, followed
+ * by a \n.
+ */
+ if (GET_U_1(bp) != '\r') {
+ bp++;
+ goto invalid;
+ }
+ bp++;
+ len--;
+ if (len == 0)
+ goto trunc;
+ if (GET_U_1(bp) != '\n') {
+ bp++;
+ goto invalid;
+ }
+ bp++;
+ len--;
+ *endp = bp;
+ if (neg) {
+ /* -1 means "null", anything else is invalid */
+ if (too_large || result != 1)
+ return (-4);
+ result = -1;
+ }
+ return (too_large ? -3 : result);
+
+trunc:
+ *endp = bp;
+ return (-2);
+
+invalid:
+ *endp = bp;
+ return (-5);
+}