mirror of
https://github.com/transmission/transmission
synced 2024-12-26 17:47:37 +00:00
387 lines
9.1 KiB
C++
387 lines
9.1 KiB
C++
/*
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* This file Copyright (C) 2008-2014 Mnemosyne LLC
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*
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* It may be used under the GNU GPL versions 2 or 3
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* or any future license endorsed by Mnemosyne LLC.
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*
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*/
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#include <ctype.h> /* isdigit() */
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#include <deque>
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#include <errno.h>
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#include <stdlib.h> /* strtoul() */
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#include <string.h> /* strlen(), memchr() */
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#include <event2/buffer.h>
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#define LIBTRANSMISSION_VARIANT_MODULE
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#include "transmission.h"
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#include "utils.h" /* tr_snprintf() */
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#include "variant.h"
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#include "variant-common.h"
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#define MAX_BENC_STR_LENGTH (128 * 1024 * 1024) /* arbitrary */
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/***
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**** tr_variantParse()
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**** tr_variantLoad()
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***/
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/**
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* The initial i and trailing e are beginning and ending delimiters.
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* You can have negative numbers such as i-3e. You cannot prefix the
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* number with a zero such as i04e. However, i0e is valid.
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* Example: i3e represents the integer "3"
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* NOTE: The maximum number of bit of this integer is unspecified,
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* but to handle it as a signed 64bit integer is mandatory to handle
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* "large files" aka .torrent for more that 4Gbyte
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*/
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int tr_bencParseInt(void const* vbuf, void const* vbufend, uint8_t const** setme_end, int64_t* setme_val)
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{
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uint8_t const* const buf = (uint8_t const*)vbuf;
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uint8_t const* const bufend = (uint8_t const*)vbufend;
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if (buf >= bufend)
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{
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return EILSEQ;
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}
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if (*buf != 'i')
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{
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return EILSEQ;
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}
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void const* begin = buf + 1;
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void const* end = memchr(begin, 'e', (bufend - buf) - 1);
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if (end == nullptr)
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{
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return EILSEQ;
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}
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errno = 0;
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char* endptr;
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int64_t val = evutil_strtoll(static_cast<char const*>(begin), &endptr, 10);
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if (errno != 0 || endptr != end) /* incomplete parse */
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{
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return EILSEQ;
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}
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if (val != 0 && *(char const*)begin == '0') /* no leading zeroes! */
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{
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return EILSEQ;
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}
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*setme_end = (uint8_t const*)end + 1;
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*setme_val = val;
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return 0;
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}
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/**
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* Byte strings are encoded as follows:
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* <string length encoded in base ten ASCII>:<string data>
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* Note that there is no constant beginning delimiter, and no ending delimiter.
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* Example: 4:spam represents the string "spam"
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*/
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int tr_bencParseStr(
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void const* vbuf,
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void const* vbufend,
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uint8_t const** setme_end,
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uint8_t const** setme_str,
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size_t* setme_strlen)
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{
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uint8_t const* const buf = (uint8_t const*)vbuf;
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uint8_t const* const bufend = (uint8_t const*)vbufend;
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if ((buf < bufend) && isdigit(*buf))
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{
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void const* end = memchr(buf, ':', bufend - buf);
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if (end != nullptr)
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{
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errno = 0;
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char* ulend;
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size_t len = strtoul((char const*)buf, &ulend, 10);
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if (errno == 0 && ulend == end && len <= MAX_BENC_STR_LENGTH)
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{
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uint8_t const* strbegin = (uint8_t const*)end + 1;
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uint8_t const* strend = strbegin + len;
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if (strbegin <= strend && strend <= bufend)
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{
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*setme_end = (uint8_t const*)end + 1 + len;
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*setme_str = (uint8_t const*)end + 1;
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*setme_strlen = len;
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return 0;
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}
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}
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}
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}
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*setme_end = nullptr;
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*setme_str = nullptr;
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*setme_strlen = 0;
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return EILSEQ;
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}
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static tr_variant* get_node(std::deque<tr_variant*>& stack, tr_quark* key, tr_variant* top, int* err)
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{
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tr_variant* node = nullptr;
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if (std::empty(stack))
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{
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node = top;
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}
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else
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{
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auto* parent = stack.back();
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if (tr_variantIsList(parent))
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{
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node = tr_variantListAdd(parent);
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}
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else if (*key != 0 && tr_variantIsDict(parent))
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{
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node = tr_variantDictAdd(parent, *key);
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*key = 0;
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}
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else
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{
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*err = EILSEQ;
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}
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}
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return node;
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}
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/**
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* This function's previous recursive implementation was
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* easier to read, but was vulnerable to a smash-stacking
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* attack via maliciously-crafted bencoded data. (#667)
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*/
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int tr_variantParseBenc(void const* buf_in, void const* bufend_in, tr_variant* top, char const** setme_end)
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{
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int err = 0;
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auto const* buf = static_cast<uint8_t const*>(buf_in);
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auto const* const bufend = static_cast<uint8_t const*>(bufend_in);
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auto stack = std::deque<tr_variant*>{};
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tr_quark key = 0;
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if ((buf_in == nullptr) || (bufend_in == nullptr) || (top == nullptr))
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{
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return EINVAL;
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}
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tr_variantInit(top, 0);
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while (buf != bufend)
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{
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if (buf > bufend) /* no more text to parse... */
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{
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err = EILSEQ;
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}
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if (err != 0)
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{
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break;
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}
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if (*buf == 'i') /* int */
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{
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int64_t val;
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uint8_t const* end;
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tr_variant* v;
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if ((err = tr_bencParseInt(buf, bufend, &end, &val)) != 0)
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{
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break;
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}
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buf = end;
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if ((v = get_node(stack, &key, top, &err)) != nullptr)
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{
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tr_variantInitInt(v, val);
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}
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}
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else if (*buf == 'l') /* list */
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{
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tr_variant* v;
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++buf;
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if ((v = get_node(stack, &key, top, &err)) != nullptr)
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{
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tr_variantInitList(v, 0);
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stack.push_back(v);
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}
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}
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else if (*buf == 'd') /* dict */
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{
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tr_variant* v;
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++buf;
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if ((v = get_node(stack, &key, top, &err)) != nullptr)
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{
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tr_variantInitDict(v, 0);
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stack.push_back(v);
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}
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}
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else if (*buf == 'e') /* end of list or dict */
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{
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++buf;
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if (std::empty(stack) || key != 0)
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{
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err = EILSEQ;
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break;
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}
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else
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{
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stack.pop_back();
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if (std::empty(stack))
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{
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break;
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}
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}
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}
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else if (isdigit(*buf)) /* string? */
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{
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tr_variant* v;
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uint8_t const* end;
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uint8_t const* str;
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size_t str_len;
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if ((err = tr_bencParseStr(buf, bufend, &end, &str, &str_len)) != 0)
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{
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break;
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}
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buf = end;
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if (key == 0 && !std::empty(stack) && tr_variantIsDict(stack.back()))
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{
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key = tr_quark_new(str, str_len);
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}
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else if ((v = get_node(stack, &key, top, &err)) != nullptr)
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{
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tr_variantInitStr(v, str, str_len);
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}
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}
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else /* invalid bencoded text... march past it */
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{
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++buf;
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}
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if (std::empty(stack))
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{
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break;
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}
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}
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if (err == 0 && (top->type == 0 || !std::empty(stack)))
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{
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err = EILSEQ;
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}
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if (err == 0)
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{
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if (setme_end != nullptr)
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{
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*setme_end = (char const*)buf;
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}
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}
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else if (top->type != 0)
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{
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tr_variantFree(top);
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tr_variantInit(top, 0);
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}
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return err;
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}
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/****
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*****
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****/
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static void saveIntFunc(tr_variant const* val, void* vevbuf)
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{
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add_printf(evbuf, "i%" PRId64 "e", val->val.i);
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}
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static void saveBoolFunc(tr_variant const* val, void* vevbuf)
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{
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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if (val->val.b)
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{
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evbuffer_add(evbuf, "i1e", 3);
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}
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else
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{
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evbuffer_add(evbuf, "i0e", 3);
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}
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}
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static void saveRealFunc(tr_variant const* val, void* vevbuf)
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{
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char buf[128];
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int const len = tr_snprintf(buf, sizeof(buf), "%f", val->val.d);
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add_printf(evbuf, "%d:", len);
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evbuffer_add(evbuf, buf, len);
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}
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static void saveStringFunc(tr_variant const* v, void* vevbuf)
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{
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size_t len;
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char const* str;
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if (!tr_variantGetStr(v, &str, &len))
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{
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len = 0;
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str = nullptr;
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}
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add_printf(evbuf, "%zu:", len);
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evbuffer_add(evbuf, str, len);
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}
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static void saveDictBeginFunc([[maybe_unused]] tr_variant const* val, void* vevbuf)
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{
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add(evbuf, "d", 1);
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}
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static void saveListBeginFunc([[maybe_unused]] tr_variant const* val, void* vevbuf)
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{
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add(evbuf, "l", 1);
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}
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static void saveContainerEndFunc([[maybe_unused]] tr_variant const* val, void* vevbuf)
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{
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auto* evbuf = static_cast<struct evbuffer*>(vevbuf);
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evbuffer_add(evbuf, "e", 1);
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}
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static struct VariantWalkFuncs const walk_funcs = {
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saveIntFunc, //
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saveBoolFunc, //
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saveRealFunc, //
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saveStringFunc, //
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saveDictBeginFunc, //
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saveListBeginFunc, //
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saveContainerEndFunc, //
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};
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void tr_variantToBufBenc(tr_variant const* top, struct evbuffer* buf)
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{
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tr_variantWalk(top, &walk_funcs, buf, true);
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}
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