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sencode: add integer size limits

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This commit is contained in:
Mirek Kratochvil 2013-07-26 09:54:55 +02:00
parent 66d7d84b13
commit 60749aa4cf
1 changed files with 16 additions and 8 deletions
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24
src/sencode.cpp
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@ -21,14 +21,14 @@
#include <sstream> #include <sstream>
#include <list> #include <list>
/* #define sencode_max_int_len 9
* TODO #define sencode_max_int 999999999
* fix: set some maximum integer to avoid overflows and keep the top limit
*/
static void parse_int (const std::string&str, int&pos, int len, static void parse_int (const std::string&str, int&pos, int len,
unsigned int&res) unsigned int&res)
{ {
int length;
res = 0; res = 0;
++pos; //skip 'i' ++pos; //skip 'i'
if (pos >= len) goto fail; if (pos >= len) goto fail;
@ -48,7 +48,8 @@ static void parse_int (const std::string&str, int&pos, int len,
} else goto fail; } else goto fail;
} }
//parse the number //parse the number, keep eye on maximum length
length = 0;
for (;;) { for (;;) {
if (pos >= len) goto fail; //not terminated if (pos >= len) goto fail; //not terminated
else if (str[pos] == 'e') break; //done good else if (str[pos] == 'e') break; //done good
@ -56,6 +57,7 @@ static void parse_int (const std::string&str, int&pos, int len,
res = (10 * res) + (unsigned int) (str[pos] - '0'); res = (10 * res) + (unsigned int) (str[pos] - '0');
else goto fail; //something weird! else goto fail; //something weird!
++pos; ++pos;
if (++length > sencode_max_int_len) goto fail;
} }
return; return;
@ -66,15 +68,17 @@ fail:
static void parse_string (const std::string&str, int&pos, int len, static void parse_string (const std::string&str, int&pos, int len,
std::string&res) std::string&res)
{ {
//first, read the amount of bytes int bytes, length;
int bytes = 0;
/* /*
* we need to keep this bijective, therefore avoid parsing of any * First, read the amount of bytes.
* We need to keep this bijective, therefore avoid parsing of any
* incorrect cases with leading zeroes except for a single zero. Such * incorrect cases with leading zeroes except for a single zero. Such
* cases can be distinguished very simply by having zero at first * cases can be distinguished very simply by having zero at first
* position and not having colon right after. * position and not having colon right after.
*/ */
bytes = 0;
if (pos >= len) goto fail; if (pos >= len) goto fail;
if (str[pos] == '0') { if (str[pos] == '0') {
++pos; ++pos;
@ -85,6 +89,7 @@ static void parse_string (const std::string&str, int&pos, int len,
} }
//parse the number. //parse the number.
length = 0;
for (;;) { for (;;) {
if (pos >= len) goto fail; if (pos >= len) goto fail;
else if (str[pos] == ':') break; //got it else if (str[pos] == ':') break; //got it
@ -92,6 +97,7 @@ static void parse_string (const std::string&str, int&pos, int len,
bytes = (10 * bytes) + (int) (str[pos] - '0'); bytes = (10 * bytes) + (int) (str[pos] - '0');
else goto fail; //weird! else goto fail; //weird!
++pos; ++pos;
if (++length > sencode_max_int_len) goto fail;
} }
bytes_done: bytes_done:
@ -196,6 +202,7 @@ std::string sencode_list::encode()
std::string sencode_int::encode() std::string sencode_int::encode()
{ {
if (i > sencode_max_int) return "i0e"; //failure fallback
std::stringstream ss; std::stringstream ss;
ss << 'i' << i << 'e'; ss << 'i' << i << 'e';
return ss.str(); return ss.str();
@ -203,6 +210,7 @@ std::string sencode_int::encode()
std::string sencode_bytes::encode() std::string sencode_bytes::encode()
{ {
if (b.length() > sencode_max_int) return "0:"; //failure fallback
std::stringstream ss; std::stringstream ss;
ss << b.length() << ':' << b; ss << b.length() << ':' << b;
return ss.str(); return ss.str();