From 2bcf1fc444d5c4b8efa879e54e7b6134b7e6b986 Mon Sep 17 00:00:00 2001 From: Pieter Wuille Date: Mon, 18 Nov 2019 15:16:50 -0800 Subject: Pass a maximum output length to DecodeBase58 and DecodeBase58Check Also remove a needless loop in DecodeBase58 to prune zeroes in the base256 output of the conversion. The number of zeroes is implied by keeping track explicitly of the length during the loop. --- src/base58.cpp | 20 +++++++++++--------- src/base58.h | 9 +++++---- src/test/base58_tests.cpp | 17 +++++++++++++++++ 3 files changed, 33 insertions(+), 13 deletions(-) diff --git a/src/base58.cpp b/src/base58.cpp index e3d2853399..a0149fb641 100644 --- a/src/base58.cpp +++ b/src/base58.cpp @@ -11,6 +11,8 @@ #include #include +#include + /** All alphanumeric characters except for "0", "I", "O", and "l" */ static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"; static const int8_t mapBase58[256] = { @@ -32,7 +34,7 @@ static const int8_t mapBase58[256] = { -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1, }; -bool DecodeBase58(const char* psz, std::vector& vch) +bool DecodeBase58(const char* psz, std::vector& vch, int max_ret_len) { // Skip leading spaces. while (*psz && IsSpace(*psz)) @@ -42,6 +44,7 @@ bool DecodeBase58(const char* psz, std::vector& vch) int length = 0; while (*psz == '1') { zeroes++; + if (zeroes > max_ret_len) return false; psz++; } // Allocate enough space in big-endian base256 representation. @@ -62,6 +65,7 @@ bool DecodeBase58(const char* psz, std::vector& vch) } assert(carry == 0); length = i; + if (length + zeroes > max_ret_len) return false; psz++; } // Skip trailing spaces. @@ -71,8 +75,6 @@ bool DecodeBase58(const char* psz, std::vector& vch) return false; // Skip leading zeroes in b256. std::vector::iterator it = b256.begin() + (size - length); - while (it != b256.end() && *it == 0) - it++; // Copy result into output vector. vch.reserve(zeroes + (b256.end() - it)); vch.assign(zeroes, 0x00); @@ -126,9 +128,9 @@ std::string EncodeBase58(const std::vector& vch) return EncodeBase58(vch.data(), vch.data() + vch.size()); } -bool DecodeBase58(const std::string& str, std::vector& vchRet) +bool DecodeBase58(const std::string& str, std::vector& vchRet, int max_ret_len) { - return DecodeBase58(str.c_str(), vchRet); + return DecodeBase58(str.c_str(), vchRet, max_ret_len); } std::string EncodeBase58Check(const std::vector& vchIn) @@ -140,9 +142,9 @@ std::string EncodeBase58Check(const std::vector& vchIn) return EncodeBase58(vch); } -bool DecodeBase58Check(const char* psz, std::vector& vchRet) +bool DecodeBase58Check(const char* psz, std::vector& vchRet, int max_ret_len) { - if (!DecodeBase58(psz, vchRet) || + if (!DecodeBase58(psz, vchRet, max_ret_len > std::numeric_limits::max() - 4 ? std::numeric_limits::max() : max_ret_len + 4) || (vchRet.size() < 4)) { vchRet.clear(); return false; @@ -157,7 +159,7 @@ bool DecodeBase58Check(const char* psz, std::vector& vchRet) return true; } -bool DecodeBase58Check(const std::string& str, std::vector& vchRet) +bool DecodeBase58Check(const std::string& str, std::vector& vchRet, int max_ret) { - return DecodeBase58Check(str.c_str(), vchRet); + return DecodeBase58Check(str.c_str(), vchRet, max_ret); } diff --git a/src/base58.h b/src/base58.h index d6e0299a1e..cfdab511b6 100644 --- a/src/base58.h +++ b/src/base58.h @@ -16,6 +16,7 @@ #include +#include #include #include @@ -35,13 +36,13 @@ std::string EncodeBase58(const std::vector& vch); * return true if decoding is successful. * psz cannot be nullptr. */ -NODISCARD bool DecodeBase58(const char* psz, std::vector& vchRet); +NODISCARD bool DecodeBase58(const char* psz, std::vector& vchRet, int max_ret_len = std::numeric_limits::max()); /** * Decode a base58-encoded string (str) into a byte vector (vchRet). * return true if decoding is successful. */ -NODISCARD bool DecodeBase58(const std::string& str, std::vector& vchRet); +NODISCARD bool DecodeBase58(const std::string& str, std::vector& vchRet, int max_ret_len = std::numeric_limits::max()); /** * Encode a byte vector into a base58-encoded string, including checksum @@ -52,12 +53,12 @@ std::string EncodeBase58Check(const std::vector& vchIn); * Decode a base58-encoded string (psz) that includes a checksum into a byte * vector (vchRet), return true if decoding is successful */ -NODISCARD bool DecodeBase58Check(const char* psz, std::vector& vchRet); +NODISCARD bool DecodeBase58Check(const char* psz, std::vector& vchRet, int max_ret_len = std::numeric_limits::max()); /** * Decode a base58-encoded string (str) that includes a checksum into a byte * vector (vchRet), return true if decoding is successful */ -NODISCARD bool DecodeBase58Check(const std::string& str, std::vector& vchRet); +NODISCARD bool DecodeBase58Check(const std::string& str, std::vector& vchRet, int max_ret_len = std::numeric_limits::max()); #endif // BITCOIN_BASE58_H diff --git a/src/test/base58_tests.cpp b/src/test/base58_tests.cpp index 52301f799a..5d53088cc6 100644 --- a/src/test/base58_tests.cpp +++ b/src/test/base58_tests.cpp @@ -7,6 +7,7 @@ #include #include #include +#include #include @@ -66,4 +67,20 @@ BOOST_AUTO_TEST_CASE(base58_DecodeBase58) BOOST_CHECK_EQUAL_COLLECTIONS(result.begin(), result.end(), expected.begin(), expected.end()); } +BOOST_AUTO_TEST_CASE(base58_random_encode_decode) +{ + for (int n = 0; n < 1000; ++n) { + unsigned int len = 1 + InsecureRandBits(8); + unsigned int zeroes = InsecureRandBool() ? InsecureRandRange(len + 1) : 0; + auto data = Cat(std::vector(zeroes, '\000'), g_insecure_rand_ctx.randbytes(len - zeroes)); + auto encoded = EncodeBase58Check(data); + std::vector decoded; + auto ok_too_small = DecodeBase58Check(encoded, decoded, InsecureRandRange(len)); + BOOST_CHECK(!ok_too_small); + auto ok = DecodeBase58Check(encoded, decoded, len + InsecureRandRange(257 - len)); + BOOST_CHECK(ok); + BOOST_CHECK(data == decoded); + } +} + BOOST_AUTO_TEST_SUITE_END() -- cgit v1.2.3