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Fix base64 validation and add unittests (#10515)

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Implement proper padding character checks
This commit is contained in:
Lars Müller 2021-05-30 20:23:12 +02:00 • committed by GitHub
parent 1bc753f655
commit 89f3991351
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4 changed files with 124 additions and 6 deletions
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29
src/util/base64.cpp
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@ -33,18 +33,39 @@ static const std::string base64_chars =
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";
static const std::string base64_chars_padding_1 = "AEIMQUYcgkosw048";
static const std::string base64_chars_padding_2 = "AQgw";
static inline bool is_base64(unsigned char c)
{
return isalnum(c) || c == '+' || c == '/' || c == '=';
return (c >= '0' && c <= '9')
|| (c >= 'A' && c <= 'Z')
|| (c >= 'a' && c <= 'z')
|| c == '+' || c == '/';
}
bool base64_is_valid(std::string const& s)
{
for (char i : s)
if (!is_base64(i))
size_t i = 0;
for (; i < s.size(); ++i)
if (!is_base64(s[i]))
break;
unsigned char padding = 3 - ((i + 3) % 4);
if ((padding == 1 && base64_chars_padding_1.find(s[i - 1]) == std::string::npos)
|| (padding == 2 && base64_chars_padding_2.find(s[i - 1]) == std::string::npos)
|| padding == 3)
return false;
int actual_padding = s.size() - i;
// omission of padding characters is allowed
if (actual_padding == 0)
return true;
// remaining characters (max. 2) may only be padding
for (; i < s.size(); ++i)
if (s[i] != '=')
return false;
return true;
// number of padding characters needs to match
return padding == actual_padding;
}
std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {