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fix(utils): reject invalid hex characters in fromHex #1818

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fix(utils): reject invalid hex characters in fromHex #1818

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13 changes: 8 additions & 5 deletions src/Utils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -108,15 +108,15 @@ void Utils::printHex(Stream& s, const uint8_t* src, size_t len) {
}
}

static uint8_t hexVal(char c) {
static int8_t hexVal(char c) {
if (c >= 'A' && c <= 'F') return c - 'A' + 10;
if (c >= 'a' && c <= 'f') return c - 'a' + 10;
if (c >= '0' && c <= '9') return c - '0';
return 0;
return -1;
}

bool Utils::isHexChar(char c) {
return c == '0' || hexVal(c) > 0;
return hexVal(c) >= 0;
}

bool Utils::fromHex(uint8_t* dest, int dest_size, const char *src_hex) {
Expand All @@ -127,7 +127,10 @@ bool Utils::fromHex(uint8_t* dest, int dest_size, const char *src_hex) {
while (dp - dest < dest_size) {
char ch = *src_hex++;
char cl = *src_hex++;
*dp++ = (hexVal(ch) << 4) | hexVal(cl);
int8_t hi = hexVal(ch);
int8_t lo = hexVal(cl);
if (hi < 0 || lo < 0) return false; // invalid chars
*dp++ = (hi << 4) | lo;
}
return true;
}
Expand All @@ -150,4 +153,4 @@ int Utils::parseTextParts(char* text, const char* parts[], int max_num, char sep
return num;
}

}
}