Make DecodeBase{32,64} take string_view arguments

Author: sipa

src/netaddress.cpp

@@ -234,7 +234,7 @@ bool CNetAddr::SetTor(const std::string& addr)
         return false;
     }
 
-    auto input = DecodeBase32(addr.substr(0, addr.size() - suffix_len));
+    auto input = DecodeBase32(std::string_view{addr}.substr(0, addr.size() - suffix_len));
 
     if (!input) {
         return false;

src/util/strencodings.cpp

@@ -126,7 +126,7 @@ std::string EncodeBase64(Span<const unsigned char> input)
     return str;
 }
 
-std::optional<std::vector<unsigned char>> DecodeBase64(const char* p)
+std::optional<std::vector<unsigned char>> DecodeBase64(std::string_view str)
 {
     static const int8_t decode64_table[256]{
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
@@ -144,42 +144,23 @@ std::optional<std::vector<unsigned char>> DecodeBase64(const char* p)
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
     };
 
-    const char* e = p;
-    std::vector<uint8_t> val;
-    val.reserve(strlen(p));
-    while (*p != 0) {
-        int x = decode64_table[(unsigned char)*p];
-        if (x == -1) break;
-        val.push_back(uint8_t(x));
-        ++p;
-    }
+    if (str.size() % 4 != 0) return {};
+    /* One or two = characters at the end are permitted. */
+    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
+    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
 
     std::vector<unsigned char> ret;
-    ret.reserve((val.size() * 3) / 4);
-    bool valid = ConvertBits<6, 8, false>([&](unsigned char c) { ret.push_back(c); }, val.begin(), val.end());
-
-    const char* q = p;
-    while (valid && *p != 0) {
-        if (*p != '=') {
-            valid = false;
-            break;
-        }
-        ++p;
-    }
-    valid = valid && (p - e) % 4 == 0 && p - q < 4;
+    ret.reserve((str.size() * 3) / 4);
+    bool valid = ConvertBits<6, 8, false>(
+        [&](unsigned char c) { ret.push_back(c); },
+        str.begin(), str.end(),
+        [](char c) { return decode64_table[uint8_t(c)]; }
+    );
     if (!valid) return {};
 
     return ret;
 }
 
-std::optional<std::vector<unsigned char>> DecodeBase64(const std::string& str)
-{
-    if (!ValidAsCString(str)) {
-        return {};
-    }
-    return DecodeBase64(str.c_str());
-}
-
 std::string EncodeBase32(Span<const unsigned char> input, bool pad)
 {
     static const char *pbase32 = "abcdefghijklmnopqrstuvwxyz234567";
@@ -200,7 +181,7 @@ std::string EncodeBase32(const std::string& str, bool pad)
     return EncodeBase32(MakeUCharSpan(str), pad);
 }
 
-std::optional<std::vector<unsigned char>> DecodeBase32(const char* p)
+std::optional<std::vector<unsigned char>> DecodeBase32(std::string_view str)
 {
     static const int8_t decode32_table[256]{
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
@@ -218,42 +199,26 @@ std::optional<std::vector<unsigned char>> DecodeBase32(const char* p)
         -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
     };
 
-    const char* e = p;
-    std::vector<uint8_t> val;
-    val.reserve(strlen(p));
-    while (*p != 0) {
-        int x = decode32_table[(unsigned char)*p];
-        if (x == -1) break;
-        val.push_back(uint8_t(x));
-        ++p;
-    }
+    if (str.size() % 8 != 0) return {};
+    /* 1, 3, 4, or 6 padding '=' suffix characters are permitted. */
+    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
+    if (str.size() >= 2 && str.substr(str.size() - 2) == "==") str.remove_suffix(2);
+    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
+    if (str.size() >= 2 && str.substr(str.size() - 2) == "==") str.remove_suffix(2);
 
     std::vector<unsigned char> ret;
-    ret.reserve((val.size() * 5) / 8);
-    bool valid = ConvertBits<5, 8, false>([&](unsigned char c) { ret.push_back(c); }, val.begin(), val.end());
-
-    const char* q = p;
-    while (valid && *p != 0) {
-        if (*p != '=') {
-            valid = false;
-            break;
-        }
-        ++p;
-    }
-    valid = valid && (p - e) % 8 == 0 && p - q < 8;
+    ret.reserve((str.size() * 5) / 8);
+    bool valid = ConvertBits<5, 8, false>(
+        [&](unsigned char c) { ret.push_back(c); },
+        str.begin(), str.end(),
+        [](char c) { return decode32_table[uint8_t(c)]; }
+    );
+
     if (!valid) return {};
 
     return ret;
 }
 
-std::optional<std::vector<unsigned char>> DecodeBase32(const std::string& str)
-{
-    if (!ValidAsCString(str)) {
-        return {};
-    }
-    return DecodeBase32(str.c_str());
-}
-
 namespace {
 template <typename T>
 bool ParseIntegral(const std::string& str, T* out)

src/util/strencodings.h

@@ -64,13 +64,11 @@ bool IsHex(std::string_view str);
 * Return true if the string is a hex number, optionally prefixed with "0x"
 */
 bool IsHexNumber(std::string_view str);
-std::optional<std::vector<unsigned char>> DecodeBase64(const char* p);
-std::optional<std::vector<unsigned char>> DecodeBase64(const std::string& str);
+std::optional<std::vector<unsigned char>> DecodeBase64(std::string_view str);
 std::string EncodeBase64(Span<const unsigned char> input);
 inline std::string EncodeBase64(Span<const std::byte> input) { return EncodeBase64(MakeUCharSpan(input)); }
 inline std::string EncodeBase64(const std::string& str) { return EncodeBase64(MakeUCharSpan(str)); }
-std::optional<std::vector<unsigned char>> DecodeBase32(const char* p);
-std::optional<std::vector<unsigned char>> DecodeBase32(const std::string& str);
+std::optional<std::vector<unsigned char>> DecodeBase32(std::string_view str);
 
 /**
  * Base32 encode.