refa pre_seed to base64

gframe/base64.h

+#ifndef BASE64_H
+#define BASE64_H
+
+#include <string>
+#include <cstring>
+
+const char kBase64Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "abcdefghijklmnopqrstuvwxyz"
+    "0123456789+/";
+
+class Base64 {
+ public:
+  static bool Encode(const std::string &in, std::string *out) {
+    int i = 0, j = 0;
+    size_t enc_len = 0;
+    unsigned char a3[3];
+    unsigned char a4[4];
+
+    out->resize(EncodedLength(in));
+
+    int input_len = in.size();
+    std::string::const_iterator input = in.begin();
+
+    while (input_len--) {
+      a3[i++] = *(input++);
+      if (i == 3) {
+        a3_to_a4(a4, a3);
+
+        for (i = 0; i < 4; i++) {
+          (*out)[enc_len++] = kBase64Alphabet[a4[i]];
+        }
+
+        i = 0;
+      }
+    }
+
+    if (i) {
+      for (j = i; j < 3; j++) {
+        a3[j] = '\0';
+      }
+
+      a3_to_a4(a4, a3);
+
+      for (j = 0; j < i + 1; j++) {
+        (*out)[enc_len++] = kBase64Alphabet[a4[j]];
+      }
+
+      while ((i++ < 3)) {
+        (*out)[enc_len++] = '=';
+      }
+    }
+
+    return (enc_len == out->size());
+  }
+
+  static bool Encode(const unsigned char *input, size_t input_length, unsigned char *out, size_t out_length) {
+    int i = 0, j = 0;
+    unsigned char *out_begin = out;
+    unsigned char a3[3];
+    unsigned char a4[4];
+
+    size_t encoded_length = EncodedLength(input_length);
+
+    if (out_length < encoded_length + 1) return false;
+    
+    std::memset(out, 0, out_length);
+    
+    while (input_length--) {
+      a3[i++] = *input++;
+      if (i == 3) {
+        a3_to_a4(a4, a3);
+
+        for (i = 0; i < 4; i++) {
+          *out++ = kBase64Alphabet[a4[i]];
+        }
+
+        i = 0;
+      }
+    }
+
+    if (i) {
+      for (j = i; j < 3; j++) {
+        a3[j] = '\0';
+      }
+
+      a3_to_a4(a4, a3);
+
+      for (j = 0; j < i + 1; j++) {
+        *out++ = kBase64Alphabet[a4[j]];
+      }
+
+      while ((i++ < 3)) {
+        *out++ = '=';
+      }
+    }
+
+    return (out == (out_begin + encoded_length));
+  }
+
+  static bool Decode(const std::string &in, std::string *out) {
+    int i = 0, j = 0;
+    size_t dec_len = 0;
+    unsigned char a3[3];
+    unsigned char a4[4];
+
+    int input_len = in.size();
+    std::string::const_iterator input = in.begin();
+
+    out->resize(DecodedLength(in));
+
+    while (input_len--) {
+      if (*input == '=') {
+        break;
+      }
+
+      a4[i++] = *(input++);
+      if (i == 4) {
+        for (i = 0; i <4; i++) {
+          a4[i] = b64_lookup(a4[i]);
+        }
+
+        a4_to_a3(a3,a4);
+
+        for (i = 0; i < 3; i++) {
+          (*out)[dec_len++] = a3[i];
+        }
+
+        i = 0;
+      }
+    }
+
+    if (i) {
+      for (j = i; j < 4; j++) {
+        a4[j] = '\0';
+      }
+
+      for (j = 0; j < 4; j++) {
+        a4[j] = b64_lookup(a4[j]);
+      }
+
+      a4_to_a3(a3,a4);
+
+      for (j = 0; j < i - 1; j++) {
+        (*out)[dec_len++] = a3[j];
+      }
+    }
+
+    return (dec_len == out->size());
+  }
+
+  static bool Decode(const unsigned char *input, size_t input_length, unsigned char *out, size_t out_length) {
+    int i = 0, j = 0;
+    unsigned char *out_begin = out;
+    unsigned char a3[3];
+    unsigned char a4[4];
+
+    size_t decoded_length = DecodedLength(input, input_length);
+
+    if (out_length < decoded_length) return false;
+
+    while (input_length--) {
+      if (*input == '=') {
+        break;
+      }
+
+      a4[i++] = *(input++);
+      if (i == 4) {
+        for (i = 0; i <4; i++) {
+          a4[i] = b64_lookup(a4[i]);
+        }
+
+        a4_to_a3(a3,a4);
+
+        for (i = 0; i < 3; i++) {
+          *out++ = a3[i];
+        }
+
+        i = 0;
+      }
+    }
+
+    if (i) {
+      for (j = i; j < 4; j++) {
+        a4[j] = '\0';
+      }
+
+      for (j = 0; j < 4; j++) {
+        a4[j] = b64_lookup(a4[j]);
+      }
+
+      a4_to_a3(a3,a4);
+
+      for (j = 0; j < i - 1; j++) {
+        *out++ = a3[j];
+      }
+    }
+
+    return (out == (out_begin + decoded_length));
+  }
+
+  static int DecodedLength(const unsigned char *in, size_t in_length) {
+    int numEq = 0;
+
+    const unsigned char *in_end = in + in_length;
+    while (*--in_end == '=') ++numEq;
+
+    return ((6 * in_length) / 8) - numEq;
+  }
+
+  static int DecodedLength(const std::string &in) {
+    int numEq = 0;
+    int n = in.size();
+
+    for (std::string::const_reverse_iterator it = in.rbegin(); *it == '='; ++it) {
+      ++numEq;
+    }
+
+    return ((6 * n) / 8) - numEq;
+  }
+
+  inline static int EncodedLength(size_t length) {
+    return (length + 2 - ((length + 2) % 3)) / 3 * 4;
+  }
+
+  inline static int EncodedLength(const std::string &in) {
+    return EncodedLength(in.length());
+  }
+
+  inline static void StripPadding(std::string *in) {
+    while (!in->empty() && *(in->rbegin()) == '=') in->resize(in->size() - 1);
+  }
+
+ private:
+  static inline void a3_to_a4(unsigned char * a4, unsigned char * a3) {
+    a4[0] = (a3[0] & 0xfc) >> 2;
+    a4[1] = ((a3[0] & 0x03) << 4) + ((a3[1] & 0xf0) >> 4);
+    a4[2] = ((a3[1] & 0x0f) << 2) + ((a3[2] & 0xc0) >> 6);
+    a4[3] = (a3[2] & 0x3f);
+  }
+
+  static inline void a4_to_a3(unsigned char * a3, unsigned char * a4) {
+    a3[0] = (a4[0] << 2) + ((a4[1] & 0x30) >> 4);
+    a3[1] = ((a4[1] & 0xf) << 4) + ((a4[2] & 0x3c) >> 2);
+    a3[2] = ((a4[2] & 0x3) << 6) + a4[3];
+  }
+
+  static inline unsigned char b64_lookup(unsigned char c) {
+    if(c >='A' && c <='Z') return c - 'A';
+    if(c >='a' && c <='z') return c - 71;
+    if(c >='0' && c <='9') return c + 4;
+    if(c == '+') return 62;
+    if(c == '/') return 63;
+    return 255;
+  }
+};
+
+
+
+#endif // BASE64_H