URL格式编码与解码

char* urlencode(const void* buf, size_t size) {
  _assert_(buf && size <= MEMMAXSIZ);
  const unsigned char* rp = (const unsigned char*)buf;
  char* zbuf = new char[size*3+1];
  char* wp = zbuf;
  for (const unsigned char* ep = rp + size; rp < ep; rp++) {
    int32_t c = *rp;
    if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') ||
        (c >= '0' && c <= '9') || (c != '' && std::strchr("_-.~", c))) {
      *(wp++) = c;
    } else {
      *(wp++) = '%';
      int32_t num = c >> 4;
      if (num < 10) {
        *(wp++) = '0' + num;
      } else {
        *(wp++) = 'a' + num - 10;
      }
      num = c & 0x0f;
      if (num < 10) {
        *(wp++) = '0' + num;
      } else {
        *(wp++) = 'a' + num - 10;
      }
    }
  }
  *wp = '';
  return zbuf;
}

decode：

char* urldecode(const char* str, size_t* sp) {
  _assert_(str && sp);
  size_t zsiz = std::strlen(str);
  char* zbuf = new char[zsiz+1];
  char* wp = zbuf;
  const char* ep = str + zsiz;
  while (str < ep) {
    int32_t c = *str;
    if (c == '%') {
      int32_t num = 0;
      if (++str >= ep) break;
      c = *str;
      if (c >= '0' && c <= '9') {
        num = c - '0';
      } else if (c >= 'a' && c <= 'f') {
        num = c - 'a' + 10;
      } else if (c >= 'A' && c <= 'F') {
        num = c - 'A' + 10;
      }
      if (++str >= ep) break;
      c = *str;
      if (c >= '0' && c <= '9') {
        num = num * 0x10 + c - '0';
      } else if (c >= 'a' && c <= 'f') {
        num = num * 0x10 + c - 'a' + 10;
      } else if (c >= 'A' && c <= 'F') {
        num = num * 0x10 + c - 'A' + 10;
      }
      *(wp++) = num;
      str++;
    } else if (c == '+') {
      *(wp++) = ' ';
      str++;
    } else if (c <= ' ' || c == 0x7f) {
      str++;
    } else {
      *(wp++) = c;
      str++;
    }
  }
  *wp = '';
  *sp = wp - zbuf;
  return zbuf;
}