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      1 /*
      2  * libjingle
      3  * Copyright 2004--2005, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef _TALK_BASE_CRYPTSTRING_H_
     29 #define _TALK_BASE_CRYPTSTRING_H_
     30 
     31 #include <cstring>
     32 #include <string>
     33 #include <vector>
     34 #include "talk/base/linked_ptr.h"
     35 #include "talk/base/scoped_ptr.h"
     36 
     37 namespace talk_base {
     38 
     39 class CryptStringImpl {
     40 public:
     41   virtual ~CryptStringImpl() {}
     42   virtual size_t GetLength() const = 0;
     43   virtual void CopyTo(char * dest, bool nullterminate) const = 0;
     44   virtual std::string UrlEncode() const = 0;
     45   virtual CryptStringImpl * Copy() const = 0;
     46   virtual void CopyRawTo(std::vector<unsigned char> * dest) const = 0;
     47 };
     48 
     49 class EmptyCryptStringImpl : public CryptStringImpl {
     50 public:
     51   virtual ~EmptyCryptStringImpl() {}
     52   virtual size_t GetLength() const { return 0; }
     53   virtual void CopyTo(char * dest, bool nullterminate) const {
     54     if (nullterminate) {
     55       *dest = '\0';
     56     }
     57   }
     58   virtual std::string UrlEncode() const { return ""; }
     59   virtual CryptStringImpl * Copy() const { return new EmptyCryptStringImpl(); }
     60   virtual void CopyRawTo(std::vector<unsigned char> * dest) const {
     61     dest->clear();
     62   }
     63 };
     64 
     65 class CryptString {
     66 public:
     67   CryptString() : impl_(new EmptyCryptStringImpl()) {}
     68   size_t GetLength() const { return impl_->GetLength(); }
     69   void CopyTo(char * dest, bool nullterminate) const { impl_->CopyTo(dest, nullterminate); }
     70   CryptString(const CryptString & other) : impl_(other.impl_->Copy()) {}
     71   explicit CryptString(const CryptStringImpl & impl) : impl_(impl.Copy()) {}
     72   CryptString & operator=(const CryptString & other) {
     73     if (this != &other) {
     74       impl_.reset(other.impl_->Copy());
     75     }
     76     return *this;
     77   }
     78   void Clear() { impl_.reset(new EmptyCryptStringImpl()); }
     79   std::string UrlEncode() const { return impl_->UrlEncode(); }
     80   void CopyRawTo(std::vector<unsigned char> * dest) const {
     81     return impl_->CopyRawTo(dest);
     82   }
     83 
     84 private:
     85   scoped_ptr<const CryptStringImpl> impl_;
     86 };
     87 
     88 
     89 // Used for constructing strings where a password is involved and we
     90 // need to ensure that we zero memory afterwards
     91 class FormatCryptString {
     92 public:
     93   FormatCryptString() {
     94     storage_ = new char[32];
     95     capacity_ = 32;
     96     length_ = 0;
     97     storage_[0] = 0;
     98   }
     99 
    100   void Append(const std::string & text) {
    101     Append(text.data(), text.length());
    102   }
    103 
    104   void Append(const char * data, size_t length) {
    105     EnsureStorage(length_ + length + 1);
    106     memcpy(storage_ + length_, data, length);
    107     length_ += length;
    108     storage_[length_] = '\0';
    109   }
    110 
    111   void Append(const CryptString * password) {
    112     size_t len = password->GetLength();
    113     EnsureStorage(length_ + len + 1);
    114     password->CopyTo(storage_ + length_, true);
    115     length_ += len;
    116   }
    117 
    118   size_t GetLength() {
    119     return length_;
    120   }
    121 
    122   const char * GetData() {
    123     return storage_;
    124   }
    125 
    126 
    127   // Ensures storage of at least n bytes
    128   void EnsureStorage(size_t n) {
    129     if (capacity_ >= n) {
    130       return;
    131     }
    132 
    133     size_t old_capacity = capacity_;
    134     char * old_storage = storage_;
    135 
    136     for (;;) {
    137       capacity_ *= 2;
    138       if (capacity_ >= n)
    139         break;
    140     }
    141 
    142     storage_ = new char[capacity_];
    143 
    144     if (old_capacity) {
    145       memcpy(storage_, old_storage, length_);
    146 
    147       // zero memory in a way that an optimizer won't optimize it out
    148       old_storage[0] = 0;
    149       for (size_t i = 1; i < old_capacity; i++) {
    150         old_storage[i] = old_storage[i - 1];
    151       }
    152       delete[] old_storage;
    153     }
    154   }
    155 
    156   ~FormatCryptString() {
    157     if (capacity_) {
    158       storage_[0] = 0;
    159       for (size_t i = 1; i < capacity_; i++) {
    160         storage_[i] = storage_[i - 1];
    161       }
    162     }
    163     delete[] storage_;
    164   }
    165 private:
    166   char * storage_;
    167   size_t capacity_;
    168   size_t length_;
    169 };
    170 
    171 class InsecureCryptStringImpl : public CryptStringImpl {
    172  public:
    173   std::string& password() { return password_; }
    174   const std::string& password() const { return password_; }
    175 
    176   virtual ~InsecureCryptStringImpl() {}
    177   virtual size_t GetLength() const { return password_.size(); }
    178   virtual void CopyTo(char * dest, bool nullterminate) const {
    179     memcpy(dest, password_.data(), password_.size());
    180     if (nullterminate) dest[password_.size()] = 0;
    181   }
    182   virtual std::string UrlEncode() const { return password_; }
    183   virtual CryptStringImpl * Copy() const {
    184     InsecureCryptStringImpl * copy = new InsecureCryptStringImpl;
    185     copy->password() = password_;
    186     return copy;
    187   }
    188   virtual void CopyRawTo(std::vector<unsigned char> * dest) const {
    189     dest->resize(password_.size());
    190     memcpy(&dest->front(), password_.data(), password_.size());
    191   }
    192  private:
    193   std::string password_;
    194 };
    195 
    196 }
    197 
    198 #endif  // _TALK_BASE_CRYPTSTRING_H_
    199