scan_name.cpp

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/*
* SCAN Name Abstraction
* (C) 2008-2009,2015 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/internal/scan_name.h>
 
#include <botan/assert.h>
#include <botan/exceptn.h>
#include <botan/internal/parsing.h>
 
namespace Botan {
 
namespace {
 
std::string make_arg(const std::vector<std::pair<size_t, std::string>>& name, size_t start) {
   std::string output = name[start].second;
   size_t level = name[start].first;
 
   size_t paren_depth = 0;
 
   for(size_t i = start + 1; i != name.size(); ++i) {
      if(name[i].first <= name[start].first) {
         break;
      }
 
      if(name[i].first > level) {
         for(size_t j = level; j < name[i].first; j++) {
            output += "(";
            ++paren_depth;
         }
         output += name[i].second;
      } else if(name[i].first < level) {
         for(size_t j = name[i].first; j < level; j++) {
            output += ")";
            BOTAN_ASSERT_NOMSG(paren_depth != 0);
            --paren_depth;
         }
         output += "," + name[i].second;
      } else {
         if(output[output.size() - 1] != '(') {
            output += ",";
         }
         output += name[i].second;
      }
 
      level = name[i].first;
   }
 
   for(size_t i = 0; i != paren_depth; ++i) {
      output += ")";
   }
 
   return output;
}
 
}  // namespace
 
SCAN_Name::SCAN_Name(std::string_view algo_spec) : m_orig_algo_spec(algo_spec) {
   if(algo_spec.empty()) {
      throw Invalid_Argument("Expected algorithm name, got empty string");
   }
 
   // Fast path for a bare name with no arguments or modes (eg "SHA-256"),
   // which is the common case. Equivalent to the general parse below, which
   // for such input produces a single token and no args/modes.
   if(algo_spec.find_first_of("(),/") == std::string_view::npos) {
      m_alg_name = std::string(algo_spec);
      return;
   }
 
   std::vector<std::pair<size_t, std::string>> name;
   size_t level = 0;
   std::pair<size_t, std::string> accum = std::make_pair(level, "");
 
   bool expect_token = true;
 
   for(const char c : algo_spec) {
      if(c == '/' || c == ',' || c == '(' || c == ')') {
         if(c == '(') {
            ++level;
         } else if(c == ')') {
            if(level == 0) {
               throw Invalid_Algorithm_Name(m_orig_algo_spec);
            }
            --level;
         }
 
         if(c == '/' && level > 0) {
            accum.second.push_back(c);
            expect_token = false;
         } else {
            if(expect_token) {
               throw Invalid_Algorithm_Name(m_orig_algo_spec);
            }
            if(!accum.second.empty()) {
               name.push_back(accum);
            }
            accum = std::make_pair(level, "");
            expect_token = (c != ')');
         }
      } else {
         accum.second.push_back(c);
         expect_token = false;
      }
   }
 
   if(!accum.second.empty()) {
      name.push_back(accum);
   }
 
   if(level != 0) {
      throw Invalid_Algorithm_Name(m_orig_algo_spec);
   }
 
   if(expect_token) {
      // A trailing separator with no following token, eg "Foo/" or "Foo,"
      throw Invalid_Algorithm_Name(m_orig_algo_spec);
   }
 
   if(name.empty()) {
      throw Invalid_Algorithm_Name(m_orig_algo_spec);
   }
 
   m_alg_name = name[0].second;
 
   bool in_modes = false;
 
   for(size_t i = 1; i != name.size(); ++i) {
      if(name[i].first == 0) {
         m_mode_info.push_back(make_arg(name, i));
         in_modes = true;
      } else if(name[i].first == 1 && !in_modes) {
         m_args.push_back(make_arg(name, i));
      }
   }
}
 
std::string SCAN_Name::arg(size_t i) const {
   if(i >= arg_count()) {
      throw Invalid_Argument("SCAN_Name::arg " + std::to_string(i) + " out of range for '" + to_string() + "'");
   }
   return m_args[i];
}
 
std::string SCAN_Name::arg(size_t i, std::string_view def_value) const {
   if(i >= arg_count()) {
      return std::string(def_value);
   }
   return m_args[i];
}
 
size_t SCAN_Name::arg_as_integer(size_t i, size_t def_value) const {
   if(i >= arg_count()) {
      return def_value;
   }
   return to_u32bit(m_args[i]);
}
 
size_t SCAN_Name::arg_as_integer(size_t i) const {
   return to_u32bit(arg(i));
}
 
}  // namespace Botan