Line data    Source code

       1             : /*
       2             :  *  Copyright (C) 2004-2024 Savoir-faire Linux Inc.
       3             :  *
       4             :  *  This program is free software: you can redistribute it and/or modify
       5             :  *  it under the terms of the GNU General Public License as published by
       6             :  *  the Free Software Foundation, either version 3 of the License, or
       7             :  *  (at your option) any later version.
       8             :  *
       9             :  *  This program is distributed in the hope that it will be useful,
      10             :  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             :  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
      12             :  *  GNU General Public License for more details.
      13             :  *
      14             :  *  You should have received a copy of the GNU General Public License
      15             :  *  along with this program. If not, see <https://www.gnu.org/licenses/>.
      16             :  */
      17             : 
      18             : #include "sdes_negotiator.h"
      19             : 
      20             : #include <iostream>
      21             : #include <sstream>
      22             : #include <algorithm>
      23             : #include <stdexcept>
      24             : #include <regex>
      25             : 
      26             : #include <cstdio>
      27             : 
      28             : namespace jami {
      29             : 
      30             : std::vector<CryptoAttribute>
      31         778 : SdesNegotiator::parse(const std::vector<std::string>& attributes)
      32             : {
      33             :     // The patterns below try to follow
      34             :     // the ABNF grammar rules described in
      35             :     // RFC4568 section 9.2 with the general
      36             :     // syntax :
      37             :     // a=crypto:tag 1*WSP crypto-suite 1*WSP key-params *(1*WSP session-param)
      38             : 
      39             :     // used to match white space (which are used as separator)
      40             : 
      41         778 :     static const std::regex generalSyntaxPattern {"[\x20\x09]+"};
      42             : 
      43         778 :     static const std::regex tagPattern {"^([0-9]{1,9})"};
      44             : 
      45             :     static const std::regex cryptoSuitePattern {"(AES_CM_128_HMAC_SHA1_80|"
      46             :                                                 "AES_CM_128_HMAC_SHA1_32|"
      47             :                                                 "F8_128_HMAC_SHA1_80|"
      48         778 :                                                 "[A-Za-z0-9_]+)"}; // srtp-crypto-suite-ext
      49             : 
      50             :     static const std::regex keyParamsPattern {"(inline|[A-Za-z0-9_]+)\\:"
      51             :                                               "([A-Za-z0-9\x2B\x2F\x3D]+)"
      52             :                                               "((\\|2\\^)([0-9]+)\\|"
      53             :                                               "([0-9]+)\\:"
      54         778 :                                               "([0-9]{1,3})\\;?)?"};
      55             : 
      56             :     // Take each line from the vector
      57             :     // and parse its content
      58             : 
      59         778 :     std::vector<CryptoAttribute> cryptoAttributeVector;
      60             : 
      61        1556 :     for (const auto& item : attributes) {
      62             :         // Split the line into its component that we will analyze further down.
      63             :         // Additional white space is added to better split the content
      64             :         // Result is stored in the sdsLine
      65             : 
      66         778 :         std::vector<std::string> sdesLine;
      67         778 :         std::smatch sm_generalSyntaxPattern;
      68             : 
      69         778 :         std::sregex_token_iterator iter(item.begin(), item.end(), generalSyntaxPattern, -1), end;
      70        3112 :         for (; iter != end; ++iter)
      71        2334 :             sdesLine.push_back(*iter);
      72             : 
      73         778 :         if (sdesLine.size() < 3) {
      74           0 :             throw ParseError("Missing components in SDES line");
      75             :         }
      76             : 
      77             :         // Check if the attribute starts with a=crypto
      78             :         // and get the tag for this line
      79             : 
      80         778 :         std::string tag;
      81         778 :         std::smatch sm_tagPattern;
      82             : 
      83         778 :         if (std::regex_search(sdesLine.at(0), sm_tagPattern, tagPattern)) {
      84         778 :             tag = sm_tagPattern[1];
      85             : 
      86             :         } else {
      87           0 :             throw ParseError("No Matching Found in Tag Attribute");
      88             :         }
      89             : 
      90             :         // Check if the crypto suite is valid and retrieve
      91             :         // its value.
      92             : 
      93         778 :         std::string cryptoSuite;
      94         778 :         std::smatch sm_cryptoSuitePattern;
      95             : 
      96         778 :         if (std::regex_search(sdesLine.at(1), sm_cryptoSuitePattern, cryptoSuitePattern)) {
      97         778 :             cryptoSuite = sm_cryptoSuitePattern[1];
      98             : 
      99             :         } else {
     100           0 :             throw ParseError("No Matching Found in CryptoSuite Attribute");
     101             :         }
     102             : 
     103             :         // Parse one or more key-params field.
     104             :         // Group number is used to locate different paras
     105             : 
     106         778 :         std::string srtpKeyInfo;
     107         778 :         std::string srtpKeyMethod;
     108         778 :         std::string lifetime;
     109         778 :         std::string mkiLength;
     110         778 :         std::string mkiValue;
     111         778 :         std::smatch sm_keyParamsPattern;
     112             : 
     113         778 :         if (std::regex_search(sdesLine.at(2), sm_keyParamsPattern, keyParamsPattern)) {
     114         778 :             srtpKeyMethod = sm_keyParamsPattern[1];
     115         778 :             srtpKeyInfo = sm_keyParamsPattern[2];
     116         778 :             lifetime = sm_keyParamsPattern[5];
     117         778 :             mkiValue = sm_keyParamsPattern[6];
     118         778 :             mkiLength = sm_keyParamsPattern[7];
     119             : 
     120             :         } else {
     121           0 :             throw ParseError("No Matching Found in Key-params Attribute");
     122             :         }
     123             : 
     124             :         // Add the new CryptoAttribute to the vector
     125         778 :         cryptoAttributeVector.emplace_back(std::move(tag),
     126         778 :                                            std::move(cryptoSuite),
     127         778 :                                            std::move(srtpKeyMethod),
     128         778 :                                            std::move(srtpKeyInfo),
     129         778 :                                            std::move(lifetime),
     130         778 :                                            std::move(mkiValue),
     131         778 :                                            std::move(mkiLength));
     132         778 :     }
     133         778 :     return cryptoAttributeVector;
     134           0 : }
     135             : 
     136             : CryptoAttribute
     137         778 : SdesNegotiator::negotiate(const std::vector<std::string>& attributes)
     138             : {
     139             :     try {
     140         778 :         auto cryptoAttributeVector(parse(attributes));
     141         778 :         for (const auto& iter_offer : cryptoAttributeVector) {
     142         778 :             for (const auto& iter_local : CryptoSuites) {
     143         778 :                 if (iter_offer.getCryptoSuite() == iter_local.name)
     144         778 :                     return iter_offer;
     145             :             }
     146             :         }
     147         778 :     } catch (const ParseError& exception) {
     148           0 :     }
     149           0 :     return {};
     150             : }
     151             : 
     152             : } // namespace jami