Support a trusted SHA1 fingerprint to be configured for each IRC server

louloulibs/network/credentials_manager.cpp

@@ -26,11 +26,17 @@ bool Basic_Credentials_Manager::certs_loaded = false;
 
 Basic_Credentials_Manager::Basic_Credentials_Manager(const TCPSocketHandler* const socket_handler):
     Botan::Credentials_Manager(),
-    socket_handler(socket_handler)
+    socket_handler(socket_handler),
+    trusted_fingerprint{}
 {
   this->load_certs();
 }
 
+void Basic_Credentials_Manager::set_trusted_fingerprint(const std::string& fingerprint)
+{
+  this->trusted_fingerprint = fingerprint;
+}
+
 void Basic_Credentials_Manager::verify_certificate_chain(const std::string& type,
                                                          const std::string& purported_hostname,
                                                          const std::vector<Botan::X509_Certificate>& certs)
@@ -44,6 +50,13 @@ void Basic_Credentials_Manager::verify_certificate_chain(const std::string& type
   catch (const std::exception& tls_exception)
     {
       log_warning("TLS certificate check failed: " << tls_exception.what());
+      if (!this->trusted_fingerprint.empty() && !certs.empty() &&
+          this->trusted_fingerprint == certs[0].fingerprint() &&
+          certs[0].matches_dns_name(purported_hostname))
+        // We trust the certificate, based on the trusted fingerprint and
+        // the fact that the hostname matches
+        return;
+
       if (this->socket_handler->abort_on_invalid_cert())
         throw;
     }

louloulibs/network/credentials_manager.hpp

@@ -19,6 +19,7 @@ public:
                                 const std::vector<Botan::X509_Certificate>&) override final;
   std::vector<Botan::Certificate_Store*> trusted_certificate_authorities(const std::string& type,
                                                                          const std::string& context) override final;
+  void set_trusted_fingerprint(const std::string& fingerprint);
 
 private:
   const TCPSocketHandler* const socket_handler;
@@ -26,6 +27,7 @@ private:
   static void load_certs();
   static Botan::Certificate_Store_In_Memory certificate_store;
   static bool certs_loaded;
+  std::string trusted_fingerprint;
 };
 
 #endif //BOTAN_FOUND

louloulibs/network/tcp_socket_handler.hpp

@@ -248,7 +248,9 @@ private:
   static Botan::AutoSeeded_RNG rng;
   static Botan::TLS::Policy policy;
   static Botan::TLS::Session_Manager_In_Memory session_manager;
+protected:
   Basic_Credentials_Manager credential_manager;
+private:
   /**
    * We use a unique_ptr because we may not want to create the object at
    * all. The Botan::TLS::Client object generates a handshake message and