[4497] Fix constness of methods in Option classes.

30 files changed, 129 insertions, 130 deletions

diff --git a/src/lib/dhcp/option.cc b/src/lib/dhcp/option.cc
index b3f8786980..d91c4a411c 100644
--- a/src/lib/dhcp/option.cc
+++ b/src/lib/dhcp/option.cc
@@ -54,7 +54,7 @@ Option::Option(Universe u, uint16_t type, OptionBufferConstIter first,
 }
 
 void
-Option::check() {
+Option::check() const {
     if ( (universe_ != V4) && (universe_ != V6) ) {
         isc_throw(BadValue, "Invalid universe type specified. "
                   << "Only V4 and V6 are allowed.");
@@ -77,7 +77,7 @@ Option::check() {
     // both types and data size.
 }
 
-void Option::pack(isc::util::OutputBuffer& buf) {
+void Option::pack(isc::util::OutputBuffer& buf) const {
     // Write a header.
     packHeader(buf);
     // Write data.
@@ -89,7 +89,7 @@ void Option::pack(isc::util::OutputBuffer& buf) {
 }
 
 void
-Option::packHeader(isc::util::OutputBuffer& buf) {
+Option::packHeader(isc::util::OutputBuffer& buf) const {
     if (universe_ == V4) {
         if (len() > 255) {
             isc_throw(OutOfRange, "DHCPv4 Option " << type_ << " is too big. "
@@ -109,7 +109,7 @@ Option::packHeader(isc::util::OutputBuffer& buf) {
 }
 
 void
-Option::packOptions(isc::util::OutputBuffer& buf) {
+Option::packOptions(isc::util::OutputBuffer& buf) const {
     switch (universe_) {
     case V4:
         LibDHCP::packOptions4(buf, options_);
@@ -141,7 +141,7 @@ Option::unpackOptions(const OptionBuffer& buf) {
     }
 }
 
-uint16_t Option::len() {
+uint16_t Option::len() const {
     // Returns length of the complete option (data length + DHCPv4/DHCPv6
     // option header)
 
@@ -149,7 +149,7 @@ uint16_t Option::len() {
     size_t length = getHeaderLen() + data_.size();
 
     // ... and sum of lengths of all suboptions
-    for (OptionCollection::iterator it = options_.begin();
+    for (OptionCollection::const_iterator it = options_.begin();
          it != options_.end();
          ++it) {
         length += (*it).second->len();
@@ -162,7 +162,7 @@ uint16_t Option::len() {
 }
 
 bool
-Option::valid() {
+Option::valid() const {
     if (universe_ != V4 &&
         universe_ != V6) {
         return (false);
@@ -171,7 +171,7 @@ Option::valid() {
     return (true);
 }
 
-OptionPtr Option::getOption(uint16_t opt_type) {
+OptionPtr Option::getOption(uint16_t opt_type) const {
     isc::dhcp::OptionCollection::const_iterator x =
         options_.find(opt_type);
     if ( x != options_.end() ) {
@@ -190,7 +190,7 @@ bool Option::delOption(uint16_t opt_type) {
 }
 
 
-std::string Option::toText(int indent) {
+std::string Option::toText(int indent) const {
     std::stringstream output;
     output << headerToText(indent) << ": ";
 
@@ -209,13 +209,13 @@ std::string Option::toText(int indent) {
 }
 
 std::string
-Option::toString() {
+Option::toString() const {
     /// @todo: Implement actual conversion in derived classes.
     return (toText(0));
 }
 
 std::vector<uint8_t>
-Option::toBinary(const bool include_header) {
+Option::toBinary(const bool include_header) const {
     OutputBuffer buf(len());
     try {
         // If the option is too long, exception will be thrown. We allow
@@ -236,7 +236,7 @@ Option::toBinary(const bool include_header) {
 }
 
 std::string
-Option::toHexString(const bool include_header) {
+Option::toHexString(const bool include_header) const {
     // Prepare binary version of the option.
     std::vector<uint8_t> option_vec = toBinary(include_header);
 
@@ -250,7 +250,7 @@ Option::toHexString(const bool include_header) {
 }
 
 std::string
-Option::headerToText(const int indent, const std::string& type_name) {
+Option::headerToText(const int indent, const std::string& type_name) const {
     std::stringstream output;
     for (int i = 0; i < indent; i++)
         output << " ";
@@ -284,7 +284,7 @@ Option::suboptionsToText(const int indent) const {
 }
 
 uint16_t
-Option::getHeaderLen() {
+Option::getHeaderLen() const {
     switch (universe_) {
     case V4:
         return OPTION4_HDR_LEN; // header length for v4
@@ -305,7 +305,7 @@ void Option::addOption(OptionPtr opt) {
     options_.insert(make_pair(opt->getType(), opt));
 }
 
-uint8_t Option::getUint8() {
+uint8_t Option::getUint8() const {
     if (data_.size() < sizeof(uint8_t) ) {
         isc_throw(OutOfRange, "Attempt to read uint8 from option " << type_
                   << " that has size " << data_.size());
@@ -313,12 +313,12 @@ uint8_t Option::getUint8() {
     return (data_[0]);
 }
 
-uint16_t Option::getUint16() {
+uint16_t Option::getUint16() const {
     // readUint16() checks and throws OutOfRange if data_ is too small.
     return (readUint16(&data_[0], data_.size()));
 }
 
-uint32_t Option::getUint32() {
+uint32_t Option::getUint32() const {
     // readUint32() checks and throws OutOfRange if data_ is too small.
     return (readUint32(&data_[0], data_.size()));
 }
diff --git a/src/lib/dhcp/option.h b/src/lib/dhcp/option.h
index 61eade0d64..181f28924a 100644
--- a/src/lib/dhcp/option.h
+++ b/src/lib/dhcp/option.h
@@ -158,7 +158,7 @@ public:
     /// @param buf pointer to a buffer
     ///
     /// @throw BadValue Universe of the option is neither V4 nor V6.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer.
     ///
@@ -172,7 +172,7 @@ public:
     /// @param indent number of spaces before printing text
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns string representation of the value
     ///
@@ -180,7 +180,7 @@ public:
     /// refers to a specific option.
     ///
     /// @return string that represents the value of the option.
-    virtual std::string toString();
+    virtual std::string toString() const;
 
     /// @brief Returns binary representation of the option.
     ///
@@ -189,7 +189,7 @@ public:
     /// header fields.
     ///
     /// @return Vector holding binary representation of the option.
-    virtual std::vector<uint8_t> toBinary(const bool include_header = false);
+    virtual std::vector<uint8_t> toBinary(const bool include_header = false) const;
 
     /// @brief Returns string containing hexadecimal representation of option.
     ///
@@ -198,7 +198,7 @@ public:
     /// header fields.
     ///
     /// @return String containing hexadecimal representation of the option.
-    virtual std::string toHexString(const bool include_header = false);
+    virtual std::string toHexString(const bool include_header = false) const;
 
     /// Returns option type (0-255 for DHCPv4, 0-65535 for DHCPv6)
     ///
@@ -209,17 +209,17 @@ public:
     /// option header)
     ///
     /// @return length of the option
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns length of header (2 for v4, 4 for v6)
     ///
     /// @return length of option header
-    virtual uint16_t getHeaderLen();
+    virtual uint16_t getHeaderLen() const;
 
     /// returns if option is valid (e.g. option may be truncated)
     ///
     /// @return true, if option is valid
-    virtual bool valid();
+    virtual bool valid() const;
 
     /// Returns pointer to actual data.
     ///
@@ -246,7 +246,7 @@ public:
     /// @param type type of requested suboption
     ///
     /// @return shared_ptr to requested suoption
-    OptionPtr getOption(uint16_t type);
+    OptionPtr getOption(uint16_t type) const;
 
     /// @brief Returns all encapsulated options.
     ///
@@ -269,21 +269,21 @@ public:
     /// @throw isc::OutOfRange Thrown if the option has a length of 0.
     ///
     /// @return value of the first byte
-    uint8_t getUint8();
+    uint8_t getUint8() const;
 
     /// @brief Returns content of first word.
     ///
     /// @throw isc::OutOfRange Thrown if the option has a length less than 2.
     ///
     /// @return uint16_t value stored on first two bytes
-    uint16_t getUint16();
+    uint16_t getUint16() const;
 
     /// @brief Returns content of first double word.
     ///
     /// @throw isc::OutOfRange Thrown if the option has a length less than 4.
     ///
     /// @return uint32_t value stored on first four bytes
-    uint32_t getUint32();
+    uint32_t getUint32() const;
 
     /// @brief Sets content of this option to singe uint8 value.
     ///
@@ -378,7 +378,7 @@ protected:
     /// directly by other classes.
     ///
     /// @param [out] buf output buffer.
-    void packHeader(isc::util::OutputBuffer& buf);
+    void packHeader(isc::util::OutputBuffer& buf) const;
 
     /// @brief Store sub options in a buffer.
     ///
@@ -393,7 +393,7 @@ protected:
     /// exceptions thrown by pack methods invoked on objects
     /// representing sub options. We should consider whether to aggregate
     /// those into one exception which can be documented here.
-    void packOptions(isc::util::OutputBuffer& buf);
+    void packOptions(isc::util::OutputBuffer& buf) const;
 
     /// @brief Builds a collection of sub options from the buffer.
     ///
@@ -420,7 +420,7 @@ protected:
     ///
     /// @return Option header in the textual format.
     std::string headerToText(const int indent = 0,
-                             const std::string& type_name = "");
+                             const std::string& type_name = "") const;
 
     /// @brief Returns collection of suboptions in the textual format.
     ///
@@ -441,7 +441,7 @@ protected:
     /// It is used in constructors. In there are any problems detected
     /// (like specifying type > 255 for DHCPv4 option), it will throw
     /// BadValue or OutOfRange exceptions.
-    void check();
+    void check() const;
 
     /// option universe (V4 or V6)
     Universe universe_;
diff --git a/src/lib/dhcp/option4_addrlst.cc b/src/lib/dhcp/option4_addrlst.cc
index 8e24c5e0ca..981fe8dc75 100644
--- a/src/lib/dhcp/option4_addrlst.cc
+++ b/src/lib/dhcp/option4_addrlst.cc
@@ -56,7 +56,7 @@ Option4AddrLst::Option4AddrLst(uint8_t type, const IOAddress& addr)
 }
 
 void
-Option4AddrLst::pack(isc::util::OutputBuffer& buf) {
+Option4AddrLst::pack(isc::util::OutputBuffer& buf) const {
 
     if (addrs_.size() * V4ADDRESS_LEN > 255) {
         isc_throw(OutOfRange, "DHCPv4 Option4AddrLst " << type_ << " is too big."
@@ -106,13 +106,13 @@ void Option4AddrLst::addAddress(const isc::asiolink::IOAddress& addr) {
     addrs_.push_back(addr);
 }
 
-uint16_t Option4AddrLst::len() {
+uint16_t Option4AddrLst::len() const {
 
     // Returns length of the complete option (option header + data length)
     return (getHeaderLen() + addrs_.size() * V4ADDRESS_LEN);
 }
 
-std::string Option4AddrLst::toText(int indent) {
+std::string Option4AddrLst::toText(int indent) const {
     std::stringstream output;
     output << headerToText(indent) << ":";
 
diff --git a/src/lib/dhcp/option4_addrlst.h b/src/lib/dhcp/option4_addrlst.h
index 2a4f41cd79..02777569f2 100644
--- a/src/lib/dhcp/option4_addrlst.h
+++ b/src/lib/dhcp/option4_addrlst.h
@@ -85,20 +85,20 @@ public:
     /// Method will throw if option storing fails for some reason.
     ///
     /// @param buf output buffer (option will be stored there)
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// Returns string representation of the option.
     ///
     /// @param indent number of spaces before printing text
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// Returns length of the complete option (data length + DHCPv4/DHCPv6
     /// option header)
     ///
     /// @return length of the option
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns vector with addresses.
     ///
diff --git a/src/lib/dhcp/option4_client_fqdn.cc b/src/lib/dhcp/option4_client_fqdn.cc
index 3fda78635e..5dd571bceb 100644
--- a/src/lib/dhcp/option4_client_fqdn.cc
+++ b/src/lib/dhcp/option4_client_fqdn.cc
@@ -463,7 +463,7 @@ Option4ClientFqdn::getDomainNameType() const {
 }
 
 void
-Option4ClientFqdn::pack(isc::util::OutputBuffer& buf) {
+Option4ClientFqdn::pack(isc::util::OutputBuffer& buf) const {
     // Header = option code and length.
     packHeader(buf);
     // Flags field.
@@ -487,7 +487,7 @@ Option4ClientFqdn::unpack(OptionBufferConstIter first,
 }
 
 std::string
-Option4ClientFqdn::toText(int indent) {
+Option4ClientFqdn::toText(int indent) const {
     std::ostringstream stream;
     std::string in(indent, ' '); // base indentation
     stream << in  << "type=" << type_ << " (CLIENT_FQDN), "
@@ -504,7 +504,7 @@ Option4ClientFqdn::toText(int indent) {
 }
 
 uint16_t
-Option4ClientFqdn::len() {
+Option4ClientFqdn::len() const {
     uint16_t domain_name_length = 0;
     // Try to calculate the length of the domain name only if there is
     // any domain name specified.
diff --git a/src/lib/dhcp/option4_client_fqdn.h b/src/lib/dhcp/option4_client_fqdn.h
index f59bc4ecd1..c23bb8ecc7 100644
--- a/src/lib/dhcp/option4_client_fqdn.h
+++ b/src/lib/dhcp/option4_client_fqdn.h
@@ -299,7 +299,7 @@ public:
    /// @brief Writes option in the wire format into a buffer.
     ///
     /// @param [out] buf output buffer where option data will be stored.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses option from the received buffer.
     ///
@@ -322,13 +322,13 @@ public:
     /// @param indent number of spaces before printed text.
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns length of the complete option (data length +
     /// DHCPv4 option header).
     ///
     /// @return length of the option.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     ///
     /// @name Well known Rcode declarations for DHCPv4 Client FQDN %Option
diff --git a/src/lib/dhcp/option6_addrlst.cc b/src/lib/dhcp/option6_addrlst.cc
index 5547187eae..f71537c254 100644
--- a/src/lib/dhcp/option6_addrlst.cc
+++ b/src/lib/dhcp/option6_addrlst.cc
@@ -56,7 +56,7 @@ Option6AddrLst::setAddresses(const AddressContainer& addrs) {
     addrs_ = addrs;
 }
 
-void Option6AddrLst::pack(isc::util::OutputBuffer& buf) {
+void Option6AddrLst::pack(isc::util::OutputBuffer& buf) const {
 
     buf.writeUint16(type_);
 
@@ -89,7 +89,7 @@ void Option6AddrLst::unpack(OptionBufferConstIter begin,
     }
 }
 
-std::string Option6AddrLst::toText(int indent) {
+std::string Option6AddrLst::toText(int indent) const {
     stringstream output;
     output << headerToText(indent) << ":";
 
@@ -100,7 +100,7 @@ std::string Option6AddrLst::toText(int indent) {
     return (output.str());
 }
 
-uint16_t Option6AddrLst::len() {
+uint16_t Option6AddrLst::len() const {
     return (OPTION6_HDR_LEN + addrs_.size() * V6ADDRESS_LEN);
 }
 
diff --git a/src/lib/dhcp/option6_addrlst.h b/src/lib/dhcp/option6_addrlst.h
index da6475d3eb..0b22a1b4f8 100644
--- a/src/lib/dhcp/option6_addrlst.h
+++ b/src/lib/dhcp/option6_addrlst.h
@@ -48,7 +48,7 @@ public:
     /// @brief Assembles on-wire form of this option
     ///
     /// @param buf pointer to packet buffer
-    void pack(isc::util::OutputBuffer& buf);
+    void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received data
     ///
@@ -57,7 +57,7 @@ public:
     virtual void unpack(OptionBufferConstIter begin,
                         OptionBufferConstIter end);
 
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Sets a single address.
     ///
@@ -80,7 +80,7 @@ public:
     AddressContainer getAddresses() const { return addrs_; };
 
     // returns data length (data length + DHCPv4/DHCPv6 option header)
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
 protected:
     AddressContainer addrs_;
diff --git a/src/lib/dhcp/option6_client_fqdn.cc b/src/lib/dhcp/option6_client_fqdn.cc
index cad4282254..020f8efe24 100644
--- a/src/lib/dhcp/option6_client_fqdn.cc
+++ b/src/lib/dhcp/option6_client_fqdn.cc
@@ -395,7 +395,7 @@ Option6ClientFqdn::getDomainNameType() const {
 }
 
 void
-Option6ClientFqdn::pack(isc::util::OutputBuffer& buf) {
+Option6ClientFqdn::pack(isc::util::OutputBuffer& buf) const {
     // Header = option code and length.
     packHeader(buf);
     // Flags field.
@@ -416,7 +416,7 @@ Option6ClientFqdn::unpack(OptionBufferConstIter first,
 }
 
 std::string
-Option6ClientFqdn::toText(int indent) {
+Option6ClientFqdn::toText(int indent) const {
     std::ostringstream stream;
     std::string in(indent, ' '); // base indentation
     stream << in  << "type=" << type_ << "(CLIENT_FQDN)" << ", "
@@ -432,7 +432,7 @@ Option6ClientFqdn::toText(int indent) {
 }
 
 uint16_t
-Option6ClientFqdn::len() {
+Option6ClientFqdn::len() const {
     uint16_t domain_name_length = 0;
     if (impl_->domain_name_) {
         // If domain name is partial, the NULL terminating character
diff --git a/src/lib/dhcp/option6_client_fqdn.h b/src/lib/dhcp/option6_client_fqdn.h
index fae7b312f0..3f7d5f6c9c 100644
--- a/src/lib/dhcp/option6_client_fqdn.h
+++ b/src/lib/dhcp/option6_client_fqdn.h
@@ -217,7 +217,7 @@ public:
    /// @brief Writes option in the wire format into a buffer.
     ///
     /// @param [out] buf output buffer where option data will be stored.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses option from the received buffer.
     ///
@@ -240,13 +240,13 @@ public:
     /// @param indent number of spaces before printed text.
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns length of the complete option (data length +
     /// DHCPv6 option header).
     ///
     /// @return length of the option.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
 private:
 
diff --git a/src/lib/dhcp/option6_ia.cc b/src/lib/dhcp/option6_ia.cc
index ccb4d82425..bfcce7e244 100644
--- a/src/lib/dhcp/option6_ia.cc
+++ b/src/lib/dhcp/option6_ia.cc
@@ -48,7 +48,7 @@ Option6IA::Option6IA(uint16_t type, OptionBufferConstIter begin,
     unpack(begin, end);
 }
 
-void Option6IA::pack(isc::util::OutputBuffer& buf) {
+void Option6IA::pack(isc::util::OutputBuffer& buf) const {
     buf.writeUint16(type_);
     buf.writeUint16(len() - OPTION6_HDR_LEN);
     buf.writeUint32(iaid_);
@@ -76,7 +76,7 @@ void Option6IA::unpack(OptionBufferConstIter begin,
     unpackOptions(OptionBuffer(begin, end));
 }
 
-std::string Option6IA::toText(int indent) {
+std::string Option6IA::toText(int indent) const {
     stringstream output;
 
     switch(getType()) {
@@ -96,13 +96,13 @@ std::string Option6IA::toText(int indent) {
     return (output.str());
 }
 
-uint16_t Option6IA::len() {
+uint16_t Option6IA::len() const {
 
     uint16_t length = OPTION6_HDR_LEN /*header (4)*/ +
         OPTION6_IA_LEN  /* option content (12) */;
 
     // length of all suboptions
-    for (OptionCollection::iterator it = options_.begin();
+    for (OptionCollection::const_iterator it = options_.begin();
          it != options_.end();
          ++it) {
         length += (*it).second->len();
diff --git a/src/lib/dhcp/option6_ia.h b/src/lib/dhcp/option6_ia.h
index bd49c36fdb..315b6ff3ef 100644
--- a/src/lib/dhcp/option6_ia.h
+++ b/src/lib/dhcp/option6_ia.h
@@ -43,7 +43,7 @@ public:
     /// byte after stored option.
     ///
     /// @param buf buffer (option will be stored here)
-    void pack(isc::util::OutputBuffer& buf);
+    void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer
     ///
@@ -59,8 +59,7 @@ public:
     /// @param indent number of leading space characters
     ///
     /// @return string with text represenation
-    virtual std::string
-    toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// Sets T1 timer.
     ///
@@ -98,7 +97,7 @@ public:
     /// Returns length of this option, including option header and suboptions
     ///
     /// @return length of this option
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
 protected:
 
diff --git a/src/lib/dhcp/option6_iaaddr.cc b/src/lib/dhcp/option6_iaaddr.cc
index c360889535..4f6812130d 100644
--- a/src/lib/dhcp/option6_iaaddr.cc
+++ b/src/lib/dhcp/option6_iaaddr.cc
@@ -42,7 +42,7 @@ Option6IAAddr::Option6IAAddr(uint32_t type, OptionBuffer::const_iterator begin,
     unpack(begin, end);
 }
 
-void Option6IAAddr::pack(isc::util::OutputBuffer& buf) {
+void Option6IAAddr::pack(isc::util::OutputBuffer& buf) const {
 
     buf.writeUint16(type_);
 
@@ -81,7 +81,7 @@ void Option6IAAddr::unpack(OptionBuffer::const_iterator begin,
     unpackOptions(OptionBuffer(begin, end));
 }
 
-std::string Option6IAAddr::toText(int indent) {
+std::string Option6IAAddr::toText(int indent) const {
     std::stringstream output;
     output << headerToText(indent, "IAADDR") << ": "
            << "address=" << addr_
@@ -92,14 +92,14 @@ std::string Option6IAAddr::toText(int indent) {
     return (output.str());
 }
 
-uint16_t Option6IAAddr::len() {
+uint16_t Option6IAAddr::len() const {
 
     uint16_t length = OPTION6_HDR_LEN + OPTION6_IAADDR_LEN;
 
     // length of all suboptions
     // TODO implement:
     // protected: unsigned short Option::lenHelper(int header_size);
-    for (OptionCollection::iterator it = options_.begin();
+    for (OptionCollection::const_iterator it = options_.begin();
          it != options_.end();
          ++it) {
         length += (*it).second->len();
diff --git a/src/lib/dhcp/option6_iaaddr.h b/src/lib/dhcp/option6_iaaddr.h
index 83996581b3..1425a4ce1f 100644
--- a/src/lib/dhcp/option6_iaaddr.h
+++ b/src/lib/dhcp/option6_iaaddr.h
@@ -52,7 +52,7 @@ public:
     /// byte after stored option.
     ///
     /// @param buf pointer to a buffer
-    void pack(isc::util::OutputBuffer& buf);
+    void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer.
     ///
@@ -67,7 +67,7 @@ public:
     ///
     /// @return string with text representation.
     virtual std::string
-    toText(int indent = 0);
+    toText(int indent = 0) const;
 
 
     /// sets address in this option.
@@ -106,7 +106,7 @@ public:
     getValid() const { return valid_; }
 
     /// returns data length (data length + DHCPv4/DHCPv6 option header)
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
 protected:
     /// contains an IPv6 address
diff --git a/src/lib/dhcp/option6_iaprefix.cc b/src/lib/dhcp/option6_iaprefix.cc
index b61bd88dcb..5b96247169 100644
--- a/src/lib/dhcp/option6_iaprefix.cc
+++ b/src/lib/dhcp/option6_iaprefix.cc
@@ -44,7 +44,7 @@ Option6IAPrefix::Option6IAPrefix(uint32_t type, OptionBuffer::const_iterator beg
     unpack(begin, end);
 }
 
-void Option6IAPrefix::pack(isc::util::OutputBuffer& buf) {
+void Option6IAPrefix::pack(isc::util::OutputBuffer& buf) const {
     if (!addr_.isV6()) {
         isc_throw(isc::BadValue, addr_ << " is not an IPv6 address");
     }
@@ -90,7 +90,7 @@ void Option6IAPrefix::unpack(OptionBuffer::const_iterator begin,
     unpackOptions(OptionBuffer(begin, end));
 }
 
-std::string Option6IAPrefix::toText(int indent) {
+std::string Option6IAPrefix::toText(int indent) const {
     std::stringstream output;
     output << headerToText(indent, "IAPREFIX") << ": "
            << "prefix=" << addr_ << "/" << static_cast<int>(prefix_len_)
@@ -101,7 +101,7 @@ std::string Option6IAPrefix::toText(int indent) {
     return (output.str());
 }
 
-uint16_t Option6IAPrefix::len() {
+uint16_t Option6IAPrefix::len() const {
 
     uint16_t length = OPTION6_HDR_LEN + OPTION6_IAPREFIX_LEN;
 
@@ -117,7 +117,7 @@ void
 Option6IAPrefix::mask(OptionBuffer::const_iterator begin,
                       OptionBuffer::const_iterator end,
                       const uint8_t len,
-                      OptionBuffer& output_address) {
+                      OptionBuffer& output_address) const {
     output_address.resize(16, 0);
     if (len >= 128) {
         std::copy(begin, end, output_address.begin());
diff --git a/src/lib/dhcp/option6_iaprefix.h b/src/lib/dhcp/option6_iaprefix.h
index d15786b03e..e6c588d5e9 100644
--- a/src/lib/dhcp/option6_iaprefix.h
+++ b/src/lib/dhcp/option6_iaprefix.h
@@ -82,7 +82,7 @@ public:
     /// @throw BadValue if the address is not IPv6
     ///
     /// @param buf pointer to a buffer
-    void pack(isc::util::OutputBuffer& buf);
+    void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer.
     ///
@@ -103,7 +103,7 @@ public:
     /// @param indent number of spaces before printing text
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// sets address in this option.
     ///
@@ -115,7 +115,7 @@ public:
     uint8_t getLength() const { return prefix_len_; }
 
     /// returns data length (data length + DHCPv4/DHCPv6 option header)
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
 private:
 
@@ -130,7 +130,7 @@ private:
     void mask(OptionBuffer::const_iterator begin,
               OptionBuffer::const_iterator end,
               const uint8_t len,
-              OptionBuffer& output_address);
+              OptionBuffer& output_address) const;
 
     uint8_t prefix_len_;
 };
diff --git a/src/lib/dhcp/option6_status_code.cc b/src/lib/dhcp/option6_status_code.cc
index 5277843ff2..e46315839f 100644
--- a/src/lib/dhcp/option6_status_code.cc
+++ b/src/lib/dhcp/option6_status_code.cc
@@ -41,7 +41,7 @@ Option6StatusCode::Option6StatusCode(OptionBufferConstIter begin,
 }
 
 void
-Option6StatusCode::pack(isc::util::OutputBuffer& buf) {
+Option6StatusCode::pack(isc::util::OutputBuffer& buf) const {
     // Pack option header.
     packHeader(buf);
     // Write numeric status code.
@@ -69,12 +69,12 @@ Option6StatusCode::unpack(OptionBufferConstIter begin, OptionBufferConstIter end
 }
 
 uint16_t
-Option6StatusCode::len() {
+Option6StatusCode::len() const {
     return (getHeaderLen() + sizeof(uint16_t) + status_message_.size());
 }
 
 std::string
-Option6StatusCode::toText(int indent) {
+Option6StatusCode::toText(int indent) const {
     std::ostringstream output;
     output << headerToText(indent) << ": " << dataToText();
 
diff --git a/src/lib/dhcp/option6_status_code.h b/src/lib/dhcp/option6_status_code.h
index 028cf2609f..c022c59e43 100644
--- a/src/lib/dhcp/option6_status_code.h
+++ b/src/lib/dhcp/option6_status_code.h
@@ -43,7 +43,7 @@ public:
     /// byte after stored option.
     ///
     /// @param [out] buf Pointer to the output buffer.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer.
     ///
@@ -54,12 +54,12 @@ public:
     /// @brief Returns total length of the option.
     ///
     /// The returned length is a sum of the option header and data fields.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns textual representation of the option.
     ///
     /// @param indent Number of spaces before printing text.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns textual representation of the option data.
     ///
diff --git a/src/lib/dhcp/option_custom.cc b/src/lib/dhcp/option_custom.cc
index 79d0aca57e..1d99da7449 100644
--- a/src/lib/dhcp/option_custom.cc
+++ b/src/lib/dhcp/option_custom.cc
@@ -357,7 +357,7 @@ OptionCustom::dataFieldToText(const OptionDataType data_type,
 }
 
 void
-OptionCustom::pack(isc::util::OutputBuffer& buf) {
+OptionCustom::pack(isc::util::OutputBuffer& buf) const {
 
     // Pack DHCP header (V4 or V6).
     packHeader(buf);
@@ -494,7 +494,7 @@ OptionCustom::unpack(OptionBufferConstIter begin,
 }
 
 uint16_t
-OptionCustom::len() {
+OptionCustom::len() const {
     // The length of the option is a sum of option header ...
     size_t length = getHeaderLen();
 
@@ -505,7 +505,7 @@ OptionCustom::len() {
     }
 
     // ... and lengths of all suboptions
-    for (OptionCollection::iterator it = options_.begin();
+    for (OptionCollection::const_iterator it = options_.begin();
          it != options_.end();
          ++it) {
         length += (*it).second->len();
@@ -523,7 +523,7 @@ void OptionCustom::initialize(const OptionBufferConstIter first,
     createBuffers(getData());
 }
 
-std::string OptionCustom::toText(int indent) {
+std::string OptionCustom::toText(int indent) const {
     std::stringstream output;
 
     output << headerToText(indent) << ":";
diff --git a/src/lib/dhcp/option_custom.h b/src/lib/dhcp/option_custom.h
index d3e0147afc..e766ebef18 100644
--- a/src/lib/dhcp/option_custom.h
+++ b/src/lib/dhcp/option_custom.h
@@ -243,7 +243,7 @@ public:
     /// @brief Writes DHCP option in a wire format to a buffer.
     ///
     /// @param buf output buffer (option will be stored there).
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer.
     ///
@@ -257,13 +257,13 @@ public:
     /// @param indent number of spaces before printed text.
     ///
     /// @return string with text representation.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns length of the complete option (data length +
     ///        DHCPv4/DHCPv6 option header)
     ///
     /// @return length of the option
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Sets content of this option from buffer.
     ///
diff --git a/src/lib/dhcp/option_int.h b/src/lib/dhcp/option_int.h
index 868ee3ca58..2aa81ecbc8 100644
--- a/src/lib/dhcp/option_int.h
+++ b/src/lib/dhcp/option_int.h
@@ -98,7 +98,7 @@ public:
     /// @throw isc::dhcp::InvalidDataType if size of a data field type is not
     /// equal to 1, 2 or 4 bytes. The data type is not checked in this function
     /// because it is checked in a constructor.
-    void pack(isc::util::OutputBuffer& buf) {
+    void pack(isc::util::OutputBuffer& buf) const {
         // Pack option header.
         packHeader(buf);
         // Depending on the data type length we use different utility functions
@@ -184,13 +184,13 @@ public:
     /// Returns length of this option, including option header and suboptions
     ///
     /// @return length of this option
-    virtual uint16_t len() {
+    virtual uint16_t len() const {
         // Calculate the length of the header.
         uint16_t length = (getUniverse() == Option::V4) ? OPTION4_HDR_LEN : OPTION6_HDR_LEN;
         // The data length is equal to size of T.
         length += sizeof(T);;
         // length of all suboptions
-        for (OptionCollection::iterator it = options_.begin();
+        for (OptionCollection::const_iterator it = options_.begin();
              it != options_.end();
              ++it) {
             length += (*it).second->len();
@@ -204,7 +204,7 @@ public:
     /// The returned value also includes the suboptions if present.
     ///
     /// @param indent Number of spaces to be inserted before the text.
-    virtual std::string toText(int indent = 0) {
+    virtual std::string toText(int indent = 0) const {
         std::stringstream output;
         output << headerToText(indent) << ": ";
 
diff --git a/src/lib/dhcp/option_int_array.h b/src/lib/dhcp/option_int_array.h
index 6ed029db95..d8a533ab7f 100644
--- a/src/lib/dhcp/option_int_array.h
+++ b/src/lib/dhcp/option_int_array.h
@@ -131,7 +131,7 @@ public:
     /// @throw isc::dhcp::InvalidDataType if size of a data fields type is not
     /// equal to 1, 2 or 4 bytes. The data type is not checked in this function
     /// because it is checked in a constructor.
-    void pack(isc::util::OutputBuffer& buf) {
+    void pack(isc::util::OutputBuffer& buf) const {
         // Pack option header.
         packHeader(buf);
         // Pack option data.
@@ -229,11 +229,11 @@ public:
     /// Returns length of this option, including option header and suboptions
     ///
     /// @return length of this option
-    virtual uint16_t len() {
+    virtual uint16_t len() const {
         uint16_t length = (getUniverse() == Option::V4) ? OPTION4_HDR_LEN : OPTION6_HDR_LEN;
         length += values_.size() * sizeof(T);
         // length of all suboptions
-        for (OptionCollection::iterator it = options_.begin();
+        for (OptionCollection::const_iterator it = options_.begin();
              it != options_.end();
              ++it) {
             length += (*it).second->len();
@@ -247,7 +247,7 @@ public:
     /// the text.
     ///
     /// @return textual representation of the option.
-    virtual std::string toText(int indent = 0) {
+    virtual std::string toText(int indent = 0) const {
         std::stringstream output;
         output << headerToText(indent) << ":";
 
diff --git a/src/lib/dhcp/option_opaque_data_tuples.cc b/src/lib/dhcp/option_opaque_data_tuples.cc
index 1358b6c2d3..28a4a5982a 100644
--- a/src/lib/dhcp/option_opaque_data_tuples.cc
+++ b/src/lib/dhcp/option_opaque_data_tuples.cc
@@ -26,7 +26,7 @@ OptionOpaqueDataTuples::OptionOpaqueDataTuples(Option::Universe u,
 }
 
 void
-OptionOpaqueDataTuples::pack(isc::util::OutputBuffer& buf) {
+OptionOpaqueDataTuples::pack(isc::util::OutputBuffer& buf) const {
     packHeader(buf);
 
     for (TuplesCollection::const_iterator it = tuples_.begin();
@@ -107,7 +107,7 @@ OptionOpaqueDataTuples::hasTuple(const std::string& tuple_str) const {
 }
 
 uint16_t
-OptionOpaqueDataTuples::len() {
+OptionOpaqueDataTuples::len() const {
     // The option starts with the header.
     uint16_t length = getHeaderLen();
     // Now iterate over existing tuples and add their size.
@@ -120,7 +120,7 @@ OptionOpaqueDataTuples::len() {
 }
 
 std::string
-OptionOpaqueDataTuples::toText(int indent) {
+OptionOpaqueDataTuples::toText(int indent) const {
     std::ostringstream s;
 
     // Apply indentation
diff --git a/src/lib/dhcp/option_opaque_data_tuples.h b/src/lib/dhcp/option_opaque_data_tuples.h
index e6016dccbc..18b977c5e5 100644
--- a/src/lib/dhcp/option_opaque_data_tuples.h
+++ b/src/lib/dhcp/option_opaque_data_tuples.h
@@ -65,7 +65,7 @@ public:
     /// @brief Renders option into the buffer in the wire format.
     ///
     /// @param [out] buf Buffer to which the option is rendered.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses buffer holding an option.
     ///
@@ -123,13 +123,13 @@ public:
     bool hasTuple(const std::string& tuple_str) const;
 
     /// @brief Returns the full length of the option, including option header.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns text representation of the option.
     ///
     /// @param indent Number of space characters before text.
     /// @return Text representation of the option.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
 private:
 
diff --git a/src/lib/dhcp/option_string.cc b/src/lib/dhcp/option_string.cc
index c875143217..4e8e6b3a3d 100644
--- a/src/lib/dhcp/option_string.cc
+++ b/src/lib/dhcp/option_string.cc
@@ -48,12 +48,12 @@ OptionString::setValue(const std::string& value) {
 
 
 uint16_t
-OptionString::len() {
+OptionString::len() const {
     return (getHeaderLen() + getData().size());
 }
 
 void
-OptionString::pack(isc::util::OutputBuffer& buf) {
+OptionString::pack(isc::util::OutputBuffer& buf) const {
     // Pack option header.
     packHeader(buf);
     // Pack data.
@@ -76,7 +76,7 @@ OptionString::unpack(OptionBufferConstIter begin,
 }
 
 std::string
-OptionString::toText(int indent) {
+OptionString::toText(int indent) const {
     std::ostringstream output;
     output << headerToText(indent) << ": "
            << "\"" << getValue() << "\" (string)";
@@ -85,7 +85,7 @@ OptionString::toText(int indent) {
 }
 
 std::string
-OptionString::toString() {
+OptionString::toString() const {
     return (getValue());
 }
 
diff --git a/src/lib/dhcp/option_string.h b/src/lib/dhcp/option_string.h
index 147251d4fa..d3a8f83b0d 100644
--- a/src/lib/dhcp/option_string.h
+++ b/src/lib/dhcp/option_string.h
@@ -59,7 +59,7 @@ public:
     /// @brief Returns length of the whole option, including header.
     ///
     /// @return length of the whole option.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns the string value held by the option.
     ///
@@ -80,7 +80,7 @@ public:
     /// is moved to the end of stored data.
     ///
     /// @param [out] buf output buffer where the option will be stored.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Decodes option data from the provided buffer.
     ///
@@ -101,13 +101,13 @@ public:
     /// the text.
     ///
     /// @return Option information in the textual format.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
     /// @brief Returns actual value of the option in string format.
     ///
     /// This method is used in client classification.
     /// @return Content of the option.
-    virtual std::string toString();
+    virtual std::string toString() const;
 };
 
 /// Pointer to the OptionString object.
diff --git a/src/lib/dhcp/option_vendor.cc b/src/lib/dhcp/option_vendor.cc
index 210abac8b0..dd85a2793c 100644
--- a/src/lib/dhcp/option_vendor.cc
+++ b/src/lib/dhcp/option_vendor.cc
@@ -24,7 +24,7 @@ OptionVendor::OptionVendor(Option::Universe u, OptionBufferConstIter begin,
 }
 
 
-void OptionVendor::pack(isc::util::OutputBuffer& buf) {
+void OptionVendor::pack(isc::util::OutputBuffer& buf) const {
     packHeader(buf);
 
     // Store vendor-id
@@ -59,7 +59,7 @@ void OptionVendor::unpack(OptionBufferConstIter begin,
     }
 }
 
-uint16_t OptionVendor::len() {
+uint16_t OptionVendor::len() const {
     uint16_t length = getHeaderLen();
 
     length += sizeof(uint32_t); // Vendor-id field
@@ -70,7 +70,7 @@ uint16_t OptionVendor::len() {
     }
 
     // length of all suboptions
-    for (OptionCollection::iterator it = options_.begin();
+    for (OptionCollection::const_iterator it = options_.begin();
          it != options_.end();
          ++it) {
         length += (*it).second->len();
@@ -79,7 +79,7 @@ uint16_t OptionVendor::len() {
 }
 
 uint8_t
-OptionVendor::dataLen() {
+OptionVendor::dataLen() const {
     // Calculate and store data-len as follows:
     // data-len = total option length - header length
     //            - enterprise id field length - data-len field size
@@ -87,7 +87,7 @@ OptionVendor::dataLen() {
 }
 
 std::string
-OptionVendor::toText(int indent) {
+OptionVendor::toText(int indent) const {
     std::stringstream output;
     output << headerToText(indent) << ": "
            << getVendorId() << " (uint32)";
diff --git a/src/lib/dhcp/option_vendor.h b/src/lib/dhcp/option_vendor.h
index 47fb194022..a0b5b1734e 100644
--- a/src/lib/dhcp/option_vendor.h
+++ b/src/lib/dhcp/option_vendor.h
@@ -54,7 +54,7 @@ public:
     /// unused byte after stored option.
     ///
     /// @param [out] buf buffer (option will be stored here)
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses received buffer
     ///
@@ -82,14 +82,14 @@ public:
     /// Returns length of this option, including option header and suboptions
     ///
     /// @return length of this option
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns the option in the textual format.
     ///
     /// @param indent Number of spaces to be inserted before the text.
     ///
     /// @return Vendor option in the textual format.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
 private:
 
@@ -101,7 +101,7 @@ private:
     /// this value.
     ///
     /// @return Returns calculated data-len value.
-    uint8_t dataLen();
+    uint8_t dataLen() const;
 
     uint32_t vendor_id_;  ///< Enterprise-id
 };
diff --git a/src/lib/dhcp/option_vendor_class.cc b/src/lib/dhcp/option_vendor_class.cc
index b3db4641f0..7ecf5d1e4f 100644
--- a/src/lib/dhcp/option_vendor_class.cc
+++ b/src/lib/dhcp/option_vendor_class.cc
@@ -28,7 +28,7 @@ OptionVendorClass::OptionVendorClass(Option::Universe u,
 }
 
 void
-OptionVendorClass::pack(isc::util::OutputBuffer& buf) {
+OptionVendorClass::pack(isc::util::OutputBuffer& buf) const {
     packHeader(buf);
 
     buf.writeUint32(getVendorId());
@@ -138,7 +138,7 @@ OptionVendorClass::hasTuple(const std::string& tuple_str) const {
 
 
 uint16_t
-OptionVendorClass::len() {
+OptionVendorClass::len() const {
     // The option starts with the header and enterprise id.
     uint16_t length = getHeaderLen() + sizeof(uint32_t);
     // Now iterate over existing tuples and add their size.
@@ -157,7 +157,7 @@ OptionVendorClass::len() {
 }
 
 std::string
-OptionVendorClass::toText(int indent) {
+OptionVendorClass::toText(int indent) const {
     std::ostringstream s;
 
     // Apply indentation
diff --git a/src/lib/dhcp/option_vendor_class.h b/src/lib/dhcp/option_vendor_class.h
index 33b76d9606..2018c838fd 100644
--- a/src/lib/dhcp/option_vendor_class.h
+++ b/src/lib/dhcp/option_vendor_class.h
@@ -72,7 +72,7 @@ public:
     /// @brief Renders option into the buffer in the wire format.
     ///
     /// @param [out] buf Buffer to which the option is rendered.
-    virtual void pack(isc::util::OutputBuffer& buf);
+    virtual void pack(isc::util::OutputBuffer& buf) const;
 
     /// @brief Parses buffer holding an option.
     ///
@@ -135,13 +135,13 @@ public:
     bool hasTuple(const std::string& tuple_str) const;
 
     /// @brief Returns the full length of the option, including option header.
-    virtual uint16_t len();
+    virtual uint16_t len() const;
 
     /// @brief Returns text representation of the option.
     ///
     /// @param indent Number of space characters before text.
     /// @return Text representation of the option.
-    virtual std::string toText(int indent = 0);
+    virtual std::string toText(int indent = 0) const;
 
 private: