Botan::IPv4Subnet Class Reference

#include <ipv4_address.h>

Public Member Functions
const IPv4Address &	address () const
	The network address (host bits already zeroed).
bool	contains (const IPv4Address &ip) const
	True iff ip falls within this subnet.
	IPv4Subnet (IPv4Address address, size_t prefix_length)
bool	is_host () const
	True iff prefix_length() == 32.
size_t	prefix_length () const
	Prefix length in [0, 32].
std::vector< uint8_t >	serialize () const
std::string	to_string () const
	CIDR-style "10.0.0.0/8".

Static Public Member Functions
static std::optional< IPv4Subnet >	from_address_and_mask (std::span< const uint8_t, 8 > addr_and_mask)
static std::optional< IPv4Subnet >	from_address_and_mask (uint32_t addr, uint32_t mask)
static std::optional< IPv4Subnet >	from_string (std::string_view str)
static IPv4Subnet	host (IPv4Address address)

Friends
bool	operator== (const IPv4Subnet &, const IPv4Subnet &)=default

Detailed Description

An IPv4 subnet in CIDR form: a network address paired with a prefix length

Definition at line 90 of file ipv4_address.h.

Constructor & Destructor Documentation

IPv4Subnet()

Botan::IPv4Subnet::IPv4Subnet	(	IPv4Address	address,
		size_t	prefix_length )

Construct from a network address and a prefix length in [0, 32]. Host bits of address are cleared.

Throws Invalid_Argument if prefix_length > 32.

Definition at line 139 of file ipv4_address.cpp.

                                                                :
      m_address(address & IPv4Address::netmask(prefix_length)), m_prefix_length(static_cast<uint8_t>(prefix_length)) {
   // IPv4Address::netmask validates prefix_length <= 32, so by this point
   // the static_cast is in range.
}

References address(), and prefix_length().

Referenced by from_address_and_mask(), from_string(), host(), and operator==.

Member Function Documentation

address()

const IPv4Address & Botan::IPv4Subnet::address ( ) const

inline

The network address (host bits already zeroed).

Definition at line 132 of file ipv4_address.h.

{ return m_address; }

Referenced by host(), IPv4Subnet(), and serialize().

contains()

bool Botan::IPv4Subnet::contains

(

const IPv4Address &

ip

)

const

True iff ip falls within this subnet.

Definition at line 197 of file ipv4_address.cpp.

                                                     {
   return (ip & IPv4Address::netmask(m_prefix_length)) == m_address;
}

References Botan::IPv4Address::netmask().

from_address_and_mask() [1/2]

std::optional< IPv4Subnet > Botan::IPv4Subnet::from_address_and_mask ( std::span< const uint8_t, 8 > addr_and_mask )

static

Construct from a network address and a netmask (4 bytes each) Returns nullopt if netmask is not a valid contiguous CIDR prefix.

Definition at line 154 of file ipv4_address.cpp.

                                                                                                 {
   const IPv4Address addr(load_be<uint32_t>(addr_and_mask.data(), 0));
   const IPv4Address mask(load_be<uint32_t>(addr_and_mask.data(), 1));
 
   if(const auto plen = mask.prefix_length()) {
      return IPv4Subnet(addr, *plen);
   } else {
      return {};
   }
}

References IPv4Subnet(), Botan::load_be(), and Botan::IPv4Address::prefix_length().

Referenced by Botan::GeneralName::decode_from(), from_address_and_mask(), and Botan::GeneralName::ipv4_address().

from_address_and_mask() [2/2]

std::optional< IPv4Subnet > Botan::IPv4Subnet::from_address_and_mask ( uint32_t addr, uint32_t mask )

static

Construct from a network address and a netmask (4 bytes each) Returns nullopt if netmask is not a valid contiguous CIDR prefix.

Definition at line 146 of file ipv4_address.cpp.

                                                                                      {
   std::array<uint8_t, 8> addr_and_mask{};
   store_be(&addr_and_mask[0], addr);  // NOLINT(*-container-data-pointer)
   store_be(&addr_and_mask[4], mask);
   return IPv4Subnet::from_address_and_mask(addr_and_mask);
}

References from_address_and_mask(), and Botan::store_be().

from_string()

std::optional< IPv4Subnet > Botan::IPv4Subnet::from_string ( std::string_view str )

static

Parse CIDR-style form "10.0.0.0/8".

The "/N" suffix is required: bare addresses should be parsed via IPv4Address::from_string and wrapped with IPv4Subnet::host if needed. The input must already be canonical, such that from_string and to_string are exact inverses: the prefix length is canonical decimal ("/8", not "/08") and the host bits are clear ("10.0.0.0/8", not "10.1.2.3/8").

Returns nullopt on parse failure or out-of-range prefix length.

Definition at line 166 of file ipv4_address.cpp.

                                                                  {
   const auto slash = str.find('/');
   if(slash == std::string_view::npos) {
      return std::nullopt;
   }
 
   auto addr = IPv4Address::from_string(str.substr(0, slash));
   if(!addr.has_value()) {
      return std::nullopt;
   }
 
   // Parse the prefix length as a canonical decimal integer in [0, 32]
   const auto plen_str = str.substr(slash + 1);
 
   const auto plen = parse_sz(plen_str, /*require_canonical=*/true);
 
   if(!plen.has_value() || plen.value() > 32) {
      return std::nullopt;
   }
 
   const IPv4Subnet subnet(*addr, plen.value());
 
   // Require the input to already be canonical: from_string and to_string
   // are exact inverses, so a set host bit is rejected rather than masked away
   if(subnet.to_string() != str) {
      return std::nullopt;
   }
 
   return subnet;
}

References Botan::IPv4Address::from_string(), IPv4Subnet(), Botan::parse_sz(), and to_string().

host()

IPv4Subnet Botan::IPv4Subnet::host ( IPv4Address address )

inlinestatic

A single-host subnet (prefix length 32) covering exactly address.

Definition at line 129 of file ipv4_address.h.

{ return IPv4Subnet(address, 32); }

References address(), and IPv4Subnet().

Referenced by Botan::GeneralName::ipv4_address().

is_host()

bool Botan::IPv4Subnet::is_host ( ) const

inline

True iff prefix_length() == 32.

Definition at line 138 of file ipv4_address.h.

{ return m_prefix_length == 32; }

Referenced by serialize().

prefix_length()

size_t Botan::IPv4Subnet::prefix_length ( ) const

inline

Prefix length in [0, 32].

Definition at line 135 of file ipv4_address.h.

{ return m_prefix_length; }

Referenced by IPv4Subnet().

serialize()

std::vector< uint8_t > Botan::IPv4Subnet::serialize

(

)

const

Bytes for use in a DER-encoded GeneralName iPAddress field.

If this is an address (is_host returns true) the output is 4 bytes (the address in network order) Otherwise it is a subnet and the output is 8 bytes (address || netmask)

Definition at line 205 of file ipv4_address.cpp.

                                               {
   std::vector<uint8_t> out;
   if(is_host()) {
      out.resize(4);
      store_be(m_address.address(), out.data());
      return out;
   }
   out.resize(8);
   store_be(m_address.address(), out.data());
   store_be(IPv4Address::netmask(m_prefix_length).address(), out.data() + 4);
   return out;
}

References address(), is_host(), Botan::IPv4Address::netmask(), and Botan::store_be().

to_string()

std::string Botan::IPv4Subnet::to_string

(

)

const

CIDR-style "10.0.0.0/8".

Definition at line 201 of file ipv4_address.cpp.

                                      {
   return fmt("{}/{}", m_address.to_string(), static_cast<size_t>(m_prefix_length));
}

References Botan::fmt().

Referenced by from_string().

Friends And Related Symbol Documentation

operator==

bool operator== ( const IPv4Subnet & , const IPv4Subnet &  )

friend

References IPv4Subnet().

---

The documentation for this class was generated from the following files:

• src/lib/utils/ip_address/ipv4_address.h
• src/lib/utils/ip_address/ipv4_address.cpp