netadapter.cpp

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// Copyright (C) 2024+ GPL 3 and higher by Ingo Höft, <Ingo@Hoeft-online.de>
// Redistribution only with this Copyright remark. Last modified: 2025-09-15
#include <UPnPsdk/netadapter.hpp>
#include <UPnPsdk/synclog.hpp>
 
 
namespace UPnPsdk {
 
uint8_t netmask_to_bitmask(const ::sockaddr_storage* a_netmask) {
    TRACE("Executing netmask_to_bitmask()")
    if (a_netmask == nullptr)
        throw std::runtime_error(UPnPsdk_LOGEXCEPT(
            "MSG1059") "No network socket address information given.\n");
 
    uint8_t bitmask{};
    uint8_t nullbits{};
    switch (a_netmask->ss_family) {
    case AF_INET6: {
        // Count set bits.
        for (size_t i{}; i < sizeof(in6_addr); i++) {
            uint8_t s6addr = reinterpret_cast<const ::sockaddr_in6*>(a_netmask)
                                 ->sin6_addr.s6_addr[i];
            if (s6addr == 255) {
                bitmask += 8;
            } else {
                while (s6addr) {
                    bitmask++;
                    s6addr <<= 1;
                }
                break; // for() loop
            }
        }
        // Check if all remaining bits are zero.
        for (int i{sizeof(in6_addr) - 1}; i >= 0; i--) {
            uint8_t s6addr = reinterpret_cast<const ::sockaddr_in6*>(a_netmask)
                                 ->sin6_addr.s6_addr[i];
            if (s6addr == 0) {
                nullbits += 8;
            } else {
                while ((s6addr & 1) == 0) {
                    nullbits++;
                    s6addr >>= 1;
                }
                break; // for() loop
            }
        }
        // Check valid netmask.
        if (bitmask + nullbits != 128) {
            char ip_str[INET6_ADDRSTRLEN]{};
            ::inet_ntop(
                AF_INET6,
                &reinterpret_cast<const ::sockaddr_in6*>(a_netmask)->sin6_addr,
                ip_str, sizeof(ip_str));
            throw std::runtime_error(
                UPnPsdk_LOGEXCEPT(
                    "MSG1067") "Invalid ip-address prefix bitmask \"[" +
                std::string(ip_str) + "]\".\n");
        }
    } break; // switch()
 
    case AF_INET: {
        in_addr_t saddr = ntohl(
            reinterpret_cast<const ::sockaddr_in*>(a_netmask)->sin_addr.s_addr);
        in_addr_t saddr0 = saddr;
        // Count set bits.
        while (saddr) {
            bitmask++;
            saddr <<= 1;
        }
        // Check if all remaining bits are zero.
        for (int i{}; (saddr0 & 1) == 0 && i < 32; i++) {
            nullbits++;
            saddr0 >>= 1;
        }
        // Check valid netmask.
        if (bitmask + nullbits != 32) {
            char ip_str[INET_ADDRSTRLEN]{};
            ::inet_ntop(
                AF_INET,
                &reinterpret_cast<const ::sockaddr_in*>(a_netmask)->sin_addr,
                ip_str, sizeof(ip_str));
            throw std::runtime_error(
                UPnPsdk_LOGEXCEPT("MSG1069") "Invalid ip-address netmask \"" +
                std::string(ip_str) + "\".\n");
        }
    } break;
 
    case AF_UNSPEC:
        return 0;
 
    default:
        throw std::runtime_error(
            UPnPsdk_LOGEXCEPT("MSG1028") "Unsupported address family(" +
            std::to_string(a_netmask->ss_family) + "), only AF_INET6(" +
            std::to_string(AF_INET6) + "), AF_INET(" + std::to_string(AF_INET) +
            "), or AF_UNSPEC(" + std::to_string(AF_UNSPEC) + ") are valid.\n");
    } // switch()
 
    return bitmask;
}
 
 
void bitmask_to_netmask(const ::sockaddr_storage* a_saddr,
                        const unsigned int a_prefixlength,
                        SSockaddr& a_saddrObj) {
    TRACE("Executing bitmask_to_netmask()")
    if (a_saddr == nullptr)
        throw std::runtime_error(UPnPsdk_LOGEXCEPT(
            "MSG1070") "No associated socket address for the netmask given.\n");
 
    switch (a_saddr->ss_family) {
    case AF_INET6: {
        // I have to manage 16 bytes from the binary IPv6 address to set its
        // bits. 15 bytes are all ones or all zero bits. Only one byte may have
        // partly ones and zero bits. First I calculate how many leading bytes
        // have full one bits. Following is the partial set byte. The rest are
        // bytes with full zero bits set.
        in6_addr netmask6{};
 
        // All prefix lengths > 128 will throw this exception.
        if (a_prefixlength > 128)
            throw std::runtime_error(
                UPnPsdk_LOGEXCEPT(
                    "MSG1124") "Invalid IPv6 address prefix bitmask(" +
                std::to_string(a_prefixlength) + ") exceeds 128.\n");
 
        // Calculate number of leading bytes with full one bits.
        unsigned int ones_bytes{a_prefixlength / 8};
 
        // Fill leading bytes with all bit ones.
        unsigned int i{};
        for (; i < ones_bytes; i++)
            netmask6.s6_addr[i] = static_cast<uint8_t>(~0);
 
        // Handle the one partly bit-set byte.
        if (i < 16 /*bytes*/) {
            // Preset byte with all bit ones.
            netmask6.s6_addr[i] = static_cast<uint8_t>(~0);
            // Shift remaining zero bits from right into byte with using the
            // reminder from the byte devision.
            netmask6.s6_addr[i] <<= (8 - (a_prefixlength % 8));
            i++;
 
            // Fill remaining bytes with zero bits.
            for (; i < 16 /*bytes*/; i++)
                netmask6.s6_addr[i] = 0;
        }
 
        // Return the result.
        a_saddrObj = "";
        a_saddrObj.sin6.sin6_family = AF_INET6;
        memcpy(&a_saddrObj.sin6.sin6_addr, &netmask6,
               sizeof(a_saddrObj.sin6.sin6_addr));
    } break;
 
    case AF_INET: {
        // All prefix lengths > 32 will throw this exception.
        if (a_prefixlength > 32) {
            throw std::runtime_error(
                UPnPsdk_LOGEXCEPT(
                    "MSG1125") "Invalid IPv4 address prefix bitmask(" +
                std::to_string(a_prefixlength) + ") exceeds 32.\n");
        }
        // Prepare socket address and shift zero bits from right into the mask.
        ::sockaddr_in saddr{};
        saddr.sin_family = AF_INET;
        if (a_prefixlength) {
            in_addr_t bitshift{~0u}; // all one bits
            bitshift <<= (32 - a_prefixlength); // shift zero bits from right
            saddr.sin_addr.s_addr = htonl(bitshift);
        }
        // Return the result.
        a_saddrObj.sin = saddr;
    } break;
 
    case AF_UNSPEC: {
        a_saddrObj = "";
    } break;
 
    default: {
        throw std::runtime_error(
            UPnPsdk_LOGEXCEPT("MSG1126") "Unsupported address family(" +
            std::to_string(a_saddr->ss_family) + "), only AF_INET6(" +
            std::to_string(AF_INET6) + "), AF_INET(" + std::to_string(AF_INET) +
            "), or AF_UNSPEC(" + std::to_string(AF_UNSPEC) + ") are valid.\n");
    }
    } // switch
}
 
 
// CNetadapter class
// =================
CNetadapter::CNetadapter(PNetadapter_platform a_na_platformPtr)
    : m_na_platformPtr(a_na_platformPtr) {
    TRACE2(this, " Construct CNetadapter()") //
}
 
CNetadapter::~CNetadapter() {
    TRACE2(this, " Destruct CNetadapter()")
}
 
void CNetadapter::get_first() { m_na_platformPtr->get_first(); }
 
bool CNetadapter::get_next() { return m_na_platformPtr->get_next(); }
 
unsigned int CNetadapter::index() const { return m_na_platformPtr->index(); }
 
std::string CNetadapter::name() const { return m_na_platformPtr->name(); }
 
void CNetadapter::sockaddr(SSockaddr& a_saddr) const {
    SSockaddr saddr;
    m_na_platformPtr->sockaddr(saddr);
 
    // If there is an IPv4 address then map it to IPv6.
    if (saddr.ss.ss_family == AF_INET) {
        // We will get something like "[::ffff:192.168.1.2]:49494".
        SSockaddr saddr4to6;
        saddr4to6.sin6.sin6_family = AF_INET6;
        saddr4to6.sin6.sin6_port = saddr.sin.sin_port;
        in6_addr& sa6{saddr4to6.sin6.sin6_addr};
        sa6.s6_addr[10] = 0xff; // prefix id for ipv4 mapping.
        sa6.s6_addr[11] = 0xff; //          ./.
        // Copy ipv4 addr into ipv6 addr behind prefix.
        ::memcpy(&sa6.s6_addr[12], &saddr.sin.sin_addr,
                 sizeof(saddr.sin.sin_addr));
 
        a_saddr = saddr4to6;
    } else {
        a_saddr = saddr;
    }
}
 
void CNetadapter::socknetmask(SSockaddr& a_snetmask) const {
    SSockaddr saObj;
    m_na_platformPtr->socknetmask(saObj);
    if (saObj.ss.ss_family == AF_INET) // This will be V4MAPPED
        saObj = "[ffff:ffff:ffff:ffff:ffff:ffff::]"; // V4MAPPED has bitmask 96
    a_snetmask = saObj;
}
 
unsigned int CNetadapter::bitmask() const {
    SSockaddr saObj;
    m_na_platformPtr->sockaddr(saObj);
    if (saObj.ss.ss_family == AF_INET) // This will be V4MAPPED
        return 96; // V4MAPPED has bitmask 96
    return m_na_platformPtr->bitmask();
}
 
void CNetadapter::reset() noexcept {
    m_find_index = 0;
    m_state = Find::finish;
    m_na_platformPtr->reset();
}
 
 
bool CNetadapter::find_first(std::string_view a_name_or_addr) {
    TRACE2(this, " Executing CNetadapter::find_first()")
    SSockaddr nad_saObj;
 
    // By default look for a valid ip address without loopback, no matter what
    // local network adapter.
    // -----------------------------------------------------------------------
    // The operating system presents one as best choise.
    if (a_name_or_addr.empty()) {
        this->reset(); // noexcept
        if (this->index() == 0)
            return false; // There isn't any adapter.
 
        do {
            this->sockaddr(nad_saObj);
            if (!nad_saObj.is_loopback()) {
                m_state = Find::best;
                return true;
            }
        } while (this->get_next());
 
        // No usable address found, nothing more to do.
        return false;
    }
 
    // Look for a loopback interface, no matter what local network adapter.
    // --------------------------------------------------------------------
    if (a_name_or_addr == "loopback") {
        this->reset(); // noexcept
        do {
            this->sockaddr(nad_saObj);
            if (nad_saObj.is_loopback()) {
                m_state = Find::loopback;
                return true;
            }
        } while (this->get_next());
 
        // No loopback interface found, nothing more to do.
        return false;
    }
 
    // Look for a local network adapter name that has at least one ip address
    // that isn't a loopback address.
    // ----------------------------------------------------------------------
    this->reset(); // noexcept
    do {
        if (this->name() == a_name_or_addr) {
            this->sockaddr(nad_saObj);
            if (!nad_saObj.is_loopback()) {
                m_find_index = this->index();
                m_state = Find::index;
                return true;
            }
        }
    } while (this->get_next());
    // Nothing found, reset pointer.
    this->reset(); // noexcept
 
    // No name found, look for the ip address of a local network adapter.
    // ------------------------------------------------------------------
    // Last attempt to get a socket address from the input argument.
    SSockaddr input_saObj;
    try { // Throws exception if invalid.
        input_saObj = std::string(a_name_or_addr);
    } catch (std::exception&) {
        return false;
    }
    // Parse network adapter list for the given input ip address.
    do {
        this->sockaddr(nad_saObj);
        if (nad_saObj == input_saObj) {
            // With a unique ip address given, there cannot be another.
            m_state = Find::finish;
            return true;
        }
    } while (this->get_next());
 
    return false;
}
 
bool CNetadapter::find_first(unsigned int a_index) {
    TRACE2(this, " Executing CNetadapter::find_first(" +
                     std::to_string(a_index) + ")")
    this->reset(); // noexcept
    if (this->index() == 0)
        return false; // There isn't any adapter.
 
    SSockaddr nad_saObj;
    do {
        if (this->index() == a_index) {
            this->sockaddr(nad_saObj);
            if (!nad_saObj.is_loopback()) {
                m_find_index = a_index;
                m_state = Find::index;
                return true;
            }
        }
    } while (this->get_next());
 
    return false;
}
 
bool CNetadapter::find_next() {
    TRACE2(this, " Executing CNetadapter::find_next()")
    SSockaddr nadap_saObj;
 
    switch (m_state) {
    case Find::finish:
        return false;
 
    case Find::best: { // without loopback
        while (this->get_next()) {
            this->sockaddr(nadap_saObj);
            if (!nadap_saObj.is_loopback())
                return true;
        } // while
    } break;
 
    case Find::loopback: {
        while (this->get_next()) {
            this->sockaddr(nadap_saObj);
            if (nadap_saObj.is_loopback())
                return true;
        } // while
    } break;
 
    case Find::index: { // without loopback
        while (this->get_next()) {
            const unsigned int index{this->index()};
            if (index == m_find_index) {
                this->sockaddr(nadap_saObj);
                if (!nadap_saObj.is_loopback())
                    return true;
            }
        } // while
    } break;
    } // switch
 
    m_state = Find::finish;
    return false;
}
 
} // namespace UPnPsdk