add: Implement function for socket address lookup/creation

src/net/sock_address_factory.cpp

+#include "net/sock_address_factory.hpp"
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <netinet/in.h>
+#include <netdb.h>
+
+#include <net/address.hpp>
+
+namespace rmrf::net {
+
+    std::string format_network_error(int error) {
+        switch (error) {
+        case EAI_ADDRFAMILY:
+            return "There was no compatible address for the requested families. (EAI_ADDRFAMILY)";
+        case EAI_AGAIN:
+            return "The consulted DNS server reported a temporary lookup failure. Try again later. (EAI_AGAIN)";
+        case EAI_BADFLAGS:
+            return "The supplied host information did not suffice to identify a host. (EAI_BADFLAGS)";
+        case EAI_FAIL:
+            return "The DNS server crashed. (EAI_FAIL)";
+        case EAI_FAMILY:
+            return "The required protocol family is not supported by this host. (EAI_FAMILY)";
+        case EAI_MEMORY:
+            return "Out of Memory while performing DNS lookup. (EAI_MEMORY)";
+        case EAI_NODATA:
+            return "The requested DNS entry does not contain an A or AAAA entry. (EAI_NODATA)";
+        case EAI_NONAME:
+            return "There was no matching nodename, service tuple. (EAI_NONAME)";
+        case EAI_SERVICE:
+            return "The requested service entry is not avaiable with the requested socket type. (EAI_SERVICE)";
+        case EAI_SOCKTYPE:
+            return "There was a mismatch of the requested socket type (TCP and UDP are mutually exclusive). (EAI_SOCKTYPE)";
+        default:
+            return std::to_string(error);
+        }
+    }
+
+    bool decode_address(std::list<socketaddr> &l, addrinfo* looked_up_addrs, const int port) {
+        if (looked_up_addrs->ai_family == AF_UNIX) {
+            const sockaddr_un* unix_addr = (sockaddr_un*) looked_up_addrs->ai_addr;
+            const sockaddr_un addr{*unix_addr};
+            socketaddr sa{addr};
+            l.push_back(sa);
+        } else if (looked_up_addrs->ai_family == AF_INET6) {
+            const sockaddr_in6* ip6_addr = (sockaddr_in6*) looked_up_addrs->ai_addr;
+            sockaddr_in6 addr{*ip6_addr};
+
+            if (port != -1) {
+                addr.sin6_port = htons((uint16_t) port);
+            }
+
+            socketaddr sa{addr};
+            l.push_back(sa);
+        } else if (looked_up_addrs->ai_family == AF_INET) {
+            const sockaddr_in* ip6_addr = (sockaddr_in*) looked_up_addrs->ai_addr;
+            sockaddr_in addr{*ip6_addr};
+
+            if (port != -1) {
+                addr.sin_port = htons((uint16_t) port);
+            }
+
+            socketaddr sa{addr};
+            l.push_back(sa);
+        } else {
+            throw std::invalid_argument("The resulting address family should exist. Instead it is " + std::to_string(looked_up_addrs->ai_family));
+        }
+
+        return true;
+    }
+
+    bool is_plain_ip_address(const std::string &interface_description) {
+        if (
+            interface_description.starts_with("[") &&
+            interface_description.ends_with("]") &&
+            is_valid_ip6addr(
+                interface_description.substr(1, interface_description.length() - 2)
+            )
+        ) {
+            return true;
+        }
+
+        return is_valid_ip4addr(interface_description) || is_valid_ip6addr(interface_description);
+    }
+
+    socketaddr parse_plain_ip_address(const std::string &interface_description, const uint16_t port, const socket_t socket_type) {
+        (void)socket_type;
+
+        if (interface_description.find(':') != std::string::npos) {
+            // Assume IPv6
+            struct in6_addr addr;
+
+            if (interface_description.starts_with("[") && interface_description.ends_with("]")) {
+                const std::string tmp = interface_description.substr(1, interface_description.length() - 2);
+
+                if (::inet_pton(AF_INET6, tmp.c_str(), &addr) != 1) {
+                    return {};
+                }
+            } else {
+                if (::inet_pton(AF_INET6, interface_description.c_str(), &addr) != 1) {
+                    return {};
+                }
+            }
+
+            sockaddr_in6 addr_ip6;
+            addr_ip6.sin6_family = AF_INET6;
+            addr_ip6.sin6_addr = addr;
+            addr_ip6.sin6_port = htons(port);
+            socketaddr sa{addr_ip6};
+            return sa;
+        } else {
+            // Assume IPv4
+            struct in_addr addr;
+
+            if (::inet_pton(AF_INET, interface_description.c_str(), &addr) != 1) {
+                return {};
+            }
+
+            sockaddr_in addr_ip4;
+            addr_ip4.sin_family = AF_INET;
+            addr_ip4.sin_addr = addr;
+            addr_ip4.sin_port = htons(port);
+            socketaddr sa{addr_ip4};
+            return sa;
+        }
+    }
+
+    std::list<socketaddr> get_socketaddr_list(const std::string &interface_description, const std::string &service_or_port, const socket_t socket_type) {
+        int port = -1;
+
+        try {
+            port = (uint16_t) std::stoi(service_or_port);
+        } catch (const std::invalid_argument &_) {
+            // Could not parse port. Continue as service
+        }
+
+        // TODO sort to prioritize local addresses over more remote ones
+
+        if (port != -1 && is_plain_ip_address(interface_description)) {
+            std::list<socketaddr> l = {parse_plain_ip_address(interface_description, (uint16_t) port, socket_type)};
+            return l;
+        }
+
+        struct addrinfo hints = {};
+
+        struct addrinfo* addrs;
+
+        hints.ai_family = AF_INET6;
+
+        hints.ai_socktype = socket_type == socket_t::TCP ? SOCK_STREAM : SOCK_DGRAM;
+
+        hints.ai_protocol =  socket_type == socket_t::TCP ? IPPROTO_TCP : IPPROTO_UDP;
+
+        if (auto dns_error = getaddrinfo(interface_description.c_str(), port == -1 ? service_or_port.c_str() : NULL, &hints, &addrs); dns_error != 0) {
+            hints.ai_family = AF_UNSPEC;
+            dns_error = getaddrinfo(interface_description.c_str(), NULL, &hints, &addrs);
+
+            if (dns_error != 0) {
+                freeaddrinfo(addrs);
+                throw std::invalid_argument("Something went wrong with the DNS lookup. Error code: " + format_network_error(dns_error));
+            }
+        }
+
+        std::list<socketaddr> l;
+
+        for (auto result_ptr = addrs; result_ptr != NULL; result_ptr = result_ptr->ai_next) {
+            decode_address(l, result_ptr, port);
+        }
+
+        freeaddrinfo(addrs);
+        return l;
+    }
+
+    socketaddr get_first_general_socketaddr(const std::string &interface_description, const std::string &service, const socket_t socket_type) {
+        const auto l = get_socketaddr_list(interface_description, service, socket_type);
+
+        if (l.size() > 0) {
+            return l.front();
+        } else {
+            throw std::invalid_argument("No suitable socket address was found.");
+        }
+    }
+
+    socketaddr get_first_general_socketaddr(const std::string &interface_description, const uint16_t port, const socket_t socket_type) {
+        return get_first_general_socketaddr(interface_description, std::to_string(port), socket_type);
+    }
+
+}

src/net/sock_address_factory.hpp

+#pragma once
+
+#include <list>
+#include <stdexcept>
+#include <string>
+
+#include "net/socketaddress.hpp"
+
+namespace rmrf::net {
+    std::string format_network_error(int error);
+
+    enum class socket_t {
+        UDP,
+        TCP
+    };
+
+    /**
+     * This method constructs a new sockaddr object and prefers IPv6 while doing so. In case of multiple looked up
+     * addresses for a host, it returns the first one.
+     * @brief Construct a sockaddr object from string address
+     * @param interface_description The human readable representation of an IP address or DNS name
+     * @param port The port to connect to
+     * @param socket_type Optional. The socket type to perform the lookup for. Defaults to TCP.
+     * @return The constructed sockaddr object
+     */
+    socketaddr get_first_general_socketaddr(const std::string& interface_description, const uint16_t port, const socket_t socket_type = socket_t::TCP);
+
+    /**
+     * This method constructs a new sockaddr object and prefers IPv6 while doing so. In case of multiple looked up
+     * addresses for a host, it returns the first one.
+     * @brief Construct a sockaddr object from string address
+     * @param interface_description The human readable representation of an IP address or DNS name
+     * @param service_or_port The service to connect to
+     * @param socket_type Optional. The socket type to perform the lookup for. Defaults to TCP.
+     * @return The constructed sockaddr object
+     */
+    socketaddr get_first_general_socketaddr(const std::string& interface_description, const std::string& service_or_port, const socket_t socket_type = socket_t::TCP);
+
+    /**
+     * This method constructs a list of new sockaddr objects.
+     *
+     * @brief Construct a sockaddr object from string address
+     * @param interface_description The human readable representation of an IP address or DNS name
+     * @param port The port to connect to
+     * @param socket_type Optional. The socket type to perform the lookup for. Defaults to TCP.
+     * @return The constructed unordered list
+     */
+    std::list<socketaddr> get_socketaddr_list(const std::string& interface_description, const std::string& service_or_port, const socket_t socket_type);
+}