Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1696 insertions, 0 deletions

diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
new file mode 100644
index 0000000..beb64d8
--- /dev/null
+++ b/src/basic/socket-util.c
@@ -0,0 +1,1696 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <arpa/inet.h>
+#include <errno.h>
+#include <limits.h>
+#include <net/if.h>
+#include <netdb.h>
+#include <netinet/ip.h>
+#include <poll.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include <linux/if.h>
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "io-util.h"
+#include "log.h"
+#include "memory-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "socket-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "strv.h"
+#include "sysctl-util.h"
+#include "user-util.h"
+#include "utf8.h"
+
+#if ENABLE_IDN
+#  define IDN_FLAGS NI_IDN
+#else
+#  define IDN_FLAGS 0
+#endif
+
+/* From the kernel's include/net/scm.h */
+#ifndef SCM_MAX_FD
+#  define SCM_MAX_FD 253
+#endif
+
+static const char* const socket_address_type_table[] = {
+        [SOCK_STREAM] =    "Stream",
+        [SOCK_DGRAM] =     "Datagram",
+        [SOCK_RAW] =       "Raw",
+        [SOCK_RDM] =       "ReliableDatagram",
+        [SOCK_SEQPACKET] = "SequentialPacket",
+        [SOCK_DCCP] =      "DatagramCongestionControl",
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_address_type, int);
+
+int socket_address_verify(const SocketAddress *a, bool strict) {
+        assert(a);
+
+        /* With 'strict' we enforce additional sanity constraints which are not set by the standard,
+         * but should only apply to sockets we create ourselves. */
+
+        switch (socket_address_family(a)) {
+
+        case AF_INET:
+                if (a->size != sizeof(struct sockaddr_in))
+                        return -EINVAL;
+
+                if (a->sockaddr.in.sin_port == 0)
+                        return -EINVAL;
+
+                if (!IN_SET(a->type, 0, SOCK_STREAM, SOCK_DGRAM))
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_INET6:
+                if (a->size != sizeof(struct sockaddr_in6))
+                        return -EINVAL;
+
+                if (a->sockaddr.in6.sin6_port == 0)
+                        return -EINVAL;
+
+                if (!IN_SET(a->type, 0, SOCK_STREAM, SOCK_DGRAM))
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_UNIX:
+                if (a->size < offsetof(struct sockaddr_un, sun_path))
+                        return -EINVAL;
+                if (a->size > sizeof(struct sockaddr_un) + !strict)
+                        /* If !strict, allow one extra byte, since getsockname() on Linux will append
+                         * a NUL byte if we have path sockets that are above sun_path's full size. */
+                        return -EINVAL;
+
+                if (a->size > offsetof(struct sockaddr_un, sun_path) &&
+                    a->sockaddr.un.sun_path[0] != 0 &&
+                    strict) {
+                        /* Only validate file system sockets here, and only in strict mode */
+                        const char *e;
+
+                        e = memchr(a->sockaddr.un.sun_path, 0, sizeof(a->sockaddr.un.sun_path));
+                        if (e) {
+                                /* If there's an embedded NUL byte, make sure the size of the socket address matches it */
+                                if (a->size != offsetof(struct sockaddr_un, sun_path) + (e - a->sockaddr.un.sun_path) + 1)
+                                        return -EINVAL;
+                        } else {
+                                /* If there's no embedded NUL byte, then the size needs to match the whole
+                                 * structure or the structure with one extra NUL byte suffixed. (Yeah, Linux is awful,
+                                 * and considers both equivalent: getsockname() even extends sockaddr_un beyond its
+                                 * size if the path is non NUL terminated.) */
+                                if (!IN_SET(a->size, sizeof(a->sockaddr.un.sun_path), sizeof(a->sockaddr.un.sun_path)+1))
+                                        return -EINVAL;
+                        }
+                }
+
+                if (!IN_SET(a->type, 0, SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET))
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_NETLINK:
+
+                if (a->size != sizeof(struct sockaddr_nl))
+                        return -EINVAL;
+
+                if (!IN_SET(a->type, 0, SOCK_RAW, SOCK_DGRAM))
+                        return -EINVAL;
+
+                return 0;
+
+        case AF_VSOCK:
+                if (a->size != sizeof(struct sockaddr_vm))
+                        return -EINVAL;
+
+                if (!IN_SET(a->type, 0, SOCK_STREAM, SOCK_DGRAM))
+                        return -EINVAL;
+
+                return 0;
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int socket_address_print(const SocketAddress *a, char **ret) {
+        int r;
+
+        assert(a);
+        assert(ret);
+
+        r = socket_address_verify(a, false); /* We do non-strict validation, because we want to be
+                                              * able to pretty-print any socket the kernel considers
+                                              * valid. We still need to do validation to know if we
+                                              * can meaningfully print the address. */
+        if (r < 0)
+                return r;
+
+        if (socket_address_family(a) == AF_NETLINK) {
+                _cleanup_free_ char *sfamily = NULL;
+
+                r = netlink_family_to_string_alloc(a->protocol, &sfamily);
+                if (r < 0)
+                        return r;
+
+                r = asprintf(ret, "%s %u", sfamily, a->sockaddr.nl.nl_groups);
+                if (r < 0)
+                        return -ENOMEM;
+
+                return 0;
+        }
+
+        return sockaddr_pretty(&a->sockaddr.sa, a->size, false, true, ret);
+}
+
+bool socket_address_can_accept(const SocketAddress *a) {
+        assert(a);
+
+        return
+                IN_SET(a->type, SOCK_STREAM, SOCK_SEQPACKET);
+}
+
+bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
+        assert(a);
+        assert(b);
+
+        /* Invalid addresses are unequal to all */
+        if (socket_address_verify(a, false) < 0 ||
+            socket_address_verify(b, false) < 0)
+                return false;
+
+        if (a->type != b->type)
+                return false;
+
+        if (socket_address_family(a) != socket_address_family(b))
+                return false;
+
+        switch (socket_address_family(a)) {
+
+        case AF_INET:
+                if (a->sockaddr.in.sin_addr.s_addr != b->sockaddr.in.sin_addr.s_addr)
+                        return false;
+
+                if (a->sockaddr.in.sin_port != b->sockaddr.in.sin_port)
+                        return false;
+
+                break;
+
+        case AF_INET6:
+                if (memcmp(&a->sockaddr.in6.sin6_addr, &b->sockaddr.in6.sin6_addr, sizeof(a->sockaddr.in6.sin6_addr)) != 0)
+                        return false;
+
+                if (a->sockaddr.in6.sin6_port != b->sockaddr.in6.sin6_port)
+                        return false;
+
+                break;
+
+        case AF_UNIX:
+                if (a->size <= offsetof(struct sockaddr_un, sun_path) ||
+                    b->size <= offsetof(struct sockaddr_un, sun_path))
+                        return false;
+
+                if ((a->sockaddr.un.sun_path[0] == 0) != (b->sockaddr.un.sun_path[0] == 0))
+                        return false;
+
+                if (a->sockaddr.un.sun_path[0]) {
+                        if (!path_equal_or_inode_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, 0))
+                                return false;
+                } else {
+                        if (a->size != b->size)
+                                return false;
+
+                        if (memcmp(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, a->size) != 0)
+                                return false;
+                }
+
+                break;
+
+        case AF_NETLINK:
+                if (a->protocol != b->protocol)
+                        return false;
+
+                if (a->sockaddr.nl.nl_groups != b->sockaddr.nl.nl_groups)
+                        return false;
+
+                break;
+
+        case AF_VSOCK:
+                if (a->sockaddr.vm.svm_cid != b->sockaddr.vm.svm_cid)
+                        return false;
+
+                if (a->sockaddr.vm.svm_port != b->sockaddr.vm.svm_port)
+                        return false;
+
+                break;
+
+        default:
+                /* Cannot compare, so we assume the addresses are different */
+                return false;
+        }
+
+        return true;
+}
+
+const char* socket_address_get_path(const SocketAddress *a) {
+        assert(a);
+
+        if (socket_address_family(a) != AF_UNIX)
+                return NULL;
+
+        if (a->sockaddr.un.sun_path[0] == 0)
+                return NULL;
+
+        /* Note that this is only safe because we know that there's an extra NUL byte after the sockaddr_un
+         * structure. On Linux AF_UNIX file system socket addresses don't have to be NUL terminated if they take up the
+         * full sun_path space. */
+        assert_cc(sizeof(union sockaddr_union) >= sizeof(struct sockaddr_un)+1);
+        return a->sockaddr.un.sun_path;
+}
+
+bool socket_ipv6_is_supported(void) {
+        static int cached = -1;
+
+        if (cached < 0) {
+
+                if (access("/proc/net/if_inet6", F_OK) < 0) {
+
+                        if (errno != ENOENT) {
+                                log_debug_errno(errno, "Unexpected error when checking whether /proc/net/if_inet6 exists: %m");
+                                return false;
+                        }
+
+                        cached = false;
+                } else
+                        cached = true;
+        }
+
+        return cached;
+}
+
+bool socket_ipv6_is_enabled(void) {
+        _cleanup_free_ char *v = NULL;
+        int r;
+
+        /* Much like socket_ipv6_is_supported(), but also checks that the sysctl that disables IPv6 on all
+         * interfaces isn't turned on */
+
+        if (!socket_ipv6_is_supported())
+                return false;
+
+        r = sysctl_read_ip_property(AF_INET6, "all", "disable_ipv6", &v);
+        if (r < 0) {
+                log_debug_errno(r, "Unexpected error reading 'net.ipv6.conf.all.disable_ipv6' sysctl: %m");
+                return true;
+        }
+
+        r = parse_boolean(v);
+        if (r < 0) {
+                log_debug_errno(r, "Failed to pare 'net.ipv6.conf.all.disable_ipv6' sysctl: %m");
+                return true;
+        }
+
+        return !r;
+}
+
+bool socket_address_matches_fd(const SocketAddress *a, int fd) {
+        SocketAddress b;
+        socklen_t solen;
+
+        assert(a);
+        assert(fd >= 0);
+
+        b.size = sizeof(b.sockaddr);
+        if (getsockname(fd, &b.sockaddr.sa, &b.size) < 0)
+                return false;
+
+        if (b.sockaddr.sa.sa_family != a->sockaddr.sa.sa_family)
+                return false;
+
+        solen = sizeof(b.type);
+        if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &b.type, &solen) < 0)
+                return false;
+
+        if (b.type != a->type)
+                return false;
+
+        if (a->protocol != 0)  {
+                solen = sizeof(b.protocol);
+                if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &b.protocol, &solen) < 0)
+                        return false;
+
+                if (b.protocol != a->protocol)
+                        return false;
+        }
+
+        return socket_address_equal(a, &b);
+}
+
+int sockaddr_port(const struct sockaddr *_sa, unsigned *ret_port) {
+        const union sockaddr_union *sa = (const union sockaddr_union*) _sa;
+
+        /* Note, this returns the port as 'unsigned' rather than 'uint16_t', as AF_VSOCK knows larger ports */
+
+        assert(sa);
+
+        switch (sa->sa.sa_family) {
+
+        case AF_INET:
+                *ret_port = be16toh(sa->in.sin_port);
+                return 0;
+
+        case AF_INET6:
+                *ret_port = be16toh(sa->in6.sin6_port);
+                return 0;
+
+        case AF_VSOCK:
+                *ret_port = sa->vm.svm_port;
+                return 0;
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+const union in_addr_union *sockaddr_in_addr(const struct sockaddr *_sa) {
+        const union sockaddr_union *sa = (const union sockaddr_union*) _sa;
+
+        if (!sa)
+                return NULL;
+
+        switch (sa->sa.sa_family) {
+
+        case AF_INET:
+                return (const union in_addr_union*) &sa->in.sin_addr;
+
+        case AF_INET6:
+                return (const union in_addr_union*) &sa->in6.sin6_addr;
+
+        default:
+                return NULL;
+        }
+}
+
+int sockaddr_set_in_addr(
+                union sockaddr_union *u,
+                int family,
+                const union in_addr_union *a,
+                uint16_t port) {
+
+        assert(u);
+        assert(a);
+
+        switch (family) {
+
+        case AF_INET:
+                u->in = (struct sockaddr_in) {
+                        .sin_family = AF_INET,
+                        .sin_addr = a->in,
+                        .sin_port = htobe16(port),
+                };
+
+                return 0;
+
+        case AF_INET6:
+                u->in6 = (struct sockaddr_in6) {
+                        .sin6_family = AF_INET6,
+                        .sin6_addr = a->in6,
+                        .sin6_port = htobe16(port),
+                };
+
+                return 0;
+
+        default:
+                return -EAFNOSUPPORT;
+
+        }
+}
+
+int sockaddr_pretty(
+                const struct sockaddr *_sa,
+                socklen_t salen,
+                bool translate_ipv6,
+                bool include_port,
+                char **ret) {
+
+        union sockaddr_union *sa = (union sockaddr_union*) _sa;
+        char *p;
+        int r;
+
+        assert(sa);
+        assert(salen >= sizeof(sa->sa.sa_family));
+
+        switch (sa->sa.sa_family) {
+
+        case AF_INET: {
+                uint32_t a;
+
+                a = be32toh(sa->in.sin_addr.s_addr);
+
+                if (include_port)
+                        r = asprintf(&p,
+                                     "%u.%u.%u.%u:%u",
+                                     a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
+                                     be16toh(sa->in.sin_port));
+                else
+                        r = asprintf(&p,
+                                     "%u.%u.%u.%u",
+                                     a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF);
+                if (r < 0)
+                        return -ENOMEM;
+                break;
+        }
+
+        case AF_INET6: {
+                static const unsigned char ipv4_prefix[] = {
+                        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
+                };
+
+                if (translate_ipv6 &&
+                    memcmp(&sa->in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
+                        const uint8_t *a = sa->in6.sin6_addr.s6_addr+12;
+                        if (include_port)
+                                r = asprintf(&p,
+                                             "%u.%u.%u.%u:%u",
+                                             a[0], a[1], a[2], a[3],
+                                             be16toh(sa->in6.sin6_port));
+                        else
+                                r = asprintf(&p,
+                                             "%u.%u.%u.%u",
+                                             a[0], a[1], a[2], a[3]);
+                        if (r < 0)
+                                return -ENOMEM;
+                } else {
+                        const char *a = IN6_ADDR_TO_STRING(&sa->in6.sin6_addr);
+
+                        if (include_port) {
+                                if (asprintf(&p,
+                                             "[%s]:%u%s%s",
+                                             a,
+                                             be16toh(sa->in6.sin6_port),
+                                             sa->in6.sin6_scope_id != 0 ? "%" : "",
+                                             FORMAT_IFNAME_FULL(sa->in6.sin6_scope_id, FORMAT_IFNAME_IFINDEX)) < 0)
+                                        return -ENOMEM;
+                        } else {
+                                if (sa->in6.sin6_scope_id != 0)
+                                        p = strjoin(a, "%", FORMAT_IFNAME_FULL(sa->in6.sin6_scope_id, FORMAT_IFNAME_IFINDEX));
+                                else
+                                        p = strdup(a);
+                                if (!p)
+                                        return -ENOMEM;
+                        }
+                }
+
+                break;
+        }
+
+        case AF_UNIX:
+                if (salen <= offsetof(struct sockaddr_un, sun_path) ||
+                    (sa->un.sun_path[0] == 0 && salen == offsetof(struct sockaddr_un, sun_path) + 1))
+                        /* The name must have at least one character (and the leading NUL does not count) */
+                        p = strdup("<unnamed>");
+                else {
+                        /* Note that we calculate the path pointer here through the .un_buffer[] field, in order to
+                         * outtrick bounds checking tools such as ubsan, which are too smart for their own good: on
+                         * Linux the kernel may return sun_path[] data one byte longer than the declared size of the
+                         * field. */
+                        char *path = (char*) sa->un_buffer + offsetof(struct sockaddr_un, sun_path);
+                        size_t path_len = salen - offsetof(struct sockaddr_un, sun_path);
+
+                        if (path[0] == 0) {
+                                /* Abstract socket. When parsing address information from, we
+                                 * explicitly reject overly long paths and paths with embedded NULs.
+                                 * But we might get such a socket from the outside. Let's return
+                                 * something meaningful and printable in this case. */
+
+                                _cleanup_free_ char *e = NULL;
+
+                                e = cescape_length(path + 1, path_len - 1);
+                                if (!e)
+                                        return -ENOMEM;
+
+                                p = strjoin("@", e);
+                        } else {
+                                if (path[path_len - 1] == '\0')
+                                        /* We expect a terminating NUL and don't print it */
+                                        path_len --;
+
+                                p = cescape_length(path, path_len);
+                        }
+                }
+                if (!p)
+                        return -ENOMEM;
+
+                break;
+
+        case AF_VSOCK:
+                if (include_port) {
+                        if (sa->vm.svm_cid == VMADDR_CID_ANY)
+                                r = asprintf(&p, "vsock::%u", sa->vm.svm_port);
+                        else
+                                r = asprintf(&p, "vsock:%u:%u", sa->vm.svm_cid, sa->vm.svm_port);
+                } else
+                        r = asprintf(&p, "vsock:%u", sa->vm.svm_cid);
+                if (r < 0)
+                        return -ENOMEM;
+                break;
+
+        default:
+                return -EOPNOTSUPP;
+        }
+
+        *ret = p;
+        return 0;
+}
+
+int getpeername_pretty(int fd, bool include_port, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+        int r;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getpeername(fd, &sa.sa, &salen) < 0)
+                return -errno;
+
+        if (sa.sa.sa_family == AF_UNIX) {
+                struct ucred ucred = UCRED_INVALID;
+
+                /* UNIX connection sockets are anonymous, so let's use
+                 * PID/UID as pretty credentials instead */
+
+                r = getpeercred(fd, &ucred);
+                if (r < 0)
+                        return r;
+
+                if (asprintf(ret, "PID "PID_FMT"/UID "UID_FMT, ucred.pid, ucred.uid) < 0)
+                        return -ENOMEM;
+
+                return 0;
+        }
+
+        /* For remote sockets we translate IPv6 addresses back to IPv4
+         * if applicable, since that's nicer. */
+
+        return sockaddr_pretty(&sa.sa, salen, true, include_port, ret);
+}
+
+int getsockname_pretty(int fd, char **ret) {
+        union sockaddr_union sa;
+        socklen_t salen = sizeof(sa);
+
+        assert(fd >= 0);
+        assert(ret);
+
+        if (getsockname(fd, &sa.sa, &salen) < 0)
+                return -errno;
+
+        /* For local sockets we do not translate IPv6 addresses back
+         * to IPv6 if applicable, since this is usually used for
+         * listening sockets where the difference between IPv4 and
+         * IPv6 matters. */
+
+        return sockaddr_pretty(&sa.sa, salen, false, true, ret);
+}
+
+int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
+        int r;
+        char host[NI_MAXHOST], *ret;
+
+        assert(_ret);
+
+        r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0, IDN_FLAGS);
+        if (r != 0) {
+                int saved_errno = errno;
+
+                r = sockaddr_pretty(&sa->sa, salen, true, true, &ret);
+                if (r < 0)
+                        return r;
+
+                log_debug_errno(saved_errno, "getnameinfo(%s) failed: %m", ret);
+        } else {
+                ret = strdup(host);
+                if (!ret)
+                        return -ENOMEM;
+        }
+
+        *_ret = ret;
+        return 0;
+}
+
+static const char* const netlink_family_table[] = {
+        [NETLINK_ROUTE]          = "route",
+        [NETLINK_FIREWALL]       = "firewall",
+        [NETLINK_INET_DIAG]      = "inet-diag",
+        [NETLINK_NFLOG]          = "nflog",
+        [NETLINK_XFRM]           = "xfrm",
+        [NETLINK_SELINUX]        = "selinux",
+        [NETLINK_ISCSI]          = "iscsi",
+        [NETLINK_AUDIT]          = "audit",
+        [NETLINK_FIB_LOOKUP]     = "fib-lookup",
+        [NETLINK_CONNECTOR]      = "connector",
+        [NETLINK_NETFILTER]      = "netfilter",
+        [NETLINK_IP6_FW]         = "ip6-fw",
+        [NETLINK_DNRTMSG]        = "dnrtmsg",
+        [NETLINK_KOBJECT_UEVENT] = "kobject-uevent",
+        [NETLINK_GENERIC]        = "generic",
+        [NETLINK_SCSITRANSPORT]  = "scsitransport",
+        [NETLINK_ECRYPTFS]       = "ecryptfs",
+        [NETLINK_RDMA]           = "rdma",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(netlink_family, int, INT_MAX);
+
+static const char* const socket_address_bind_ipv6_only_table[_SOCKET_ADDRESS_BIND_IPV6_ONLY_MAX] = {
+        [SOCKET_ADDRESS_DEFAULT] = "default",
+        [SOCKET_ADDRESS_BOTH] = "both",
+        [SOCKET_ADDRESS_IPV6_ONLY] = "ipv6-only"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(socket_address_bind_ipv6_only, SocketAddressBindIPv6Only);
+
+SocketAddressBindIPv6Only socket_address_bind_ipv6_only_or_bool_from_string(const char *n) {
+        int r;
+
+        r = parse_boolean(n);
+        if (r > 0)
+                return SOCKET_ADDRESS_IPV6_ONLY;
+        if (r == 0)
+                return SOCKET_ADDRESS_BOTH;
+
+        return socket_address_bind_ipv6_only_from_string(n);
+}
+
+bool sockaddr_equal(const union sockaddr_union *a, const union sockaddr_union *b) {
+        assert(a);
+        assert(b);
+
+        if (a->sa.sa_family != b->sa.sa_family)
+                return false;
+
+        if (a->sa.sa_family == AF_INET)
+                return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr;
+
+        if (a->sa.sa_family == AF_INET6)
+                return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0;
+
+        if (a->sa.sa_family == AF_VSOCK)
+                return a->vm.svm_cid == b->vm.svm_cid;
+
+        return false;
+}
+
+int fd_set_sndbuf(int fd, size_t n, bool increase) {
+        int r, value;
+        socklen_t l = sizeof(value);
+
+        if (n > INT_MAX)
+                return -ERANGE;
+
+        r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && increase ? (size_t) value >= n*2 : (size_t) value == n*2)
+                return 0;
+
+        /* First, try to set the buffer size with SO_SNDBUF. */
+        r = setsockopt_int(fd, SOL_SOCKET, SO_SNDBUF, n);
+        if (r < 0)
+                return r;
+
+        /* SO_SNDBUF above may set to the kernel limit, instead of the requested size.
+         * So, we need to check the actual buffer size here. */
+        l = sizeof(value);
+        r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && increase ? (size_t) value >= n*2 : (size_t) value == n*2)
+                return 1;
+
+        /* If we have the privileges we will ignore the kernel limit. */
+        r = setsockopt_int(fd, SOL_SOCKET, SO_SNDBUFFORCE, n);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+int fd_set_rcvbuf(int fd, size_t n, bool increase) {
+        int r, value;
+        socklen_t l = sizeof(value);
+
+        if (n > INT_MAX)
+                return -ERANGE;
+
+        r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && increase ? (size_t) value >= n*2 : (size_t) value == n*2)
+                return 0;
+
+        /* First, try to set the buffer size with SO_RCVBUF. */
+        r = setsockopt_int(fd, SOL_SOCKET, SO_RCVBUF, n);
+        if (r < 0)
+                return r;
+
+        /* SO_RCVBUF above may set to the kernel limit, instead of the requested size.
+         * So, we need to check the actual buffer size here. */
+        l = sizeof(value);
+        r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && increase ? (size_t) value >= n*2 : (size_t) value == n*2)
+                return 1;
+
+        /* If we have the privileges we will ignore the kernel limit. */
+        r = setsockopt_int(fd, SOL_SOCKET, SO_RCVBUFFORCE, n);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static const char* const ip_tos_table[] = {
+        [IPTOS_LOWDELAY]    = "low-delay",
+        [IPTOS_THROUGHPUT]  = "throughput",
+        [IPTOS_RELIABILITY] = "reliability",
+        [IPTOS_LOWCOST]     = "low-cost",
+};
+
+DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ip_tos, int, 0xff);
+
+bool ifname_valid_char(char a) {
+        if ((unsigned char) a >= 127U)
+                return false;
+
+        if ((unsigned char) a <= 32U)
+                return false;
+
+        if (IN_SET(a,
+                   ':',  /* colons are used by the legacy "alias" interface logic */
+                   '/',  /* slashes cannot work, since we need to use network interfaces in sysfs paths, and in paths slashes are separators */
+                   '%')) /* %d is used in the kernel's weird foo%d format string naming feature which we really really don't want to ever run into by accident */
+                return false;
+
+        return true;
+}
+
+bool ifname_valid_full(const char *p, IfnameValidFlags flags) {
+        bool numeric = true;
+
+        /* Checks whether a network interface name is valid. This is inspired by dev_valid_name() in the kernel sources
+         * but slightly stricter, as we only allow non-control, non-space ASCII characters in the interface name. We
+         * also don't permit names that only container numbers, to avoid confusion with numeric interface indexes. */
+
+        assert(!(flags & ~_IFNAME_VALID_ALL));
+
+        if (isempty(p))
+                return false;
+
+        /* A valid ifindex? If so, it's valid iff IFNAME_VALID_NUMERIC is set */
+        if (parse_ifindex(p) >= 0)
+                return flags & IFNAME_VALID_NUMERIC;
+
+        if (flags & IFNAME_VALID_ALTERNATIVE) {
+                if (strlen(p) >= ALTIFNAMSIZ)
+                        return false;
+        } else {
+                if (strlen(p) >= IFNAMSIZ)
+                        return false;
+        }
+
+        if (dot_or_dot_dot(p))
+                return false;
+
+        /* Let's refuse "all" and "default" as interface name, to avoid collisions with the special sysctl
+         * directories /proc/sys/net/{ipv4,ipv6}/conf/{all,default} */
+        if (!FLAGS_SET(flags, IFNAME_VALID_SPECIAL) && STR_IN_SET(p, "all", "default"))
+                return false;
+
+        for (const char *t = p; *t; t++) {
+                if (!ifname_valid_char(*t))
+                        return false;
+
+                numeric = numeric && ascii_isdigit(*t);
+        }
+
+        /* It's fully numeric but didn't parse as valid ifindex above? if so, it must be too large or zero or
+         * so, let's refuse that. */
+        if (numeric)
+                return false;
+
+        return true;
+}
+
+bool address_label_valid(const char *p) {
+
+        if (isempty(p))
+                return false;
+
+        if (strlen(p) >= IFNAMSIZ)
+                return false;
+
+        while (*p) {
+                if ((uint8_t) *p >= 127U)
+                        return false;
+
+                if ((uint8_t) *p <= 31U)
+                        return false;
+                p++;
+        }
+
+        return true;
+}
+
+int getpeercred(int fd, struct ucred *ucred) {
+        socklen_t n = sizeof(struct ucred);
+        struct ucred u;
+        int r;
+
+        assert(fd >= 0);
+        assert(ucred);
+
+        r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &u, &n);
+        if (r < 0)
+                return -errno;
+
+        if (n != sizeof(struct ucred))
+                return -EIO;
+
+        /* Check if the data is actually useful and not suppressed due to namespacing issues */
+        if (!pid_is_valid(u.pid))
+                return -ENODATA;
+
+        /* Note that we don't check UID/GID here, as namespace translation works differently there: instead of
+         * receiving in "invalid" user/group we get the overflow UID/GID. */
+
+        *ucred = u;
+        return 0;
+}
+
+int getpeersec(int fd, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        socklen_t n = 64;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        for (;;) {
+                s = new0(char, n+1);
+                if (!s)
+                        return -ENOMEM;
+
+                if (getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n) >= 0)
+                        break;
+
+                if (errno != ERANGE)
+                        return -errno;
+
+                s = mfree(s);
+        }
+
+        if (isempty(s))
+                return -EOPNOTSUPP;
+
+        *ret = TAKE_PTR(s);
+
+        return 0;
+}
+
+int getpeergroups(int fd, gid_t **ret) {
+        socklen_t n = sizeof(gid_t) * 64;
+        _cleanup_free_ gid_t *d = NULL;
+
+        assert(fd >= 0);
+        assert(ret);
+
+        for (;;) {
+                d = malloc(n);
+                if (!d)
+                        return -ENOMEM;
+
+                if (getsockopt(fd, SOL_SOCKET, SO_PEERGROUPS, d, &n) >= 0)
+                        break;
+
+                if (errno != ERANGE)
+                        return -errno;
+
+                d = mfree(d);
+        }
+
+        assert_se(n % sizeof(gid_t) == 0);
+        n /= sizeof(gid_t);
+
+        if ((socklen_t) (int) n != n)
+                return -E2BIG;
+
+        *ret = TAKE_PTR(d);
+
+        return (int) n;
+}
+
+ssize_t send_many_fds_iov_sa(
+                int transport_fd,
+                int *fds_array, size_t n_fds_array,
+                const struct iovec *iov, size_t iovlen,
+                const struct sockaddr *sa, socklen_t len,
+                int flags) {
+
+        _cleanup_free_ struct cmsghdr *cmsg = NULL;
+        struct msghdr mh = {
+                .msg_name = (struct sockaddr*) sa,
+                .msg_namelen = len,
+                .msg_iov = (struct iovec *)iov,
+                .msg_iovlen = iovlen,
+        };
+        ssize_t k;
+
+        assert(transport_fd >= 0);
+        assert(fds_array || n_fds_array == 0);
+
+        /* The kernel will reject sending more than SCM_MAX_FD FDs at once */
+        if (n_fds_array > SCM_MAX_FD)
+                return -E2BIG;
+
+        /* We need either an FD array or data to send. If there's nothing, return an error. */
+        if (n_fds_array == 0 && !iov)
+                return -EINVAL;
+
+        if (n_fds_array > 0) {
+                mh.msg_controllen = CMSG_SPACE(sizeof(int) * n_fds_array);
+                mh.msg_control = cmsg = malloc(mh.msg_controllen);
+                if (!cmsg)
+                        return -ENOMEM;
+
+                *cmsg = (struct cmsghdr) {
+                        .cmsg_len = CMSG_LEN(sizeof(int) * n_fds_array),
+                        .cmsg_level = SOL_SOCKET,
+                        .cmsg_type = SCM_RIGHTS,
+                };
+                memcpy(CMSG_DATA(cmsg), fds_array, sizeof(int) * n_fds_array);
+        }
+        k = sendmsg(transport_fd, &mh, MSG_NOSIGNAL | flags);
+        if (k < 0)
+                return (ssize_t) -errno;
+
+        return k;
+}
+
+ssize_t send_one_fd_iov_sa(
+                int transport_fd,
+                int fd,
+                const struct iovec *iov, size_t iovlen,
+                const struct sockaddr *sa, socklen_t len,
+                int flags) {
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control = {};
+        struct msghdr mh = {
+                .msg_name = (struct sockaddr*) sa,
+                .msg_namelen = len,
+                .msg_iov = (struct iovec *)iov,
+                .msg_iovlen = iovlen,
+        };
+        ssize_t k;
+
+        assert(transport_fd >= 0);
+
+        /*
+         * We need either an FD or data to send.
+         * If there's nothing, return an error.
+         */
+        if (fd < 0 && !iov)
+                return -EINVAL;
+
+        if (fd >= 0) {
+                struct cmsghdr *cmsg;
+
+                mh.msg_control = &control;
+                mh.msg_controllen = sizeof(control);
+
+                cmsg = CMSG_FIRSTHDR(&mh);
+                cmsg->cmsg_level = SOL_SOCKET;
+                cmsg->cmsg_type = SCM_RIGHTS;
+                cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+                memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
+        }
+        k = sendmsg(transport_fd, &mh, MSG_NOSIGNAL | flags);
+        if (k < 0)
+                return (ssize_t) -errno;
+
+        return k;
+}
+
+int send_one_fd_sa(
+                int transport_fd,
+                int fd,
+                const struct sockaddr *sa, socklen_t len,
+                int flags) {
+
+        assert(fd >= 0);
+
+        return (int) send_one_fd_iov_sa(transport_fd, fd, NULL, 0, sa, len, flags);
+}
+
+ssize_t receive_many_fds_iov(
+                int transport_fd,
+                struct iovec *iov, size_t iovlen,
+                int **ret_fds_array, size_t *ret_n_fds_array,
+                int flags) {
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int) * SCM_MAX_FD)) control;
+        struct msghdr mh = {
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
+                .msg_iov = iov,
+                .msg_iovlen = iovlen,
+        };
+        _cleanup_free_ int *fds_array = NULL;
+        size_t n_fds_array = 0;
+        struct cmsghdr *cmsg;
+        ssize_t k;
+
+        assert(transport_fd >= 0);
+        assert(ret_fds_array);
+        assert(ret_n_fds_array);
+
+        /*
+         * Receive many FDs via @transport_fd. We don't care for the transport-type. We retrieve all the FDs
+         * at once. This is best used in combination with send_many_fds().
+         */
+
+        k = recvmsg_safe(transport_fd, &mh, MSG_CMSG_CLOEXEC | flags);
+        if (k < 0)
+                return k;
+
+        CMSG_FOREACH(cmsg, &mh)
+                if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
+                        size_t n = (cmsg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
+
+                        fds_array = GREEDY_REALLOC(fds_array, n_fds_array + n);
+                        if (!fds_array) {
+                                cmsg_close_all(&mh);
+                                return -ENOMEM;
+                        }
+
+                        memcpy(fds_array + n_fds_array, CMSG_TYPED_DATA(cmsg, int), sizeof(int) * n);
+                        n_fds_array += n;
+                }
+
+        if (n_fds_array == 0) {
+                cmsg_close_all(&mh);
+
+                /* If didn't receive an FD or any data, return an error. */
+                if (k == 0)
+                        return -EIO;
+        }
+
+        *ret_fds_array = TAKE_PTR(fds_array);
+        *ret_n_fds_array = n_fds_array;
+
+        return k;
+}
+
+int receive_many_fds(int transport_fd, int **ret_fds_array, size_t *ret_n_fds_array, int flags) {
+        ssize_t k;
+
+        k = receive_many_fds_iov(transport_fd, NULL, 0, ret_fds_array, ret_n_fds_array, flags);
+        if (k == 0)
+                return 0;
+
+        /* k must be negative, since receive_many_fds_iov() only returns a positive value if data was received
+         * through the iov. */
+        assert(k < 0);
+        return (int) k;
+}
+
+ssize_t receive_one_fd_iov(
+                int transport_fd,
+                struct iovec *iov, size_t iovlen,
+                int flags,
+                int *ret_fd) {
+
+        CMSG_BUFFER_TYPE(CMSG_SPACE(sizeof(int))) control;
+        struct msghdr mh = {
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
+                .msg_iov = iov,
+                .msg_iovlen = iovlen,
+        };
+        struct cmsghdr *found;
+        ssize_t k;
+
+        assert(transport_fd >= 0);
+        assert(ret_fd);
+
+        /*
+         * Receive a single FD via @transport_fd. We don't care for
+         * the transport-type. We retrieve a single FD at most, so for
+         * packet-based transports, the caller must ensure to send
+         * only a single FD per packet.  This is best used in
+         * combination with send_one_fd().
+         */
+
+        k = recvmsg_safe(transport_fd, &mh, MSG_CMSG_CLOEXEC | flags);
+        if (k < 0)
+                return k;
+
+        found = cmsg_find(&mh, SOL_SOCKET, SCM_RIGHTS, CMSG_LEN(sizeof(int)));
+        if (!found) {
+                cmsg_close_all(&mh);
+
+                /* If didn't receive an FD or any data, return an error. */
+                if (k == 0)
+                        return -EIO;
+        }
+
+        if (found)
+                *ret_fd = *CMSG_TYPED_DATA(found, int);
+        else
+                *ret_fd = -EBADF;
+
+        return k;
+}
+
+int receive_one_fd(int transport_fd, int flags) {
+        int fd;
+        ssize_t k;
+
+        k = receive_one_fd_iov(transport_fd, NULL, 0, flags, &fd);
+        if (k == 0)
+                return fd;
+
+        /* k must be negative, since receive_one_fd_iov() only returns
+         * a positive value if data was received through the iov. */
+        assert(k < 0);
+        return (int) k;
+}
+
+ssize_t next_datagram_size_fd(int fd) {
+        ssize_t l;
+        int k;
+
+        /* This is a bit like FIONREAD/SIOCINQ, however a bit more powerful. The difference being: recv(MSG_PEEK) will
+         * actually cause the next datagram in the queue to be validated regarding checksums, which FIONREAD doesn't
+         * do. This difference is actually of major importance as we need to be sure that the size returned here
+         * actually matches what we will read with recvmsg() next, as otherwise we might end up allocating a buffer of
+         * the wrong size. */
+
+        l = recv(fd, NULL, 0, MSG_PEEK|MSG_TRUNC);
+        if (l < 0) {
+                if (IN_SET(errno, EOPNOTSUPP, EFAULT))
+                        goto fallback;
+
+                return -errno;
+        }
+        if (l == 0)
+                goto fallback;
+
+        return l;
+
+fallback:
+        k = 0;
+
+        /* Some sockets (AF_PACKET) do not support null-sized recv() with MSG_TRUNC set, let's fall back to FIONREAD
+         * for them. Checksums don't matter for raw sockets anyway, hence this should be fine. */
+
+        if (ioctl(fd, FIONREAD, &k) < 0)
+                return -errno;
+
+        return (ssize_t) k;
+}
+
+/* Put a limit on how many times will attempt to call accept4(). We loop
+ * only on "transient" errors, but let's make sure we don't loop forever. */
+#define MAX_FLUSH_ITERATIONS 1024
+
+int flush_accept(int fd) {
+
+        int r, b;
+        socklen_t l = sizeof(b);
+
+        /* Similar to flush_fd() but flushes all incoming connections by accepting and immediately closing
+         * them. */
+
+        if (getsockopt(fd, SOL_SOCKET, SO_ACCEPTCONN, &b, &l) < 0)
+                return -errno;
+
+        assert(l == sizeof(b));
+        if (!b) /* Let's check if this socket accepts connections before calling accept(). accept4() can
+                 * return EOPNOTSUPP if the fd is not a listening socket, which we should treat as a fatal
+                 * error, or in case the incoming TCP connection triggered a network issue, which we want to
+                 * treat as a transient error. Thus, let's rule out the first reason for EOPNOTSUPP early, so
+                 * we can loop safely on transient errors below. */
+                return -ENOTTY;
+
+        for (unsigned iteration = 0;; iteration++) {
+                int cfd;
+
+                r = fd_wait_for_event(fd, POLLIN, 0);
+                if (r < 0) {
+                        if (r == -EINTR)
+                                continue;
+
+                        return r;
+                }
+                if (r == 0)
+                        return 0;
+
+                if (iteration >= MAX_FLUSH_ITERATIONS)
+                        return log_debug_errno(SYNTHETIC_ERRNO(EBUSY),
+                                               "Failed to flush connections within " STRINGIFY(MAX_FLUSH_ITERATIONS) " iterations.");
+
+                cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+                if (cfd < 0) {
+                        if (errno == EAGAIN)
+                                return 0;
+
+                        if (ERRNO_IS_ACCEPT_AGAIN(errno))
+                                continue;
+
+                        return -errno;
+                }
+
+                safe_close(cfd);
+        }
+}
+
+struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length) {
+        struct cmsghdr *cmsg;
+
+        assert(mh);
+
+        CMSG_FOREACH(cmsg, mh)
+                if (cmsg->cmsg_level == level &&
+                    cmsg->cmsg_type == type &&
+                    (length == (socklen_t) -1 || length == cmsg->cmsg_len))
+                        return cmsg;
+
+        return NULL;
+}
+
+void* cmsg_find_and_copy_data(struct msghdr *mh, int level, int type, void *buf, size_t buf_len) {
+        struct cmsghdr *cmsg;
+
+        assert(mh);
+        assert(buf);
+        assert(buf_len > 0);
+
+        /* This is similar to cmsg_find_data(), but copy the found data to buf. This should be typically used
+         * when reading possibly unaligned data such as timestamp, as time_t is 64-bit and size_t is 32-bit on
+         * RISCV32. See issue #27241. */
+
+        cmsg = cmsg_find(mh, level, type, CMSG_LEN(buf_len));
+        if (!cmsg)
+                return NULL;
+
+        return memcpy_safe(buf, CMSG_DATA(cmsg), buf_len);
+}
+
+int socket_ioctl_fd(void) {
+        int fd;
+
+        /* Create a socket to invoke the various network interface ioctl()s on. Traditionally only AF_INET was good for
+         * that. Since kernel 4.6 AF_NETLINK works for this too. We first try to use AF_INET hence, but if that's not
+         * available (for example, because it is made unavailable via SECCOMP or such), we'll fall back to the more
+         * generic AF_NETLINK. */
+
+        fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
+        if (fd < 0)
+                fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC);
+        if (fd < 0)
+                return -errno;
+
+        return fd;
+}
+
+int sockaddr_un_unlink(const struct sockaddr_un *sa) {
+        const char *p, * nul;
+
+        assert(sa);
+
+        if (sa->sun_family != AF_UNIX)
+                return -EPROTOTYPE;
+
+        if (sa->sun_path[0] == 0) /* Nothing to do for abstract sockets */
+                return 0;
+
+        /* The path in .sun_path is not necessarily NUL terminated. Let's fix that. */
+        nul = memchr(sa->sun_path, 0, sizeof(sa->sun_path));
+        if (nul)
+                p = sa->sun_path;
+        else
+                p = memdupa_suffix0(sa->sun_path, sizeof(sa->sun_path));
+
+        if (unlink(p) < 0)
+                return -errno;
+
+        return 1;
+}
+
+int sockaddr_un_set_path(struct sockaddr_un *ret, const char *path) {
+        size_t l;
+
+        assert(ret);
+        assert(path);
+
+        /* Initialize ret->sun_path from the specified argument. This will interpret paths starting with '@' as
+         * abstract namespace sockets, and those starting with '/' as regular filesystem sockets. It won't accept
+         * anything else (i.e. no relative paths), to avoid ambiguities. Note that this function cannot be used to
+         * reference paths in the abstract namespace that include NUL bytes in the name. */
+
+        l = strlen(path);
+        if (l < 2)
+                return -EINVAL;
+        if (!IN_SET(path[0], '/', '@'))
+                return -EINVAL;
+
+        /* Don't allow paths larger than the space in sockaddr_un. Note that we are a tiny bit more restrictive than
+         * the kernel is: we insist on NUL termination (both for abstract namespace and regular file system socket
+         * addresses!), which the kernel doesn't. We do this to reduce chance of incompatibility with other apps that
+         * do not expect non-NUL terminated file system path. */
+        if (l+1 > sizeof(ret->sun_path))
+                return path[0] == '@' ? -EINVAL : -ENAMETOOLONG; /* return a recognizable error if this is
+                                                                  * too long to fit into a sockaddr_un, but
+                                                                  * is a file system path, and thus might be
+                                                                  * connectible via O_PATH indirection. */
+
+        *ret = (struct sockaddr_un) {
+                .sun_family = AF_UNIX,
+        };
+
+        if (path[0] == '@') {
+                /* Abstract namespace socket */
+                memcpy(ret->sun_path + 1, path + 1, l); /* copy *with* trailing NUL byte */
+                return (int) (offsetof(struct sockaddr_un, sun_path) + l); /* 🔥 *don't* 🔥 include trailing NUL in size */
+
+        } else {
+                assert(path[0] == '/');
+
+                /* File system socket */
+                memcpy(ret->sun_path, path, l + 1); /* copy *with* trailing NUL byte */
+                return (int) (offsetof(struct sockaddr_un, sun_path) + l + 1); /* include trailing NUL in size */
+        }
+}
+
+int socket_bind_to_ifname(int fd, const char *ifname) {
+        assert(fd >= 0);
+
+        /* Call with NULL to drop binding */
+
+        return RET_NERRNO(setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen_ptr(ifname)));
+}
+
+int socket_bind_to_ifindex(int fd, int ifindex) {
+        char ifname[IF_NAMESIZE];
+        int r;
+
+        assert(fd >= 0);
+
+        if (ifindex <= 0)
+                /* Drop binding */
+                return RET_NERRNO(setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, NULL, 0));
+
+        r = setsockopt_int(fd, SOL_SOCKET, SO_BINDTOIFINDEX, ifindex);
+        if (r != -ENOPROTOOPT)
+                return r;
+
+        /* Fall back to SO_BINDTODEVICE on kernels < 5.0 which didn't have SO_BINDTOIFINDEX */
+        r = format_ifname(ifindex, ifname);
+        if (r < 0)
+                return r;
+
+        return socket_bind_to_ifname(fd, ifname);
+}
+
+ssize_t recvmsg_safe(int sockfd, struct msghdr *msg, int flags) {
+        ssize_t n;
+
+        /* A wrapper around recvmsg() that checks for MSG_CTRUNC, and turns it into an error, in a reasonably
+         * safe way, closing any SCM_RIGHTS fds in the error path.
+         *
+         * Note that unlike our usual coding style this might modify *msg on failure. */
+
+        n = recvmsg(sockfd, msg, flags);
+        if (n < 0)
+                return -errno;
+
+        if (FLAGS_SET(msg->msg_flags, MSG_CTRUNC)) {
+                cmsg_close_all(msg);
+                return -EXFULL; /* a recognizable error code */
+        }
+
+        return n;
+}
+
+int socket_get_family(int fd) {
+        int af;
+        socklen_t sl = sizeof(af);
+
+        if (getsockopt(fd, SOL_SOCKET, SO_DOMAIN, &af, &sl) < 0)
+                return -errno;
+
+        if (sl != sizeof(af))
+                return -EINVAL;
+
+        return af;
+}
+
+int socket_set_recvpktinfo(int fd, int af, bool b) {
+
+        if (af == AF_UNSPEC) {
+                af = socket_get_family(fd);
+                if (af < 0)
+                        return af;
+        }
+
+        switch (af) {
+
+        case AF_INET:
+                return setsockopt_int(fd, IPPROTO_IP, IP_PKTINFO, b);
+
+        case AF_INET6:
+                return setsockopt_int(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, b);
+
+        case AF_NETLINK:
+                return setsockopt_int(fd, SOL_NETLINK, NETLINK_PKTINFO, b);
+
+        case AF_PACKET:
+                return setsockopt_int(fd, SOL_PACKET, PACKET_AUXDATA, b);
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int socket_set_unicast_if(int fd, int af, int ifi) {
+        be32_t ifindex_be = htobe32(ifi);
+
+        if (af == AF_UNSPEC) {
+                af = socket_get_family(fd);
+                if (af < 0)
+                        return af;
+        }
+
+        switch (af) {
+
+        case AF_INET:
+                return RET_NERRNO(setsockopt(fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex_be, sizeof(ifindex_be)));
+
+        case AF_INET6:
+                return RET_NERRNO(setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex_be, sizeof(ifindex_be)));
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int socket_set_option(int fd, int af, int opt_ipv4, int opt_ipv6, int val) {
+        if (af == AF_UNSPEC) {
+                af = socket_get_family(fd);
+                if (af < 0)
+                        return af;
+        }
+
+        switch (af) {
+
+        case AF_INET:
+                return setsockopt_int(fd, IPPROTO_IP, opt_ipv4, val);
+
+        case AF_INET6:
+                return setsockopt_int(fd, IPPROTO_IPV6, opt_ipv6, val);
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+}
+
+int socket_get_mtu(int fd, int af, size_t *ret) {
+        int mtu, r;
+
+        if (af == AF_UNSPEC) {
+                af = socket_get_family(fd);
+                if (af < 0)
+                        return af;
+        }
+
+        switch (af) {
+
+        case AF_INET:
+                r = getsockopt_int(fd, IPPROTO_IP, IP_MTU, &mtu);
+                break;
+
+        case AF_INET6:
+                r = getsockopt_int(fd, IPPROTO_IPV6, IPV6_MTU, &mtu);
+                break;
+
+        default:
+                return -EAFNOSUPPORT;
+        }
+
+        if (r < 0)
+                return r;
+        if (mtu <= 0)
+                return -EINVAL;
+
+        *ret = (size_t) mtu;
+        return 0;
+}
+
+static int connect_unix_path_simple(int fd, const char *path) {
+        union sockaddr_union sa = {
+                .un.sun_family = AF_UNIX,
+        };
+        size_t l;
+
+        assert(fd >= 0);
+        assert(path);
+
+        l = strlen(path);
+        assert(l > 0);
+        assert(l < sizeof(sa.un.sun_path));
+
+        memcpy(sa.un.sun_path, path, l + 1);
+        return RET_NERRNO(connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + l + 1));
+}
+
+static int connect_unix_inode(int fd, int inode_fd) {
+        assert(fd >= 0);
+        assert(inode_fd >= 0);
+
+        return connect_unix_path_simple(fd, FORMAT_PROC_FD_PATH(inode_fd));
+}
+
+int connect_unix_path(int fd, int dir_fd, const char *path) {
+        _cleanup_close_ int inode_fd = -EBADF;
+
+        assert(fd >= 0);
+        assert(dir_fd == AT_FDCWD || dir_fd >= 0);
+
+        /* Connects to the specified AF_UNIX socket in the file system. Works around the 108 byte size limit
+         * in sockaddr_un, by going via O_PATH if needed. This hence works for any kind of path. */
+
+        if (!path)
+                return connect_unix_inode(fd, dir_fd); /* If no path is specified, then dir_fd refers to the socket inode to connect to. */
+
+        /* Refuse zero length path early, to make sure AF_UNIX stack won't mistake this for an abstract
+         * namespace path, since first char is NUL */
+        if (isempty(path))
+                return -EINVAL;
+
+        /* Shortcut for the simple case */
+        if (dir_fd == AT_FDCWD && strlen(path) < sizeof_field(struct sockaddr_un, sun_path))
+                return connect_unix_path_simple(fd, path);
+
+        /* If dir_fd is specified, then we need to go the indirect O_PATH route, because connectat() does not
+         * exist. If the path is too long, we also need to take the indirect route, since we can't fit this
+         * into a sockaddr_un directly. */
+
+        inode_fd = openat(dir_fd, path, O_PATH|O_CLOEXEC);
+        if (inode_fd < 0)
+                return -errno;
+
+        return connect_unix_inode(fd, inode_fd);
+}
+
+int socket_address_parse_unix(SocketAddress *ret_address, const char *s) {
+        struct sockaddr_un un;
+        int r;
+
+        assert(ret_address);
+        assert(s);
+
+        if (!IN_SET(*s, '/', '@'))
+                return -EPROTO;
+
+        r = sockaddr_un_set_path(&un, s);
+        if (r < 0)
+                return r;
+
+        *ret_address = (SocketAddress) {
+                .sockaddr.un = un,
+                .size = r,
+        };
+
+        return 0;
+}
+
+int socket_address_parse_vsock(SocketAddress *ret_address, const char *s) {
+        /* AF_VSOCK socket in vsock:cid:port notation */
+        _cleanup_free_ char *n = NULL;
+        char *e, *cid_start;
+        unsigned port, cid;
+        int type, r;
+
+        assert(ret_address);
+        assert(s);
+
+        if ((cid_start = startswith(s, "vsock:")))
+                type = 0;
+        else if ((cid_start = startswith(s, "vsock-dgram:")))
+                type = SOCK_DGRAM;
+        else if ((cid_start = startswith(s, "vsock-seqpacket:")))
+                type = SOCK_SEQPACKET;
+        else if ((cid_start = startswith(s, "vsock-stream:")))
+                type = SOCK_STREAM;
+        else
+                return -EPROTO;
+
+        e = strchr(cid_start, ':');
+        if (!e)
+                return -EINVAL;
+
+        r = safe_atou(e+1, &port);
+        if (r < 0)
+                return r;
+
+        n = strndup(cid_start, e - cid_start);
+        if (!n)
+                return -ENOMEM;
+
+        if (isempty(n))
+                cid = VMADDR_CID_ANY;
+        else {
+                r = safe_atou(n, &cid);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret_address = (SocketAddress) {
+                .sockaddr.vm = {
+                        .svm_cid = cid,
+                        .svm_family = AF_VSOCK,
+                        .svm_port = port,
+                },
+                .type = type,
+                .size = sizeof(struct sockaddr_vm),
+        };
+
+        return 0;
+}