Adding upstream version 241.upstream/241upstream

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

1 files changed, 1347 insertions, 0 deletions

diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
new file mode 100644
index 0000000..91bf801
--- /dev/null
+++ b/src/basic/socket-util.c
@@ -0,0 +1,1347 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#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 <string.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "format-util.h"
+#include "log.h"
+#include "macro.h"
+#include "missing.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 "user-util.h"
+#include "utf8.h"
+#include "util.h"
+
+#if ENABLE_IDN
+#  define IDN_FLAGS NI_IDN
+#else
+#  define IDN_FLAGS 0
+#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_parse(SocketAddress *a, const char *s) {
+        _cleanup_free_ char *n = NULL;
+        char *e;
+        int r;
+
+        assert(a);
+        assert(s);
+
+        *a = (SocketAddress) {
+                .type = SOCK_STREAM,
+        };
+
+        if (*s == '[') {
+                uint16_t port;
+
+                /* IPv6 in [x:.....:z]:p notation */
+
+                e = strchr(s+1, ']');
+                if (!e)
+                        return -EINVAL;
+
+                n = strndup(s+1, e-s-1);
+                if (!n)
+                        return -ENOMEM;
+
+                errno = 0;
+                if (inet_pton(AF_INET6, n, &a->sockaddr.in6.sin6_addr) <= 0)
+                        return errno > 0 ? -errno : -EINVAL;
+
+                e++;
+                if (*e != ':')
+                        return -EINVAL;
+
+                e++;
+                r = parse_ip_port(e, &port);
+                if (r < 0)
+                        return r;
+
+                a->sockaddr.in6.sin6_family = AF_INET6;
+                a->sockaddr.in6.sin6_port = htobe16(port);
+                a->size = sizeof(struct sockaddr_in6);
+
+        } else if (*s == '/') {
+                /* AF_UNIX socket */
+
+                size_t l;
+
+                l = strlen(s);
+                if (l >= sizeof(a->sockaddr.un.sun_path)) /* Note that we refuse non-NUL-terminated sockets when
+                                                           * parsing (the kernel itself is less strict here in what it
+                                                           * accepts) */
+                        return -EINVAL;
+
+                a->sockaddr.un.sun_family = AF_UNIX;
+                memcpy(a->sockaddr.un.sun_path, s, l);
+                a->size = offsetof(struct sockaddr_un, sun_path) + l + 1;
+
+        } else if (*s == '@') {
+                /* Abstract AF_UNIX socket */
+                size_t l;
+
+                l = strlen(s+1);
+                if (l >= sizeof(a->sockaddr.un.sun_path) - 1) /* Note that we refuse non-NUL-terminated sockets here
+                                                               * when parsing, even though abstract namespace sockets
+                                                               * explicitly allow embedded NUL bytes and don't consider
+                                                               * them special. But it's simply annoying to debug such
+                                                               * sockets. */
+                        return -EINVAL;
+
+                a->sockaddr.un.sun_family = AF_UNIX;
+                memcpy(a->sockaddr.un.sun_path+1, s+1, l);
+                a->size = offsetof(struct sockaddr_un, sun_path) + 1 + l;
+
+        } else if (startswith(s, "vsock:")) {
+                /* AF_VSOCK socket in vsock:cid:port notation */
+                const char *cid_start = s + STRLEN("vsock:");
+                unsigned port;
+
+                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)) {
+                        r = safe_atou(n, &a->sockaddr.vm.svm_cid);
+                        if (r < 0)
+                                return r;
+                } else
+                        a->sockaddr.vm.svm_cid = VMADDR_CID_ANY;
+
+                a->sockaddr.vm.svm_family = AF_VSOCK;
+                a->sockaddr.vm.svm_port = port;
+                a->size = sizeof(struct sockaddr_vm);
+
+        } else {
+                uint16_t port;
+
+                e = strchr(s, ':');
+                if (e) {
+                        r = parse_ip_port(e + 1, &port);
+                        if (r < 0)
+                                return r;
+
+                        n = strndup(s, e-s);
+                        if (!n)
+                                return -ENOMEM;
+
+                        /* IPv4 in w.x.y.z:p notation? */
+                        r = inet_pton(AF_INET, n, &a->sockaddr.in.sin_addr);
+                        if (r < 0)
+                                return -errno;
+
+                        if (r > 0) {
+                                /* Gotcha, it's a traditional IPv4 address */
+                                a->sockaddr.in.sin_family = AF_INET;
+                                a->sockaddr.in.sin_port = htobe16(port);
+                                a->size = sizeof(struct sockaddr_in);
+                        } else {
+                                unsigned idx;
+
+                                if (strlen(n) > IF_NAMESIZE-1)
+                                        return -EINVAL;
+
+                                /* Uh, our last resort, an interface name */
+                                idx = if_nametoindex(n);
+                                if (idx == 0)
+                                        return -EINVAL;
+
+                                a->sockaddr.in6.sin6_family = AF_INET6;
+                                a->sockaddr.in6.sin6_port = htobe16(port);
+                                a->sockaddr.in6.sin6_scope_id = idx;
+                                a->sockaddr.in6.sin6_addr = in6addr_any;
+                                a->size = sizeof(struct sockaddr_in6);
+                        }
+                } else {
+
+                        /* Just a port */
+                        r = parse_ip_port(s, &port);
+                        if (r < 0)
+                                return r;
+
+                        if (socket_ipv6_is_supported()) {
+                                a->sockaddr.in6.sin6_family = AF_INET6;
+                                a->sockaddr.in6.sin6_port = htobe16(port);
+                                a->sockaddr.in6.sin6_addr = in6addr_any;
+                                a->size = sizeof(struct sockaddr_in6);
+                        } else {
+                                a->sockaddr.in.sin_family = AF_INET;
+                                a->sockaddr.in.sin_port = htobe16(port);
+                                a->sockaddr.in.sin_addr.s_addr = INADDR_ANY;
+                                a->size = sizeof(struct sockaddr_in);
+                        }
+                }
+        }
+
+        return 0;
+}
+
+int socket_address_parse_and_warn(SocketAddress *a, const char *s) {
+        SocketAddress b;
+        int r;
+
+        /* Similar to socket_address_parse() but warns for IPv6 sockets when we don't support them. */
+
+        r = socket_address_parse(&b, s);
+        if (r < 0)
+                return r;
+
+        if (!socket_ipv6_is_supported() && b.sockaddr.sa.sa_family == AF_INET6) {
+                log_warning("Binding to IPv6 address not available since kernel does not support IPv6.");
+                return -EAFNOSUPPORT;
+        }
+
+        *a = b;
+        return 0;
+}
+
+int socket_address_parse_netlink(SocketAddress *a, const char *s) {
+        int family;
+        unsigned group = 0;
+        _cleanup_free_ char *sfamily = NULL;
+        assert(a);
+        assert(s);
+
+        zero(*a);
+        a->type = SOCK_RAW;
+
+        errno = 0;
+        if (sscanf(s, "%ms %u", &sfamily, &group) < 1)
+                return errno > 0 ? -errno : -EINVAL;
+
+        family = netlink_family_from_string(sfamily);
+        if (family < 0)
+                return -EINVAL;
+
+        a->sockaddr.nl.nl_family = AF_NETLINK;
+        a->sockaddr.nl.nl_groups = group;
+
+        a->type = SOCK_RAW;
+        a->size = sizeof(struct sockaddr_nl);
+        a->protocol = family;
+
+        return 0;
+}
+
+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, 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, 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 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, 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, 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, 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_files_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;
+}
+
+bool socket_address_is(const SocketAddress *a, const char *s, int type) {
+        struct SocketAddress b;
+
+        assert(a);
+        assert(s);
+
+        if (socket_address_parse(&b, s) < 0)
+                return false;
+
+        b.type = type;
+
+        return socket_address_equal(a, &b);
+}
+
+bool socket_address_is_netlink(const SocketAddress *a, const char *s) {
+        struct SocketAddress b;
+
+        assert(a);
+        assert(s);
+
+        if (socket_address_parse_netlink(&b, s) < 0)
+                return false;
+
+        return socket_address_equal(a, &b);
+}
+
+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) {
+        if (access("/proc/net/if_inet6", F_OK) != 0)
+                return false;
+
+        return true;
+}
+
+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) {
+        union sockaddr_union *sa = (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;
+        }
+}
+
+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 {
+                        char a[INET6_ADDRSTRLEN];
+
+                        inet_ntop(AF_INET6, &sa->in6.sin6_addr, a, sizeof(a));
+
+                        if (include_port) {
+                                r = asprintf(&p,
+                                             "[%s]:%u",
+                                             a,
+                                             be16toh(sa->in6.sin6_port));
+                                if (r < 0)
+                                        return -ENOMEM;
+                        } 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 = {};
+
+                /* 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_inc_sndbuf(int fd, size_t n) {
+        int r, value;
+        socklen_t l = sizeof(value);
+
+        r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
+                return 0;
+
+        /* If we have the privileges we will ignore the kernel limit. */
+
+        if (setsockopt_int(fd, SOL_SOCKET, SO_SNDBUF, n) < 0) {
+                r = setsockopt_int(fd, SOL_SOCKET, SO_SNDBUFFORCE, n);
+                if (r < 0)
+                        return r;
+        }
+
+        return 1;
+}
+
+int fd_inc_rcvbuf(int fd, size_t n) {
+        int r, value;
+        socklen_t l = sizeof(value);
+
+        r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
+        if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
+                return 0;
+
+        /* If we have the privileges we will ignore the kernel limit. */
+
+        if (setsockopt_int(fd, SOL_SOCKET, SO_RCVBUF, n) < 0) {
+                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(const char *p) {
+        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. */
+
+        if (isempty(p))
+                return false;
+
+        if (strlen(p) >= IFNAMSIZ)
+                return false;
+
+        if (dot_or_dot_dot(p))
+                return false;
+
+        while (*p) {
+                if ((unsigned char) *p >= 127U)
+                        return false;
+
+                if ((unsigned char) *p <= 32U)
+                        return false;
+
+                if (IN_SET(*p, ':', '/'))
+                        return false;
+
+                numeric = numeric && (*p >= '0' && *p <= '9');
+                p++;
+        }
+
+        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_one_fd_iov_sa(
+                int transport_fd,
+                int fd,
+                struct iovec *iov, size_t iovlen,
+                const struct sockaddr *sa, socklen_t len,
+                int flags) {
+
+        union {
+                struct cmsghdr cmsghdr;
+                uint8_t buf[CMSG_SPACE(sizeof(int))];
+        } control = {};
+        struct msghdr mh = {
+                .msg_name = (struct sockaddr*) sa,
+                .msg_namelen = len,
+                .msg_iov = 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));
+
+                mh.msg_controllen = CMSG_SPACE(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_one_fd_iov(
+                int transport_fd,
+                struct iovec *iov, size_t iovlen,
+                int flags,
+                int *ret_fd) {
+
+        union {
+                struct cmsghdr cmsghdr;
+                uint8_t buf[CMSG_SPACE(sizeof(int))];
+        } control = {};
+        struct msghdr mh = {
+                .msg_control = &control,
+                .msg_controllen = sizeof(control),
+                .msg_iov = iov,
+                .msg_iovlen = iovlen,
+        };
+        struct cmsghdr *cmsg, *found = NULL;
+        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(transport_fd, &mh, MSG_CMSG_CLOEXEC | flags);
+        if (k < 0)
+                return (ssize_t) -errno;
+
+        CMSG_FOREACH(cmsg, &mh) {
+                if (cmsg->cmsg_level == SOL_SOCKET &&
+                    cmsg->cmsg_type == SCM_RIGHTS &&
+                    cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
+                        assert(!found);
+                        found = cmsg;
+                        break;
+                }
+        }
+
+        if (!found)
+                cmsg_close_all(&mh);
+
+        /* If didn't receive an FD or any data, return an error. */
+        if (k == 0 && !found)
+                return -EIO;
+
+        if (found)
+                *ret_fd = *(int*) CMSG_DATA(found);
+        else
+                *ret_fd = -1;
+
+        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;
+}
+
+int flush_accept(int fd) {
+
+        struct pollfd pollfd = {
+                .fd = fd,
+                .events = POLLIN,
+        };
+        int r;
+
+        /* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
+
+        for (;;) {
+                int cfd;
+
+                r = poll(&pollfd, 1, 0);
+                if (r < 0) {
+                        if (errno == EINTR)
+                                continue;
+
+                        return -errno;
+
+                } else if (r == 0)
+                        return 0;
+
+                cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
+                if (cfd < 0) {
+                        if (errno == EINTR)
+                                continue;
+
+                        if (errno == EAGAIN)
+                                return 0;
+
+                        return -errno;
+                }
+
+                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;
+}
+
+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 == 0)
+                return -EINVAL;
+        if (!IN_SET(path[0], '/', '@'))
+                return -EINVAL;
+        if (path[1] == 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 -EINVAL;
+
+        *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 */
+        }
+}