clientname.c

Functions for looking up the remote name or addr of a socket. [詳細]

ソースコードを見る。

関数
char *	client_addr (int fd)
	Return the IP addr of the client as a string
static int	get_sockaddr_family (const struct sockaddr_storage *ss)
char *	client_name (int fd)
	Return the DNS name of the client.
void	client_sockaddr (int fd, struct sockaddr_storage *ss, socklen_t *ss_len)
	Get the sockaddr for the client.
int	lookup_name (int fd, const struct sockaddr_storage *ss, socklen_t ss_len, char *name_buf, size_t name_buf_len, char *port_buf, size_t port_buf_len)
	Look up a name from ss into name_buf.
int	compare_addrinfo_sockaddr (const struct addrinfo *ai, const struct sockaddr_storage *ss)
	Compare an addrinfo from the resolver to a sockinfo.
int	check_name (int fd, const struct sockaddr_storage *ss, char *name_buf)
	Do a forward lookup on name_buf and make sure it corresponds to ss -- otherwise we may be being spoofed.
変数
static const char	default_name [] = "UNKNOWN"
int	am_server

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説明

Functions for looking up the remote name or addr of a socket.

This file is now converted to use the new-style getaddrinfo() interface, which supports IPv6 but is also supported on recent IPv4-only machines. On systems that don't have that interface, we emulate it using the KAME implementation.

clientname.c で定義されています。

---

関数

char* client_addr

(

int

fd

)

Return the IP addr of the client as a string

clientname.c の 43 行で定義されています。

参照先 am_server・client_sockaddr()・getnameinfo()・strlcpy().

参照元 check_name()・client_name()・log_formatted()・lookup_name()・start_daemon().

{
        static char addr_buf[100];
        static int initialised;
        struct sockaddr_storage ss;
        socklen_t length = sizeof ss;
        char *ssh_info, *p;

        if (initialised)
                return addr_buf;

        initialised = 1;

        if (am_server) {        /* daemon over --rsh mode */
                strcpy(addr_buf, "0.0.0.0");
                if ((ssh_info = getenv("SSH_CONNECTION")) != NULL
                    || (ssh_info = getenv("SSH_CLIENT")) != NULL
                    || (ssh_info = getenv("SSH2_CLIENT")) != NULL) {
                        strlcpy(addr_buf, ssh_info, sizeof addr_buf);
                        /* Truncate the value to just the IP address. */
                        if ((p = strchr(addr_buf, ' ')) != NULL)
                                *p = '\0';
                }
        } else {
                client_sockaddr(fd, &ss, &length);
                getnameinfo((struct sockaddr *)&ss, length,
                            addr_buf, sizeof addr_buf, NULL, 0, NI_NUMERICHOST);
        }

        return addr_buf;
}

static int get_sockaddr_family

(

const struct sockaddr_storage *

ss

)

[static]

clientname.c の 76 行で定義されています。

参照元 check_name()・client_sockaddr()・compare_addrinfo_sockaddr().

{
        return ((struct sockaddr *) ss)->sa_family;
}

char* client_name

(

int

fd

)

Return the DNS name of the client.

The name is statically cached so that repeated lookups are quick, so there is a limit of one lookup per customer.

If anything goes wrong, including the name->addr->name check, then we just use "UNKNOWN", so you can use that value in hosts allow lines.

After translation from sockaddr to name we do a forward lookup to make sure nobody is spoofing PTR records.

clientname.c の 95 行で定義されています。

参照先 addrinfo::ai_addr・addrinfo::ai_family・am_server・check_name()・client_addr()・client_sockaddr()・default_name・FLOG・freeaddrinfo()・gai_strerror()・getaddrinfo()・lookup_name()・rprintf().

参照元 log_formatted()・start_daemon().

{
        static char name_buf[100];
        static char port_buf[100];
        static int initialised;
        struct sockaddr_storage ss;
        socklen_t ss_len;

        if (initialised)
                return name_buf;

        strcpy(name_buf, default_name);
        initialised = 1;

        memset(&ss, 0, sizeof ss);

        if (am_server) {        /* daemon over --rsh mode */
                char *addr = client_addr(fd);
                struct addrinfo hint, *answer;
                int err;

                memset(&hint, 0, sizeof hint);

#ifdef AI_NUMERICHOST
                hint.ai_flags = AI_NUMERICHOST;
#endif
                hint.ai_socktype = SOCK_STREAM;

                if ((err = getaddrinfo(addr, NULL, &hint, &answer)) != 0) {
                        rprintf(FLOG, "malformed address %s: %s\n",
                                addr, gai_strerror(err));
                        return name_buf;
                }

                switch (answer->ai_family) {
                case AF_INET:
                        ss_len = sizeof (struct sockaddr_in);
                        memcpy(&ss, answer->ai_addr, ss_len);
                        break;
#ifdef INET6
                case AF_INET6:
                        ss_len = sizeof (struct sockaddr_in6);
                        memcpy(&ss, answer->ai_addr, ss_len);
                        break;
#endif
                }
                freeaddrinfo(answer);
        } else {
                ss_len = sizeof ss;
                client_sockaddr(fd, &ss, &ss_len);
        }

        if (lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf,
                        port_buf, sizeof port_buf) == 0)
                check_name(fd, &ss, name_buf);

        return name_buf;
}

void client_sockaddr	(	int	fd,
		struct sockaddr_storage *	ss,
		socklen_t *	ss_len
	)

Get the sockaddr for the client.

If it comes in as an ipv4 address mapped into IPv6 format then we convert it back to a regular IPv4.

clientname.c の 162 行で定義されています。

参照先 errno・FLOG・get_sockaddr_family()・rsyserr().

参照元 client_addr()・client_name().

{
        memset(ss, 0, sizeof *ss);

        if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
                /* FIXME: Can we really not continue? */
                rsyserr(FLOG, errno, "getpeername on fd%d failed", fd);
                exit_cleanup(RERR_SOCKETIO);
        }

#ifdef INET6
        if (get_sockaddr_family(ss) == AF_INET6 &&
            IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
                /* OK, so ss is in the IPv6 family, but it is really
                 * an IPv4 address: something like
                 * "::ffff:10.130.1.2".  If we use it as-is, then the
                 * reverse lookup might fail or perhaps something else
                 * bad might happen.  So instead we convert it to an
                 * equivalent address in the IPv4 address family.  */
                struct sockaddr_in6 sin6;
                struct sockaddr_in *sin;

                memcpy(&sin6, ss, sizeof sin6);
                sin = (struct sockaddr_in *)ss;
                memset(sin, 0, sizeof *sin);
                sin->sin_family = AF_INET;
                *ss_len = sizeof (struct sockaddr_in);
#ifdef HAVE_SOCKADDR_IN_LEN
                sin->sin_len = *ss_len;
#endif
                sin->sin_port = sin6.sin6_port;

                /* There is a macro to extract the mapped part
                 * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
                 * to be present in the Linux headers. */
                memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12],
                    sizeof sin->sin_addr);
        }
#endif
}

int lookup_name	(	int	fd,
		const struct sockaddr_storage *	ss,
		socklen_t	ss_len,
		char *	name_buf,
		size_t	name_buf_len,
		char *	port_buf,
		size_t	port_buf_len
	)

Look up a name from ss into name_buf.

引数:

fd

file descriptor for client socket.

clientname.c の 211 行で定義されています。

参照先 client_addr()・default_name・FLOG・gai_strerror()・getnameinfo()・rprintf().

参照元 client_name().

{
        int name_err;

        /* reverse lookup */
        name_err = getnameinfo((struct sockaddr *) ss, ss_len,
                               name_buf, name_buf_len,
                               port_buf, port_buf_len,
                               NI_NAMEREQD | NI_NUMERICSERV);
        if (name_err != 0) {
                strcpy(name_buf, default_name);
                rprintf(FLOG, "name lookup failed for %s: %s\n",
                        client_addr(fd), gai_strerror(name_err));
                return name_err;
        }

        return 0;
}

int compare_addrinfo_sockaddr	(	const struct addrinfo *	ai,
		const struct sockaddr_storage *	ss
	)

Compare an addrinfo from the resolver to a sockinfo.

Like strcmp, returns 0 for identical.

clientname.c の 240 行で定義されています。

参照先 addrinfo::ai_addr・addrinfo::ai_addrlen・addrinfo::ai_family・FLOG・get_sockaddr_family()・rprintf().

参照元 check_name().

{
        int ss_family = get_sockaddr_family(ss);
        const char fn[] = "compare_addrinfo_sockaddr";

        if (ai->ai_family != ss_family) {
                rprintf(FLOG, "%s: response family %d != %d\n",
                        fn, ai->ai_family, ss_family);
                return 1;
        }

        /* The comparison method depends on the particular AF. */
        if (ss_family == AF_INET) {
                const struct sockaddr_in *sin1, *sin2;

                sin1 = (const struct sockaddr_in *) ss;
                sin2 = (const struct sockaddr_in *) ai->ai_addr;

                return memcmp(&sin1->sin_addr, &sin2->sin_addr,
                              sizeof sin1->sin_addr);
        }

#ifdef INET6
        if (ss_family == AF_INET6) {
                const struct sockaddr_in6 *sin1, *sin2;

                sin1 = (const struct sockaddr_in6 *) ss;
                sin2 = (const struct sockaddr_in6 *) ai->ai_addr;

                if (ai->ai_addrlen < sizeof (struct sockaddr_in6)) {
                        rprintf(FLOG, "%s: too short sockaddr_in6; length=%d\n",
                                fn, ai->ai_addrlen);
                        return 1;
                }

                if (memcmp(&sin1->sin6_addr, &sin2->sin6_addr,
                           sizeof sin1->sin6_addr))
                        return 1;

#ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
                if (sin1->sin6_scope_id != sin2->sin6_scope_id)
                        return 1;
#endif
                return 0;
        }
#endif /* INET6 */

        /* don't know */
        return 1;
}

int check_name	(	int	fd,
		const struct sockaddr_storage *	ss,
		char *	name_buf
	)

Do a forward lookup on name_buf and make sure it corresponds to ss -- otherwise we may be being spoofed.

If we suspect we are, then we don't abort the connection but just emit a warning, and change name_buf to be "UNKNOWN".

We don't do anything with the service when checking the name, because it doesn't seem that it could be spoofed in any way, and getaddrinfo on random service names seems to cause problems on AIX.

clientname.c の 303 行で定義されています。

参照先 addrinfo::ai_next・client_addr()・compare_addrinfo_sockaddr()・default_name・FLOG・freeaddrinfo()・gai_strerror()・get_sockaddr_family()・getaddrinfo()・rprintf().

参照元 client_name().

{
        struct addrinfo hints, *res, *res0;
        int error;
        int ss_family = get_sockaddr_family(ss);

        memset(&hints, 0, sizeof hints);
        hints.ai_family = ss_family;
        hints.ai_flags = AI_CANONNAME;
        hints.ai_socktype = SOCK_STREAM;
        error = getaddrinfo(name_buf, NULL, &hints, &res0);
        if (error) {
                rprintf(FLOG, "forward name lookup for %s failed: %s\n",
                        name_buf, gai_strerror(error));
                strcpy(name_buf, default_name);
                return error;
        }

        /* Given all these results, we expect that one of them will be
         * the same as ss.  The comparison is a bit complicated. */
        for (res = res0; res; res = res->ai_next) {
                if (!compare_addrinfo_sockaddr(res, ss))
                        break;  /* OK, identical */
        }

        if (!res0) {
                /* We hit the end of the list without finding an
                 * address that was the same as ss. */
                rprintf(FLOG, "no known address for \"%s\": "
                        "spoofed address?\n", name_buf);
                strcpy(name_buf, default_name);
        } else if (res == NULL) {
                /* We hit the end of the list without finding an
                 * address that was the same as ss. */
                rprintf(FLOG, "%s is not a known address for \"%s\": "
                        "spoofed address?\n", client_addr(fd), name_buf);
                strcpy(name_buf, default_name);
        }

        freeaddrinfo(res0);
        return 0;
}

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変数

const char default_name[] = "UNKNOWN" [static]

clientname.c の 36 行で定義されています。

参照元 check_name()・client_name()・lookup_name().

int am_server

options.c の 75 行で定義されています。

参照元 check_timeout()・clean_flist()・client_addr()・client_name()・client_run()・do_delete_pass()・do_recv()・end_progress()・generate_files()・handle_stats()・local_child()・log_delete()・log_item()・lp_load()・main()・maybe_log_item()・parse_arguments()・parse_filter_file()・read_msg_fd()・recv_files()・rflush()・rsync_module()・rwrite()・send_files()・setup_iconv()・setup_protocol()・show_filelist_p()・show_malloc_stats()・show_progress()・sigusr2_handler()・start_daemon()・who_am_i().

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