/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include "nm-sd-adapt-shared.h"

#include <errno.h>

#include <limits.h>

#include <stdio.h>

#include <sys/utsname.h>

#include <unistd.h>

#include "alloc-util.h"

#include "hostname-util.h"

#include "string-util.h"

#include "strv.h"

#if 0 /* NM_IGNORED */

char* gethostname_malloc(void) {

        struct utsname u;

        const char *s;

        /* This call tries to return something useful, either the actual hostname

         * or it makes something up. The only reason it might fail is OOM.

         * It might even return "localhost" if that's set. */

        assert_se(uname(&u) >= 0);

        s = u.nodename;

        if (isempty(s) || streq(s, "(none)"))

                s = FALLBACK_HOSTNAME;

        return strdup(s);

}

char* gethostname_short_malloc(void) {

        struct utsname u;

        const char *s;

        /* Like above, but kills the FQDN part if present. */

        assert_se(uname(&u) >= 0);

        s = u.nodename;

        if (isempty(s) || streq(s, "(none)") || s[0] == '.') {

                s = FALLBACK_HOSTNAME;

                assert(s[0] != '.');

        }

        return strndup(s, strcspn(s, "."));

}

#endif /* NM_IGNORED */

int gethostname_strict(char **ret) {

        struct utsname u;

        char *k;

        /* This call will rather fail than make up a name. It will not return "localhost" either. */

        assert_se(uname(&u) >= 0);

        if (isempty(u.nodename))

                return -ENXIO;

        if (streq(u.nodename, "(none)"))

                return -ENXIO;

        if (is_localhost(u.nodename))

                return -ENXIO;

        k = strdup(u.nodename);

        if (!k)

                return -ENOMEM;

        *ret = k;

        return 0;

}

bool valid_ldh_char(char c) {

        /* "LDH" → "Letters, digits, hyphens", as per RFC 5890, Section 2.3.1 */

        return

                (c >= 'a' && c <= 'z') ||

                (c >= 'A' && c <= 'Z') ||

                (c >= '0' && c <= '9') ||

                c == '-';

}

bool hostname_is_valid(const char *s, ValidHostnameFlags flags) {

        unsigned n_dots = 0;

        const char *p;

        bool dot, hyphen;

        /* Check if s looks like a valid hostname or FQDN. This does not do full DNS validation, but only

         * checks if the name is composed of allowed characters and the length is not above the maximum

         * allowed by Linux (c.f. dns_name_is_valid()). A trailing dot is allowed if

         * VALID_HOSTNAME_TRAILING_DOT flag is set and at least two components are present in the name. Note

         * that due to the restricted charset and length this call is substantially more conservative than

         * dns_name_is_valid(). Doesn't accept empty hostnames, hostnames with leading dots, and hostnames

         * with multiple dots in a sequence. Doesn't allow hyphens at the beginning or end of label. */

        if (isempty(s))

                return false;

        if (streq(s, ".host")) /* Used by the container logic to denote the "root container" */

                return FLAGS_SET(flags, VALID_HOSTNAME_DOT_HOST);

        for (p = s, dot = hyphen = true; *p; p++)

                if (*p == '.') {

                        if (dot || hyphen)

                                return false;

                        dot = true;

                        hyphen = false;

                        n_dots++;

                } else if (*p == '-') {

                        if (dot)

                                return false;

                        dot = false;

                        hyphen = true;

                } else {

                        if (!valid_ldh_char(*p))

                                return false;

                        dot = false;

                        hyphen = false;

                }

        if (dot && (n_dots < 2 || !FLAGS_SET(flags, VALID_HOSTNAME_TRAILING_DOT)))

                return false;

        if (hyphen)

                return false;

        if (p-s > HOST_NAME_MAX) /* Note that HOST_NAME_MAX is 64 on Linux, but DNS allows domain names up to

                                  * 255 characters */

                return false;

        return true;

}

char* hostname_cleanup(char *s) {

        char *p, *d;

        bool dot, hyphen;

        assert(s);

        for (p = s, d = s, dot = hyphen = true; *p && d - s < HOST_NAME_MAX; p++)

                if (*p == '.') {

                        if (dot || hyphen)

                                continue;

                        *(d++) = '.';

                        dot = true;

                        hyphen = false;

                } else if (*p == '-') {

                        if (dot)

                                continue;

                        *(d++) = '-';

                        dot = false;

                        hyphen = true;

                } else if (valid_ldh_char(*p)) {

                        *(d++) = *p;

                        dot = false;

                        hyphen = false;

                }

        if (d > s && IN_SET(d[-1], '-', '.'))

                /* The dot can occur at most once, but we might have multiple

                 * hyphens, hence the loop */

                d--;

        *d = 0;

        return s;

}

bool is_localhost(const char *hostname) {

        assert(hostname);

        /* This tries to identify local host and domain names

         * described in RFC6761 plus the redhatism of localdomain */

        return STRCASE_IN_SET(

                        hostname,

                        "localhost",

                        "localhost.",

                        "localhost.localdomain",

                        "localhost.localdomain.") ||

                endswith_no_case(hostname, ".localhost") ||

                endswith_no_case(hostname, ".localhost.") ||

                endswith_no_case(hostname, ".localhost.localdomain") ||

                endswith_no_case(hostname, ".localhost.localdomain.");

}