New upstream version 1.29.90 upstream/1.29.90

1 files changed, 714 insertions, 0 deletions

diff --git a/src/core/dhcp/nm-dhcp-dhclient-utils.c b/src/core/dhcp/nm-dhcp-dhclient-utils.c
new file mode 100644
index 00000000..ad1e097f
--- /dev/null
+++ b/src/core/dhcp/nm-dhcp-dhclient-utils.c
@@ -0,0 +1,714 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ */
+
+#include "src/core/nm-default-daemon.h"
+
+#include "nm-dhcp-dhclient-utils.h"
+
+#include <ctype.h>
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <linux/if_ether.h>
+
+#include "nm-glib-aux/nm-dedup-multi.h"
+
+#include "nm-dhcp-utils.h"
+#include "nm-ip4-config.h"
+#include "nm-utils.h"
+#include "platform/nm-platform.h"
+#include "NetworkManagerUtils.h"
+
+#define TIMEOUT_TAG  "timeout "
+#define RETRY_TAG    "retry "
+#define CLIENTID_TAG "send dhcp-client-identifier"
+
+#define HOSTNAME4_TAG    "send host-name"
+#define HOSTNAME4_FORMAT HOSTNAME4_TAG " \"%s\"; # added by NetworkManager"
+
+#define FQDN_TAG_PREFIX "send fqdn."
+#define FQDN_TAG        FQDN_TAG_PREFIX "fqdn"
+#define FQDN_FORMAT     FQDN_TAG " \"%s\"; # added by NetworkManager"
+
+#define ALSOREQ_TAG "also request "
+#define REQ_TAG     "request "
+
+#define MUDURLv4_DEF "option mudurl code 161 = text;\n"
+#define MUDURLv4_FMT "send mudurl \"%s\";\n"
+
+#define MUDURLv6_DEF "option dhcp6.mudurl code 112 = text;\n"
+#define MUDURLv6_FMT "send dhcp6.mudurl \"%s\";\n"
+
+static void
+add_request(GPtrArray *array, const char *item)
+{
+    guint i;
+
+    for (i = 0; i < array->len; i++) {
+        if (nm_streq(array->pdata[i], item))
+            return;
+    }
+    g_ptr_array_add(array, g_strdup(item));
+}
+
+static gboolean
+grab_request_options(GPtrArray *store, const char *line)
+{
+    gs_free const char **line_v = NULL;
+    gsize                i;
+
+    /* Grab each 'request' or 'also request'  option and save for later */
+    line_v = nm_utils_strsplit_set(line, "\t ,");
+    for (i = 0; line_v && line_v[i]; i++) {
+        const char *ss = nm_str_skip_leading_spaces(line_v[i]);
+        gsize       l;
+        gboolean    end = FALSE;
+
+        if (!ss[0])
+            continue;
+        if (ss[0] == ';') {
+            /* all done */
+            return TRUE;
+        }
+
+        if (!g_ascii_isalnum(ss[0]))
+            continue;
+
+        l = strlen(ss);
+
+        while (l > 0 && g_ascii_isspace(ss[l - 1])) {
+            ((char *) ss)[l - 1] = '\0';
+            l--;
+        }
+        if (l > 0 && ss[l - 1] == ';') {
+            /* Remove the EOL marker */
+            ((char *) ss)[l - 1] = '\0';
+            end                  = TRUE;
+        }
+
+        if (ss[0])
+            add_request(store, ss);
+
+        if (end)
+            return TRUE;
+    }
+
+    return FALSE;
+}
+
+static void
+add_ip4_config(GString *           str,
+               GBytes *            client_id,
+               const char *        hostname,
+               gboolean            use_fqdn,
+               NMDhcpHostnameFlags hostname_flags)
+{
+    if (client_id) {
+        const char *p;
+        gsize       l;
+        guint       i;
+
+        p = g_bytes_get_data(client_id, &l);
+        nm_assert(p);
+
+        /* Allow type 0 (non-hardware address) to be represented as a string
+         * as long as all the characters are printable.
+         */
+        for (i = 1; (p[0] == 0) && i < l; i++) {
+            if (!g_ascii_isprint(p[i]) || p[i] == '\\' || p[i] == '"')
+                break;
+        }
+
+        g_string_append(str, CLIENTID_TAG " ");
+        if (i < l) {
+            /* Unprintable; convert to a hex string */
+            for (i = 0; i < l; i++) {
+                if (i > 0)
+                    g_string_append_c(str, ':');
+                g_string_append_printf(str, "%02x", (guint8) p[i]);
+            }
+        } else {
+            /* Printable; just add to the line with type 0 */
+            g_string_append_c(str, '"');
+            g_string_append(str, "\\x00");
+            g_string_append_len(str, p + 1, l - 1);
+            g_string_append_c(str, '"');
+        }
+        g_string_append(str, "; # added by NetworkManager\n");
+    }
+
+    if (hostname) {
+        if (use_fqdn) {
+            g_string_append_printf(str, FQDN_FORMAT "\n", hostname);
+
+            g_string_append_printf(str,
+                                   FQDN_TAG_PREFIX "encoded %s;\n",
+                                   (hostname_flags & NM_DHCP_HOSTNAME_FLAG_FQDN_ENCODED) ? "on"
+                                                                                         : "off");
+
+            g_string_append_printf(
+                str,
+                FQDN_TAG_PREFIX "server-update %s;\n",
+                (hostname_flags & NM_DHCP_HOSTNAME_FLAG_FQDN_SERV_UPDATE) ? "on" : "off");
+
+            g_string_append_printf(str,
+                                   FQDN_TAG_PREFIX "no-client-update %s;\n",
+                                   (hostname_flags & NM_DHCP_HOSTNAME_FLAG_FQDN_NO_UPDATE) ? "on"
+                                                                                           : "off");
+        } else
+            g_string_append_printf(str, HOSTNAME4_FORMAT "\n", hostname);
+    }
+
+    g_string_append_c(str, '\n');
+
+    /* Define options for classless static routes */
+    g_string_append(
+        str,
+        "option rfc3442-classless-static-routes code 121 = array of unsigned integer 8;\n");
+    g_string_append(str,
+                    "option ms-classless-static-routes code 249 = array of unsigned integer 8;\n");
+    /* Web Proxy Auto-Discovery option (bgo #368423) */
+    g_string_append(str, "option wpad code 252 = string;\n");
+
+    g_string_append_c(str, '\n');
+}
+
+static void
+add_hostname6(GString *str, const char *hostname, NMDhcpHostnameFlags hostname_flags)
+{
+    if (hostname) {
+        g_string_append_printf(str, FQDN_FORMAT "\n", hostname);
+        if (hostname_flags & NM_DHCP_HOSTNAME_FLAG_FQDN_SERV_UPDATE)
+            g_string_append(str, FQDN_TAG_PREFIX "server-update on;\n");
+        if (hostname_flags & NM_DHCP_HOSTNAME_FLAG_FQDN_NO_UPDATE)
+            g_string_append(str, FQDN_TAG_PREFIX "no-client-update on;\n");
+        g_string_append_c(str, '\n');
+    }
+}
+
+static void
+add_mud_url_config(GString *str, const char *mud_url, int addr_family)
+{
+    if (mud_url) {
+        if (addr_family == AF_INET) {
+            g_string_append(str, MUDURLv4_DEF);
+            g_string_append_printf(str, MUDURLv4_FMT, mud_url);
+        } else {
+            g_string_append(str, MUDURLv6_DEF);
+            g_string_append_printf(str, MUDURLv6_FMT, mud_url);
+        }
+    }
+}
+
+static GBytes *
+read_client_id(const char *str)
+{
+    gs_free char *s = NULL;
+    char *        p;
+    int           i = 0, j = 0;
+
+    nm_assert(!strncmp(str, CLIENTID_TAG, NM_STRLEN(CLIENTID_TAG)));
+    str += NM_STRLEN(CLIENTID_TAG);
+
+    if (!g_ascii_isspace(*str))
+        return NULL;
+    while (g_ascii_isspace(*str))
+        str++;
+
+    if (*str == '"') {
+        /* Parse string literal with escape sequences */
+        s = g_strdup(str + 1);
+        p = strrchr(s, '"');
+        if (p)
+            *p = '\0';
+        else
+            return NULL;
+
+        if (!s[0])
+            return NULL;
+
+        while (s[i]) {
+            if (s[i] == '\\' && s[i + 1] == 'x' && g_ascii_isxdigit(s[i + 2])
+                && g_ascii_isxdigit(s[i + 3])) {
+                s[j++] = (g_ascii_xdigit_value(s[i + 2]) << 4) + g_ascii_xdigit_value(s[i + 3]);
+                i += 4;
+                continue;
+            }
+            if (s[i] == '\\' && s[i + 1] >= '0' && s[i + 1] <= '7' && s[1 + 2] >= '0'
+                && s[i + 2] <= '7' && s[1 + 3] >= '0' && s[i + 3] <= '7') {
+                s[j++] = ((s[i + 1] - '0') << 6) + ((s[i + 2] - '0') << 3) + (s[i + 3] - '0');
+                i += 4;
+                continue;
+            }
+            s[j++] = s[i++];
+        }
+        return g_bytes_new_take(g_steal_pointer(&s), j);
+    }
+
+    /* Otherwise, try to read a hexadecimal sequence */
+    s = g_strdup(str);
+    g_strchomp(s);
+    if (s[strlen(s) - 1] == ';')
+        s[strlen(s) - 1] = '\0';
+
+    return nm_utils_hexstr2bin(s);
+}
+
+static gboolean
+read_interface(const char *line, char *interface, guint size)
+{
+    gs_free char *dup = g_strdup(line + NM_STRLEN("interface"));
+    char *        ptr = dup, *end;
+
+    while (g_ascii_isspace(*ptr))
+        ptr++;
+
+    if (*ptr == '"') {
+        ptr++;
+        end = strchr(ptr, '"');
+        if (!end)
+            return FALSE;
+        *end = '\0';
+    } else {
+        end = strchr(ptr, ' ');
+        if (!end)
+            end = strchr(ptr, '{');
+        if (!end)
+            return FALSE;
+        *end = '\0';
+    }
+
+    if (ptr[0] == '\0' || strlen(ptr) + 1 > size)
+        return FALSE;
+
+    snprintf(interface, size, "%s", ptr);
+
+    return TRUE;
+}
+
+char *
+nm_dhcp_dhclient_create_config(const char *        interface,
+                               int                 addr_family,
+                               GBytes *            client_id,
+                               const char *        anycast_addr,
+                               const char *        hostname,
+                               guint32             timeout,
+                               gboolean            use_fqdn,
+                               NMDhcpHostnameFlags hostname_flags,
+                               const char *        mud_url,
+                               const char *const * reject_servers,
+                               const char *        orig_path,
+                               const char *        orig_contents,
+                               GBytes **           out_new_client_id)
+{
+    nm_auto_free_gstring GString *new_contents = NULL;
+    gs_unref_ptrarray GPtrArray *fqdn_opts     = NULL;
+    gs_unref_ptrarray GPtrArray *reqs          = NULL;
+    gboolean                     reset_reqlist = FALSE;
+    int                          i;
+
+    g_return_val_if_fail(!anycast_addr || nm_utils_hwaddr_valid(anycast_addr, ETH_ALEN), NULL);
+    g_return_val_if_fail(NM_IN_SET(addr_family, AF_INET, AF_INET6), NULL);
+    g_return_val_if_fail(!reject_servers || addr_family == AF_INET, NULL);
+    nm_assert(!out_new_client_id || !*out_new_client_id);
+
+    new_contents = g_string_new(_("# Created by NetworkManager\n"));
+    reqs         = g_ptr_array_new_full(5, g_free);
+
+    if (orig_contents) {
+        gs_free const char **lines = NULL;
+        gsize                line_i;
+        nm_auto_free_gstring GString *blocks_stack = NULL;
+        guint                         blocks_skip  = 0;
+        gboolean                      in_alsoreq   = FALSE;
+        gboolean                      in_req       = FALSE;
+        char                          intf[IFNAMSIZ];
+
+        blocks_stack = g_string_new(NULL);
+        g_string_append_printf(new_contents, _("# Merged from %s\n\n"), orig_path);
+        intf[0] = '\0';
+
+        lines = nm_utils_strsplit_set(orig_contents, "\n\r");
+        for (line_i = 0; lines && lines[line_i]; line_i++) {
+            const char *line = nm_str_skip_leading_spaces(lines[line_i]);
+            const char *p;
+
+            if (line[0] == '\0')
+                continue;
+
+            g_strchomp((char *) line);
+
+            p = line;
+            if (in_req) {
+                /* pass */
+            } else if (strchr(p, '{')) {
+                if (NM_STR_HAS_PREFIX(p, "lease") || NM_STR_HAS_PREFIX(p, "alias")
+                    || NM_STR_HAS_PREFIX(p, "interface") || NM_STR_HAS_PREFIX(p, "pseudo")) {
+                    /* skip over these blocks, except 'interface' when it
+                     * matches the current interface */
+                    blocks_skip++;
+                    g_string_append_c(blocks_stack, 'b');
+                    if (!intf[0] && NM_STR_HAS_PREFIX(p, "interface")) {
+                        if (read_interface(p, intf, sizeof(intf)))
+                            continue;
+                    }
+                } else {
+                    /* allow other blocks (conditionals) */
+                    if (!strchr(p, '}')) /* '} else {'  */
+                        g_string_append_c(blocks_stack, 'c');
+                }
+            } else if (strchr(p, '}')) {
+                if (blocks_stack->len > 0) {
+                    if (blocks_stack->str[blocks_stack->len - 1] == 'b') {
+                        g_string_truncate(blocks_stack, blocks_stack->len - 1);
+                        nm_assert(blocks_skip > 0);
+                        blocks_skip--;
+                        intf[0] = '\0';
+                        continue;
+                    }
+                    g_string_truncate(blocks_stack, blocks_stack->len - 1);
+                }
+            }
+
+            if (blocks_skip > 0 && !intf[0])
+                continue;
+
+            if (intf[0] && !nm_streq(intf, interface))
+                continue;
+
+            /* Some timing parameters in dhclient should not be imported (timeout, retry).
+             * The retry parameter will be simply not used as we will exit on first failure.
+             * The timeout one instead may affect NetworkManager behavior: if the timeout
+             * elapses before dhcp-timeout dhclient will report failure and cause NM to
+             * fail the dhcp process before dhcp-timeout. So, always skip importing timeout
+             * as we will need to add one greater than dhcp-timeout.
+             */
+            if (!strncmp(p, TIMEOUT_TAG, strlen(TIMEOUT_TAG))
+                || !strncmp(p, RETRY_TAG, strlen(RETRY_TAG)))
+                continue;
+
+            if (!strncmp(p, CLIENTID_TAG, strlen(CLIENTID_TAG))) {
+                /* Override config file "dhcp-client-id" and use one from the connection */
+                if (client_id)
+                    continue;
+
+                /* Otherwise, capture and return the existing client id */
+                if (out_new_client_id)
+                    nm_clear_pointer(out_new_client_id, g_bytes_unref);
+                NM_SET_OUT(out_new_client_id, read_client_id(p));
+            }
+
+            /* Override config file hostname and use one from the connection */
+            if (hostname) {
+                if (strncmp(p, HOSTNAME4_TAG, strlen(HOSTNAME4_TAG)) == 0)
+                    continue;
+                if (strncmp(p, FQDN_TAG, strlen(FQDN_TAG)) == 0)
+                    continue;
+            }
+
+            /* To let user's FQDN options (except "fqdn.fqdn") override the
+             * default ones set by NM, add them later
+             */
+            if (!strncmp(p, FQDN_TAG_PREFIX, NM_STRLEN(FQDN_TAG_PREFIX))) {
+                if (!fqdn_opts)
+                    fqdn_opts = g_ptr_array_new_full(5, g_free);
+                g_ptr_array_add(fqdn_opts, g_strdup(p + NM_STRLEN(FQDN_TAG_PREFIX)));
+                continue;
+            }
+
+            /* Ignore 'script' since we pass our own */
+            if (g_str_has_prefix(p, "script "))
+                continue;
+
+            /* Check for "request" */
+            if (!strncmp(p, REQ_TAG, strlen(REQ_TAG))) {
+                in_req = TRUE;
+                p += strlen(REQ_TAG);
+                g_ptr_array_set_size(reqs, 0);
+                reset_reqlist = TRUE;
+            }
+
+            /* Save all request options for later use */
+            if (in_req) {
+                in_req = !grab_request_options(reqs, p);
+                continue;
+            }
+
+            /* Check for "also require" */
+            if (!strncmp(p, ALSOREQ_TAG, strlen(ALSOREQ_TAG))) {
+                in_alsoreq = TRUE;
+                p += strlen(ALSOREQ_TAG);
+            }
+
+            if (in_alsoreq) {
+                in_alsoreq = !grab_request_options(reqs, p);
+                continue;
+            }
+
+            /* Existing configuration line is OK, add it to new configuration */
+            g_string_append(new_contents, line);
+            g_string_append_c(new_contents, '\n');
+        }
+    } else
+        g_string_append_c(new_contents, '\n');
+
+    /* ensure dhclient timeout is greater than dhcp-timeout: as dhclient timeout default value is
+     * 60 seconds, we need this only if dhcp-timeout is greater than 60.
+     */
+    if (timeout >= 60) {
+        timeout = timeout < G_MAXINT32 ? timeout + 1 : G_MAXINT32;
+        g_string_append_printf(new_contents, "timeout %u;\n", timeout);
+    }
+
+    add_mud_url_config(new_contents, mud_url, addr_family);
+
+    if (reject_servers && reject_servers[0]) {
+        g_string_append(new_contents, "reject ");
+        for (i = 0; reject_servers[i]; i++) {
+            if (i != 0)
+                g_string_append(new_contents, ", ");
+            g_string_append(new_contents, reject_servers[i]);
+        }
+        g_string_append(new_contents, ";\n");
+    }
+
+    if (addr_family == AF_INET) {
+        add_ip4_config(new_contents, client_id, hostname, use_fqdn, hostname_flags);
+        add_request(reqs, "rfc3442-classless-static-routes");
+        add_request(reqs, "ms-classless-static-routes");
+        add_request(reqs, "static-routes");
+        add_request(reqs, "wpad");
+        add_request(reqs, "ntp-servers");
+        add_request(reqs, "root-path");
+    } else {
+        add_hostname6(new_contents, hostname, hostname_flags);
+        add_request(reqs, "dhcp6.name-servers");
+        add_request(reqs, "dhcp6.domain-search");
+
+        /* FIXME: internal client does not support requesting client-id option. Does this even work? */
+        add_request(reqs, "dhcp6.client-id");
+    }
+
+    if (reset_reqlist)
+        g_string_append(new_contents, "request; # override dhclient defaults\n");
+    /* And add it to the dhclient configuration */
+    for (i = 0; i < reqs->len; i++)
+        g_string_append_printf(new_contents, "also request %s;\n", (char *) reqs->pdata[i]);
+
+    if (fqdn_opts) {
+        for (i = 0; i < fqdn_opts->len; i++) {
+            const char *t = fqdn_opts->pdata[i];
+
+            if (i == 0)
+                g_string_append_printf(new_contents, "\n# FQDN options from %s\n", orig_path);
+            g_string_append_printf(new_contents, FQDN_TAG_PREFIX "%s\n", t);
+        }
+    }
+
+    g_string_append_c(new_contents, '\n');
+
+    if (anycast_addr) {
+        g_string_append_printf(new_contents,
+                               "interface \"%s\" {\n"
+                               " initial-interval 1; \n"
+                               " anycast-mac ethernet %s;\n"
+                               "}\n",
+                               interface,
+                               anycast_addr);
+    }
+
+    return g_string_free(g_steal_pointer(&new_contents), FALSE);
+}
+
+/* Roughly follow what dhclient's quotify_buf() and pretty_escape() functions do */
+char *
+nm_dhcp_dhclient_escape_duid(GBytes *duid)
+{
+    char *        escaped;
+    const guint8 *s, *s0;
+    gsize         len;
+    char *        d;
+
+    g_return_val_if_fail(duid, NULL);
+
+    s0 = g_bytes_get_data(duid, &len);
+    s  = s0;
+
+    d = escaped = g_malloc((len * 4) + 1);
+    while (s < (s0 + len)) {
+        if (!g_ascii_isprint(*s)) {
+            *d++ = '\\';
+            *d++ = '0' + ((*s >> 6) & 0x7);
+            *d++ = '0' + ((*s >> 3) & 0x7);
+            *d++ = '0' + (*s++ & 0x7);
+        } else if (*s == '"' || *s == '\'' || *s == '$' || *s == '`' || *s == '\\' || *s == '|'
+                   || *s == '&') {
+            *d++ = '\\';
+            *d++ = *s++;
+        } else
+            *d++ = *s++;
+    }
+    *d++ = '\0';
+    return escaped;
+}
+
+static gboolean
+isoctal(const guint8 *p)
+{
+    return (p[0] >= '0' && p[0] <= '3' && p[1] >= '0' && p[1] <= '7' && p[2] >= '0' && p[2] <= '7');
+}
+
+GBytes *
+nm_dhcp_dhclient_unescape_duid(const char *duid)
+{
+    GByteArray *  unescaped;
+    const guint8 *p = (const guint8 *) duid;
+    guint         i, len;
+    guint8        octal;
+
+    /* FIXME: it's wrong to have an "unescape-duid" function. dhclient
+     * defines a file format with escaping. So we need a general unescape
+     * function that can handle dhclient syntax. */
+
+    len       = strlen(duid);
+    unescaped = g_byte_array_sized_new(len);
+    for (i = 0; i < len; i++) {
+        if (p[i] == '\\') {
+            i++;
+            if (isdigit(p[i])) {
+                /* Octal escape sequence */
+                if (i + 2 >= len || !isoctal(p + i))
+                    goto error;
+                octal = ((p[i] - '0') << 6) + ((p[i + 1] - '0') << 3) + (p[i + 2] - '0');
+                g_byte_array_append(unescaped, &octal, 1);
+                i += 2;
+            } else {
+                /* FIXME: don't warn on untrusted data. Either signal an error, or accept
+                 * it silently. */
+
+                /* One of ", ', $, `, \, |, or & */
+                g_warn_if_fail(p[i] == '"' || p[i] == '\'' || p[i] == '$' || p[i] == '`'
+                               || p[i] == '\\' || p[i] == '|' || p[i] == '&');
+                g_byte_array_append(unescaped, &p[i], 1);
+            }
+        } else
+            g_byte_array_append(unescaped, &p[i], 1);
+    }
+
+    return g_byte_array_free_to_bytes(unescaped);
+
+error:
+    g_byte_array_free(unescaped, TRUE);
+    return NULL;
+}
+
+#define DUID_PREFIX "default-duid \""
+
+/* Beware: @error may be unset even if the function returns %NULL. */
+GBytes *
+nm_dhcp_dhclient_read_duid(const char *leasefile, GError **error)
+{
+    gs_free char *       contents   = NULL;
+    gs_free const char **contents_v = NULL;
+    gsize                i;
+
+    if (!g_file_test(leasefile, G_FILE_TEST_EXISTS))
+        return NULL;
+
+    if (!g_file_get_contents(leasefile, &contents, NULL, error))
+        return NULL;
+
+    contents_v = nm_utils_strsplit_set(contents, "\n\r");
+    for (i = 0; contents_v && contents_v[i]; i++) {
+        const char *p = nm_str_skip_leading_spaces(contents_v[i]);
+        GBytes *    duid;
+
+        if (!NM_STR_HAS_PREFIX(p, DUID_PREFIX))
+            continue;
+
+        p += NM_STRLEN(DUID_PREFIX);
+
+        g_strchomp((char *) p);
+
+        if (!NM_STR_HAS_SUFFIX(p, "\";"))
+            continue;
+
+        ((char *) p)[strlen(p) - 2] = '\0';
+
+        duid = nm_dhcp_dhclient_unescape_duid(p);
+        if (duid)
+            return duid;
+    }
+
+    return NULL;
+}
+
+gboolean
+nm_dhcp_dhclient_save_duid(const char *leasefile, GBytes *duid, GError **error)
+{
+    gs_free char *       escaped_duid = NULL;
+    gs_free const char **lines        = NULL;
+    nm_auto_free_gstring GString *s   = NULL;
+    const char *const *           iter;
+    gsize                         len = 0;
+
+    g_return_val_if_fail(leasefile != NULL, FALSE);
+    if (!duid) {
+        nm_utils_error_set_literal(error, NM_UTILS_ERROR_UNKNOWN, "missing duid");
+        g_return_val_if_reached(FALSE);
+    }
+
+    escaped_duid = nm_dhcp_dhclient_escape_duid(duid);
+    nm_assert(escaped_duid);
+
+    if (g_file_test(leasefile, G_FILE_TEST_EXISTS)) {
+        gs_free char *contents = NULL;
+
+        if (!g_file_get_contents(leasefile, &contents, &len, error)) {
+            g_prefix_error(error, "failed to read lease file %s: ", leasefile);
+            return FALSE;
+        }
+
+        lines = nm_utils_strsplit_set_with_empty(contents, "\n\r");
+    }
+
+    s = g_string_sized_new(len + 50);
+    g_string_append_printf(s, DUID_PREFIX "%s\";\n", escaped_duid);
+
+    /* Preserve existing leasefile contents */
+    if (lines) {
+        for (iter = lines; *iter; iter++) {
+            const char *str = *iter;
+            const char *l;
+
+            /* If we find an uncommented DUID in the file, check if
+             * equal to the one we are going to write: if so, no need
+             * to update the lease file, otherwise skip the old DUID.
+             */
+            l = nm_str_skip_leading_spaces(str);
+            if (g_str_has_prefix(l, DUID_PREFIX)) {
+                gs_strfreev char **split = NULL;
+
+                split = g_strsplit(l, "\"", -1);
+                if (split[0] && nm_streq0(split[1], escaped_duid))
+                    return TRUE;
+
+                continue;
+            }
+
+            if (str)
+                g_string_append(s, str);
+            /* avoid to add an extra '\n' at the end of file */
+            if ((iter[1]) != NULL)
+                g_string_append_c(s, '\n');
+        }
+    }
+
+    if (!g_file_set_contents(leasefile, s->str, -1, error)) {
+        g_prefix_error(error, "failed to set DUID in lease file %s: ", leasefile);
+        return FALSE;
+    }
+
+    return TRUE;
+}