resolved: split out all code dealing with /etc/resolv.conf into its own .c file

No functional changes.

1 files changed, 306 insertions, 0 deletions

diff --git a/src/resolve/resolved-resolv-conf.c b/src/resolve/resolved-resolv-conf.c
new file mode 100644
index 0000000000..5a6e3812df
--- /dev/null
+++ b/src/resolve/resolved-resolv-conf.c
@@ -0,0 +1,306 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Tom Gundersen <teg@jklm.no>
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ ***/
+
+#include <resolv.h>
+
+#include "alloc-util.h"
+#include "dns-domain.h"
+#include "fd-util.h"
+#include "fileio-label.h"
+#include "fileio.h"
+#include "ordered-set.h"
+#include "resolved-conf.h"
+#include "resolved-resolv-conf.h"
+#include "string-util.h"
+#include "strv.h"
+
+int manager_read_resolv_conf(Manager *m) {
+        _cleanup_fclose_ FILE *f = NULL;
+        struct stat st, own;
+        char line[LINE_MAX];
+        DnsServer *s;
+        usec_t t;
+        int r;
+
+        assert(m);
+
+        /* Reads the system /etc/resolv.conf, if it exists and is not
+         * symlinked to our own resolv.conf instance */
+
+        if (!m->read_resolv_conf)
+                return 0;
+
+        r = stat("/etc/resolv.conf", &st);
+        if (r < 0) {
+                if (errno == ENOENT)
+                        r = 0;
+                else
+                        r = log_warning_errno(errno, "Failed to open /etc/resolv.conf: %m");
+                goto clear;
+        }
+
+        /* Have we already seen the file? */
+        t = timespec_load(&st.st_mtim);
+        if (t == m->resolv_conf_mtime)
+                return 0;
+
+        m->resolv_conf_mtime = t;
+
+        /* Is it symlinked to our own file? */
+        if (stat("/run/systemd/resolve/resolv.conf", &own) >= 0 &&
+            st.st_dev == own.st_dev &&
+            st.st_ino == own.st_ino) {
+                r = 0;
+                goto clear;
+        }
+
+        f = fopen("/etc/resolv.conf", "re");
+        if (!f) {
+                if (errno == ENOENT)
+                        r = 0;
+                else
+                        r = log_warning_errno(errno, "Failed to open /etc/resolv.conf: %m");
+                goto clear;
+        }
+
+        if (fstat(fileno(f), &st) < 0) {
+                r = log_error_errno(errno, "Failed to stat open file: %m");
+                goto clear;
+        }
+
+        manager_mark_dns_servers(m, DNS_SERVER_SYSTEM);
+
+        FOREACH_LINE(line, f, r = -errno; goto clear) {
+                _cleanup_strv_free_ char **d = NULL;
+                const char *a;
+                char *l;
+
+                truncate_nl(line);
+
+                l = strstrip(line);
+                if (*l == '#' || *l == ';')
+                        continue;
+
+                a = first_word(l, "nameserver");
+                if (a) {
+                        r = manager_add_dns_server_by_string(m, DNS_SERVER_SYSTEM, a);
+                        if (r < 0)
+                                log_warning_errno(r, "Failed to parse DNS server address '%s', ignoring.", a);
+
+                        continue;
+                }
+        }
+
+        manager_flush_marked_dns_servers(m, DNS_SERVER_SYSTEM);
+
+        /* Whenever /etc/resolv.conf changes, start using the first
+         * DNS server of it. This is useful to deal with broken
+         * network managing implementations (like NetworkManager),
+         * that when connecting to a VPN place both the VPN DNS
+         * servers and the local ones in /etc/resolv.conf. Without
+         * resetting the DNS server to use back to the first entry we
+         * will continue to use the local one thus being unable to
+         * resolve VPN domains. */
+        manager_set_dns_server(m, m->dns_servers);
+
+        return 0;
+
+clear:
+        while (m->dns_servers) {
+                s = m->dns_servers;
+
+                LIST_REMOVE(servers, m->dns_servers, s);
+                dns_server_unref(s);
+        }
+
+        return r;
+}
+
+static void write_resolv_conf_server(DnsServer *s, FILE *f, unsigned *count) {
+        _cleanup_free_ char *t  = NULL;
+        int r;
+
+        assert(s);
+        assert(f);
+        assert(count);
+
+        r = in_addr_to_string(s->family, &s->address, &t);
+        if (r < 0) {
+                log_warning_errno(r, "Invalid DNS address. Ignoring: %m");
+                return;
+        }
+
+        if (*count == MAXNS)
+                fputs("# Too many DNS servers configured, the following entries may be ignored.\n", f);
+        (*count) ++;
+
+        fprintf(f, "nameserver %s\n", t);
+}
+
+static void write_resolv_conf_search(
+                const char *domain,
+                FILE *f,
+                unsigned *count,
+                unsigned *length) {
+
+        assert(domain);
+        assert(f);
+        assert(length);
+
+        if (*count >= MAXDNSRCH ||
+            *length + strlen(domain) > 256) {
+                if (*count == MAXDNSRCH)
+                        fputs(" # Too many search domains configured, remaining ones ignored.", f);
+                if (*length <= 256)
+                        fputs(" # Total length of all search domains is too long, remaining ones ignored.", f);
+
+                return;
+        }
+
+        (*length) += strlen(domain);
+        (*count) ++;
+
+        fputc(' ', f);
+        fputs(domain, f);
+}
+
+static int write_resolv_conf_contents(FILE *f, OrderedSet *dns, OrderedSet *domains) {
+        Iterator i;
+
+        fputs("# This file is managed by systemd-resolved(8). Do not edit.\n#\n"
+              "# Third party programs must not access this file directly, but\n"
+              "# only through the symlink at /etc/resolv.conf. To manage\n"
+              "# resolv.conf(5) in a different way, replace the symlink by a\n"
+              "# static file or a different symlink.\n\n", f);
+
+        if (ordered_set_isempty(dns))
+                fputs("# No DNS servers known.\n", f);
+        else {
+                unsigned count = 0;
+                DnsServer *s;
+
+                ORDERED_SET_FOREACH(s, dns, i)
+                        write_resolv_conf_server(s, f, &count);
+        }
+
+        if (!ordered_set_isempty(domains)) {
+                unsigned length = 0, count = 0;
+                char *domain;
+
+                fputs("search", f);
+                ORDERED_SET_FOREACH(domain, domains, i)
+                        write_resolv_conf_search(domain, f, &count, &length);
+                fputs("\n", f);
+        }
+
+        return fflush_and_check(f);
+}
+
+int manager_write_resolv_conf(Manager *m) {
+        static const char path[] = "/run/systemd/resolve/resolv.conf";
+        _cleanup_free_ char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        _cleanup_ordered_set_free_ OrderedSet *dns = NULL, *domains = NULL;
+        DnsServer *s;
+        Iterator i;
+        Link *l;
+        int r;
+
+        assert(m);
+
+        /* Read the system /etc/resolv.conf first */
+        manager_read_resolv_conf(m);
+
+        /* Add the full list to a set, to filter out duplicates */
+        dns = ordered_set_new(&dns_server_hash_ops);
+        if (!dns)
+                return -ENOMEM;
+
+        domains = ordered_set_new(&dns_name_hash_ops);
+        if (!domains)
+                return -ENOMEM;
+
+        /* First add the system-wide servers and domains */
+        LIST_FOREACH(servers, s, m->dns_servers) {
+                r = ordered_set_put(dns, s);
+                if (r == -EEXIST)
+                        continue;
+                if (r < 0)
+                        return r;
+        }
+
+        /* Then, add the per-link servers and domains */
+        HASHMAP_FOREACH(l, m->links, i) {
+                char **domain;
+
+                LIST_FOREACH(servers, s, l->dns_servers) {
+                        r = ordered_set_put(dns, s);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+
+                if (!l->unicast_scope)
+                        continue;
+
+                STRV_FOREACH(domain, l->unicast_scope->domains) {
+                        r = ordered_set_put(domains, *domain);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        /* If we found nothing, add the fallback servers */
+        if (ordered_set_isempty(dns)) {
+                LIST_FOREACH(servers, s, m->fallback_dns_servers) {
+                        r = ordered_set_put(dns, s);
+                        if (r == -EEXIST)
+                                continue;
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        r = fopen_temporary_label(path, path, &f, &temp_path);
+        if (r < 0)
+                return r;
+
+        fchmod(fileno(f), 0644);
+
+        r = write_resolv_conf_contents(f, dns, domains);
+        if (r < 0)
+                goto fail;
+
+        if (rename(temp_path, path) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        return 0;
+
+fail:
+        (void) unlink(path);
+        (void) unlink(temp_path);
+        return r;
+}