resolved: add daemon to manage resolv.conf

Also remove the equivalent functionality from networkd.

1 files changed, 320 insertions, 0 deletions

diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
new file mode 100644
index 0000000000..ae173991da
--- /dev/null
+++ b/src/resolve/resolved-manager.c
@@ -0,0 +1,320 @@
+/*-*- 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 <arpa/inet.h>
+#include <resolv.h>
+#include <linux/if.h>
+
+#include "resolved.h"
+#include "event-util.h"
+#include "network-util.h"
+#include "sd-dhcp-lease.h"
+#include "dhcp-lease-internal.h"
+#include "network-internal.h"
+#include "conf-parser.h"
+#include "mkdir.h"
+
+static int set_fallback_dns(Manager *m, const char *string) {
+        char *word, *state;
+        size_t length;
+        int r;
+
+        assert(m);
+        assert(string);
+
+        FOREACH_WORD_QUOTED(word, length, string, state) {
+                _cleanup_free_ Address *address = NULL;
+                Address *tail;
+                _cleanup_free_ char *addrstr = NULL;
+
+                address = new0(Address, 1);
+                if (!address)
+                        return -ENOMEM;
+
+                addrstr = strndup(word, length);
+                if (!addrstr)
+                        return -ENOMEM;
+
+                r = net_parse_inaddr(addrstr, &address->family, &address->in_addr);
+                if (r < 0) {
+                        log_debug("Ignoring invalid DNS address '%s'", addrstr);
+                        continue;
+                }
+
+                LIST_FIND_TAIL(addresses, m->fallback_dns, tail);
+                LIST_INSERT_AFTER(addresses, m->fallback_dns, tail, address);
+                address = NULL;
+        }
+
+        return 0;
+}
+
+int config_parse_dnsv(
+                const char *unit,
+                const char *filename,
+                unsigned line,
+                const char *section,
+                unsigned section_line,
+                const char *lvalue,
+                int ltype,
+                const char *rvalue,
+                void *data,
+                void *userdata) {
+
+        Manager *m = userdata;
+        Address *address;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(m);
+
+        while ((address = m->fallback_dns)) {
+                LIST_REMOVE(addresses, m->fallback_dns, address);
+                free(address);
+        }
+
+        set_fallback_dns(m, rvalue);
+
+        return 0;
+}
+
+static int manager_parse_config_file(Manager *m) {
+        static const char fn[] = "/etc/systemd/resolved.conf";
+        _cleanup_fclose_ FILE *f = NULL;
+        int r;
+
+        assert(m);
+
+        f = fopen(fn, "re");
+        if (!f) {
+                if (errno == ENOENT)
+                        return 0;
+
+                log_warning("Failed to open configuration file %s: %m", fn);
+                return -errno;
+        }
+
+        r = config_parse(NULL, fn, f, "Resolve\0", config_item_perf_lookup,
+                         (void*) resolved_gperf_lookup, false, false, m);
+        if (r < 0)
+                log_warning("Failed to parse configuration file: %s", strerror(-r));
+
+        return r;
+}
+
+int manager_new(Manager **ret) {
+        _cleanup_manager_free_ Manager *m = NULL;
+        int r;
+
+        m = new0(Manager, 1);
+        if (!m)
+                return -ENOMEM;
+
+        r = set_fallback_dns(m, DNS_SERVERS);
+        if (r < 0)
+                return r;
+
+        r = manager_parse_config_file(m);
+        if (r < 0)
+                return r;
+
+        r = sd_event_default(&m->event);
+        if (r < 0)
+                return r;
+
+        sd_event_add_signal(m->event, NULL, SIGTERM, NULL,  NULL);
+        sd_event_add_signal(m->event, NULL, SIGINT, NULL, NULL);
+
+        sd_event_set_watchdog(m->event, true);
+
+        *ret = m;
+        m = NULL;
+
+        return 0;
+}
+
+void manager_free(Manager *m) {
+        Address *address;
+
+        if (!m)
+                return;
+
+        sd_event_unref(m->event);
+
+        while ((address = m->fallback_dns)) {
+                LIST_REMOVE(addresses, m->fallback_dns, address);
+                free(address);
+        }
+
+        free(m);
+}
+
+static void append_dns(FILE *f, void *dns, unsigned char family, unsigned *count) {
+        char buf[INET6_ADDRSTRLEN];
+        const char *address;
+
+        assert(f);
+        assert(dns);
+        assert(count);
+
+        address = inet_ntop(family, dns, buf, INET6_ADDRSTRLEN);
+        if (!address) {
+                log_warning("Invalid DNS address. Ignoring.");
+                return;
+        }
+
+        if (*count == MAXNS)
+                fputs("# Too many DNS servers configured, the following entries "
+                      "may be ignored\n", f);
+
+        fprintf(f, "nameserver %s\n", address);
+
+        (*count) ++;
+}
+
+int manager_update_resolv_conf(Manager *m) {
+        _cleanup_free_ char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+         _cleanup_free_ unsigned *indices = NULL;
+        Address *address;
+        unsigned count = 0;
+        int n, r, i;
+
+        assert(m);
+
+        r = fopen_temporary("/run/systemd/network/resolv.conf", &f, &temp_path);
+        if (r < 0)
+                return r;
+
+        fchmod(fileno(f), 0644);
+
+        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);
+
+        n = sd_network_get_ifindices(&indices);
+        if (n < 0)
+                n = 0;
+
+        for (i = 0; i < n; i++) {
+                _cleanup_dhcp_lease_unref_ sd_dhcp_lease *lease = NULL;
+                struct in_addr *nameservers;
+                struct in6_addr *nameservers6;
+                size_t nameservers_size;
+
+                r = sd_network_dhcp_use_dns(indices[i]);
+                if (r > 0) {
+                        r = sd_network_get_dhcp_lease(indices[i], &lease);
+                        if (r >= 0) {
+                                r = sd_dhcp_lease_get_dns(lease, &nameservers, &nameservers_size);
+                                if (r >= 0) {
+                                        unsigned j;
+
+                                        for (j = 0; j < nameservers_size; j++)
+                                                append_dns(f, &nameservers[j], AF_INET, &count);
+                                }
+                        }
+                }
+
+                r = sd_network_get_dns(indices[i], &nameservers, &nameservers_size);
+                if (r >= 0) {
+                        unsigned j;
+
+                        for (j = 0; j < nameservers_size; j++)
+                                append_dns(f, &nameservers[j], AF_INET, &count);
+
+                        free(nameservers);
+                }
+
+                r = sd_network_get_dns6(indices[i], &nameservers6, &nameservers_size);
+                if (r >= 0) {
+                        unsigned j;
+
+                        for (j = 0; j < nameservers_size; j++)
+                                append_dns(f, &nameservers6[j], AF_INET6, &count);
+
+                        free(nameservers6);
+                }
+        }
+
+        LIST_FOREACH(addresses, address, m->fallback_dns)
+                append_dns(f, &address->in_addr, address->family, &count);
+
+        fflush(f);
+
+        if (ferror(f) || rename(temp_path, "/run/systemd/network/resolv.conf") < 0) {
+                r = -errno;
+                unlink("/run/systemd/network/resolv.conf");
+                unlink(temp_path);
+                return r;
+        }
+
+        return 0;
+}
+
+static int manager_network_event_handler(sd_event_source *s, int fd, uint32_t revents,
+                                         void *userdata) {
+        Manager *m = userdata;
+        int r;
+
+        assert(m);
+
+        r = manager_update_resolv_conf(m);
+        if (r < 0)
+                log_warning("Could not update resolv.conf: %s", strerror(-r));
+
+        sd_network_monitor_flush(m->network_monitor);
+
+        return 0;
+}
+
+int manager_network_monitor_listen(Manager *m) {
+        _cleanup_event_source_unref_ sd_event_source *event_source = NULL;
+        _cleanup_network_monitor_unref_ sd_network_monitor *monitor = NULL;
+        int r, fd, events;
+
+        r = sd_network_monitor_new(NULL, &monitor);
+        if (r < 0)
+                return r;
+
+        fd = sd_network_monitor_get_fd(monitor);
+        if (fd < 0)
+                return fd;
+
+        events = sd_network_monitor_get_events(monitor);
+        if (events < 0)
+                return events;
+
+        r = sd_event_add_io(m->event, &event_source, fd, events,
+                            &manager_network_event_handler, m);
+        if (r < 0)
+                return r;
+
+        m->network_monitor = monitor;
+        m->network_event_source = event_source;
+        monitor = NULL;
+        event_source = NULL;
+
+        return 0;
+}