From 5cb36f41f01cf4b1f4395abfffd1b33116591e58 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Fri, 1 Aug 2014 17:03:28 +0200 Subject: [PATCH] resolved: read the system /etc/resolv.conf unless we wrote it ourselves This way we integrate nicely with foreign network management stacks, such as NM. --- src/resolve/resolved-conf.c | 21 ++++-- src/resolve/resolved-link.c | 6 +- src/resolve/resolved-manager.c | 116 ++++++++++++++++++++++++++++++++- src/resolve/resolved-manager.h | 4 ++ src/shared/util.c | 24 +++++-- src/shared/util.h | 2 +- 6 files changed, 153 insertions(+), 20 deletions(-) diff --git a/src/resolve/resolved-conf.c b/src/resolve/resolved-conf.c index 0def80e3a57..ae3773f4f7c 100644 --- a/src/resolve/resolved-conf.c +++ b/src/resolve/resolved-conf.c @@ -94,19 +94,26 @@ int config_parse_dnsv( else l = &m->dns_servers; - /* Empty assignment means clear the list */ if (isempty(rvalue)) { + + /* Empty assignment means clear the list */ while (*l) dns_server_free(*l); - return 0; + } else { + + /* Otherwise add to the list */ + r = manager_parse_dns_server(m, ltype, rvalue); + if (r < 0) { + log_syntax(unit, LOG_ERR, filename, line, -r, "Failed to parse DNS server string '%s'. Ignoring.", rvalue); + return 0; + } } - r = manager_parse_dns_server(m, ltype, rvalue); - if (r < 0) { - log_syntax(unit, LOG_ERR, filename, line, -r, "Failed to parse DNS server string '%s'. Ignoring.", rvalue); - return 0; - } + /* If we have a manual setting, then we stop reading + * /etc/resolv.conf */ + if (ltype == DNS_SERVER_SYSTEM) + m->read_resolv_conf = false; return 0; } diff --git a/src/resolve/resolved-link.c b/src/resolve/resolved-link.c index 93ccc04491c..7418ea1ed99 100644 --- a/src/resolve/resolved-link.c +++ b/src/resolve/resolved-link.c @@ -150,13 +150,13 @@ static int link_update_dns_servers(Link *l) { assert(l); - LIST_FOREACH(servers, s, l->dns_servers) - s->marked = true; - r = sd_network_get_dns(l->ifindex, &nameservers); if (r < 0) goto clear; + LIST_FOREACH(servers, s, l->dns_servers) + s->marked = true; + STRV_FOREACH(nameserver, nameservers) { union in_addr_union a; int family; diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c index 1e86c1003b8..ba2380d6828 100644 --- a/src/resolve/resolved-manager.c +++ b/src/resolve/resolved-manager.c @@ -184,7 +184,6 @@ fail: return 0; } - static int manager_rtnl_listen(Manager *m) { _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL, *reply = NULL; sd_rtnl_message *i; @@ -410,6 +409,7 @@ int manager_new(Manager **ret) { m->hostname_fd = -1; m->llmnr_support = SUPPORT_YES; + m->read_resolv_conf = true; r = manager_parse_dns_server(m, DNS_SERVER_FALLBACK, DNS_SERVERS); if (r < 0) @@ -520,6 +520,110 @@ Manager *manager_free(Manager *m) { return NULL; } +int manager_read_resolv_conf(Manager *m) { + _cleanup_fclose_ FILE *f = NULL; + struct stat st, own; + char line[LINE_MAX]; + DnsServer *s, *nx; + 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) + log_warning("Failed to open /etc/resolv.conf: %m"); + r = -errno; + 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) + log_warning("Failed to open /etc/resolv.conf: %m"); + r = -errno; + goto clear; + } + + if (fstat(fileno(f), &st) < 0) { + log_error("Failed to stat open file: %m"); + r = -errno; + goto clear; + } + + LIST_FOREACH(servers, s, m->dns_servers) + s->marked = true; + + FOREACH_LINE(line, f, r = -errno; goto clear) { + union in_addr_union address; + int family; + char *l; + const char *a; + + truncate_nl(line); + + l = strstrip(line); + if (*l == '#' || *l == ';') + continue; + + a = first_word(l, "nameserver"); + if (!a) + continue; + + r = in_addr_from_string_auto(a, &family, &address); + if (r < 0) { + log_warning("Failed to parse name server %s.", a); + continue; + } + + LIST_FOREACH(servers, s, m->dns_servers) + if (s->family == family && in_addr_equal(family, &s->address, &address) > 0) + break; + + if (s) + s->marked = false; + else { + r = dns_server_new(m, NULL, DNS_SERVER_SYSTEM, NULL, family, &address); + if (r < 0) + goto clear; + } + } + + LIST_FOREACH_SAFE(servers, s, nx, m->dns_servers) + if (s->marked) + dns_server_free(s); + + return 0; + +clear: + while (m->dns_servers) + dns_server_free(m->dns_servers); + + return r; +} + static void write_resolve_conf_server(DnsServer *s, FILE *f, unsigned *count) { _cleanup_free_ char *t = NULL; int r; @@ -553,6 +657,9 @@ int manager_write_resolv_conf(Manager *m) { assert(m); + /* Read the system /etc/resolv.conf first */ + manager_read_resolv_conf(m); + r = fopen_temporary(path, &f, &temp_path); if (r < 0) return r; @@ -953,11 +1060,11 @@ bool manager_known_dns_server(Manager *m, int family, const union in_addr_union assert(in_addr); LIST_FOREACH(servers, s, m->dns_servers) - if (s->family == family && in_addr_equal(family, &s->address, in_addr)) + if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0) return true; LIST_FOREACH(servers, s, m->fallback_dns_servers) - if (s->family == family && in_addr_equal(family, &s->address, in_addr)) + if (s->family == family && in_addr_equal(family, &s->address, in_addr) > 0) return true; return false; @@ -985,6 +1092,9 @@ DnsServer *manager_get_dns_server(Manager *m) { Link *l; assert(m); + /* Try to read updates resolv.conf */ + manager_read_resolv_conf(m); + if (!m->current_dns_server) manager_set_dns_server(m, m->dns_servers); diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h index 03386f0a4f6..7bb18c0d666 100644 --- a/src/resolve/resolved-manager.h +++ b/src/resolve/resolved-manager.h @@ -78,6 +78,9 @@ struct Manager { LIST_HEAD(DnsServer, fallback_dns_servers); DnsServer *current_dns_server; + bool read_resolv_conf; + usec_t resolv_conf_mtime; + LIST_HEAD(DnsScope, dns_scopes); DnsScope *unicast_scope; @@ -111,6 +114,7 @@ struct Manager { int manager_new(Manager **ret); Manager* manager_free(Manager *m); +int manager_read_resolv_conf(Manager *m); int manager_write_resolv_conf(Manager *m); bool manager_known_dns_server(Manager *m, int family, const union in_addr_union *in_addr); diff --git a/src/shared/util.c b/src/shared/util.c index 4c30a98318b..e2c955bc070 100644 --- a/src/shared/util.c +++ b/src/shared/util.c @@ -140,26 +140,38 @@ char* endswith(const char *s, const char *postfix) { return (char*) s + sl - pl; } -bool first_word(const char *s, const char *word) { +char* first_word(const char *s, const char *word) { size_t sl, wl; + const char *p; assert(s); assert(word); + /* Checks if the string starts with the specified word, either + * followed by NUL or by whitespace. Returns a pointer to the + * NUL or the first character after the whitespace. */ + sl = strlen(s); wl = strlen(word); if (sl < wl) - return false; + return NULL; if (wl == 0) - return true; + return (char*) s; if (memcmp(s, word, wl) != 0) - return false; + return NULL; - return s[wl] == 0 || - strchr(WHITESPACE, s[wl]); + p = s + wl; + if (*p == 0) + return (char*) p; + + if (!strchr(WHITESPACE, *p)) + return NULL; + + p += strspn(p, WHITESPACE); + return (char*) p; } int close_nointr(int fd) { diff --git a/src/shared/util.h b/src/shared/util.h index 45294800e4d..fd999bd9426 100644 --- a/src/shared/util.h +++ b/src/shared/util.h @@ -169,7 +169,7 @@ static inline const char *startswith_no_case(const char *s, const char *prefix) char *endswith(const char *s, const char *postfix) _pure_; -bool first_word(const char *s, const char *word) _pure_; +char *first_word(const char *s, const char *word) _pure_; int close_nointr(int fd); int safe_close(int fd);