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resolvconf-compat: first parse provided interface name as is

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Then, try to drop multiple protocol specifiers at the end.

Strictly speaking, this breaks backward compatibility:
if eth0 and eth0.42 exists, then previously,
    echo 'nameserver 192.168.0.1' | resolvconf -a eth0.42
adds the DNS server to eth0 instead of eth0.42, as we unconditionally
dropped the specifier after the last dot, and
    echo 'nameserver 192.168.0.1' | resolvconf -a eth0.42.dhcp
adds the DNS server to eth0.42. However, with this commit, now
the both commands add the DNS server to eth0.42. But, hopefully,
this should be preferable behavior.

Fixes #25032.
This commit is contained in:
Yu Watanabe 2022-10-18 17:18:55 +09:00
parent 427eeb44f2
commit 7d4e850323
2 changed files with 65 additions and 37 deletions
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93
src/resolve/resolvectl.c
View file

@ -108,51 +108,74 @@ static int interface_info_compare(const InterfaceInfo *a, const InterfaceInfo *b
return strcmp_ptr(a->name, b->name);
}
int ifname_mangle(const char *s) {
_cleanup_free_ char *iface = NULL;
int ifi;
int ifname_mangle_full(const char *s, bool drop_protocol_specifier) {
_cleanup_(sd_netlink_unrefp) sd_netlink *rtnl = NULL;
_cleanup_strv_free_ char **found = NULL;
int r;
assert(s);
iface = strdup(s);
if (!iface)
return log_oom();
if (drop_protocol_specifier) {
_cleanup_free_ char *buf = NULL;
int ifindex_longest_name = -ENODEV;
ifi = rtnl_resolve_interface(NULL, iface);
if (ifi < 0) {
if (ifi == -ENODEV && arg_ifindex_permissive) {
log_debug("Interface '%s' not found, but -f specified, ignoring.", iface);
return 0; /* done */
/* When invoked as resolvconf, drop the protocol specifier(s) at the end. */
buf = strdup(s);
if (!buf)
return log_oom();
for (;;) {
r = rtnl_resolve_interface(&rtnl, buf);
if (r > 0) {
if (ifindex_longest_name <= 0)
ifindex_longest_name = r;
r = strv_extend(&found, buf);
if (r < 0)
return log_oom();
}
char *dot = strrchr(buf, '.');
if (!dot)
break;
*dot = '\0';
}
return log_error_errno(ifi, "Failed to resolve interface \"%s\": %m", iface);
unsigned n = strv_length(found);
if (n > 1) {
_cleanup_free_ char *joined = NULL;
joined = strv_join(found, ", ");
log_warning("Found multiple interfaces (%s) matching with '%s'. Using '%s' (ifindex=%i).",
strna(joined), s, found[0], ifindex_longest_name);
} else if (n == 1) {
const char *proto;
proto = ASSERT_PTR(startswith(s, found[0]));
if (!isempty(proto))
log_info("Dropped protocol specifier '%s' from '%s'. Using '%s' (ifindex=%i).",
proto, s, found[0], ifindex_longest_name);
}
r = ifindex_longest_name;
} else
r = rtnl_resolve_interface(&rtnl, s);
if (r < 0) {
if (ERRNO_IS_DEVICE_ABSENT(r) && arg_ifindex_permissive) {
log_debug_errno(r, "Interface '%s' not found, but -f specified, ignoring: %m", s);
return 0; /* done */
}
return log_error_errno(r, "Failed to resolve interface \"%s\": %m", s);
}
if (arg_ifindex > 0 && arg_ifindex != ifi)
if (arg_ifindex > 0 && arg_ifindex != r)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Specified multiple different interfaces. Refusing.");
arg_ifindex = ifi;
free_and_replace(arg_ifname, iface);
return 1;
}
int ifname_resolvconf_mangle(const char *s) {
const char *dot;
assert(s);
dot = strrchr(s, '.');
if (dot) {
_cleanup_free_ char *iface = NULL;
log_debug("Ignoring protocol specifier '%s'.", dot + 1);
iface = strndup(s, dot - s);
if (!iface)
return log_oom();
return ifname_mangle(iface);
} else
return ifname_mangle(s);
arg_ifindex = r;
return free_and_strdup_warn(&arg_ifname, found ? found[0] : s); /* found */
}
static void print_source(uint64_t flags, usec_t rtt) {

9
src/resolve/resolvectl.h
View file

@ -26,5 +26,10 @@ extern char **arg_set_dns;
extern char **arg_set_domain;
extern bool arg_ifindex_permissive;
int ifname_mangle(const char *s);
int ifname_resolvconf_mangle(const char *s);
int ifname_mangle_full(const char *s, bool drop_protocol_specifier);
static inline int ifname_mangle(const char *s) {
return ifname_mangle_full(s, false);
}
static inline int ifname_resolvconf_mangle(const char *s) {
return ifname_mangle_full(s, true);
}