[systemd-devel] [PATCH v3] Added support for Uplink Failure Detection using BindCarrier

Tom Gundersen teg at jklm.no
Sat Feb 14 06:50:29 PST 2015


On Sat, Feb 14, 2015 at 3:05 PM, Zbigniew Jędrzejewski-Szmek
<zbyszek at in.waw.pl> wrote:
> On Fri, Feb 13, 2015 at 10:27:07PM +0100, Tom Gundersen wrote:
>> Hi Alin,
>>
>> Thanks for the patch. This is starting to look pretty good now.
>>
>> I still have some questions/requests regarding some implementation
>> details (below), but hopefully we can get this merged after the next
>> release (trying to stabilize things at the moment).
>>
>> On Tue, Feb 10, 2015 at 12:30 PM, Alin Rauta <alin.rauta at intel.com> wrote:
>> > ---
>> >  man/systemd.network.xml                  |  11 ++
>> >  src/libsystemd/sd-network/sd-network.c   |   4 +
>> >  src/network/networkctl.c                 | 211 ++++++++++++++++++++++++++++---
>> >  src/network/networkd-link.c              | 123 +++++++++++++++++-
>> >  src/network/networkd-link.h              |   1 +
>> >  src/network/networkd-manager.c           |   7 +
>> >  src/network/networkd-network-gperf.gperf |   1 +
>> >  src/network/networkd-network.c           |  10 ++
>> >  src/network/networkd.h                   |   2 +-
>> >  src/systemd/sd-network.h                 |   3 +
>> >  10 files changed, 355 insertions(+), 18 deletions(-)
>> >
>> > diff --git a/man/systemd.network.xml b/man/systemd.network.xml
>> > index 9b3a92d..8b2ca4e 100644
>> > --- a/man/systemd.network.xml
>> > +++ b/man/systemd.network.xml
>> > @@ -270,6 +270,17 @@
>> >            </listitem>
>> >          </varlistentry>
>> >          <varlistentry>
>> > +          <term><varname>BindCarrier=</varname></term>
>> > +          <listitem>
>> > +            <para>A port or a list of ports. When set, controls the
>> > +            behaviour of the current interface. When all ports in the list
>> > +            are operational down, the failure is propagated to the current
> "operational down" does not follow normal grammar rules. "are in an operational
> down state"?
>
>> > +            interface. When at least one port has carrier, the current
>> > +            interface is brought up.
>> > +            </para>
>>
>> Maybe we should make it clear that this is not necessarily a failure
>> (the uplink may be down on purpose), and that the way we propagate it
>> is to set the downlink administrative down.
>>
>> > +          </listitem>
>> > +        </varlistentry>
>> > +        <varlistentry>
>> >            <term><varname>Address=</varname></term>
>> >            <listitem>
>> >              <para>A static IPv4 or IPv6 address and its prefix length,
>> > diff --git a/src/libsystemd/sd-network/sd-network.c b/src/libsystemd/sd-network/sd-network.c
>> > index c735cac..b574d19 100644
>> > --- a/src/libsystemd/sd-network/sd-network.c
>> > +++ b/src/libsystemd/sd-network/sd-network.c
>> > @@ -264,6 +264,10 @@ _public_ int sd_network_link_get_domains(int ifindex, char ***ret) {
>> >          return network_get_link_strv("DOMAINS", ifindex, ret);
>> >  }
>> >
>> > +_public_ int sd_network_link_get_carriers(int ifindex, char ***ret) {
>> > +        return network_get_link_strv("CARRIERS", ifindex, ret);
>> > +}
>>
>> I don't find get_carriers() very clear. At least call it
>> get_carrier_bound_to() or something like that. I must say I agree with
>> Lennart and Zbigniew, we should introduce the API in both directions,
>> and then we can worry about the performance if that turns out to be a
>> problem (worst case all the processing could be hidden in the
>> sd-network library, but I don't think that will be necessary to be
>> honest).
>>
>> >  _public_ int sd_network_link_get_wildcard_domain(int ifindex) {
>> >          int r;
>> >          _cleanup_free_ char *p = NULL, *s = NULL;
>> > diff --git a/src/network/networkctl.c b/src/network/networkctl.c
>> > index aa83f32..ffb38e8 100644
>> > --- a/src/network/networkctl.c
>> > +++ b/src/network/networkctl.c
>> > @@ -22,6 +22,7 @@
>> >  #include <stdbool.h>
>> >  #include <getopt.h>
>> >  #include <net/if.h>
>> > +#include <fnmatch.h>
>> >
>> >  #include "sd-network.h"
>> >  #include "sd-rtnl.h"
>> > @@ -393,6 +394,161 @@ static int get_gateway_description(
>> >          return -ENODATA;
>> >  }
>> >
>> > +static bool is_carrier(const char *ifname,
>> > +                       char **carriers) {
>> > +       char **i;
>> > +
>> > +       STRV_FOREACH(i, carriers)
>> > +               if (fnmatch(*i, ifname, 0) == 0)
>> > +                       return true;
>> > +
>> > +       return false;
>> > +}
>> > +
>> > +/* get the links that are bound to this port. */
>> > +static int get_downlinks(const char *name,
>> > +                         sd_rtnl_message *m,
>> > +                         LinkInfo **downlinks,
>> > +                         int *down_count) {
>> > +        _cleanup_free_ LinkInfo  *links = NULL;
>> > +        sd_rtnl_message *i;
>> > +        size_t size = 0;
>> > +        size_t c = 0;
> Why is c size_t?
>
>> > +        int r;
>> > +
>> > +        assert(m);
>> > +        assert(name);
>> > +
>> > +        *down_count = 0;
>> > +        *downlinks = NULL;
> Why do you initialize this here? If an error happens, it is nice to not modify output
> parameters at all.
>
>> > +        for (i = m; i; i = sd_rtnl_message_next(i)) {
>> > +                _cleanup_strv_free_ char **carriers = NULL;
>> > +                const char *link_name;
>> > +                int ifindex;
>> > +
>> > +                r = sd_rtnl_message_link_get_ifindex(i, &ifindex);
>> > +                if (r < 0)
>> > +                        return r;
>> > +
>> > +                r = sd_rtnl_message_read_string(i, IFLA_IFNAME, &link_name);
>> > +                if (r < 0)
>> > +                        return r;
>> > +
>> > +                r = sd_network_link_get_carriers(ifindex, &carriers);
>> > +                if (r == -ENODATA || strv_isempty(carriers))
>> > +                        continue;
>> > +
>> > +                if (r < 0) {
>> > +                        log_warning("Failed to get carrier list for port: %s", name);
>> > +                        continue;
>> > +                }
>> > +
>> > +                if (is_carrier(name, carriers)) {
>> > +                         if (!GREEDY_REALLOC(links, size, c+1))
>> > +                                 return -ENOMEM;
>> > +
>> > +                         links[c].name = link_name;
>> > +                         c++;
>> > +                }
>> > +        }
>> > +
>> > +        *downlinks = links;
>> > +        *down_count = (int) c;
>> > +
>> > +        links = NULL;
>> > +
>> > +        return 0;
>> > +}
>> > +
>> > +/* get the links to which current port is bound to. */
>> > +static int get_uplinks(int ifindex,
>> > +                       sd_rtnl_message *m,
>> > +                       LinkInfo **uplinks,
>> > +                       int *up_count) {
>> > +        _cleanup_free_ LinkInfo  *links = NULL;
>> > +        _cleanup_strv_free_ char **carriers = NULL;
>> > +        sd_rtnl_message *i;
>> > +        size_t size = 0, c = 0;
>> > +        int r;
>> > +
>> > +        assert(m);
>> > +
>> > +        *up_count = 0;
>> > +        *uplinks = NULL;
>> > +
>> > +        /* check if this port has carriers. */
>> > +        r = sd_network_link_get_carriers(ifindex, &carriers);
>> > +        if (r == -ENODATA || strv_isempty(carriers))
>> > +                return 0;
>> > +
>> > +        if (r < 0)
>> > +                return r;
>> > +
>> > +        for (i = m; i; i = sd_rtnl_message_next(i)) {
>> > +                const char *name;
>> > +
>> > +                r = sd_rtnl_message_read_string(i, IFLA_IFNAME, &name);
>> > +                if (r < 0)
>> > +                        return r;
>> > +
>> > +                if (is_carrier(name, carriers)) {
>> > +                         if (!GREEDY_REALLOC(links, size, c+1))
>> > +                                 return -ENOMEM;
>> > +
>> > +                         links[c].name = name;
>> > +                         c++;
>> > +                }
>> > +        }
>> > +
>> > +        *uplinks = links;
>> > +        *up_count = (int) c;
>> > +
>> > +        links = NULL;
>> > +
>> > +        return 0;
>> > +}
>> > +
>> > +static int get_links(sd_rtnl *rtnl,
>> > +                     sd_rtnl_message **ret) {
>> > +        _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL, *reply = NULL;
>> > +        int r;
>> > +        assert(rtnl);
>> > +
>> > +        r = sd_rtnl_message_new_link(rtnl, &req, RTM_GETLINK, 0);
>> > +        if (r < 0)
>> > +                return rtnl_log_create_error(r);
>> > +
>> > +        r = sd_rtnl_message_request_dump(req, true);
>> > +        if (r < 0)
>> > +                return rtnl_log_create_error(r);
>> > +
>> > +        r = sd_rtnl_call(rtnl, req, 0, &reply);
>> > +        if (r < 0) {
>> > +                log_error("Failed to enumerate links: %s", strerror(-r));
>> > +                return r;
>> > +        }
>> > +
>> > +        *ret = reply;
>> > +        reply = NULL;
>> > +
>> > +        return 0;
>> > +}
>> > +
>> > +static void dump_carrier_list(const char *prefix,
>> > +                              LinkInfo *links,
>> > +                              int len) {
>> > +        int i;
>> > +
>> > +        assert(links);
>> > +
>> > +        for (i = 0; i < len; i++)
>> > +                printf("%*s%s\n",
>> > +                       (int) strlen(prefix),
>> > +                       i == 0 ? prefix : "",
>> > +                       links[i].name);
>> > +}
>> > +
>> >  static int dump_gateways(
>> >                  sd_rtnl *rtnl,
>> >                  sd_hwdb *hwdb,
>> > @@ -508,11 +664,16 @@ static int link_status_one(
>> >          const char *driver = NULL, *path = NULL, *vendor = NULL, *model = NULL, *link = NULL;
>> >          const char *on_color_operational, *off_color_operational,
>> >                     *on_color_setup, *off_color_setup;
>> > +        _cleanup_rtnl_message_unref_ sd_rtnl_message *link_list = NULL;
>> > +        _cleanup_free_ LinkInfo *uplinks = NULL;    /* links to which current port is bound to. */
>> > +        _cleanup_free_ LinkInfo *downlinks = NULL;  /* links that are bound to current port. */
>> >          struct ether_addr e;
>> >          unsigned iftype;
>> >          int r, ifindex;
>> >          bool have_mac;
>> >          uint32_t mtu;
>> > +        int up_count;
>> > +        int down_count;
>> >
>> >          assert(rtnl);
>> >          assert(udev);
>> > @@ -606,12 +767,24 @@ static int link_status_one(
>> >
>> >          sd_network_link_get_network_file(ifindex, &network);
>> >
>> > +        r = get_links(rtnl, &link_list);
>> > +        if (r < 0)
>> > +                return r;
>> > +
>> > +        r = get_uplinks(ifindex, link_list, &uplinks, &up_count);
>> > +        if (r < 0)
>> > +                log_warning("Failed to get uplinks for port: %d", ifindex);
>> > +
>> > +        r = get_downlinks(name, link_list, &downlinks, &down_count);
>> > +        if (r < 0)
>> > +                log_warning("Failed to get downlinks for port: %d", ifindex);
>> > +
>> >          printf("%s%s%s %i: %s\n", on_color_operational, draw_special_char(DRAW_BLACK_CIRCLE), off_color_operational, ifindex, name);
>> >
>> > -        printf("   Link File: %s\n"
>> > -               "Network File: %s\n"
>> > -               "        Type: %s\n"
>> > -               "       State: %s%s%s (%s%s%s)\n",
>> > +        printf("       Link File: %s\n"
>> > +               "    Network File: %s\n"
>> > +               "            Type: %s\n"
>> > +               "           State: %s%s%s (%s%s%s)\n",
>> >                 strna(link),
>> >                 strna(network),
>> >                 strna(t),
>> > @@ -619,13 +792,13 @@ static int link_status_one(
>> >                 on_color_setup, strna(setup_state), off_color_setup);
>> >
>> >          if (path)
>> > -                printf("        Path: %s\n", path);
>> > +                printf("            Path: %s\n", path);
>> >          if (driver)
>> > -                printf("      Driver: %s\n", driver);
>> > +                printf("          Driver: %s\n", driver);
>> >          if (vendor)
>> > -                printf("      Vendor: %s\n", vendor);
>> > +                printf("          Vendor: %s\n", vendor);
>> >          if (model)
>> > -                printf("       Model: %s\n", model);
>> > +                printf("           Model: %s\n", model);
>> >
>> >          if (have_mac) {
>> >                  _cleanup_free_ char *description = NULL;
>> > @@ -634,23 +807,29 @@ static int link_status_one(
>> >                  ieee_oui(hwdb, &e, &description);
>> >
>> >                  if (description)
>> > -                        printf("  HW Address: %s (%s)\n", ether_addr_to_string(&e, ea), description);
>> > +                        printf("      HW Address: %s (%s)\n", ether_addr_to_string(&e, ea), description);
>> >                  else
>> > -                        printf("  HW Address: %s\n", ether_addr_to_string(&e, ea));
>> > +                        printf("      HW Address: %s\n", ether_addr_to_string(&e, ea));
>> >          }
>> >
>> >          if (mtu > 0)
>> > -                printf("         MTU: %u\n", mtu);
>> > +                printf("             MTU: %u\n", mtu);
>> >
>> > -        dump_addresses(rtnl, "     Address: ", ifindex);
>> > -        dump_gateways(rtnl, hwdb, "     Gateway: ", ifindex);
>> > +        dump_addresses(rtnl, "         Address: ", ifindex);
>> > +        dump_gateways(rtnl, hwdb, "         Gateway: ", ifindex);
>> >
>> >          if (!strv_isempty(dns))
>> > -                dump_list("         DNS: ", dns);
>> > +                dump_list("             DNS: ", dns);
>> >          if (!strv_isempty(domains))
>> > -                dump_list("      Domain: ", domains);
>> > +                dump_list("          Domain: ", domains);
>> >          if (!strv_isempty(ntp))
>> > -                dump_list("         NTP: ", ntp);
>> > +                dump_list("             NTP: ", ntp);
>> > +
>> > +        if (uplinks)
>> > +                dump_carrier_list("Carrier Bound To: ", uplinks, up_count);
>> > +
>> > +        if (downlinks)
>> > +                dump_carrier_list("Carrier Bound By: ", downlinks, down_count);
>> >
>> >          return 0;
>> >  }
>> > diff --git a/src/network/networkd-link.c b/src/network/networkd-link.c
>> > index 0b1cac1..ccd255a 100644
>> > --- a/src/network/networkd-link.c
>> > +++ b/src/network/networkd-link.c
>> > @@ -22,6 +22,7 @@
>> >  #include <netinet/ether.h>
>> >  #include <linux/if.h>
>> >  #include <unistd.h>
>> > +#include <fnmatch.h>
>> >
>> >  #include "util.h"
>> >  #include "virt.h"
>> > @@ -1151,6 +1152,58 @@ static int link_up(Link *link) {
>> >          return 0;
>> >  }
>> >
>> > +static int link_down_handler(sd_rtnl *rtnl, sd_rtnl_message *m, void *userdata) {
>> > +        _cleanup_link_unref_ Link *link = userdata;
>> > +        int r;
>> > +
>> > +        assert(link);
>> > +
>> > +        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
>> > +                return 1;
>> > +
>> > +        r = sd_rtnl_message_get_errno(m);
>> > +        if (r < 0)
>> > +                log_link_warning_errno(link, -r, "%-*s: could not bring down interface: %m", IFNAMSIZ, link->ifname);
>> > +
>> > +        return 1;
>> > +}
>> > +
>> > +static int link_down(Link *link) {
>> > +        _cleanup_rtnl_message_unref_ sd_rtnl_message *req = NULL;
>> > +        int r;
>> > +
>> > +        assert(link);
>> > +        assert(link->manager);
>> > +        assert(link->manager->rtnl);
>> > +
>> > +        r = sd_rtnl_message_new_link(link->manager->rtnl, &req,
>> > +                                     RTM_SETLINK, link->ifindex);
>> > +        if (r < 0) {
>> > +                log_link_error(link, "Could not allocate RTM_SETLINK message");
>> > +                return r;
>> > +        }
>> > +
>> > +        r = sd_rtnl_message_link_set_flags(req, 0, IFF_UP);
>> > +        if (r < 0) {
>> > +                log_link_error(link, "Could not set link flags: %s",
>> > +                               strerror(-r));
>> > +                return r;
>> > +        }
>> > +
>> > +        r = sd_rtnl_call_async(link->manager->rtnl, req, link_down_handler, link,
>> > +                               0, NULL);
>> > +        if (r < 0) {
>> > +                log_link_error(link,
>> > +                               "Could not send rtnetlink message: %s",
>> > +                               strerror(-r));
>> > +                return r;
>> > +        }
>>
>> Hm, we need to introduce a new administrative state here I think
>> (LINK_STATE_DOWN), and then make sure we don't accidentally leave it
>> in case we get some other event after bringing the interface down.
>>
>> > +        link_ref(link);
>> > +
>> > +        return 0;
>> > +}
>> > +
>> >  static int link_joined(Link *link) {
>> >          int r;
>> >
>> > @@ -1982,7 +2035,7 @@ int link_save(Link *link) {
>> >                  admin_state, oper_state);
>> >
>> >          if (link->network) {
>> > -                char **address, **domain;
>> > +                char **address, **domain, **carrier;
>> >                  bool space;
>> >
>> >                  fprintf(f, "NETWORK_FILE=%s\n", link->network->filename);
>> > @@ -2061,6 +2114,15 @@ int link_save(Link *link) {
>> >
>> >                  fprintf(f, "LLMNR=%s\n",
>> >                          llmnr_support_to_string(link->network->llmnr));
>> > +
>> > +                fputs("CARRIERS=", f);
>> > +                space = false;
>> > +                STRV_FOREACH(carrier, link->network->carriers) {
>> > +                        if (space)
>> > +                                fputc(' ', f);
>> > +                        fputs(*carrier, f);
>> > +                        space = true;
>> > +                }
>> >          }
>> >
>> >          if (link->dhcp_lease) {
>> > @@ -2106,6 +2168,65 @@ fail:
>> >          return r;
>> >  }
>> >
>> > +int link_handle_carriers(Link *link) {
>> > +        Manager *m;
>> > +        char **carrier;
>> > +        Link *downlink;
>> > +        Link *uplink;
>> > +        Iterator i;
>> > +        Iterator j;
>> > +        int r;
>> > +
>> > +        assert(link);
>> > +        assert(link->manager);
>> > +
>> > +        m = link->manager;
>> > +
>> > +        /* go through the list of available links. */
>> > +        HASHMAP_FOREACH (downlink, m->links, i) {
>> > +                if (downlink->network && !strv_isempty(downlink->network->carriers)) {
>> > +                        bool has_carrier;
>> > +                        bool required_up = false;
>> > +                        bool found_match = false;
>> > +
>> > +                        has_carrier = link_has_carrier(downlink);
>> > +
>> > +                        STRV_FOREACH (carrier, downlink->network->carriers) {
>> > +                                HASHMAP_FOREACH (uplink, m->links, j) {
>> > +                                        if (fnmatch(*carrier, uplink->ifname, 0) == 0) {
>> > +                                                found_match = true;
>> > +
>> > +                                                if (link_has_carrier(uplink)) {
>> > +                                                        required_up = true;
>> > +                                                        break;
>> > +                                                }
>> > +                                        }
>> > +                                }
>> > +
>> > +                                if (required_up)
>> > +                                        break;
>> > +                        }
>> > +
>> > +                        if (found_match) {
>> > +                                if (has_carrier && !required_up) {
>> > +                                        r = link_down(downlink);
>> > +                                        if (r < 0)
>> > +                                                return r;
>> > +                                }
>> > +                                else if (!has_carrier && required_up) {
>> > +                                        if (!(downlink->flags & IFF_UP)) {
>> > +                                                r = link_up(downlink);
>> > +                                                if (r < 0)
>> > +                                                        return r;
>> > +                                        }
>> > +                                }
>> > +                        }
>> > +                }
>> > +        }
>> > +
>> > +        return 0;
>> > +}
>>
>> I would split this in two.
>>
>> First, whenever a link is added/removed resolve the globbing and store
>> in each Link object pointers to its associated down/uplinks.
>>
>> Second, whenever an uplink gains/loses its carrier, triggers each of
>> its associated downlinks (which have already been resolved) to go
>> through each of their uplinks (also already resolved) to see if any of
>> them has a carrier, and act accordingly.
>>
>> Makes sense?
>>
>> >  static const char* const link_state_table[_LINK_STATE_MAX] = {
>> >          [LINK_STATE_PENDING] = "pending",
>> >          [LINK_STATE_ENSLAVING] = "configuring",
>> > diff --git a/src/network/networkd-link.h b/src/network/networkd-link.h
>> > index 449dbc8..d94e9cd 100644
>> > --- a/src/network/networkd-link.h
>> > +++ b/src/network/networkd-link.h
>> > @@ -106,6 +106,7 @@ int link_save(Link *link);
>> >
>> >  int link_carrier_reset(Link *link);
>> >  bool link_has_carrier(Link *link);
>> > +int link_handle_carriers(Link *link);
>> >
>> >  int link_set_mtu(Link *link, uint32_t mtu);
>> >  int link_set_hostname(Link *link, const char *hostname);
>> > diff --git a/src/network/networkd-manager.c b/src/network/networkd-manager.c
>> > index 4617f11..06807df 100644
>> > --- a/src/network/networkd-manager.c
>> > +++ b/src/network/networkd-manager.c
>> > @@ -356,6 +356,13 @@ static int manager_rtnl_process_link(sd_rtnl *rtnl, sd_rtnl_message *message, vo
>> >                  assert_not_reached("Received invalid RTNL message type.");
>> >          }
>> >
>> > +        link = hashmap_first(m->links);
>> > +        if (link) {
>> > +                r = link_handle_carriers(link);
>> > +                if (r < 0)
>> > +                        return 0;
>> > +        }
>>
>> Hm, this looks really wrong. Why hashmap_first()? What if this was a
>> change or remove event, hashmp_first() will have nothing to do with
>> the link in question, no? How about splitting this up as suggested
>> above?
>>
>> >          return 1;
>> >  }
>> >
>> > diff --git a/src/network/networkd-network-gperf.gperf b/src/network/networkd-network-gperf.gperf
>> > index 1731e04..e191380 100644
>> > --- a/src/network/networkd-network-gperf.gperf
>> > +++ b/src/network/networkd-network-gperf.gperf
>> > @@ -48,6 +48,7 @@ Network.LLMNR,               config_parse_llmnr,                 0,
>> >  Network.NTP,                 config_parse_strv,                  0,                             offsetof(Network, ntp)
>> >  Network.IPForward,           config_parse_address_family_boolean,0,                             offsetof(Network, ip_forward)
>> >  Network.IPMasquerade,        config_parse_bool,                  0,                             offsetof(Network, ip_masquerade)
>> > +Network.BindCarrier,         config_parse_strv,                  0,                             offsetof(Network, carriers)
>> >  Address.Address,             config_parse_address,               0,                             0
>> >  Address.Peer,                config_parse_address,               0,                             0
>> >  Address.Broadcast,           config_parse_broadcast,             0,                             0
>> > diff --git a/src/network/networkd-network.c b/src/network/networkd-network.c
>> > index 3ebd4d7..9c4425e 100644
>> > --- a/src/network/networkd-network.c
>> > +++ b/src/network/networkd-network.c
>> > @@ -21,6 +21,7 @@
>> >
>> >  #include <ctype.h>
>> >  #include <net/if.h>
>> > +#include <fnmatch.h>
>> >
>> >  #include "path-util.h"
>> >  #include "conf-files.h"
>> > @@ -37,6 +38,7 @@ static int network_load_one(Manager *manager, const char *filename) {
>> >          char *d;
>> >          Route *route;
>> >          Address *address;
>> > +        char **carrier;
>> >          int r;
>> >
>> >          assert(manager);
>> > @@ -154,6 +156,13 @@ static int network_load_one(Manager *manager, const char *filename) {
>> >                  }
>> >          }
>> >
>> > +        if (!strv_isempty(network->carriers))
>> > +                STRV_FOREACH(carrier, network->carriers)
>> > +                        if (fnmatch(*carrier, network->match_name, 0) == 0) {
>> > +                                log_error("Link bound to itself: %s", network->match_name);
>> > +                                return -EINVAL;
> Maybe just log a warning and drop it from the list? Seems like this could be common enough
> error with globs, but probably not worth refusing to parse the configuration over.

Oh, this won't really work I think. There is no reason that *carrier
should match match_name (this may be unset, or a glob itself). If we
want to detect self-references we should be doing this at runtime I
think, once we know how the matches have been resolved.

>> > +                        }
>> > +
>> >          network = NULL;
>> >
>> >          return 0;
>> > @@ -209,6 +218,7 @@ void network_free(Network *network) {
>> >          strv_free(network->ntp);
>> >          strv_free(network->dns);
>> >          strv_free(network->domains);
>> > +        strv_free(network->carriers);
>> >
>> >          netdev_unref(network->bridge);
>> >
>> > diff --git a/src/network/networkd.h b/src/network/networkd.h
>> > index 22cc51d..04596a8 100644
>> > --- a/src/network/networkd.h
>> > +++ b/src/network/networkd.h
>> > @@ -151,7 +151,7 @@ struct Network {
>> >          Hashmap *fdb_entries_by_section;
>> >
>> >          bool wildcard_domain;
>> > -        char **domains, **dns, **ntp;
>> > +        char **domains, **dns, **ntp, **carriers;
>> >
>> >          LLMNRSupport llmnr;
>> >
>> > diff --git a/src/systemd/sd-network.h b/src/systemd/sd-network.h
>> > index 027730d..0a7adf2 100644
>> > --- a/src/systemd/sd-network.h
>> > +++ b/src/systemd/sd-network.h
>> > @@ -116,6 +116,9 @@ int sd_network_link_get_lldp(int ifindex, char **lldp);
>> >  /* Get the DNS domain names for a given link. */
>> >  int sd_network_link_get_domains(int ifindex, char ***domains);
>> >
>> > +/* Get the CARRIERS to which current link is bound to. */
>> > +int sd_network_link_get_carriers(int ifindex, char ***carriers);
>> > +
>> >  /* Returns whether or not domains that don't match any link should be resolved
>> >   * on this link. 1 for yes, 0 for no and negative value for error */
>> >  int sd_network_link_get_wildcard_domain(int ifindex);
>
> Zbyszek


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