[avahi] AvahiPublishFlags#AVAHI_PUBLISH_UPDATE what does it mean?

[Ruoruo Zhang(Lily)]

I am trying to understand different AvahiPublishFlags to choose a right
one. What does AvahiPublishFlags#AVAHI_PUBLISH_UPDATE mean?

Documentation says:
Update existing records instead of adding new ones.

Reference:
http://avahi.org/download/doxygen/defs_8h.html#a4b10ef40d32caa6ef2e2d62cae00b4a3

I traced the implementation into entry.c#server_add_service_strlst_nocopy()
as follows but still, AVAHI_PUBLISH_UPDATE is only used for error checking.
Any help is welcomed

static int server_add_service_strlst_nocopy(
    AvahiServer *s,
    AvahiSEntryGroup *g,
    AvahiIfIndex interface,
    AvahiProtocol protocol,
    AvahiPublishFlags flags,
    const char *name,
    const char *type,
    const char *domain,
    const char *host,
    uint16_t port,
    AvahiStringList *strlst) {

    char ptr_name[AVAHI_DOMAIN_NAME_MAX], svc_name[AVAHI_DOMAIN_NAME_MAX],
enum_ptr[AVAHI_DOMAIN_NAME_MAX], *h = NULL;
    AvahiRecord *r = NULL;
    int ret = AVAHI_OK;
    AvahiEntry *srv_entry = NULL, *txt_entry = NULL, *ptr_entry = NULL,
*enum_entry = NULL;

    assert(s);
    assert(type);
    assert(name);

    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, AVAHI_IF_VALID(interface),
AVAHI_ERR_INVALID_INTERFACE);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, AVAHI_PROTO_VALID(protocol),
AVAHI_ERR_INVALID_PROTOCOL);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, AVAHI_FLAGS_VALID(flags,

AVAHI_PUBLISH_NO_COOKIE|

AVAHI_PUBLISH_UPDATE|

AVAHI_PUBLISH_USE_WIDE_AREA|

AVAHI_PUBLISH_USE_MULTICAST), AVAHI_ERR_INVALID_FLAGS);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s,
avahi_is_valid_service_name(name), AVAHI_ERR_INVALID_SERVICE_NAME);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s,
avahi_is_valid_service_type_strict(type), AVAHI_ERR_INVALID_SERVICE_TYPE);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, !domain ||
avahi_is_valid_domain_name(domain), AVAHI_ERR_INVALID_DOMAIN_NAME);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, !host ||
avahi_is_valid_fqdn(host), AVAHI_ERR_INVALID_HOST_NAME);

    if (!domain)
        domain = s->domain_name;

    if (!host)
        host = s->host_name_fqdn;

    transport_flags_from_domain(s, &flags, domain);
    AVAHI_CHECK_VALIDITY_SET_RET_GOTO_FAIL(s, flags &
AVAHI_PUBLISH_USE_MULTICAST, AVAHI_ERR_NOT_SUPPORTED);

    if (!(h = avahi_normalize_name_strdup(host))) {
        ret = avahi_server_set_errno(s, AVAHI_ERR_NO_MEMORY);
        goto fail;
    }

    if ((ret = avahi_service_name_join(svc_name, sizeof(svc_name), name,
type, domain)) < 0 ||
        (ret = avahi_service_name_join(ptr_name, sizeof(ptr_name), NULL,
type, domain)) < 0 ||
        (ret = avahi_service_name_join(enum_ptr, sizeof(enum_ptr), NULL,
"_services._dns-sd._udp", domain)) < 0) {
        avahi_server_set_errno(s, ret);
        goto fail;
    }

    /* Add service enumeration PTR record */

    if (!(ptr_entry = server_add_ptr_internal(s, g, interface, protocol, 0,
AVAHI_DEFAULT_TTL, ptr_name, svc_name))) {
        ret = avahi_server_errno(s);
        goto fail;
    }

    /* Add SRV record */

    if (!(r = avahi_record_new_full(svc_name, AVAHI_DNS_CLASS_IN,
AVAHI_DNS_TYPE_SRV, AVAHI_DEFAULT_TTL_HOST_NAME))) {
        ret = avahi_server_set_errno(s, AVAHI_ERR_NO_MEMORY);
        goto fail;
    }

    r->data.srv.priority = 0;
    r->data.srv.weight = 0;
    r->data.srv.port = port;
    r->data.srv.name = h;
    h = NULL;
    srv_entry = server_add_internal(s, g, interface, protocol,
AVAHI_PUBLISH_UNIQUE, r);
    avahi_record_unref(r);

    if (!srv_entry) {
        ret = avahi_server_errno(s);
        goto fail;
    }

    /* Add TXT record */

    if (!(flags & AVAHI_PUBLISH_NO_COOKIE))
        strlst = add_magic_cookie(s, strlst);

    txt_entry = server_add_txt_strlst_nocopy(s, g, interface, protocol,
AVAHI_PUBLISH_UNIQUE, AVAHI_DEFAULT_TTL, svc_name, strlst);
    strlst = NULL;

    if (!txt_entry) {
        ret = avahi_server_errno(s);
        goto fail;
    }

    /* Add service type enumeration record */

    if (!(enum_entry = server_add_ptr_internal(s, g, interface, protocol,
0, AVAHI_DEFAULT_TTL, enum_ptr, ptr_name))) {
        ret = avahi_server_errno(s);
        goto fail;
    }

fail:
    if (ret != AVAHI_OK && !(flags & AVAHI_PUBLISH_UPDATE)) {
        if (srv_entry)
            avahi_entry_free(s, srv_entry);
        if (txt_entry)
            avahi_entry_free(s, txt_entry);
        if (ptr_entry)
            avahi_entry_free(s, ptr_entry);
        if (enum_entry)
            avahi_entry_free(s, enum_entry);
    }

    avahi_string_list_free(strlst);
    avahi_free(h);

    return ret;
}



Ruoruo Zhang(Lily)

_______________________________________________
avahi mailing list
avahi@lists.freedesktop.org
http://lists.freedesktop.org/mailman/listinfo/avahi