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udhcpd: support per-client hostnames in static leases

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function                                             old     new   delta
read_staticlease                                     222     299     +77
add_server_options                                    92     154     +62
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 139/0)             Total: 139 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2019-05-16 11:18:49 +02:00
parent 9bf6780c28
commit a840884531
3 changed files with 71 additions and 16 deletions
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9
examples/udhcp/udhcpd.conf
View File

@ -44,7 +44,7 @@ interface eth0
#notify_file # default: no script
#notify_file dumpleases # useful for debugging
# The following are bootp specific options
# The following are BOOTP specific options
# next server to use in bootstrap
#siaddr 192.168.0.22 # default: 0.0.0.0 (none)
# tftp server name
@ -52,9 +52,14 @@ interface eth0
# tftp file to download (e.g. kernel image)
#boot_file /var/nfs_root # default: none
# NOTE: "boot_file FILE" and "opt bootfile FILE" are conceptually the same,
# but "boot_file" goes into BOOTP-defined fixed-size field in the packet,
# whereas "opt bootfile" goes into DHCP option 0x43.
# Same for "sname HOST" and "opt tftp HOST".
# Static leases map
#static_lease 00:60:08:11:CE:4E 192.168.0.54
#static_lease 00:60:08:11:CE:3E 192.168.0.44
#static_lease 00:60:08:11:CE:3E 192.168.0.44 optional_hostname
# The remainder of options are DHCP options and can be specified with the
# keyword 'opt' or 'option'. If an option can take multiple items, such

72
networking/udhcp/dhcpd.c
View File

@ -48,14 +48,23 @@
#define g_leases ((struct dyn_lease*)ptr_to_globals)
/* struct server_config_t server_config is in bb_common_bufsiz1 */
struct static_lease {
struct static_lease *next;
uint32_t nip;
uint8_t mac[6];
uint8_t opt[1];
};
/* Takes the address of the pointer to the static_leases linked list,
* address to a 6 byte mac address,
* 4 byte IP address */
static void add_static_lease(struct static_lease **st_lease_pp,
uint8_t *mac,
uint32_t nip)
uint32_t nip,
const char *opts)
{
struct static_lease *st_lease;
unsigned optlen;
/* Find the tail of the list */
while ((st_lease = *st_lease_pp) != NULL) {
@ -63,10 +72,17 @@ static void add_static_lease(struct static_lease **st_lease_pp,
}
/* Add new node */
*st_lease_pp = st_lease = xzalloc(sizeof(*st_lease));
optlen = (opts ? 1+1+strnlen(opts, 120) : 0);
*st_lease_pp = st_lease = xzalloc(sizeof(*st_lease) + optlen);
memcpy(st_lease->mac, mac, 6);
st_lease->nip = nip;
/*st_lease->next = NULL;*/
if (optlen) {
st_lease->opt[OPT_CODE] = DHCP_HOST_NAME;
optlen -= 2;
st_lease->opt[OPT_LEN] = optlen;
memcpy(&st_lease->opt[OPT_DATA], opts, optlen);
}
}
/* Find static lease IP by mac */
@ -344,6 +360,7 @@ static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
char *line;
char *mac_string;
char *ip_string;
char *opts;
struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
uint32_t nip;
@ -358,7 +375,10 @@ static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
if (!ip_string || !udhcp_str2nip(ip_string, &nip))
return 0;
add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
opts = strtok_r(NULL, " \t", &line);
/* opts might be NULL, that's not an error */
add_static_lease(arg, (uint8_t*) &mac_bytes, nip, opts);
log_static_leases(arg);
@ -626,14 +646,49 @@ static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacke
*/
static void add_server_options(struct dhcp_packet *packet)
{
struct option_set *curr = server_config.options;
struct option_set *config_opts;
uint8_t *client_hostname_opt;
while (curr) {
if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
udhcp_add_binary_option(packet, curr->data);
curr = curr->next;
client_hostname_opt = NULL;
if (packet->yiaddr) { /* if we aren't from send_inform()... */
struct static_lease *st_lease = server_config.static_leases;
while (st_lease) {
if (st_lease->nip == packet->yiaddr) {
if (st_lease->opt[0] != 0)
client_hostname_opt = st_lease->opt;
break;
}
st_lease = st_lease->next;
}
}
config_opts = server_config.options;
while (config_opts) {
if (config_opts->data[OPT_CODE] != DHCP_LEASE_TIME) {
/* ^^^^
* DHCP_LEASE_TIME is already filled, or in case of
* send_inform(), should not be filled at all.
*/
if (config_opts->data[OPT_CODE] != DHCP_HOST_NAME
|| !client_hostname_opt
) {
/* Why "!client_hostname_opt":
* add hostname only if client has no hostname
* on its static lease line.
* (Not that "opt hostname HOST"
* makes much sense in udhcpd.conf,
* that'd give all clients the same hostname,
* but it's a valid configuration).
*/
udhcp_add_binary_option(packet, config_opts->data);
}
}
config_opts = config_opts->next;
}
if (client_hostname_opt)
udhcp_add_binary_option(packet, client_hostname_opt);
packet->siaddr_nip = server_config.siaddr_nip;
if (server_config.sname)
@ -753,7 +808,6 @@ static NOINLINE void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
lease_time_sec = select_lease_time(oldpacket);
udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
add_server_options(&packet);
addr.s_addr = yiaddr;

6
networking/udhcp/dhcpd.h
View File

@ -15,11 +15,7 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
#define DHCPD_CONF_FILE "/etc/udhcpd.conf"
struct static_lease {
struct static_lease *next;
uint32_t nip;
uint8_t mac[6];
};
struct static_lease;
struct server_config_t {
char *interface; /* interface to use */