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Merge pull request #1931 from bengal/dhcp-fqdn-v2

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libsystemd-network: add support for "Client FQDN" DHCP option (v2)
This commit is contained in:
Tom Gundersen 2015-11-19 02:27:10 +01:00
commit dc9715d419
6 changed files with 122 additions and 10 deletions
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2
src/basic/hostname-util.c
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@ -72,7 +72,7 @@ static bool hostname_valid_char(char c) {
* allow_trailing_dot is true and at least two components are present
* in the name. Note that due to the restricted charset and length
* this call is substantially more conservative than
* dns_domain_is_valid().
* dns_name_is_valid().
*/
bool hostname_is_valid(const char *s, bool allow_trailing_dot) {
unsigned n_dots = 0;

10
src/libsystemd-network/dhcp-protocol.h
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@ -137,6 +137,7 @@ enum {
DHCP_OPTION_REBINDING_T2_TIME = 59,
DHCP_OPTION_VENDOR_CLASS_IDENTIFIER = 60,
DHCP_OPTION_CLIENT_IDENTIFIER = 61,
DHCP_OPTION_FQDN = 81,
DHCP_OPTION_NEW_POSIX_TIMEZONE = 100,
DHCP_OPTION_NEW_TZDB_TIMEZONE = 101,
DHCP_OPTION_CLASSLESS_STATIC_ROUTE = 121,
@ -144,3 +145,12 @@ enum {
DHCP_OPTION_PRIVATE_LAST = 254,
DHCP_OPTION_END = 255,
};
#define DHCP_MAX_FQDN_LENGTH 255
enum {
DHCP_FQDN_FLAG_S = (1 << 0),
DHCP_FQDN_FLAG_O = (1 << 1),
DHCP_FQDN_FLAG_E = (1 << 2),
DHCP_FQDN_FLAG_N = (1 << 3),
};

53
src/libsystemd-network/sd-dhcp-client.c
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@ -34,6 +34,8 @@
#include "dhcp-internal.h"
#include "dhcp-lease-internal.h"
#include "dhcp-protocol.h"
#include "dns-domain.h"
#include "hostname-util.h"
#include "random-util.h"
#include "string-util.h"
#include "util.h"
@ -298,6 +300,9 @@ int sd_dhcp_client_set_hostname(sd_dhcp_client *client,
assert_return(client, -EINVAL);
if (!hostname_is_valid(hostname, false) && !dns_name_is_valid(hostname))
return -EINVAL;
if (streq_ptr(client->hostname, hostname))
return 0;
@ -539,6 +544,24 @@ static int client_message_init(sd_dhcp_client *client, DHCPPacket **ret,
return 0;
}
static int client_append_fqdn_option(DHCPMessage *message, size_t optlen, size_t *optoffset,
const char *fqdn) {
uint8_t buffer[3 + DHCP_MAX_FQDN_LENGTH];
int r;
buffer[0] = DHCP_FQDN_FLAG_S | /* Request server to perform A RR DNS updates */
DHCP_FQDN_FLAG_E; /* Canonical wire format */
buffer[1] = 0; /* RCODE1 (deprecated) */
buffer[2] = 0; /* RCODE2 (deprecated) */
r = dns_name_to_wire_format(fqdn, buffer + 3, sizeof(buffer) - 3);
if (r > 0)
r = dhcp_option_append(message, optlen, optoffset, 0,
DHCP_OPTION_FQDN, 3 + r, buffer);
return r;
}
static int dhcp_client_send_raw(sd_dhcp_client *client, DHCPPacket *packet,
size_t len) {
dhcp_packet_append_ip_headers(packet, INADDR_ANY, DHCP_PORT_CLIENT,
@ -576,13 +599,21 @@ static int client_send_discover(sd_dhcp_client *client) {
return r;
}
/* it is unclear from RFC 2131 if client should send hostname in
DHCPDISCOVER but dhclient does and so we do as well
*/
if (client->hostname) {
r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
DHCP_OPTION_HOST_NAME,
strlen(client->hostname), client->hostname);
/* According to RFC 4702 "clients that send the Client FQDN option in
their messages MUST NOT also send the Host Name option". Just send
one of the two depending on the hostname type.
*/
if (dns_name_single_label(client->hostname)) {
/* it is unclear from RFC 2131 if client should send hostname in
DHCPDISCOVER but dhclient does and so we do as well
*/
r = dhcp_option_append(&discover->dhcp, optlen, &optoffset, 0,
DHCP_OPTION_HOST_NAME,
strlen(client->hostname), client->hostname);
} else
r = client_append_fqdn_option(&discover->dhcp, optlen, &optoffset,
client->hostname);
if (r < 0)
return r;
}
@ -688,9 +719,13 @@ static int client_send_request(sd_dhcp_client *client) {
}
if (client->hostname) {
r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
DHCP_OPTION_HOST_NAME,
strlen(client->hostname), client->hostname);
if (dns_name_single_label(client->hostname))
r = dhcp_option_append(&request->dhcp, optlen, &optoffset, 0,
DHCP_OPTION_HOST_NAME,
strlen(client->hostname), client->hostname);
else
r = client_append_fqdn_option(&request->dhcp, optlen, &optoffset,
client->hostname);
if (r < 0)
return r;
}

34
src/shared/dns-domain.c
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@ -715,3 +715,37 @@ int dns_name_single_label(const char *name) {
return r == 0 && *name == 0;
}
/* Encode a domain name according to RFC 1035 Section 3.1 */
int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len) {
uint8_t *label_length;
uint8_t *out;
int r;
assert_return(buffer, -EINVAL);
assert_return(domain, -EINVAL);
assert_return(domain[0], -EINVAL);
out = buffer;
do {
/* reserve a byte for label length */
if (len == 0)
return -ENOBUFS;
len--;
label_length = out;
out++;
/* convert and copy a single label */
r = dns_label_unescape(&domain, (char *) out, len);
if (r < 0)
return r;
/* fill label length, move forward */
*label_length = r;
out += r;
len -= r;
} while (r != 0);
return out - buffer;
}

2
src/shared/dns-domain.h
View File

@ -67,3 +67,5 @@ int dns_name_address(const char *p, int *family, union in_addr_union *a);
int dns_name_root(const char *name);
int dns_name_single_label(const char *name);
int dns_name_to_wire_format(const char *domain, uint8_t *buffer, size_t len);

31
src/test/test-dns-domain.c
View File

@ -52,6 +52,36 @@ static void test_dns_label_unescape(void) {
test_dns_label_unescape_one("foobar.", "foobar", 20, 6);
}
static void test_dns_name_to_wire_format_one(const char *what, const char *expect, size_t buffer_sz, int ret) {
uint8_t buffer[buffer_sz];
int r;
r = dns_name_to_wire_format(what, buffer, buffer_sz);
assert_se(r == ret);
if (r < 0)
return;
assert_se(!memcmp(buffer, expect, r));
}
static void test_dns_name_to_wire_format(void) {
const char out1[] = { 3, 'f', 'o', 'o', 0 };
const char out2[] = { 5, 'h', 'a', 'l', 'l', 'o', 3, 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
const char out3[] = { 4, ' ', 'f', 'o', 'o', 3, 'b', 'a', 'r', 0 };
test_dns_name_to_wire_format_one("", NULL, 0, -EINVAL);
test_dns_name_to_wire_format_one("foo", out1, sizeof(out1), sizeof(out1));
test_dns_name_to_wire_format_one("foo", out1, sizeof(out1) + 1, sizeof(out1));
test_dns_name_to_wire_format_one("foo", out1, sizeof(out1) - 1, -ENOBUFS);
test_dns_name_to_wire_format_one("hallo.foo.bar", out2, sizeof(out2), sizeof(out2));
test_dns_name_to_wire_format_one("hallo.foo..bar", NULL, 32, -EINVAL);
test_dns_name_to_wire_format_one("\\032foo.bar", out3, sizeof(out3), sizeof(out3));
}
static void test_dns_label_unescape_suffix_one(const char *what, const char *expect1, const char *expect2, size_t buffer_sz, int ret1, int ret2) {
char buffer[buffer_sz];
const char *label;
@ -300,6 +330,7 @@ int main(int argc, char *argv[]) {
test_dns_name_reverse();
test_dns_name_concat();
test_dns_name_is_valid();
test_dns_name_to_wire_format();
return 0;
}