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relay role implementation

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This commit is contained in:
Yegor Alexeyev
2021-04-20 15:11:53 +02:00
committed by Zbigniew Jędrzejewski-Szmek
parent d5bfddf037
commit c95df5879e
17 changed files with 222 additions and 21 deletions
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src/libsystemd-network/dhcp-server-internal.h
+1
View File
@@ -39,6 +39,7 @@ typedef struct DHCPLease {
} DHCPLease;
struct sd_dhcp_server {
struct in_addr relay_target;
unsigned n_ref;
sd_event *event;
src/libsystemd-network/sd-dhcp-server.c
+89 -21
View File
@@ -114,6 +114,12 @@ int sd_dhcp_server_is_running(sd_dhcp_server *server) {
return !!server->receive_message;
}
int sd_dhcp_server_is_in_relay_mode(sd_dhcp_server *server) {
assert_return(server, -EINVAL);
return in4_addr_is_set(&server->relay_target);
}
void client_id_hash_func(const DHCPClientId *id, struct siphash *state) {
assert(id);
assert(id->length);
@@ -343,10 +349,27 @@ static int dhcp_server_send_udp(sd_dhcp_server *server, be32_t destination,
return 0;
}
static bool requested_broadcast(DHCPRequest *req) {
assert(req);
static bool requested_broadcast(DHCPMessage *message) {
assert(message);
return message->flags & htobe16(0x8000);
}
return req->message->flags & htobe16(0x8000);
static int dhcp_server_send(sd_dhcp_server *server, be32_t destination, uint16_t destination_port,
DHCPPacket *packet, size_t optoffset, bool l2_broadcast) {
if (destination != INADDR_ANY)
return dhcp_server_send_udp(server, destination,
destination_port, &packet->dhcp,
sizeof(DHCPMessage) + optoffset);
else if (l2_broadcast)
return dhcp_server_send_udp(server, INADDR_BROADCAST,
destination_port, &packet->dhcp,
sizeof(DHCPMessage) + optoffset);
else
/* we cannot send UDP packet to specific MAC address when the
address is not yet configured, so must fall back to raw
packets */
return dhcp_server_send_unicast_raw(server, packet,
sizeof(DHCPPacket) + optoffset);
}
int dhcp_server_send_packet(sd_dhcp_server *server,
@@ -404,20 +427,8 @@ int dhcp_server_send_packet(sd_dhcp_server *server,
} else if (req->message->ciaddr && type != DHCP_NAK)
destination = req->message->ciaddr;
if (destination != INADDR_ANY)
return dhcp_server_send_udp(server, destination,
destination_port, &packet->dhcp,
sizeof(DHCPMessage) + optoffset);
else if (requested_broadcast(req) || type == DHCP_NAK)
return dhcp_server_send_udp(server, INADDR_BROADCAST,
destination_port, &packet->dhcp,
sizeof(DHCPMessage) + optoffset);
else
/* we cannot send UDP packet to specific MAC address when the
address is not yet configured, so must fall back to raw
packets */
return dhcp_server_send_unicast_raw(server, packet,
sizeof(DHCPPacket) + optoffset);
bool l2_broadcast = requested_broadcast(req->message) || type == DHCP_NAK;
return dhcp_server_send(server, destination, destination_port, packet, optoffset, l2_broadcast);
}
static int server_message_init(sd_dhcp_server *server, DHCPPacket **ret,
@@ -701,6 +712,47 @@ static int get_pool_offset(sd_dhcp_server *server, be32_t requested_ip) {
return be32toh(requested_ip & ~server->netmask) - server->pool_offset;
}
static int dhcp_server_relay_message(sd_dhcp_server *server, DHCPMessage *message, size_t opt_length) {
_cleanup_free_ DHCPPacket *packet = NULL;
assert(server);
assert(message);
assert(sd_dhcp_server_is_in_relay_mode(server));
if (message->op == BOOTREQUEST) {
log_dhcp_server(server, "(relay agent) BOOTREQUEST (0x%x)", be32toh(message->xid));
if (message->hops >= 16)
return -ETIME;
message->hops++;
/* https://tools.ietf.org/html/rfc1542#section-4.1.1 */
if (message->giaddr == 0)
message->giaddr = server->address;
return dhcp_server_send_udp(server, server->relay_target.s_addr, DHCP_PORT_SERVER, message, sizeof(DHCPMessage) + opt_length);
} else if (message->op == BOOTREPLY) {
log_dhcp_server(server, "(relay agent) BOOTREPLY (0x%x)", be32toh(message->xid));
if (message->giaddr != server->address) {
return log_dhcp_server_errno(server, SYNTHETIC_ERRNO(EBADMSG),
"(relay agent) BOOTREPLY giaddr mismatch, discarding");
}
int message_type = dhcp_option_parse(message, sizeof(DHCPMessage) + opt_length, NULL, NULL, NULL);
if (message_type < 0)
return message_type;
packet = malloc0(sizeof(DHCPPacket) + opt_length);
if (!packet)
return -ENOMEM;
memcpy(&packet->dhcp, message, sizeof(DHCPMessage) + opt_length);
bool l2_broadcast = requested_broadcast(message) || message_type == DHCP_NAK;
const be32_t destination = message_type == DHCP_NAK ? INADDR_ANY : message->ciaddr;
return dhcp_server_send(server, destination, DHCP_PORT_CLIENT, packet, opt_length, l2_broadcast);
}
return -EBADMSG;
}
#define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30)
int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message,
@@ -999,10 +1051,15 @@ static int server_receive_message(sd_event_source *s, int fd,
}
}
r = dhcp_server_handle_message(server, message, (size_t) len);
if (r < 0)
log_dhcp_server_errno(server, r, "Couldn't process incoming message: %m");
if (sd_dhcp_server_is_in_relay_mode(server)) {
r = dhcp_server_relay_message(server, message, len - sizeof(DHCPMessage));
if (r < 0)
log_dhcp_server_errno(server, r, "Couldn't relay message: %m");
} else {
r = dhcp_server_handle_message(server, message, (size_t) len);
if (r < 0)
log_dhcp_server_errno(server, r, "Couldn't process incoming message: %m");
}
return 0;
}
@@ -1238,3 +1295,14 @@ int sd_dhcp_server_set_callback(sd_dhcp_server *server, sd_dhcp_server_callback_
return 0;
}
int sd_dhcp_server_set_relay_target(sd_dhcp_server *server, const struct in_addr* address) {
assert_return(server, -EINVAL);
assert_return(!sd_dhcp_server_is_running(server), -EBUSY);
if (memcmp(address, &server->relay_target, sizeof(struct in_addr)) == 0)
return 0;
server->relay_target = *address;
return 1;
}