diff options
Diffstat (limited to 'src/libsystemd-network/sd-dhcp-server.c')
| -rw-r--r-- | src/libsystemd-network/sd-dhcp-server.c | 85 |
1 files changed, 55 insertions, 30 deletions
diff --git a/src/libsystemd-network/sd-dhcp-server.c b/src/libsystemd-network/sd-dhcp-server.c index b96cee4830..1f167485e3 100644 --- a/src/libsystemd-network/sd-dhcp-server.c +++ b/src/libsystemd-network/sd-dhcp-server.c @@ -22,6 +22,7 @@ #include <sys/ioctl.h> +#include "in-addr-util.h" #include "siphash24.h" #include "sd-dhcp-server.h" @@ -31,38 +32,63 @@ #define DHCP_DEFAULT_LEASE_TIME_USEC USEC_PER_HOUR #define DHCP_MAX_LEASE_TIME_USEC (USEC_PER_HOUR*12) -int sd_dhcp_server_set_lease_pool(sd_dhcp_server *server, - struct in_addr *address, - size_t size) { +/* configures the server's address and subnet, and optionally the pool's size and offset into the subnet + * the whole pool must fit into the subnet, and may not contain the first (any) nor last (broadcast) address + * moreover, the server's own address may be in the pool, and is in that case reserved in order not to + * accidentally hand it out */ +int sd_dhcp_server_configure_pool(sd_dhcp_server *server, struct in_addr *address, unsigned char prefixlen, uint32_t offset, uint32_t size) { + struct in_addr netmask_addr; + be32_t netmask; + uint32_t server_off, broadcast_off, size_max; + assert_return(server, -EINVAL); assert_return(address, -EINVAL); - assert_return(address->s_addr, -EINVAL); - assert_return(size, -EINVAL); - assert_return(server->pool_start == htobe32(INADDR_ANY), -EBUSY); - assert_return(!server->pool_size, -EBUSY); - assert_return(!server->bound_leases, -EBUSY); + assert_return(address->s_addr != INADDR_ANY, -EINVAL); + assert_return(prefixlen <= 32, -ERANGE); + assert_return(server->address == INADDR_ANY, -EBUSY); + + assert_se(in_addr_prefixlen_to_netmask(&netmask_addr, prefixlen)); + netmask = netmask_addr.s_addr; + + server_off = be32toh(address->s_addr & ~netmask); + broadcast_off = be32toh(~netmask); + + /* the server address cannot be the subnet address */ + assert_return(server_off != 0, -ERANGE); + + /* nor the broadcast address */ + assert_return(server_off != broadcast_off, -ERANGE); + + /* 0 offset means we should set a default, we skip the first (subnet) address + and take the next one */ + if (offset == 0) + offset = 1; + + size_max = (broadcast_off + 1) /* the number of addresses in the subnet */ + - offset /* exclude the addresses before the offset */ + - 1; /* exclude the last (broadcast) address */ + + /* The pool must contain at least one address */ + assert_return(size_max >= 1, -ERANGE); + + if (size != 0) + assert_return(size <= size_max, -ERANGE); + else + size = size_max; server->bound_leases = new0(DHCPLease*, size); if (!server->bound_leases) return -ENOMEM; - server->pool_start = address->s_addr; + server->pool_offset = offset; server->pool_size = size; - return 0; -} - -int sd_dhcp_server_set_address(sd_dhcp_server *server, struct in_addr *address, - unsigned char prefixlen) { - assert_return(server, -EINVAL); - assert_return(address, -EINVAL); - assert_return(address->s_addr, -EINVAL); - assert_return(prefixlen <= 32, -ERANGE); - assert_return(server->address == htobe32(INADDR_ANY), -EBUSY); - assert_return(server->netmask == htobe32(INADDR_ANY), -EBUSY); - server->address = address->s_addr; - server->netmask = htobe32(0xfffffffflu << (32 - prefixlen)); + server->netmask = netmask; + server->subnet = address->s_addr & netmask; + + if (server_off >= offset && server_off - offset < size) + server->bound_leases[server_off - offset] = &server->invalid_lease; return 0; } @@ -661,12 +687,11 @@ static int get_pool_offset(sd_dhcp_server *server, be32_t requested_ip) { if (!server->pool_size) return -EINVAL; - if (be32toh(requested_ip) < be32toh(server->pool_start) || - be32toh(requested_ip) >= be32toh(server->pool_start) + - + server->pool_size) - return -EINVAL; + if (be32toh(requested_ip) < (be32toh(server->subnet) | server->pool_offset) || + be32toh(requested_ip) >= (be32toh(server->subnet) | (server->pool_offset + server->pool_size))) + return -ERANGE; - return be32toh(requested_ip) - be32toh(server->pool_start); + return be32toh(requested_ip & ~server->netmask) - server->pool_offset; } #define HASH_KEY SD_ID128_MAKE(0d,1d,fe,bd,f1,24,bd,b3,47,f1,dd,6e,73,21,93,30) @@ -718,7 +743,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, if (existing_lease) address = existing_lease->address; else { - size_t next_offer; + uint32_t next_offer; /* even with no persistence of leases, we try to offer the same client the same IP address. we do this by using the hash of the client id @@ -728,7 +753,7 @@ int dhcp_server_handle_message(sd_dhcp_server *server, DHCPMessage *message, for (i = 0; i < server->pool_size; i++) { if (!server->bound_leases[next_offer]) { - address = htobe32(be32toh(server->pool_start) + next_offer); + address = server->subnet | htobe32(server->pool_offset + next_offer); break; } else next_offer = (next_offer + 1) % server->pool_size; @@ -1022,7 +1047,7 @@ int sd_dhcp_server_forcerenew(sd_dhcp_server *server) { for (i = 0; i < server->pool_size; i++) { DHCPLease *lease = server->bound_leases[i]; - if (!lease) + if (!lease || lease == &server->invalid_lease) continue; r = server_send_forcerenew(server, lease->address, |