diff options
| -rw-r--r-- | networking/udhcp/dhcpc.c | 108 |
1 files changed, 90 insertions, 18 deletions
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index 9713e81..f685a1d 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -346,31 +346,34 @@ static ALWAYS_INLINE uint32_t random_xid(void) /* Initialize the packet with the proper defaults */ static void init_packet(struct dhcp_packet *packet, char type) { + /* Fill in: op, htype, hlen, cookie fields; message type option: */ udhcp_init_header(packet, type); + + packet->xid = random_xid(); + memcpy(packet->chaddr, client_config.client_mac, 6); if (client_config.clientid) udhcp_add_binary_option(packet, client_config.clientid); +} + +static void add_client_options(struct dhcp_packet *packet) +{ + uint8_t c; + int i, end, len; + + udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE)); if (client_config.hostname) udhcp_add_binary_option(packet, client_config.hostname); if (client_config.fqdn) udhcp_add_binary_option(packet, client_config.fqdn); - if (type != DHCPDECLINE - && type != DHCPRELEASE - && client_config.vendorclass - ) { + if (client_config.vendorclass) udhcp_add_binary_option(packet, client_config.vendorclass); - } -} -static void add_client_options(struct dhcp_packet *packet) -{ /* Add a "param req" option with the list of options we'd like to have * from stubborn DHCP servers. Pull the data from the struct in common.c. * No bounds checking because it goes towards the head of the packet. */ - uint8_t c; - int end = udhcp_end_option(packet->options); - int i, len = 0; - + end = udhcp_end_option(packet->options); + len = 0; for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) { if (( (dhcp_optflags[i].flags & OPTION_REQ) && !client_config.no_default_options @@ -432,13 +435,20 @@ static int send_discover(uint32_t xid, uint32_t requested) { struct dhcp_packet packet; + /* Fill in: op, htype, hlen, cookie, chaddr fields, + * random xid field (we override it below), + * client-id option (unless -C), message type option: + */ init_packet(&packet, DHCPDISCOVER); + packet.xid = xid; if (requested) udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested); - /* Explicitly saying that we want RFC-compliant packets helps - * some buggy DHCP servers to NOT send bigger packets */ - udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576)); + + /* Add options: maxsize, + * optionally: hostname, fqdn, vendorclass, + * "param req" option according to -O, options specified with -x + */ add_client_options(&packet); bb_info_msg("Sending discover..."); @@ -454,10 +464,33 @@ static int send_select(uint32_t xid, uint32_t server, uint32_t requested) struct dhcp_packet packet; struct in_addr addr; +/* + * RFC 2131 4.3.2 DHCPREQUEST message + * ... + * If the DHCPREQUEST message contains a 'server identifier' + * option, the message is in response to a DHCPOFFER message. + * Otherwise, the message is a request to verify or extend an + * existing lease. If the client uses a 'client identifier' + * in a DHCPREQUEST message, it MUST use that same 'client identifier' + * in all subsequent messages. If the client included a list + * of requested parameters in a DHCPDISCOVER message, it MUST + * include that list in all subsequent messages. + */ + /* Fill in: op, htype, hlen, cookie, chaddr fields, + * random xid field (we override it below), + * client-id option (unless -C), message type option: + */ init_packet(&packet, DHCPREQUEST); + packet.xid = xid; udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested); + udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server); + + /* Add options: maxsize, + * optionally: hostname, fqdn, vendorclass, + * "param req" option according to -O, and options specified with -x + */ add_client_options(&packet); addr.s_addr = requested; @@ -470,9 +503,33 @@ static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr) { struct dhcp_packet packet; +/* + * RFC 2131 4.3.2 DHCPREQUEST message + * ... + * DHCPREQUEST generated during RENEWING state: + * + * 'server identifier' MUST NOT be filled in, 'requested IP address' + * option MUST NOT be filled in, 'ciaddr' MUST be filled in with + * client's IP address. In this situation, the client is completely + * configured, and is trying to extend its lease. This message will + * be unicast, so no relay agents will be involved in its + * transmission. Because 'giaddr' is therefore not filled in, the + * DHCP server will trust the value in 'ciaddr', and use it when + * replying to the client. + */ + /* Fill in: op, htype, hlen, cookie, chaddr fields, + * random xid field (we override it below), + * client-id option (unless -C), message type option: + */ init_packet(&packet, DHCPREQUEST); + packet.xid = xid; packet.ciaddr = ciaddr; + + /* Add options: maxsize, + * optionally: hostname, fqdn, vendorclass, + * "param req" option according to -O, and options specified with -x + */ add_client_options(&packet); bb_info_msg("Sending renew..."); @@ -489,9 +546,20 @@ static int send_decline(uint32_t xid, uint32_t server, uint32_t requested) { struct dhcp_packet packet; + /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields, + * client-id option (unless -C), message type option: + */ init_packet(&packet, DHCPDECLINE); + + /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client, + * but in case the server is buggy and wants DHCPDECLINE's xid + * to match the xid which started entire handshake, + * we use the same xid we used in initial DHCPDISCOVER: + */ packet.xid = xid; + /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */ udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested); + udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server); bb_info_msg("Sending decline..."); @@ -504,8 +572,12 @@ static int send_release(uint32_t server, uint32_t ciaddr) { struct dhcp_packet packet; + /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields, + * client-id option (unless -C), message type option: + */ init_packet(&packet, DHCPRELEASE); - packet.xid = random_xid(); + + /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */ packet.ciaddr = ciaddr; udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server); @@ -1254,7 +1326,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) /* Ignore packets that aren't for us */ if (packet.hlen != 6 - || memcmp(packet.chaddr, client_config.client_mac, 6) + || memcmp(packet.chaddr, client_config.client_mac, 6) != 0 ) { //FIXME: need to also check that last 10 bytes are zero log1("chaddr does not match, ignoring packet"); // log2? @@ -1280,7 +1352,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) } /* it IS unaligned sometimes, don't "optimize" */ move_from_unaligned32(server_addr, temp); - xid = packet.xid; + /*xid = packet.xid; - already is */ requested_ip = packet.yiaddr; /* enter requesting state */ |