From 739e30fbc3363756e574b5761ff63ea97ffd61c1 Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Fri, 26 Sep 2008 23:45:20 +0000 Subject: udhcp: add inline docs; small code shrink function old new delta send_packet 103 87 -16 udhcpc_main 2359 2323 -36 --- networking/udhcp/clientpacket.c | 22 ++++++++++++++++++++-- networking/udhcp/common.h | 32 +++++++++++++++++--------------- networking/udhcp/dhcpc.c | 23 ++++++++++++++--------- networking/udhcp/options.h | 18 ++++++++---------- networking/udhcp/packet.c | 8 ++++---- networking/udhcp/serverpacket.c | 2 +- 6 files changed, 64 insertions(+), 41 deletions(-) (limited to 'networking/udhcp') diff --git a/networking/udhcp/clientpacket.c b/networking/udhcp/clientpacket.c index 1ab17321d..3f9522ff8 100644 --- a/networking/udhcp/clientpacket.c +++ b/networking/udhcp/clientpacket.c @@ -78,6 +78,23 @@ static void add_param_req_option(struct dhcpMessage *packet) } } +/* RFC 2131 + * 4.4.4 Use of broadcast and unicast + * + * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM + * messages, unless the client knows the address of a DHCP server. + * The client unicasts DHCPRELEASE messages to the server. Because + * the client is declining the use of the IP address supplied by the server, + * the client broadcasts DHCPDECLINE messages. + * + * When the DHCP client knows the address of a DHCP server, in either + * INIT or REBOOTING state, the client may use that address + * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address. + * The client may also use unicast to send DHCPINFORM messages + * to a known DHCP server. If the client receives no response to DHCP + * messages sent to the IP address of a known DHCP server, the DHCP + * client reverts to using the IP broadcast address. + */ static int raw_bcast_from_client_config_ifindex(struct dhcpMessage *packet) { @@ -90,7 +107,6 @@ static int raw_bcast_from_client_config_ifindex(struct dhcpMessage *packet) #if ENABLE_FEATURE_UDHCPC_ARPING /* Broadcast a DHCP decline message */ -//FIXME: maybe it should be unicast? int FAST_FUNC send_decline(uint32_t xid, uint32_t server, uint32_t requested) { struct dhcpMessage packet; @@ -128,7 +144,9 @@ int FAST_FUNC send_discover(uint32_t xid, uint32_t requested) /* Broadcasts a DHCP request message */ -//FIXME: maybe it should be unicast? +/* RFC 2131 3.1 paragraph 3: + * "The client _broadcasts_ a DHCPREQUEST message..." + */ int FAST_FUNC send_select(uint32_t xid, uint32_t server, uint32_t requested) { struct dhcpMessage packet; diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h index 68fa65cf5..66a0b0d8b 100644 --- a/networking/udhcp/common.h +++ b/networking/udhcp/common.h @@ -27,21 +27,23 @@ extern const uint8_t MAC_BCAST_ADDR[6]; /* six all-ones */ #define DHCP_OPTIONS_BUFSIZE 308 struct dhcpMessage { - uint8_t op; - uint8_t htype; - uint8_t hlen; - uint8_t hops; - uint32_t xid; - uint16_t secs; - uint16_t flags; - uint32_t ciaddr; - uint32_t yiaddr; - uint32_t siaddr; - uint32_t giaddr; - uint8_t chaddr[16]; - uint8_t sname[64]; - uint8_t file[128]; - uint32_t cookie; + uint8_t op; /* 1 = BOOTREQUEST, 2 = BOOTREPLY */ + uint8_t htype; /* hardware address type. 1 = 10mb ethernet */ + uint8_t hlen; /* hardware address length */ + uint8_t hops; /* used by relay agents only */ + uint32_t xid; /* unique id */ + uint16_t secs; /* elapsed since client began acquisition/renewal */ + uint16_t flags; /* only one flag so far: */ +#define BROADCAST_FLAG 0x8000 /* "I need broadcast replies" */ + uint32_t ciaddr; /* client IP (if client is in BOUND, RENEW or REBINDING state) */ + uint32_t yiaddr; /* 'your' (client) IP address */ + uint32_t siaddr; /* IP address of next server to use in bootstrap, + * returned in DHCPOFFER, DHCPACK by server */ + uint32_t giaddr; /* relay agent IP address */ + uint8_t chaddr[16];/* link-layer client hardware address (MAC) */ + uint8_t sname[64]; /* server host name (ASCIZ) */ + uint8_t file[128]; /* boot file name (ASCIZ) */ + uint32_t cookie; /* fixed first four option bytes (99,130,83,99 dec) */ uint8_t options[DHCP_OPTIONS_BUFSIZE + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS]; } PACKED; diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c index 8985cc705..2d48980d9 100644 --- a/networking/udhcp/dhcpc.c +++ b/networking/udhcp/dhcpc.c @@ -452,7 +452,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) } /* select() didn't timeout, something did happen. */ - /* Is is a packet? */ + /* Is it a packet? */ if (listen_mode != LISTEN_NONE && FD_ISSET(sockfd, &rfds)) { int len; /* A packet is ready, read it */ @@ -474,7 +474,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) continue; if (packet.xid != xid) { - DEBUG("Ignoring XID %x (our xid is %x)", + DEBUG("Ignoring xid %x (our xid is %x)", (unsigned)packet.xid, (unsigned)xid); continue; } @@ -524,17 +524,24 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) bb_error_msg("no lease time with ACK, using 1 hour lease"); lease_seconds = 60 * 60; } else { - /* can be misaligned, thus memcpy */ - memcpy(&lease_seconds, temp, 4); + /* it IS unaligned sometimes, don't "optimize" */ + lease_seconds = get_unaligned_u32p((uint32_t*)temp); lease_seconds = ntohl(lease_seconds); lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */ if (lease_seconds < 10) /* and not too small */ lease_seconds = 10; } -//FIXME: why do we check ARP only after we've got DHCPACK? -//Shouldn't we do it immediately after DHCPOFFER? #if ENABLE_FEATURE_UDHCPC_ARPING if (opt & OPT_a) { +/* RFC 2131 3.1 paragraph 5: + * "The client receives the DHCPACK message with configuration + * parameters. The client SHOULD perform a final check on the + * parameters (e.g., ARP for allocated network address), and notes + * the duration of the lease specified in the DHCPACK message. At this + * point, the client is configured. If the client detects that the + * address is already in use (e.g., through the use of ARP), + * the client MUST send a DHCPDECLINE message to the server and restarts + * the configuration process..." */ if (!arpping(packet.yiaddr, (uint32_t) 0, client_config.arp, @@ -542,8 +549,6 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) ) { bb_info_msg("offered address is in use " "(got ARP reply), declining"); -//NB: not clear whether it should be unicast or bcast. -//Currently it is a bcast. Why? send_decline(xid, server_addr, packet.yiaddr); if (state != REQUESTING) @@ -568,7 +573,7 @@ int udhcpc_main(int argc UNUSED_PARAM, char **argv) } requested_ip = packet.yiaddr; udhcp_run_script(&packet, - ((state == RENEWING || state == REBINDING) ? "renew" : "bound")); + ((state == RENEWING || state == REBINDING) ? "renew" : "bound")); state = BOUND; change_listen_mode(LISTEN_NONE); diff --git a/networking/udhcp/options.h b/networking/udhcp/options.h index 70b8704d2..fcf1c9a6d 100644 --- a/networking/udhcp/options.h +++ b/networking/udhcp/options.h @@ -78,16 +78,14 @@ enum { #define ETH_10MB 1 #define ETH_10MB_LEN 6 -#define DHCPDISCOVER 1 -#define DHCPOFFER 2 -#define DHCPREQUEST 3 -#define DHCPDECLINE 4 -#define DHCPACK 5 -#define DHCPNAK 6 -#define DHCPRELEASE 7 -#define DHCPINFORM 8 - -#define BROADCAST_FLAG 0x8000 +#define DHCPDISCOVER 1 /* client -> server */ +#define DHCPOFFER 2 /* client <- server */ +#define DHCPREQUEST 3 /* client -> server */ +#define DHCPDECLINE 4 /* client -> server */ +#define DHCPACK 5 /* client <- server */ +#define DHCPNAK 6 /* client <- server */ +#define DHCPRELEASE 7 /* client -> server */ +#define DHCPINFORM 8 /* client -> server */ #define OPTION_FIELD 0 #define FILE_FIELD 1 diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c index 4eedbb53a..1a6f7e6a0 100644 --- a/networking/udhcp/packet.c +++ b/networking/udhcp/packet.c @@ -18,12 +18,12 @@ void FAST_FUNC udhcp_init_header(struct dhcpMessage *packet, char type) { memset(packet, 0, sizeof(struct dhcpMessage)); - packet->op = BOOTREQUEST; + packet->op = BOOTREQUEST; /* if client to a server */ switch (type) { case DHCPOFFER: case DHCPACK: case DHCPNAK: - packet->op = BOOTREPLY; + packet->op = BOOTREPLY; /* if server to client */ } packet->htype = ETH_10MB; packet->hlen = ETH_10MB_LEN; @@ -65,7 +65,7 @@ int FAST_FUNC udhcp_recv_kernel_packet(struct dhcpMessage *packet, int fd) if (vendor[OPT_LEN - 2] == (uint8_t)strlen(broken_vendors[i]) && !strncmp((char*)vendor, broken_vendors[i], vendor[OPT_LEN - 2]) ) { - DEBUG("broken client (%s), forcing broadcast", + DEBUG("broken client (%s), forcing broadcast replies", broken_vendors[i]); packet->flags |= htons(BROADCAST_FLAG); } @@ -74,7 +74,7 @@ int FAST_FUNC udhcp_recv_kernel_packet(struct dhcpMessage *packet, int fd) if (vendor[OPT_LEN - 2] == (uint8_t)(sizeof("MSFT 98")-1) && memcmp(vendor, "MSFT 98", sizeof("MSFT 98")-1) == 0 ) { - DEBUG("broken client (%s), forcing broadcast", "MSFT 98"); + DEBUG("broken client (%s), forcing broadcast replies", "MSFT 98"); packet->flags |= htons(BROADCAST_FLAG); } #endif diff --git a/networking/udhcp/serverpacket.c b/networking/udhcp/serverpacket.c index 5b1c61517..dcc234c7d 100644 --- a/networking/udhcp/serverpacket.c +++ b/networking/udhcp/serverpacket.c @@ -50,7 +50,7 @@ static int send_packet_to_client(struct dhcpMessage *payload, int force_broadcas DEBUG("unicasting packet to client ciaddr"); ciaddr = payload->ciaddr; chaddr = payload->chaddr; - } else if (ntohs(payload->flags) & BROADCAST_FLAG) { + } else if (payload->flags & htons(BROADCAST_FLAG)) { DEBUG("broadcasting packet to client (requested)"); ciaddr = INADDR_BROADCAST; chaddr = MAC_BCAST_ADDR; -- cgit v1.2.3