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udhcp: add inline docs; small code shrink

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function                                             old     new   delta
send_packet                                          103      87     -16
udhcpc_main                                         2359    2323     -36
This commit is contained in:
Denis Vlasenko 2008-09-26 23:45:20 +00:00
parent 7d9399e8dc
commit 739e30fbc3
6 changed files with 64 additions and 41 deletions
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22
networking/udhcp/clientpacket.c
View File

@ -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;

32
networking/udhcp/common.h
View File

@ -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;

21
networking/udhcp/dhcpc.c
View File

@ -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)

18
networking/udhcp/options.h
View File

@ -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

8
networking/udhcp/packet.c
View File

@ -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

2
networking/udhcp/serverpacket.c
View File

@ -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;