[git commit master] dhcp: readability cleanups and small code shrink

Denys Vlasenko vda.linux at googlemail.com
Sun May 30 21:41:23 UTC 2010


commit: http://git.busybox.net/busybox/commit/?id=b7d19cc400f14ccd64a1fedebe14022fe115029a
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

function                                             old     new   delta
udhcp_run_script                                     654     617     -37

Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 networking/udhcp/common.c |    4 +-
 networking/udhcp/common.h |   14 +++++++++++-
 networking/udhcp/dhcpc.c  |   37 +++++++++++++++++++----------------
 networking/udhcp/packet.c |   46 ++++++++++++++++++--------------------------
 4 files changed, 53 insertions(+), 48 deletions(-)

diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 7cda34a..90a07ed 100644
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -176,7 +176,7 @@ unsigned FAST_FUNC udhcp_option_idx(const char *name)
 	}
 }
 
-/* get an option with bounds checking (warning, result is not aligned). */
+/* Get an option with bounds checking (warning, result is not aligned) */
 uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code)
 {
 	uint8_t *optionptr;
@@ -240,7 +240,7 @@ uint8_t* FAST_FUNC udhcp_get_option(struct dhcp_packet *packet, int code)
 	return NULL;
 }
 
-/* return the position of the 'end' option (no bounds checking) */
+/* Return the position of the 'end' option (no bounds checking) */
 int FAST_FUNC udhcp_end_option(uint8_t *optionptr)
 {
 	int i = 0;
diff --git a/networking/udhcp/common.h b/networking/udhcp/common.h
index c9dd0bb..75b787a 100644
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -57,10 +57,20 @@ struct ip_udp_dhcp_packet {
 	struct dhcp_packet data;
 } PACKED;
 
+struct udp_dhcp_packet {
+	struct udphdr udp;
+	struct dhcp_packet data;
+} PACKED;
+
+enum {
+	IP_UPD_DHCP_SIZE = sizeof(struct ip_udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
+	UPD_DHCP_SIZE    = sizeof(struct udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
+	DHCP_SIZE        = sizeof(struct dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
+};
+
 /* Let's see whether compiler understood us right */
 struct BUG_bad_sizeof_struct_ip_udp_dhcp_packet {
-	char BUG_bad_sizeof_struct_ip_udp_dhcp_packet
-		[(sizeof(struct ip_udp_dhcp_packet) != 576 + CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS) ? -1 : 1];
+	char c[IP_UPD_DHCP_SIZE == 576 ? 1 : -1];
 };
 
 
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 24ff82d..c2b21c6 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -229,37 +229,41 @@ static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_
 /* put all the parameters into the environment */
 static char **fill_envp(struct dhcp_packet *packet)
 {
-	int num_options = 0;
+	int envc;
 	int i;
 	char **envp, **curr;
 	const char *opt_name;
 	uint8_t *temp;
-	uint8_t over = 0;
-
+	uint8_t overload = 0;
+
+	/* We need 6 elements for:
+	 * "interface=IFACE"
+	 * "ip=N.N.N.N" from packet->yiaddr
+	 * "siaddr=IP" from packet->siaddr_nip (unless 0)
+	 * "boot_file=FILE" from packet->file (unless overloaded)
+	 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
+	 * terminating NULL
+	 */
+	envc = 6;
+	/* +1 element for each option, +2 for subnet option: */
 	if (packet) {
 		for (i = 0; dhcp_optflags[i].code; i++) {
 			if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
-				num_options++;
 				if (dhcp_optflags[i].code == DHCP_SUBNET)
-					num_options++; /* for mton */
+					envc++; /* for mton */
+				envc++;
 			}
 		}
-		if (packet->siaddr_nip)
-			num_options++;
 		temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
 		if (temp)
-			over = *temp;
-		if (!(over & FILE_FIELD) && packet->file[0])
-			num_options++;
-		if (!(over & SNAME_FIELD) && packet->sname[0])
-			num_options++;
+			overload = *temp;
 	}
+	curr = envp = xzalloc(sizeof(char *) * envc);
 
-	curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
 	*curr = xasprintf("interface=%s", client_config.interface);
 	putenv(*curr++);
 
-	if (packet == NULL)
+	if (!packet)
 		return envp;
 
 	*curr = xmalloc(sizeof("ip=255.255.255.255"));
@@ -274,9 +278,8 @@ static char **fill_envp(struct dhcp_packet *packet)
 			goto next;
 		*curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
 		putenv(*curr++);
-
-		/* Fill in a subnet bits option for things like /24 */
 		if (dhcp_optflags[i].code == DHCP_SUBNET) {
+			/* Subnet option: make things like "$ip/$mask" possible */
 			uint32_t subnet;
 			move_from_unaligned32(subnet, temp);
 			*curr = xasprintf("mask=%d", mton(subnet));
@@ -291,12 +294,12 @@ static char **fill_envp(struct dhcp_packet *packet)
 		sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
 		putenv(*curr++);
 	}
-	if (!(over & FILE_FIELD) && packet->file[0]) {
+	if (!(overload & FILE_FIELD) && packet->file[0]) {
 		/* watch out for invalid packets */
 		*curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
 		putenv(*curr++);
 	}
-	if (!(over & SNAME_FIELD) && packet->sname[0]) {
+	if (!(overload & SNAME_FIELD) && packet->sname[0]) {
 		/* watch out for invalid packets */
 		*curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
 		putenv(*curr++);
diff --git a/networking/udhcp/packet.c b/networking/udhcp/packet.c
index 1bfe120..c01fb7d 100644
--- a/networking/udhcp/packet.c
+++ b/networking/udhcp/packet.c
@@ -167,44 +167,40 @@ uint16_t FAST_FUNC udhcp_checksum(void *addr, int count)
 
 /* Construct a ip/udp header for a packet, send packet */
 int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
-		uint32_t source_ip, int source_port,
-		uint32_t dest_ip, int dest_port, const uint8_t *dest_arp,
+		uint32_t source_nip, int source_port,
+		uint32_t dest_nip, int dest_port, const uint8_t *dest_arp,
 		int ifindex)
 {
-	struct sockaddr_ll dest;
+	struct sockaddr_ll dest_sll;
 	struct ip_udp_dhcp_packet packet;
 	int fd;
 	int result = -1;
 	const char *msg;
 
-	enum {
-		IP_UPD_DHCP_SIZE = sizeof(struct ip_udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
-		UPD_DHCP_SIZE    = IP_UPD_DHCP_SIZE - offsetof(struct ip_udp_dhcp_packet, udp),
-	};
-
 	fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
 	if (fd < 0) {
 		msg = "socket(%s)";
 		goto ret_msg;
 	}
 
-	memset(&dest, 0, sizeof(dest));
-	memset(&packet, 0, sizeof(packet));
+	memset(&dest_sll, 0, sizeof(dest_sll));
+	memset(&packet, 0, offsetof(struct ip_udp_dhcp_packet, data));
 	packet.data = *dhcp_pkt; /* struct copy */
 
-	dest.sll_family = AF_PACKET;
-	dest.sll_protocol = htons(ETH_P_IP);
-	dest.sll_ifindex = ifindex;
-	dest.sll_halen = 6;
-	memcpy(dest.sll_addr, dest_arp, 6);
-	if (bind(fd, (struct sockaddr *)&dest, sizeof(dest)) < 0) {
+	dest_sll.sll_family = AF_PACKET;
+	dest_sll.sll_protocol = htons(ETH_P_IP);
+	dest_sll.sll_ifindex = ifindex;
+	dest_sll.sll_halen = 6;
+	memcpy(dest_sll.sll_addr, dest_arp, 6);
+
+	if (bind(fd, (struct sockaddr *)&dest_sll, sizeof(dest_sll)) < 0) {
 		msg = "bind(%s)";
 		goto ret_close;
 	}
 
 	packet.ip.protocol = IPPROTO_UDP;
-	packet.ip.saddr = source_ip;
-	packet.ip.daddr = dest_ip;
+	packet.ip.saddr = source_nip;
+	packet.ip.daddr = dest_nip;
 	packet.udp.source = htons(source_port);
 	packet.udp.dest = htons(dest_port);
 	/* size, excluding IP header: */
@@ -225,7 +221,7 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
 	 */
 	udhcp_dump_packet(dhcp_pkt);
 	result = sendto(fd, &packet, IP_UPD_DHCP_SIZE, 0,
-				(struct sockaddr *) &dest, sizeof(dest));
+			(struct sockaddr *) &dest_sll, sizeof(dest_sll));
 	msg = "sendto";
  ret_close:
 	close(fd);
@@ -239,18 +235,14 @@ int FAST_FUNC udhcp_send_raw_packet(struct dhcp_packet *dhcp_pkt,
 
 /* Let the kernel do all the work for packet generation */
 int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
-		uint32_t source_ip, int source_port,
-		uint32_t dest_ip, int dest_port)
+		uint32_t source_nip, int source_port,
+		uint32_t dest_nip, int dest_port)
 {
 	struct sockaddr_in client;
 	int fd;
 	int result = -1;
 	const char *msg;
 
-	enum {
-		DHCP_SIZE = sizeof(struct dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
-	};
-
 	fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
 	if (fd < 0) {
 		msg = "socket(%s)";
@@ -261,7 +253,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
 	memset(&client, 0, sizeof(client));
 	client.sin_family = AF_INET;
 	client.sin_port = htons(source_port);
-	client.sin_addr.s_addr = source_ip;
+	client.sin_addr.s_addr = source_nip;
 	if (bind(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
 		msg = "bind(%s)";
 		goto ret_close;
@@ -270,7 +262,7 @@ int FAST_FUNC udhcp_send_kernel_packet(struct dhcp_packet *dhcp_pkt,
 	memset(&client, 0, sizeof(client));
 	client.sin_family = AF_INET;
 	client.sin_port = htons(dest_port);
-	client.sin_addr.s_addr = dest_ip;
+	client.sin_addr.s_addr = dest_nip;
 	if (connect(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
 		msg = "connect";
 		goto ret_close;
-- 
1.6.3.3



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