dhcp: readability cleanups and small code shrink

function                                             old     new   delta
udhcp_run_script                                     654     617     -37

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

4 files changed, 54 insertions, 49 deletions

diff --git a/networking/udhcp/common.c b/networking/udhcp/common.c
index 7cda34a18..90a07ed09 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 c9dd0bb25..75b787a80 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 24ff82d2f..c2b21c695 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 1bfe12041..c01fb7d7c 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;