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    Contents of /trunk/mkinitrd-magellan/busybox/networking/udhcp/packet.c

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    Revision 816 - (show annotations) (download)
    Fri Apr 24 18:33:46 2009 UTC (15 years ago) by niro
    File MIME type: text/plain
    File size: 6142 byte(s) 
    -updated to busybox-1.13.4
    1 /* vi: set sw=4 ts=4: */
    2
    3 #include <netinet/in.h>
    4 #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined _NEWLIB_VERSION
    5 #include <netpacket/packet.h>
    6 #include <net/ethernet.h>
    7 #else
    8 #include <asm/types.h>
    9 #include <linux/if_packet.h>
    10 #include <linux/if_ether.h>
    11 #endif
    12
    13 #include "common.h"
    14 #include "dhcpd.h"
    15 #include "options.h"
    16
    17
    18 void FAST_FUNC udhcp_init_header(struct dhcpMessage *packet, char type)
    19 {
    20 memset(packet, 0, sizeof(struct dhcpMessage));
    21 packet->op = BOOTREQUEST; /* if client to a server */
    22 switch (type) {
    23 case DHCPOFFER:
    24 case DHCPACK:
    25 case DHCPNAK:
    26 packet->op = BOOTREPLY; /* if server to client */
    27 }
    28 packet->htype = ETH_10MB;
    29 packet->hlen = ETH_10MB_LEN;
    30 packet->cookie = htonl(DHCP_MAGIC);
    31 packet->options[0] = DHCP_END;
    32 add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
    33 }
    34
    35
    36 /* read a packet from socket fd, return -1 on read error, -2 on packet error */
    37 int FAST_FUNC udhcp_recv_kernel_packet(struct dhcpMessage *packet, int fd)
    38 {
    39 int bytes;
    40 unsigned char *vendor;
    41
    42 memset(packet, 0, sizeof(*packet));
    43 bytes = safe_read(fd, packet, sizeof(*packet));
    44 if (bytes < 0) {
    45 DEBUG("cannot read on listening socket, ignoring");
    46 return bytes; /* returns -1 */
    47 }
    48
    49 if (packet->cookie != htonl(DHCP_MAGIC)) {
    50 bb_error_msg("received bogus message, ignoring");
    51 return -2;
    52 }
    53 DEBUG("Received a packet");
    54
    55 if (packet->op == BOOTREQUEST) {
    56 vendor = get_option(packet, DHCP_VENDOR);
    57 if (vendor) {
    58 #if 0
    59 static const char broken_vendors[][8] = {
    60 "MSFT 98",
    61 ""
    62 };
    63 int i;
    64 for (i = 0; broken_vendors[i][0]; i++) {
    65 if (vendor[OPT_LEN - 2] == (uint8_t)strlen(broken_vendors[i])
    66 && !strncmp((char*)vendor, broken_vendors[i], vendor[OPT_LEN - 2])
    67 ) {
    68 DEBUG("broken client (%s), forcing broadcast replies",
    69 broken_vendors[i]);
    70 packet->flags |= htons(BROADCAST_FLAG);
    71 }
    72 }
    73 #else
    74 if (vendor[OPT_LEN - 2] == (uint8_t)(sizeof("MSFT 98")-1)
    75 && memcmp(vendor, "MSFT 98", sizeof("MSFT 98")-1) == 0
    76 ) {
    77 DEBUG("broken client (%s), forcing broadcast replies", "MSFT 98");
    78 packet->flags |= htons(BROADCAST_FLAG);
    79 }
    80 #endif
    81 }
    82 }
    83
    84 return bytes;
    85 }
    86
    87
    88 uint16_t FAST_FUNC udhcp_checksum(void *addr, int count)
    89 {
    90 /* Compute Internet Checksum for "count" bytes
    91 * beginning at location "addr".
    92 */
    93 int32_t sum = 0;
    94 uint16_t *source = (uint16_t *) addr;
    95
    96 while (count > 1) {
    97 /* This is the inner loop */
    98 sum += *source++;
    99 count -= 2;
    100 }
    101
    102 /* Add left-over byte, if any */
    103 if (count > 0) {
    104 /* Make sure that the left-over byte is added correctly both
    105 * with little and big endian hosts */
    106 uint16_t tmp = 0;
    107 *(uint8_t*)&tmp = *(uint8_t*)source;
    108 sum += tmp;
    109 }
    110 /* Fold 32-bit sum to 16 bits */
    111 while (sum >> 16)
    112 sum = (sum & 0xffff) + (sum >> 16);
    113
    114 return ~sum;
    115 }
    116
    117
    118 /* Construct a ip/udp header for a packet, send packet */
    119 int FAST_FUNC udhcp_send_raw_packet(struct dhcpMessage *payload,
    120 uint32_t source_ip, int source_port,
    121 uint32_t dest_ip, int dest_port, const uint8_t *dest_arp,
    122 int ifindex)
    123 {
    124 struct sockaddr_ll dest;
    125 struct udp_dhcp_packet packet;
    126 int fd;
    127 int result = -1;
    128 const char *msg;
    129
    130 enum {
    131 IP_UPD_DHCP_SIZE = sizeof(struct udp_dhcp_packet) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
    132 UPD_DHCP_SIZE = IP_UPD_DHCP_SIZE - offsetof(struct udp_dhcp_packet, udp),
    133 };
    134
    135 fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
    136 if (fd < 0) {
    137 msg = "socket(%s)";
    138 goto ret_msg;
    139 }
    140
    141 memset(&dest, 0, sizeof(dest));
    142 memset(&packet, 0, sizeof(packet));
    143 packet.data = *payload; /* struct copy */
    144
    145 dest.sll_family = AF_PACKET;
    146 dest.sll_protocol = htons(ETH_P_IP);
    147 dest.sll_ifindex = ifindex;
    148 dest.sll_halen = 6;
    149 memcpy(dest.sll_addr, dest_arp, 6);
    150 if (bind(fd, (struct sockaddr *)&dest, sizeof(dest)) < 0) {
    151 msg = "bind(%s)";
    152 goto ret_close;
    153 }
    154
    155 packet.ip.protocol = IPPROTO_UDP;
    156 packet.ip.saddr = source_ip;
    157 packet.ip.daddr = dest_ip;
    158 packet.udp.source = htons(source_port);
    159 packet.udp.dest = htons(dest_port);
    160 /* size, excluding IP header: */
    161 packet.udp.len = htons(UPD_DHCP_SIZE);
    162 /* for UDP checksumming, ip.len is set to UDP packet len */
    163 packet.ip.tot_len = packet.udp.len;
    164 packet.udp.check = udhcp_checksum(&packet, IP_UPD_DHCP_SIZE);
    165 /* but for sending, it is set to IP packet len */
    166 packet.ip.tot_len = htons(IP_UPD_DHCP_SIZE);
    167 packet.ip.ihl = sizeof(packet.ip) >> 2;
    168 packet.ip.version = IPVERSION;
    169 packet.ip.ttl = IPDEFTTL;
    170 packet.ip.check = udhcp_checksum(&packet.ip, sizeof(packet.ip));
    171
    172 /* Currently we send full-sized DHCP packets (zero padded).
    173 * If you need to change this: last byte of the packet is
    174 * packet.data.options[end_option(packet.data.options)]
    175 */
    176 result = sendto(fd, &packet, IP_UPD_DHCP_SIZE, 0,
    177 (struct sockaddr *) &dest, sizeof(dest));
    178 msg = "sendto";
    179 ret_close:
    180 close(fd);
    181 if (result < 0) {
    182 ret_msg:
    183 bb_perror_msg(msg, "PACKET");
    184 }
    185 return result;
    186 }
    187
    188
    189 /* Let the kernel do all the work for packet generation */
    190 int FAST_FUNC udhcp_send_kernel_packet(struct dhcpMessage *payload,
    191 uint32_t source_ip, int source_port,
    192 uint32_t dest_ip, int dest_port)
    193 {
    194 struct sockaddr_in client;
    195 int fd;
    196 int result = -1;
    197 const char *msg;
    198
    199 enum {
    200 DHCP_SIZE = sizeof(struct dhcpMessage) - CONFIG_UDHCPC_SLACK_FOR_BUGGY_SERVERS,
    201 };
    202
    203 fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
    204 if (fd < 0) {
    205 msg = "socket(%s)";
    206 goto ret_msg;
    207 }
    208 setsockopt_reuseaddr(fd);
    209
    210 memset(&client, 0, sizeof(client));
    211 client.sin_family = AF_INET;
    212 client.sin_port = htons(source_port);
    213 client.sin_addr.s_addr = source_ip;
    214 if (bind(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
    215 msg = "bind(%s)";
    216 goto ret_close;
    217 }
    218
    219 memset(&client, 0, sizeof(client));
    220 client.sin_family = AF_INET;
    221 client.sin_port = htons(dest_port);
    222 client.sin_addr.s_addr = dest_ip;
    223 if (connect(fd, (struct sockaddr *)&client, sizeof(client)) == -1) {
    224 msg = "connect";
    225 goto ret_close;
    226 }
    227
    228 /* Currently we send full-sized DHCP packets (see above) */
    229 result = safe_write(fd, payload, DHCP_SIZE);
    230 msg = "write";
    231 ret_close:
    232 close(fd);
    233 if (result < 0) {
    234 ret_msg:
    235 bb_perror_msg(msg, "UDP");
    236 }
    237 return result;
    238 }