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

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    Revision 532 - (show annotations) (download)
    Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
    File MIME type: text/plain
    File size: 5310 byte(s) 
    -import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
    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 udhcp_init_header(struct dhcpMessage *packet, char type)
    19 {
    20 memset(packet, 0, sizeof(struct dhcpMessage));
    21 switch (type) {
    22 case DHCPDISCOVER:
    23 case DHCPREQUEST:
    24 case DHCPRELEASE:
    25 case DHCPINFORM:
    26 packet->op = BOOTREQUEST;
    27 break;
    28 case DHCPOFFER:
    29 case DHCPACK:
    30 case DHCPNAK:
    31 packet->op = BOOTREPLY;
    32 }
    33 packet->htype = ETH_10MB;
    34 packet->hlen = ETH_10MB_LEN;
    35 packet->cookie = htonl(DHCP_MAGIC);
    36 packet->options[0] = DHCP_END;
    37 add_simple_option(packet->options, DHCP_MESSAGE_TYPE, type);
    38 }
    39
    40
    41 /* read a packet from socket fd, return -1 on read error, -2 on packet error */
    42 int udhcp_get_packet(struct dhcpMessage *packet, int fd)
    43 {
    44 static const char broken_vendors[][8] = {
    45 "MSFT 98",
    46 ""
    47 };
    48 int bytes;
    49 int i;
    50 char unsigned *vendor;
    51
    52 memset(packet, 0, sizeof(struct dhcpMessage));
    53 bytes = read(fd, packet, sizeof(struct dhcpMessage));
    54 if (bytes < 0) {
    55 DEBUG("cannot read on listening socket, ignoring");
    56 return -1;
    57 }
    58
    59 if (ntohl(packet->cookie) != DHCP_MAGIC) {
    60 bb_error_msg("received bogus message, ignoring");
    61 return -2;
    62 }
    63 DEBUG("Received a packet");
    64
    65 if (packet->op == BOOTREQUEST && (vendor = get_option(packet, DHCP_VENDOR))) {
    66 for (i = 0; broken_vendors[i][0]; i++) {
    67 if (vendor[OPT_LEN - 2] == (uint8_t)strlen(broken_vendors[i])
    68 && !strncmp((char*)vendor, broken_vendors[i], vendor[OPT_LEN - 2])
    69 ) {
    70 DEBUG("broken client (%s), forcing broadcast",
    71 broken_vendors[i]);
    72 packet->flags |= htons(BROADCAST_FLAG);
    73 }
    74 }
    75 }
    76
    77 return bytes;
    78 }
    79
    80
    81 uint16_t udhcp_checksum(void *addr, int count)
    82 {
    83 /* Compute Internet Checksum for "count" bytes
    84 * beginning at location "addr".
    85 */
    86 int32_t sum = 0;
    87 uint16_t *source = (uint16_t *) addr;
    88
    89 while (count > 1) {
    90 /* This is the inner loop */
    91 sum += *source++;
    92 count -= 2;
    93 }
    94
    95 /* Add left-over byte, if any */
    96 if (count > 0) {
    97 /* Make sure that the left-over byte is added correctly both
    98 * with little and big endian hosts */
    99 uint16_t tmp = 0;
    100 *(uint8_t *) (&tmp) = * (uint8_t *) source;
    101 sum += tmp;
    102 }
    103 /* Fold 32-bit sum to 16 bits */
    104 while (sum >> 16)
    105 sum = (sum & 0xffff) + (sum >> 16);
    106
    107 return ~sum;
    108 }
    109
    110
    111 /* Construct a ip/udp header for a packet, and specify the source and dest hardware address */
    112 void BUG_sizeof_struct_udp_dhcp_packet_must_be_576(void);
    113 int udhcp_raw_packet(struct dhcpMessage *payload,
    114 uint32_t source_ip, int source_port,
    115 uint32_t dest_ip, int dest_port, uint8_t *dest_arp, int ifindex)
    116 {
    117 int fd;
    118 int result;
    119 struct sockaddr_ll dest;
    120 struct udp_dhcp_packet packet;
    121
    122 fd = socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
    123 if (fd < 0) {
    124 bb_perror_msg("socket");
    125 return -1;
    126 }
    127
    128 memset(&dest, 0, sizeof(dest));
    129 memset(&packet, 0, sizeof(packet));
    130
    131 dest.sll_family = AF_PACKET;
    132 dest.sll_protocol = htons(ETH_P_IP);
    133 dest.sll_ifindex = ifindex;
    134 dest.sll_halen = 6;
    135 memcpy(dest.sll_addr, dest_arp, 6);
    136 if (bind(fd, (struct sockaddr *)&dest, sizeof(struct sockaddr_ll)) < 0) {
    137 bb_perror_msg("bind");
    138 close(fd);
    139 return -1;
    140 }
    141
    142 packet.ip.protocol = IPPROTO_UDP;
    143 packet.ip.saddr = source_ip;
    144 packet.ip.daddr = dest_ip;
    145 packet.udp.source = htons(source_port);
    146 packet.udp.dest = htons(dest_port);
    147 packet.udp.len = htons(sizeof(packet.udp) + sizeof(struct dhcpMessage)); /* cheat on the psuedo-header */
    148 packet.ip.tot_len = packet.udp.len;
    149 memcpy(&(packet.data), payload, sizeof(struct dhcpMessage));
    150 packet.udp.check = udhcp_checksum(&packet, sizeof(struct udp_dhcp_packet));
    151
    152 packet.ip.tot_len = htons(sizeof(struct udp_dhcp_packet));
    153 packet.ip.ihl = sizeof(packet.ip) >> 2;
    154 packet.ip.version = IPVERSION;
    155 packet.ip.ttl = IPDEFTTL;
    156 packet.ip.check = udhcp_checksum(&(packet.ip), sizeof(packet.ip));
    157
    158 if (sizeof(struct udp_dhcp_packet) != 576)
    159 BUG_sizeof_struct_udp_dhcp_packet_must_be_576();
    160
    161 result = sendto(fd, &packet, sizeof(struct udp_dhcp_packet), 0,
    162 (struct sockaddr *) &dest, sizeof(dest));
    163 if (result <= 0) {
    164 bb_perror_msg("sendto");
    165 }
    166 close(fd);
    167 return result;
    168 }
    169
    170
    171 /* Let the kernel do all the work for packet generation */
    172 int udhcp_kernel_packet(struct dhcpMessage *payload,
    173 uint32_t source_ip, int source_port,
    174 uint32_t dest_ip, int dest_port)
    175 {
    176 int fd, result;
    177 struct sockaddr_in client;
    178
    179 fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
    180 if (fd < 0)
    181 return -1;
    182
    183 if (setsockopt_reuseaddr(fd) == -1) {
    184 close(fd);
    185 return -1;
    186 }
    187
    188 memset(&client, 0, sizeof(client));
    189 client.sin_family = AF_INET;
    190 client.sin_port = htons(source_port);
    191 client.sin_addr.s_addr = source_ip;
    192
    193 if (bind(fd, (struct sockaddr *)&client, sizeof(struct sockaddr)) == -1) {
    194 close(fd);
    195 return -1;
    196 }
    197
    198 memset(&client, 0, sizeof(client));
    199 client.sin_family = AF_INET;
    200 client.sin_port = htons(dest_port);
    201 client.sin_addr.s_addr = dest_ip;
    202
    203 if (connect(fd, (struct sockaddr *)&client, sizeof(struct sockaddr)) == -1) {
    204 close(fd);
    205 return -1;
    206 }
    207
    208 result = write(fd, payload, sizeof(struct dhcpMessage));
    209 close(fd);
    210 return result;
    211 }