clientpacket.h File Reference

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Functions

unsigned long random_xid (void)
int send_discover (unsigned long xid, unsigned long requested)
int send_selecting (unsigned long xid, unsigned long server, unsigned long requested)
int send_renew (unsigned long xid, unsigned long server, unsigned long ciaddr)
int send_release (unsigned long server, unsigned long ciaddr)
int get_raw_packet (struct dhcpMessage *payload, int fd)

Function Documentation

int get_raw_packet ( struct dhcpMessage *  payload,
int  fd 
)

Definition at line 182 of file clientpacket.c.

References checksum(), CLIENT_PORT, dhcpMessage::cookie, udp_dhcp_packet::data, DEBUG, DHCP_MAGIC, udp_dhcp_packet::ip, LOG, LOG_ERR, LOG_INFO, and udp_dhcp_packet::udp.

Referenced by udhcp().

00183 {
00184         int bytes;
00185         struct udp_dhcp_packet packet;
00186         u_int32_t source, dest;
00187         u_int16_t check;
00188 
00189         memset(&packet, 0, sizeof(struct udp_dhcp_packet));
00190         bytes = read(fd, &packet, sizeof(struct udp_dhcp_packet));
00191         if (bytes < 0) {
00192                 DEBUG(LOG_INFO, "couldn't read on raw listening socket -- ignoring");
00193                 usleep(500000); /* possible down interface, looping condition */
00194                 return -1;
00195         }
00196         
00197         if (bytes < (int) (sizeof(struct iphdr) + sizeof(struct udphdr))) {
00198                 DEBUG(LOG_INFO, "message too short, ignoring");
00199                 return -2;
00200         }
00201         
00202         if (bytes < ntohs(packet.ip.tot_len)) {
00203                 DEBUG(LOG_INFO, "Truncated packet");
00204                 return -2;
00205         }
00206         
00207         /* ignore any extra garbage bytes */
00208         bytes = ntohs(packet.ip.tot_len);
00209         
00210         /* Make sure its the right packet for us, and that it passes sanity checks */
00211         if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION ||
00212             packet.ip.ihl != sizeof(packet.ip) >> 2 || packet.udp.dest != htons(CLIENT_PORT) ||
00213             bytes > (int) sizeof(struct udp_dhcp_packet) ||
00214             ntohs(packet.udp.len) != (short) (bytes - sizeof(packet.ip))) {
00215                 DEBUG(LOG_INFO, "unrelated/bogus packet");
00216                 return -2;
00217         }
00218 
00219         /* check IP checksum */
00220         check = packet.ip.check;
00221         packet.ip.check = 0;
00222         if (check != checksum(&(packet.ip), sizeof(packet.ip))) {
00223                 DEBUG(LOG_INFO, "bad IP header checksum, ignoring");
00224                 return -1;
00225         }
00226         
00227         /* verify the UDP checksum by replacing the header with a psuedo header */
00228         source = packet.ip.saddr;
00229         dest = packet.ip.daddr;
00230         check = packet.udp.check;
00231         packet.udp.check = 0;
00232         memset(&packet.ip, 0, sizeof(packet.ip));
00233 
00234         packet.ip.protocol = IPPROTO_UDP;
00235         packet.ip.saddr = source;
00236         packet.ip.daddr = dest;
00237         packet.ip.tot_len = packet.udp.len; /* cheat on the psuedo-header */
00238         if (check && check != checksum(&packet, bytes)) {
00239                 DEBUG(LOG_ERR, "packet with bad UDP checksum received, ignoring");
00240                 return -2;
00241         }
00242         
00243         memcpy(payload, &(packet.data), bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
00244         
00245         if (ntohl(payload->cookie) != DHCP_MAGIC) {
00246                 LOG(LOG_ERR, "received bogus message (bad magic) -- ignoring");
00247                 return -2;
00248         }
00249         DEBUG(LOG_INFO, "oooooh!!! got some!");
00250         return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
00251         
00252 }

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unsigned long random_xid ( void   ) 

Definition at line 52 of file clientpacket.c.

References LOG, and LOG_WARNING.

Referenced by send_release(), and udhcp().

00053 {
00054         static int initialized;
00055         if (!initialized) {
00056                 int fd;
00057                 unsigned long seed;
00058 
00059                 fd = open("/dev/urandom", 0);
00060                 if (fd < 0 || read(fd, &seed, sizeof(seed)) < 0) {
00061                         LOG(LOG_WARNING, "Could not load seed from /dev/urandom: %s",
00062                                 strerror(errno));
00063                         seed = time(0);
00064                 }
00065                 if (fd >= 0) close(fd);
00066                 srand(seed);
00067                 initialized++;
00068         }
00069         return rand();
00070 }

int send_discover ( unsigned long  xid,
unsigned long  requested 
)

Definition at line 108 of file clientpacket.c.

References client_config, CLIENT_PORT, DHCP_REQUESTED_IP, DHCPDISCOVER, client_config_t::ifindex, LOG, LOG_DEBUG, MAC_BCAST_ADDR, dhcpMessage::options, raw_packet(), SERVER_PORT, and dhcpMessage::xid.

Referenced by udhcp().

00109 {
00110         struct dhcpMessage packet;
00111 
00112         init_packet(&packet, DHCPDISCOVER);
00113         packet.xid = xid;
00114         if (requested)
00115                 add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
00116 
00117         add_requests(&packet);
00118         LOG(LOG_DEBUG, "Sending discover...");
00119         return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, 
00120                                 SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
00121 }

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int send_release ( unsigned long  server,
unsigned long  ciaddr 
)

Definition at line 165 of file clientpacket.c.

References dhcpMessage::ciaddr, CLIENT_PORT, DHCP_REQUESTED_IP, DHCP_SERVER_ID, DHCPRELEASE, kernel_packet(), LOG, LOG_DEBUG, dhcpMessage::options, random_xid(), SERVER_PORT, and dhcpMessage::xid.

00166 {
00167         struct dhcpMessage packet;
00168 
00169         init_packet(&packet, DHCPRELEASE);
00170         packet.xid = random_xid();
00171         packet.ciaddr = ciaddr;
00172         
00173         add_simple_option(packet.options, DHCP_REQUESTED_IP, ciaddr);
00174         add_simple_option(packet.options, DHCP_SERVER_ID, server);
00175 
00176         LOG(LOG_DEBUG, "Sending release...");
00177         return kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
00178 }

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int send_renew ( unsigned long  xid,
unsigned long  server,
unsigned long  ciaddr 
)

Definition at line 145 of file clientpacket.c.

References dhcpMessage::ciaddr, client_config, CLIENT_PORT, DHCPREQUEST, client_config_t::ifindex, kernel_packet(), LOG, LOG_DEBUG, MAC_BCAST_ADDR, raw_packet(), SERVER_PORT, and dhcpMessage::xid.

Referenced by udhcp().

00146 {
00147         struct dhcpMessage packet;
00148         int ret = 0;
00149 
00150         init_packet(&packet, DHCPREQUEST);
00151         packet.xid = xid;
00152         packet.ciaddr = ciaddr;
00153 
00154         add_requests(&packet);
00155         LOG(LOG_DEBUG, "Sending renew...");
00156         if (server) 
00157                 ret = kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
00158         else ret = raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST,
00159                                 SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
00160         return ret;
00161 }

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int send_selecting ( unsigned long  xid,
unsigned long  server,
unsigned long  requested 
)

Definition at line 125 of file clientpacket.c.

References client_config, CLIENT_PORT, DHCP_REQUESTED_IP, DHCP_SERVER_ID, DHCPREQUEST, client_config_t::ifindex, LOG, LOG_DEBUG, MAC_BCAST_ADDR, dhcpMessage::options, raw_packet(), SERVER_PORT, and dhcpMessage::xid.

Referenced by udhcp().

00126 {
00127         struct dhcpMessage packet;
00128         struct in_addr addr;
00129 
00130         init_packet(&packet, DHCPREQUEST);
00131         packet.xid = xid;
00132 
00133         add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
00134         add_simple_option(packet.options, DHCP_SERVER_ID, server);
00135         
00136         add_requests(&packet);
00137         addr.s_addr = requested;
00138         LOG(LOG_DEBUG, "Sending select for %s...", inet_ntoa(addr));
00139         return raw_packet(&packet, INADDR_ANY, CLIENT_PORT, INADDR_BROADCAST, 
00140                                 SERVER_PORT, MAC_BCAST_ADDR, client_config.ifindex);
00141 }

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