--- /dev/null
+/******************************************************************************
+ * Copyright (c) 2004, 2008 IBM Corporation
+ * All rights reserved.
+ * This program and the accompanying materials
+ * are made available under the terms of the BSD License
+ * which accompanies this distribution, and is available at
+ * http://www.opensource.org/licenses/bsd-license.php
+ *
+ * Contributors:
+ * IBM Corporation - initial implementation
+ *****************************************************************************/
+
+
+/*>>>>>>>>>>>>>>>>>>>>> DEFINITIONS & DECLARATIONS <<<<<<<<<<<<<<<<<<<<<<*/
+
+#include <ipv4.h>
+#include <udp.h>
+#include <tcp.h>
+#include <ethernet.h>
+#include <time.h>
+#include <sys/socket.h>
+#include <string.h>
+
+/* ARP Message types */
+#define ARP_REQUEST 1
+#define ARP_REPLY 2
+
+/* ARP talbe size (+1) */
+#define ARP_ENTRIES 10
+
+/* ICMP Message types */
+#define ICMP_ECHO_REPLY 0
+#define ICMP_DST_UNREACHABLE 3
+#define ICMP_SRC_QUENCH 4
+#define ICMP_REDIRECT 5
+#define ICMP_ECHO_REQUEST 8
+#define ICMP_TIME_EXCEEDED 11
+#define ICMP_PARAMETER_PROBLEM 12
+#define ICMP_TIMESTAMP_REQUEST 13
+#define ICMP_TIMESTAMP_REPLY 14
+#define ICMP_INFORMATION_REQUEST 15
+#define ICMP_INFORMATION_REPLY 16
+
+/** \struct arp_entry
+ * A entry that describes a mapping between IPv4- and MAC-address.
+ */
+typedef struct arp_entry arp_entry_t;
+struct arp_entry {
+ uint32_t ipv4_addr;
+ uint8_t mac_addr[6];
+ uint8_t eth_frame[ETH_MTU_SIZE];
+ int eth_len;
+ int pkt_pending;
+};
+
+/** \struct icmphdr
+ * ICMP packet
+ */
+struct icmphdr {
+ unsigned char type;
+ unsigned char code;
+ unsigned short int checksum;
+ union {
+ /* for type 3 "Destination Unreachable" */
+ unsigned int unused;
+ /* for type 0 and 8 */
+ struct echo {
+ unsigned short int id;
+ unsigned short int seq;
+ } echo;
+ } options;
+ union {
+ /* payload for destination unreachable */
+ struct dun {
+ unsigned char iphdr[20];
+ unsigned char data[64];
+ } dun;
+ /* payload for echo or echo reply */
+ /* maximum size supported is 84 */
+ unsigned char data[84];
+ } payload;
+};
+
+/*>>>>>>>>>>>>>>>>>>>>>>>>>>>>> PROTOTYPES <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<*/
+
+static unsigned short
+checksum(unsigned short *packet, int words);
+
+static void
+arp_send_request(int fd, uint32_t dest_ip);
+
+static void
+arp_send_reply(int fd, uint32_t src_ip, uint8_t * src_mac);
+
+static void
+fill_arphdr(uint8_t * packet, uint8_t opcode,
+ const uint8_t * src_mac, uint32_t src_ip,
+ const uint8_t * dest_mac, uint32_t dest_ip);
+
+static arp_entry_t*
+lookup_mac_addr(uint32_t ipv4_addr);
+
+static void
+fill_udp_checksum(struct iphdr *ipv4_hdr);
+
+static int8_t
+handle_icmp(int fd, struct iphdr * iph, uint8_t * packet, int32_t packetsize);
+
+/*>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LOCAL VARIABLES <<<<<<<<<<<<<<<<<<<<<<<<<*/
+
+/* Routing parameters */
+static uint32_t own_ip = 0;
+static uint32_t multicast_ip = 0;
+static uint32_t router_ip = 0;
+static uint32_t subnet_mask = 0;
+
+/* helper variables */
+static uint32_t ping_dst_ip;
+static const uint8_t null_mac_addr[] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
+static const uint8_t broadcast_mac[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+static uint8_t multicast_mac[] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+
+/* There are only (ARP_ENTRIES-1) effective entries because
+ * the entry that is pointed by arp_producer is never used.
+ */
+static unsigned int arp_consumer = 0;
+static unsigned int arp_producer = 0;
+static arp_entry_t arp_table[ARP_ENTRIES];
+static arp_entry_t pending_pkt;
+
+/* Function pointer send_ip. Points either to send_ipv4() or send_ipv6() */
+int (*send_ip) (int fd, void *, int);
+
+/*>>>>>>>>>>>>>>>>>>>>>>>>>>>> IMPLEMENTATION <<<<<<<<<<<<<<<<<<<<<<<<<<<*/
+
+/**
+ * IPv4: Initialize the environment for the IPv4 layer.
+ */
+static void
+ipv4_init(void)
+{
+ int i;
+
+ ping_dst_ip = 0;
+
+ // clear ARP table
+ arp_consumer = 0;
+ arp_producer = 0;
+ for(i=0; i<ARP_ENTRIES; ++i) {
+ arp_table[i].ipv4_addr = 0;
+ memset(arp_table[i].mac_addr, 0, 6);
+ arp_table[i].eth_len = 0;
+ arp_table[i].pkt_pending = 0;
+ }
+
+ /* Set IP send function to send_ipv4() */
+ send_ip = &send_ipv4;
+}
+
+/**
+ * IPv4: Set the own IPv4 address.
+ *
+ * @param _own_ip client IPv4 address (e.g. 127.0.0.1)
+ */
+void
+set_ipv4_address(uint32_t _own_ip)
+{
+ own_ip = _own_ip;
+ ipv4_init();
+}
+
+/**
+ * IPv4: Get the own IPv4 address.
+ *
+ * @return client IPv4 address (e.g. 127.0.0.1)
+ */
+uint32_t
+get_ipv4_address(void)
+{
+ return own_ip;
+}
+
+/**
+ * IPv4: Set the IPv4 multicast address.
+ *
+ * @param _own_ip multicast IPv4 address (224.0.0.0 - 239.255.255.255)
+ */
+void
+set_ipv4_multicast(uint32_t _multicast_ip)
+{
+ // is this IP Multicast out of range (224.0.0.0 - 239.255.255.255)
+ if((htonl(_multicast_ip) < 0xE0000000)
+ || (htonl(_multicast_ip) > 0xEFFFFFFF)) {
+ multicast_ip = 0;
+ memset(multicast_mac, 0xFF, 6);
+ return;
+ }
+
+ multicast_ip = _multicast_ip;
+ multicast_mac[0] = 0x01;
+ multicast_mac[1] = 0x00;
+ multicast_mac[2] = 0x5E;
+ multicast_mac[3] = (uint8_t) 0x7F & (multicast_ip >> 16);
+ multicast_mac[4] = (uint8_t) 0xFF & (multicast_ip >> 8);
+ multicast_mac[5] = (uint8_t) 0xFF & (multicast_ip >> 0);
+}
+
+/**
+ * IPv4: Get the IPv4 multicast address.
+ *
+ * @return multicast IPv4 address (224.0.0.0 - 239.255.255.255 or 0 if not set)
+ */
+uint32_t
+get_ipv4_multicast(void)
+{
+ return multicast_ip;
+}
+
+/**
+ * IPv4: Set the routers IPv4 address.
+ *
+ * @param _router_ip router IPv4 address
+ */
+void
+set_ipv4_router(uint32_t _router_ip)
+{
+ router_ip = _router_ip;
+ ipv4_init();
+}
+
+/**
+ * IPv4: Get the routers IPv4 address.
+ *
+ * @return router IPv4 address
+ */
+uint32_t
+get_ipv4_router(void)
+{
+ return router_ip;
+}
+
+/**
+ * IPv4: Set the subnet mask.
+ *
+ * @param _subnet_mask netmask of the own IPv4 address
+ */
+void
+set_ipv4_netmask(uint32_t _subnet_mask)
+{
+ subnet_mask = _subnet_mask;
+ ipv4_init();
+}
+
+/**
+ * IPv4: Get the subnet mask.
+ *
+ * @return netmask of the own IPv4 address
+ */
+uint32_t
+get_ipv4_netmask(void)
+{
+ return subnet_mask;
+}
+
+/**
+ * IPv4: Creates IP-packet. Places IP-header in a packet and fills it
+ * with corresponding information.
+ * <p>
+ * Use this function with similar functions for other network layers
+ * (fill_ethhdr, fill_udphdr, fill_dnshdr, fill_btphdr).
+ *
+ * @param packet Points to the place where IP-header must be placed.
+ * @param packetsize Size of the packet in bytes incl. this hdr and data.
+ * @param ip_proto Type of the next level protocol (e.g. UDP).
+ * @param ip_src Sender IP address
+ * @param ip_dst Receiver IP address
+ * @see iphdr
+ * @see fill_ethhdr
+ * @see fill_udphdr
+ * @see fill_dnshdr
+ * @see fill_btphdr
+ */
+void
+fill_iphdr(uint8_t * packet, uint16_t packetsize,
+ uint8_t ip_proto, uint32_t ip_src, uint32_t ip_dst) {
+ struct iphdr * iph = (struct iphdr *) packet;
+
+ iph -> ip_hlv = 0x45;
+ iph -> ip_tos = 0x10;
+ iph -> ip_len = htons(packetsize);
+ iph -> ip_id = htons(0);
+ iph -> ip_off = 0;
+ iph -> ip_ttl = 0xFF;
+ iph -> ip_p = ip_proto;
+ iph -> ip_src = htonl(ip_src);
+ iph -> ip_dst = htonl(ip_dst);
+ iph -> ip_sum = 0;
+}
+
+/**
+ * IPv4: Handles IPv4-packets according to Receive-handle diagram.
+ *
+ * @param fd socket fd
+ * @param ip_packet IP-packet to be handled
+ * @param packetsize Length of the packet
+ * @return ZERO - packet handled successfully;
+ * NON ZERO - packet was not handled (e.g. bad format)
+ * @see receive_ether
+ * @see iphdr
+ */
+int8_t
+handle_ipv4(int fd, uint8_t * ip_packet, int32_t packetsize)
+{
+ struct iphdr * iph;
+ int32_t old_sum;
+ static uint8_t ip_heap[65536 + ETH_MTU_SIZE];
+
+ if (packetsize < sizeof(struct iphdr))
+ return -1; // packet is too small
+
+ iph = (struct iphdr * ) ip_packet;
+
+ /* Drop it if destination IPv4 address is no IPv4 Broadcast, no
+ * registered IPv4 Multicast and not our Unicast address
+ */
+ if((multicast_ip == 0 && iph->ip_dst >= 0xE0000000 && iph->ip_dst <= 0xEFFFFFFF)
+ || (multicast_ip != iph->ip_dst && iph->ip_dst != 0xFFFFFFFF &&
+ own_ip != 0 && iph->ip_dst != own_ip)) {
+ return -1;
+ }
+
+ old_sum = iph -> ip_sum;
+ iph -> ip_sum = 0;
+ if (old_sum != checksum((uint16_t *) iph, sizeof (struct iphdr) >> 1))
+ return -1; // Wrong IP checksum
+
+ // is it the first fragment in a packet?
+ if (((iph -> ip_off) & 0x1FFF) == 0) {
+ // is it part of more fragments?
+ if (((iph -> ip_off) & 0x2000) == 0x2000) {
+ memcpy(ip_heap, ip_packet, iph->ip_len);
+ return 0;
+ }
+ }
+ // it's not the first fragment
+ else {
+ // get the first fragment
+ struct iphdr * iph_first = (struct iphdr * ) ip_heap;
+
+ // is this fragment not part of the first one, then exit
+ if ((iph_first->ip_id != iph->ip_id ) ||
+ (iph_first->ip_p != iph->ip_p ) ||
+ (iph_first->ip_src != iph->ip_src) ||
+ (iph_first->ip_dst != iph->ip_dst)) {
+ return 0;
+ }
+
+ // this fragment is part of the first one!
+ memcpy(ip_heap + sizeof(struct iphdr) +
+ ((iph -> ip_off) & 0x1FFF) * 8,
+ ip_packet + sizeof(struct iphdr),
+ iph -> ip_len - sizeof(struct iphdr));
+
+ // is it part of more fragments? Then return.
+ if (((iph -> ip_off) & 0x2000) == 0x2000) {
+ return 0;
+ }
+
+ // packet is completly reassambled now!
+
+ // recalculate ip_len and set iph and ip_packet to the
+ iph_first->ip_len = iph->ip_len + ((iph->ip_off) & 0x1FFF) * 8;
+
+ // set iph and ip_packet to the resulting packet.
+ ip_packet = ip_heap;
+ iph = (struct iphdr * ) ip_packet;
+ }
+
+ switch (iph -> ip_p) {
+ case IPTYPE_ICMP:
+ return handle_icmp(fd, iph, ip_packet + sizeof(struct iphdr),
+ iph -> ip_len - sizeof(struct iphdr));
+ case IPTYPE_UDP:
+ return handle_udp(fd, ip_packet + sizeof(struct iphdr),
+ iph -> ip_len - sizeof(struct iphdr));
+ case IPTYPE_TCP:
+ return handle_tcp(ip_packet + sizeof(struct iphdr),
+ iph -> ip_len - sizeof(struct iphdr));
+ default:
+ break;
+ }
+ return -1; // Unknown protocol
+}
+
+/**
+ * IPv4: Send IPv4-packets.
+ *
+ * Before the packet is sent there are some patcches performed:
+ * - IPv4 source address is replaced by our unicast IPV4 address
+ * if it is set to 0 or 1
+ * - IPv4 destination address is replaced by our multicast IPV4 address
+ * if it is set to 1
+ * - IPv4 checksum is calculaded.
+ * - If payload type is UDP, then the UDP checksum is calculated also.
+ *
+ * We send an ARP request first, if this is the first packet sent to
+ * the declared IPv4 destination address. In this case we store the
+ * the packet and send it later if we receive the ARP response.
+ * If the MAC address is known already, then we send the packet immediately.
+ * If there is already an ARP request pending, then we drop this packet
+ * and send again an ARP request.
+ *
+ * @param fd socket fd
+ * @param ip_packet IP-packet to be handled
+ * @param packetsize Length of the packet
+ * @return -2 - packet dropped (MAC address not resolved - ARP request pending)
+ * -1 - packet dropped (bad format)
+ * 0 - packet stored (ARP request sent - packet will be sent if
+ * ARP response is received)
+ * >0 - packet send (number of transmitted bytes is returned)
+ *
+ * @see receive_ether
+ * @see iphdr
+ */
+int
+send_ipv4(int fd, void* buffer, int len)
+{
+ arp_entry_t *arp_entry = 0;
+ struct iphdr *ip;
+ const uint8_t *mac_addr = 0;
+ uint32_t ip_dst = 0;
+
+ if(len + sizeof(struct ethhdr) > ETH_MTU_SIZE)
+ return -1;
+
+ ip = (struct iphdr *) buffer;
+
+ /* Replace source IPv4 address with our own unicast IPv4 address
+ * if it's 0 (= own unicast source address not specified).
+ */
+ if(ip->ip_src == 0) {
+ ip->ip_src = htonl( own_ip );
+ }
+ /* Replace source IPv4 address with our unicast IPv4 address and
+ * replace destination IPv4 address with our multicast IPv4 address
+ * if source address is set to 1.
+ */
+ else if(ip->ip_src == 1) {
+ ip->ip_src = htonl( own_ip );
+ ip->ip_dst = htonl( multicast_ip );
+ }
+
+ // Calculate the IPv4 checksum
+ ip->ip_sum = 0;
+ ip->ip_sum = checksum((uint16_t *) ip, sizeof (struct iphdr) >> 1);
+
+ // if payload type is UDP, then we need to calculate the
+ // UDP checksum that depends on the IP header
+ if(ip->ip_p == IPTYPE_UDP) {
+ fill_udp_checksum(ip);
+ }
+
+ ip_dst = ip->ip_dst;
+ // Check if the MAC address is already cached
+ if(~ip->ip_dst == 0
+ || ( ((~subnet_mask) & ip->ip_dst) == ~subnet_mask &&
+ ( subnet_mask & ip->ip_dst) == (subnet_mask & own_ip))) {
+ arp_entry = &arp_table[arp_producer];
+ mac_addr = broadcast_mac;
+ }
+ else if(ip->ip_dst == multicast_ip) {
+ arp_entry = &arp_table[arp_producer];
+ mac_addr = multicast_mac;
+ }
+ else {
+ // Check if IP address is in the same subnet as we are
+ if((subnet_mask & own_ip) == (subnet_mask & ip->ip_dst))
+ arp_entry = lookup_mac_addr(ip->ip_dst);
+ // if not then we need to know the router's IP address
+ else {
+ ip_dst = router_ip;
+ arp_entry = lookup_mac_addr(router_ip);
+ }
+ if(arp_entry && memcmp(arp_entry->mac_addr, null_mac_addr, 6) != 0)
+ mac_addr = arp_entry->mac_addr;
+ }
+
+ // If we could not resolv the MAC address by our own...
+ if(!mac_addr) {
+ // send the ARP request
+ arp_send_request(fd, ip_dst);
+
+ // drop the current packet if there is already a ARP request pending
+ if(arp_entry)
+ return -2;
+
+ // take the next entry in the ARP table to prepare a the new ARP entry.
+ arp_entry = &arp_table[arp_producer];
+ arp_producer = (arp_producer+1)%ARP_ENTRIES;
+
+ // if ARP table is full then we must drop the oldes entry.
+ if(arp_consumer == arp_producer)
+ arp_consumer = (arp_consumer+1)%ARP_ENTRIES;
+
+ // store the packet to be send if the ARP reply is received
+ arp_entry->pkt_pending = 1;
+ arp_entry->ipv4_addr = ip_dst;
+ memset(arp_entry->mac_addr, 0, 6);
+ pending_pkt.ipv4_addr = ip_dst;
+ memset(pending_pkt.mac_addr, 0, 6);
+ fill_ethhdr (pending_pkt.eth_frame, htons(ETHERTYPE_IP),
+ get_mac_address(), null_mac_addr);
+ memcpy(&pending_pkt.eth_frame[sizeof(struct ethhdr)],
+ buffer, len);
+ pending_pkt.eth_len = len + sizeof(struct ethhdr);
+
+ set_timer(TICKS_SEC);
+ do {
+ receive_ether(fd);
+ if (!arp_entry->eth_len)
+ break;
+ } while (get_timer() > 0);
+
+ return 0;
+ }
+
+ // Send the packet with the known MAC address
+ fill_ethhdr(arp_entry->eth_frame, htons(ETHERTYPE_IP),
+ get_mac_address(), mac_addr);
+ memcpy(&arp_entry->eth_frame[sizeof(struct ethhdr)], buffer, len);
+ return send_ether(fd, arp_entry->eth_frame, len + sizeof(struct ethhdr));
+}
+
+/**
+ * IPv4: Calculate UDP checksum. Places the result into the UDP-header.
+ * <p>
+ * Use this function after filling the UDP payload.
+ *
+ * @param ipv4_hdr Points to the place where IPv4-header starts.
+ */
+
+static void
+fill_udp_checksum(struct iphdr *ipv4_hdr)
+{
+ int i;
+ unsigned long checksum = 0;
+ struct iphdr ip_hdr;
+ char *ptr;
+ udp_hdr_t *udp_hdr;
+
+ udp_hdr = (udp_hdr_t *) (ipv4_hdr + 1);
+ udp_hdr->uh_sum = 0;
+
+ memset(&ip_hdr, 0, sizeof(struct iphdr));
+ ip_hdr.ip_src = ipv4_hdr->ip_src;
+ ip_hdr.ip_dst = ipv4_hdr->ip_dst;
+ ip_hdr.ip_len = udp_hdr->uh_ulen;
+ ip_hdr.ip_p = ipv4_hdr->ip_p;
+
+ ptr = (char*) udp_hdr;
+ for (i = 0; i < udp_hdr->uh_ulen; i+=2)
+ checksum += *((uint16_t*) &ptr[i]);
+
+ ptr = (char*) &ip_hdr;
+ for (i = 0; i < sizeof(struct iphdr); i+=2)
+ checksum += *((uint16_t*) &ptr[i]);
+
+ checksum = (checksum >> 16) + (checksum & 0xffff);
+ checksum += (checksum >> 16);
+ udp_hdr->uh_sum = ~checksum;
+
+ /* As per RFC 768, if the computed checksum is zero,
+ * it is transmitted as all ones (the equivalent in
+ * one's complement arithmetic).
+ */
+ if (udp_hdr->uh_sum == 0)
+ udp_hdr->uh_sum = ~udp_hdr->uh_sum;
+}
+
+/**
+ * IPv4: Calculates checksum for IP header.
+ *
+ * @param packet Points to the IP-header
+ * @param words Size of the packet in words incl. IP-header and data.
+ * @return Checksum
+ * @see iphdr
+ */
+static unsigned short
+checksum(unsigned short * packet, int words)
+{
+ unsigned long checksum;
+
+ for (checksum = 0; words > 0; words--)
+ checksum += *packet++;
+ checksum = (checksum >> 16) + (checksum & 0xffff);
+ checksum += (checksum >> 16);
+
+ return ~checksum;
+}
+
+static arp_entry_t*
+lookup_mac_addr(uint32_t ipv4_addr)
+{
+ unsigned int i;
+
+ for(i=arp_consumer; i != arp_producer; i = ((i+1)%ARP_ENTRIES) ) {
+ if(arp_table[i].ipv4_addr == ipv4_addr)
+ return &arp_table[i];
+ }
+ return 0;
+}
+
+
+/**
+ * ARP: Sends an ARP-request package.
+ * For given IPv4 retrieves MAC via ARP (makes several attempts)
+ *
+ * @param fd socket fd
+ * @param dest_ip IP of the host which MAC should be obtained
+ */
+static void
+arp_send_request(int fd, uint32_t dest_ip)
+{
+ arp_entry_t *arp_entry = &arp_table[arp_producer];
+
+ memset(arp_entry->eth_frame, 0, sizeof(struct ethhdr) + sizeof(struct arphdr));
+ fill_arphdr(&arp_entry->eth_frame[sizeof(struct ethhdr)], ARP_REQUEST,
+ get_mac_address(), own_ip, broadcast_mac, dest_ip);
+ fill_ethhdr(arp_entry->eth_frame, ETHERTYPE_ARP,
+ get_mac_address(), broadcast_mac);
+
+ send_ether(fd, arp_entry->eth_frame,
+ sizeof(struct ethhdr) + sizeof(struct arphdr));
+}
+
+/**
+ * ARP: Sends an ARP-reply package.
+ * This package is used to serve foreign requests (in case IP in
+ * foreign request matches our host IP).
+ *
+ * @param fd socket fd
+ * @param src_ip requester IP address (foreign IP)
+ * @param src_mac requester MAC address (foreign MAC)
+ */
+static void
+arp_send_reply(int fd, uint32_t src_ip, uint8_t * src_mac)
+{
+ arp_entry_t *arp_entry = &arp_table[arp_producer];
+
+ memset(arp_entry->eth_frame, 0, sizeof(struct ethhdr) + sizeof(struct arphdr));
+ fill_ethhdr(arp_entry->eth_frame, ETHERTYPE_ARP,
+ get_mac_address(), src_mac);
+ fill_arphdr(&arp_entry->eth_frame[sizeof(struct ethhdr)], ARP_REPLY,
+ get_mac_address(), own_ip, src_mac, src_ip);
+
+ send_ether(fd, arp_entry->eth_frame,
+ sizeof(struct ethhdr) + sizeof(struct arphdr));
+}
+
+/**
+ * ARP: Creates ARP package. Places ARP-header in a packet and fills it
+ * with corresponding information.
+ * <p>
+ * Use this function with similar functions for other network layers
+ * (fill_ethhdr).
+ *
+ * @param packet Points to the place where ARP-header must be placed.
+ * @param opcode Identifies is it request (ARP_REQUEST)
+ * or reply (ARP_REPLY) package.
+ * @param src_mac sender MAC address
+ * @param src_ip sender IP address
+ * @param dest_mac receiver MAC address
+ * @param dest_ip receiver IP address
+ * @see arphdr
+ * @see fill_ethhdr
+ */
+static void
+fill_arphdr(uint8_t * packet, uint8_t opcode,
+ const uint8_t * src_mac, uint32_t src_ip,
+ const uint8_t * dest_mac, uint32_t dest_ip)
+{
+ struct arphdr * arph = (struct arphdr *) packet;
+
+ arph -> hw_type = htons(1);
+ arph -> proto_type = htons(ETHERTYPE_IP);
+ arph -> hw_len = 6;
+ arph -> proto_len = 4;
+ arph -> opcode = htons(opcode);
+
+ memcpy(arph->src_mac, src_mac, 6);
+ arph->src_ip = htonl(src_ip);
+ memcpy(arph->dest_mac, dest_mac, 6);
+ arph->dest_ip = htonl(dest_ip);
+}
+
+/**
+ * ARP: Handles ARP-messages according to Receive-handle diagram.
+ * Updates arp_table for outstanding ARP requests (see arp_getmac).
+ *
+ * @param fd socket fd
+ * @param packet ARP-packet to be handled
+ * @param packetsize length of the packet
+ * @return ZERO - packet handled successfully;
+ * NON ZERO - packet was not handled (e.g. bad format)
+ * @see arp_getmac
+ * @see receive_ether
+ * @see arphdr
+ */
+int8_t
+handle_arp(int fd, uint8_t * packet, int32_t packetsize)
+{
+ struct arphdr * arph = (struct arphdr *) packet;
+
+ if (packetsize < sizeof(struct arphdr))
+ return -1; // Packet is too small
+
+ if (arph -> hw_type != htons(1) || arph -> proto_type != htons(ETHERTYPE_IP))
+ return -1; // Unknown hardware or unsupported protocol
+
+ if (arph -> dest_ip != htonl(own_ip))
+ return -1; // receiver IP doesn't match our IP
+
+ switch(htons(arph -> opcode)) {
+ case ARP_REQUEST:
+ // foreign request
+ if(own_ip != 0)
+ arp_send_reply(fd, htonl(arph->src_ip), arph -> src_mac);
+ return 0; // no error
+ case ARP_REPLY: {
+ unsigned int i;
+ // if it is not for us -> return immediately
+ if(memcmp(get_mac_address(), arph->dest_mac, 6)) {
+ return 0; // no error
+ }
+
+ if(arph->src_ip == 0) {
+ // we are not interested for a MAC address if
+ // the IPv4 address is 0.0.0.0 or ff.ff.ff.ff
+ return -1;
+ }
+
+ // now let's find the corresponding entry in the ARP table
+
+ for(i=arp_consumer; i != arp_producer; i = ((i+1)%ARP_ENTRIES) ) {
+ if(arp_table[i].ipv4_addr == arph->src_ip)
+ break;
+ }
+ if(i == arp_producer || memcmp(arp_table[i].mac_addr, null_mac_addr, 6) != 0) {
+ // we have not asked to resolve this IPv4 address !
+ return -1;
+ }
+
+ memcpy(arp_table[i].mac_addr, arph->src_mac, 6);
+
+ // do we have something to send
+ if (arp_table[i].pkt_pending) {
+ struct ethhdr * ethh = (struct ethhdr *) pending_pkt.eth_frame;
+ memcpy(ethh -> dest_mac, arp_table[i].mac_addr, 6);
+
+ send_ether(fd, pending_pkt.eth_frame, pending_pkt.eth_len);
+ pending_pkt.pkt_pending = 0;
+ arp_table[i].eth_len = 0;
+ }
+ return 0; // no error
+ }
+ default:
+ break;
+ }
+ return -1; // Invalid message type
+}
+
+/**
+ * ICMP: Send an ICMP Echo request to destination IPv4 address.
+ * This function does also set a global variable to the
+ * destination IPv4 address. If there is an ICMP Echo Reply
+ * received later then the variable is set back to 0.
+ * In other words, reading a value of 0 form this variable
+ * means that an answer to the request has been arrived.
+ *
+ * @param fd socket descriptor
+ * @param _ping_dst_ip destination IPv4 address
+ */
+void
+ping_ipv4(int fd, uint32_t _ping_dst_ip)
+{
+ unsigned char packet[sizeof(struct iphdr) + sizeof(struct icmphdr)];
+ struct icmphdr *icmp;
+
+ ping_dst_ip = _ping_dst_ip;
+
+ if(ping_dst_ip == 0)
+ return;
+
+ fill_iphdr(packet, sizeof(struct iphdr) + sizeof(struct icmphdr), IPTYPE_ICMP,
+ 0, ping_dst_ip);
+ icmp = (struct icmphdr *) (packet + sizeof(struct iphdr));
+ icmp->type = ICMP_ECHO_REQUEST;
+ icmp->code = 0;
+ icmp->checksum = 0;
+ icmp->options.echo.id = 0xd476;
+ icmp->options.echo.seq = 1;
+
+ memset(icmp->payload.data, '*', sizeof(icmp->payload.data));
+
+ icmp->checksum =
+ checksum((unsigned short *) icmp, sizeof(struct icmphdr) >> 1);
+ send_ipv4(fd, packet, sizeof(struct iphdr) + sizeof(struct icmphdr));
+}
+
+/**
+ * ICMP: Return host IPv4 address that we are waiting for a
+ * ICMP Echo reply message. If this value is 0 then we have
+ * received an reply.
+ *
+ * @return ping_dst_ip host IPv4 address
+ */
+uint32_t
+pong_ipv4(void)
+{
+ return ping_dst_ip;
+}
+
+/**
+ * ICMP: Handles ICMP-packets according to Receive-handle diagram.
+ *
+ * @param fd socket fd
+ * @param icmp_packet ICMP-packet to be handled
+ * @param packetsize Length of the packet
+ * @return ZERO - packet handled successfully;
+ * NON ZERO - packet was not handled (e.g. bad format)
+ * @see handle_ipv4
+ */
+static int8_t
+handle_icmp(int fd, struct iphdr * iph, uint8_t * packet, int32_t packetsize)
+{
+ struct icmphdr *icmp = (struct icmphdr *) packet;
+
+ switch(icmp->type) {
+ case ICMP_ECHO_REPLY:
+ if (icmp->options.echo.id != 0xd476)
+ return -1;
+ if (icmp->options.echo.seq != 1)
+ return -1;
+ if(ping_dst_ip != iph->ip_src
+ || ping_dst_ip == 0)
+ return -1;
+ ping_dst_ip = 0;
+ break;
+ case ICMP_DST_UNREACHABLE: {
+ // We've got Destination Unreachable msg
+ // Inform corresponding upper network layers
+ struct iphdr * bad_iph = (struct iphdr * ) &icmp->payload;
+
+ switch(bad_iph->ip_p) {
+ case IPTYPE_TCP:
+ handle_tcp_dun((uint8_t *) (bad_iph + 1), packetsize
+ - sizeof(struct icmphdr)
+ - sizeof(struct iphdr), icmp->code);
+ break;
+ case IPTYPE_UDP:
+ handle_udp_dun((uint8_t *) (bad_iph + 1), packetsize
+ - sizeof(struct icmphdr)
+ - sizeof(struct iphdr), icmp->code);
+ break;
+ }
+ break;
+ }
+ case ICMP_SRC_QUENCH:
+ break;
+ case ICMP_REDIRECT:
+ break;
+ case ICMP_ECHO_REQUEST: {
+ // We've got an Echo Request - answer with Echo Replay msg
+ unsigned char reply_packet[sizeof(struct iphdr) + packetsize];
+ struct icmphdr *reply_icmph;
+
+ fill_iphdr(reply_packet, sizeof(struct iphdr) + packetsize,
+ IPTYPE_ICMP, 0, iph->ip_src);
+
+ reply_icmph = (struct icmphdr *) &reply_packet[sizeof(struct iphdr)];
+ memcpy(reply_icmph, packet, packetsize);
+ reply_icmph -> type = ICMP_ECHO_REPLY;
+ reply_icmph -> checksum = 0;
+ reply_icmph->checksum = checksum((unsigned short *) reply_icmph,
+ sizeof(struct icmphdr) >> 1);
+
+ send_ipv4(fd, reply_packet, sizeof(struct iphdr) + packetsize);
+ break;
+ }
+ case ICMP_TIME_EXCEEDED:
+ break;
+ case ICMP_PARAMETER_PROBLEM:
+ break;
+ case ICMP_TIMESTAMP_REQUEST:
+ break;
+ case ICMP_TIMESTAMP_REPLY:
+ break;
+ case ICMP_INFORMATION_REQUEST:
+ break;
+ case ICMP_INFORMATION_REPLY:
+ break;
+ }
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff