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Diffstat (limited to 'src/roms/SLOF/clients/net-snk/app/netlib/ipv4.c')
| -rw-r--r-- | src/roms/SLOF/clients/net-snk/app/netlib/ipv4.c | 904 |
1 files changed, 904 insertions, 0 deletions
diff --git a/src/roms/SLOF/clients/net-snk/app/netlib/ipv4.c b/src/roms/SLOF/clients/net-snk/app/netlib/ipv4.c new file mode 100644 index 0000000..8185de5 --- /dev/null +++ b/src/roms/SLOF/clients/net-snk/app/netlib/ipv4.c @@ -0,0 +1,904 @@ +/****************************************************************************** + * 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; +} |
