diff options
Diffstat (limited to 'extras/libmemif/examples/icmp_responder/icmp_proto.c')
| -rw-r--r-- | extras/libmemif/examples/icmp_responder/icmp_proto.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/extras/libmemif/examples/icmp_responder/icmp_proto.c b/extras/libmemif/examples/icmp_responder/icmp_proto.c new file mode 100644 index 00000000..a923f209 --- /dev/null +++ b/extras/libmemif/examples/icmp_responder/icmp_proto.c @@ -0,0 +1,246 @@ +/* + *------------------------------------------------------------------ + * Copyright (c) 2017 Cisco and/or its affiliates. + * Licensed under the Apache License, Version 2.0 (the "License"); + * you may not use this file except in compliance with the License. + * You may obtain a copy of the License at: + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + *------------------------------------------------------------------ + */ + +#include <stdint.h> +#include <net/if.h> +#include <sys/types.h> +#include <fcntl.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <sys/un.h> +#include <sys/uio.h> +#include <sys/mman.h> +#include <sys/prctl.h> +#include <inttypes.h> +#include <string.h> +#include <stdio.h> +#include <netdb.h> +#include <linux/ip.h> +#include <linux/icmp.h> +#include <arpa/inet.h> +#include <stdlib.h> +#include <netinet/if_ether.h> +#include <net/if_arp.h> +#include <asm/byteorder.h> +#include <byteswap.h> + +#include <icmp_proto.h> + +static uint16_t +cksum (void *addr, ssize_t len) +{ + char *data = (char *) addr; + + uint32_t acc = 0xffff; + + ssize_t i; + for (i = 0; (i + 1) < len; i += 2) + { + uint16_t word; + memcpy (&word, data + i, 2); + acc += ntohs (word); + if (acc > 0xffff) + acc -= 0xffff; + } + + if (len & 1) + { + uint16_t word = 0; + memcpy (&word, data + len - 1, 1); + acc += ntohs (word); + if (acc > 0xffff) + acc -= 0xffff; + } + return htons (~acc); +} + +int +print_packet (void *pck) +{ + if (pck == NULL) + { + printf ("ICMP_PROTO: no data\n"); + return -1; + } + struct iphdr *ip; + struct icmphdr *icmp; + ip = (struct iphdr *) pck; + icmp = (struct icmphdr *) (pck + sizeof (struct iphdr)); + printf ("received packet:\n"); + printf ("\tiphdr:\n"); + printf ("\t\tihl: %u\n\t\tversion: %u\n\t\tlen: %u\n\t\tid: %u\n", + ip->ihl, ip->version, __bswap_16 (ip->tot_len), ip->id); + printf ("\t\tprotocol: %u\n", ip->protocol); + + printf ("\t\tsaddr: "); + int i; + for (i = 0; i < 4; i++) + { + printf ("%u.", ((uint8_t *) & ip->saddr)[i]); + } + printf ("\n"); + + printf ("\t\tdaddr: "); + for (i = 0; i < 4; i++) + { + printf ("%u.", ((uint8_t *) & ip->daddr)[i]); + } + printf ("\n"); + printf ("\ticmphdr:\n"); + printf ("\t\ttype: %s\n", + (icmp->type == ICMP_ECHO) ? "ICMP_ECHO" : "ICMP_ECHOREPLY"); + + return 0; +} + +static ssize_t +resolve_arp (void *arp) +{ + struct arphdr *resp = (struct arphdr *) arp; + + resp->ar_hrd = __bswap_16 (ARPHRD_ETHER); + + resp->ar_pro = __bswap_16 (0x0800); + + resp->ar_hln = 6; + resp->ar_pln = 4; + + resp->ar_op = __bswap_16 (ARPOP_REPLY); + + return sizeof (struct arphdr); +} + +static ssize_t +resolve_eth_arp (struct ether_arp *eth_arp, void *eth_arp_resp, + uint8_t ip_addr[4]) +{ + struct ether_arp *resp = (struct ether_arp *) eth_arp_resp; + + resolve_arp (&resp->ea_hdr); + + memcpy (resp->arp_tha, eth_arp->arp_sha, 6); + memcpy (resp->arp_tpa, eth_arp->arp_spa, 4); + + memcpy (resp->arp_sha, + (((struct ether_header *) (eth_arp_resp - + sizeof (struct ether_header)))-> + ether_shost), 6); + + memcpy (resp->arp_spa, ip_addr, 4); + + return sizeof (struct ether_arp); +} + +static ssize_t +resolve_eth (struct ether_header *eth, void *eth_resp) +{ + struct ether_header *resp = (struct ether_header *) eth_resp; + memcpy (resp->ether_dhost, eth->ether_shost, 6); + + uint8_t hw_addr[6]; + int i; + for (i = 0; i < 6; i++) + { + hw_addr[i] = 'a'; + } + memcpy (resp->ether_shost, hw_addr, 6); + + resp->ether_type = eth->ether_type; + + return sizeof (struct ether_header); +} + +static ssize_t +resolve_ip (struct iphdr *ip, void *ip_resp, uint8_t ip_addr[4]) +{ + struct iphdr *resp = (struct iphdr *) ip_resp; + resp->ihl = 5; + resp->version = 4; + resp->tos = 0; + /*len updated later */ + resp->tot_len = 0x5400; + resp->id = 0; + resp->frag_off = 0; + resp->ttl = 0x40; + resp->protocol = 1; + ((uint8_t *) & resp->saddr)[0] = ip_addr[0]; + ((uint8_t *) & resp->saddr)[1] = ip_addr[1]; + ((uint8_t *) & resp->saddr)[2] = ip_addr[2]; + ((uint8_t *) & resp->saddr)[3] = ip_addr[3]; + resp->daddr = ip->saddr; + + resp->check = cksum (resp, sizeof (struct iphdr)); + + return sizeof (struct iphdr); +} + +static ssize_t +resolve_icmp (struct icmphdr *icmp, void *icmp_resp) +{ + struct icmphdr *resp = (struct icmphdr *) icmp_resp; + resp->type = ICMP_ECHOREPLY; + resp->code = 0; + resp->un.echo.id = icmp->un.echo.id; + resp->un.echo.sequence = icmp->un.echo.sequence; + + /*resp->checksum = cksum (resp, sizeof (struct icmphdr)); */ + + return sizeof (struct icmphdr); +} + +int +resolve_packet (void *in_pck, ssize_t in_size, + void *out_pck, uint32_t * out_size, uint8_t ip_addr[4]) +{ + struct ether_header *eh; + struct ether_arp *eah; + struct iphdr *ip; + struct icmphdr *icmp; + *out_size = 0; + + eh = (struct ether_header *) in_pck; + *out_size = resolve_eth (eh, out_pck); + + if (eh->ether_type == 0x0608) + { + eah = (struct ether_arp *) (in_pck + *out_size); + *out_size += resolve_eth_arp (eah, out_pck + *out_size, ip_addr); + + } + else if (eh->ether_type == 0x0008) + { +#ifdef ICMP_DBG + print_packet (in_pck + *out_size); +#endif + ip = (struct iphdr *) (in_pck + *out_size); + *out_size += resolve_ip (ip, out_pck + *out_size, ip_addr); + if (ip->protocol == 1) + { + icmp = (struct icmphdr *) (in_pck + *out_size); + *out_size += resolve_icmp (icmp, out_pck + *out_size); + ((struct icmphdr *) (out_pck + *out_size - + sizeof (struct icmphdr)))->checksum = + cksum (out_pck + *out_size - sizeof (struct icmphdr), + sizeof (struct icmphdr)); + /* payload */ + memcpy (out_pck + *out_size, in_pck + *out_size, + in_size - *out_size); + *out_size = in_size; + } + } + return 0; +} |