i86/elks/elksnet/ktcp/ip.c

   1 /*
   2  * This file is part of the ELKS TCP/IP stack
   3  *
   4  * (C) 2001 Harry Kalogirou (harkal@rainbow.cs.unipi.gr)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 /*
  13  * TODO : IP fragmentation and reassemply of fragmented IP packets
  14  */
  15
  16 #include <sys/types.h>
  17 #include <sys/stat.h>
  18 #include <fcntl.h>
  19
  20 #include "ip.h"
  21 #include "icmp.h"
  22 #include "tcp.h"
  23 #include "mylib.h"
  24
  25 #if 0
  26 #define IP_VERSION(s)   ((s)->version_ihl>>4&0xf)
  27 #define IP_IHL(s)       ((s)->version_ihl&0xf)
  28 #define IP_FLAGS(s)     ((s)->frag_off>>13)
  29 #endif
  30
  31 /*#define DEBUG*/
  32 #define USE_ASM
  33
  34 static char ipbuf[1024];
  35
  36 int ip_init(void)
  37 {
  38     return 0;
  39 }
  40
  41 #ifndef USE_ASM
  42 __u16 ip_calc_chksum(char *data, int len)
  43 {
  44     __u32 sum = 0;
  45     int i;
  46     __u16 *p = (__u16 *) data;
  47
  48     len >>= 1;
  49
  50     for (i=0; i < len ; i++){
  51         sum += *p++;
  52     }
  53
  54     return ~((sum & 0xffff) + ((sum >> 16) & 0xffff));
  55 }
  56 #else
  57 #asm
  58 /*__u16 ip_calc_chksum(char *data, int len)*/
  59         .text
  60         .globl _ip_calc_chksum
  61 _ip_calc_chksum:
  62
  63         push    bp
  64         mov     bp,sp
  65         push    di
  66
  67         mov     cx, 6[bp]
  68         shr     cx, 1
  69         shr     cx, 1
  70         mov     di, 4[bp]
  71         xor     ax, ax
  72 loop1:
  73         adc     ax, [di]
  74         inc di
  75         inc di
  76         adc     ax, [di]
  77         inc di
  78         inc di
  79
  80         loop    loop1
  81
  82         adc     ax, 0
  83         not     ax
  84
  85         pop di
  86         pop bp
  87
  88         ret
  89 #endasm
  90
  91
  92 #endif
  93
  94 void ip_print(struct iphdr_s *head)
  95 {
  96 #ifdef DEBUG
  97     int i;
  98     __u8 *addr;
  99
 100     printf("Version/IHL :  %d/%d\n",IP_VERSION(head),IP_IHL(head));
 101     printf("TypeOfService/Length :  %d/%d\n",head->tos,ntohs(head->tot_len));
 102     printf("Id/flags/fragment offset :  %d/%d\n",head->id,head->frag_off);
 103     printf("ttl : %d\n",head->ttl);
 104     printf("Protocol : %d\n",head->protocol);
 105
 106     addr = (__u8 *)&head->saddr;
 107     printf("saddr : %d.%d.%d.%d \n",addr[0],addr[1],addr[2],addr[3]);
 108     addr = (__u8 *)&head->daddr;
 109     printf("daddr : %d.%d.%d.%d \n",addr[0],addr[1],addr[2],addr[3]);
 110
 111     printf("check sum = %d\n",ip_calc_chksum(head, 4 * IP_IHL(head)));
 112
 113     addr = (__u8 *)head + 4 * IP_IHL(head);
 114     for( i = 0 ; i < ntohs(head->tot_len) - 20 ; i++ )
 115         printf("%x ",addr[i]);
 116
 117     printf("\n");
 118 #endif
 119 }
 120
 121 void ip_recvpacket(char *packet,int size)
 122 {
 123     struct iphdr_s *iphdr;
 124     __u8 *addr, *data;
 125
 126     iphdr = (struct iphdr_s *)packet;
 127
 128     /*printf("IP: Got packet of size : %d \n",size,*packet);
 129     ip_print(iphdr);*/
 130
 131     if(IP_VERSION(iphdr) != 4){
 132 #ifdef DEBUG
 133         printf("IP : Bad IP version\n");
 134 #endif
 135         return;
 136     }
 137
 138     if(IP_IHL(iphdr) < 5){
 139 #ifdef DEBUG
 140         printf("IP : Bad IHL\n");
 141 #endif
 142         return;
 143     }
 144
 145     data = packet + 4 * IP_IHL(iphdr);
 146
 147     switch (iphdr->protocol) {
 148     case PROTO_ICMP:
 149 #ifdef DEBUG
 150                 printf("IP : ICMP packet\n");
 151 #endif
 152
 153                 icmp_process(iphdr, data);
 154                 break;
 155
 156     case PROTO_TCP:
 157 #ifdef DEBUG
 158                 printf("IP : TCP packet\n");
 159 #endif
 160                 tcp_process(iphdr);
 161                 break;
 162
 163     default:
 164         break;
 165
 166     }
 167 }
 168
 169 void ip_sendpacket(char *packet,int len,struct addr_pair *apair)
 170 {
 171     struct iphdr_s *iph = (struct iphdr_s *)&ipbuf;
 172     __u16 tlen;
 173
 174     iph->version_ihl    = 0x45;
 175
 176     tlen = 4 * IP_IHL(iph);
 177
 178     iph->tos            = 0;
 179     iph->tot_len        = htons(tlen + len);
 180     iph->id             = 0;
 181     iph->frag_off       = 0;
 182     iph->ttl            = 64;
 183     iph->protocol       = apair->protocol;
 184     iph->daddr          = apair->daddr;
 185     iph->saddr          = apair->saddr;
 186
 187     iph->check          = 0;
 188     iph->check          = ip_calc_chksum((char *)iph, tlen);
 189
 190     memcpy(&ipbuf[tlen], packet, len);
 191
 192     /* "route" */
 193     if(iph->daddr == local_ip && iph->daddr == 0x0100007f) {
 194         /* 127.0.0.1 */
 195         /* TODO */
 196     } else
 197         slip_send(&ipbuf, tlen + len);
 198 }