src/net/icmp.cpp

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/*
 panaLiX, Adrian Panasiuk 2002-5,8
 http://panalix.sf.net/
 ad.ek336@gmail.com
 
 small osdev project
 provided under GPLv3 license.
 */

#include "src/common/shared.hpp"
#include "src/memory/memset.hpp"
#include "src/memory/align.hpp"
#include "src/memory/heap.hpp"
#include "src/net/icmp.hpp"
#include "src/net/arp.hpp"
#include "src/net/ip.hpp"

#define INTERVAL_BETWEEN_ICMP_ERRORS 200
#define DEBUG_ICMP_CHECKSUM_ALERT 0

namespace Net {
   namespace ICMP {

      volatile uint64 next_icmp_error=0;

      void processDatagram(struct Net::netbuf *nb) {
         struct Net::IP::ip_header *iph = reinterpret_cast<struct Net::IP::ip_header*>(&nb->data[14]);
         struct icmp_header *icmph = reinterpret_cast<struct icmp_header*>(&nb->data[14+sizeof(uint32)*iph->hdr_len]);
         uint32 icmp_data_len = ntohs(iph->len) - iph->hdr_len*sizeof(uint32);
         if (count_checksum16_icmph(icmph, icmp_data_len/*ntohs(iph->len) - iph->hdr_len*sizeof(uint32)*/) != icmph->checksum) {
         #if DEBUG_ICMP_CHECKSUM_ALERT
            println(*icmph);
            println(*iph);
            println(*nb);
            for (int i=0;i<ntohs(iph->len)-iph->hdr_len*sizeof(uint32);i++) prin("(", i,")", ((uint8*)icmph)[i], ":");
            println();
            println("icmp packet len: ", icmp_data_len/*ntohs(iph->len) - iph->hdr_len*sizeof(uint32)*/, " checksum should be: ", count_checksum16_icmph(icmph, ntohs(iph->len) - iph->hdr_len*sizeof(uint32)));
            complain("icmp checksum erroneus, packet dropped");
         #endif
         } else {
            switch (icmph->type) {
               case 0x00: //echo reply
                        break;
               case 0x08: //echo request
                        if (Arch::x86::RTC::up_time < next_icmp_error) break;
                           else next_icmp_error = Arch::x86::RTC::up_time+INTERVAL_BETWEEN_ICMP_ERRORS; //tylko raz na jakis czas wyslac odpowiedz
                        struct packet_t *p = pbuf_alloc(icmp_data_len+200); 
                        p->off=180;
                        p->end=p->off + icmp_data_len - sizeof(struct icmp_header);
                        memmove(&p->buf[p->off], icmph->dt, icmp_data_len);
                        icmp_transmit(iph->source_ip, p, 0x00, 0x00, icmph->data  );
                        break;
            }
         }
         //nie trzeba netbuf_free(nb) bo IP to robi
      }

      uint16 count_checksum16_icmph(struct icmp_header *icmph, uint32 len) {
         assert(sizeof(struct icmp_header) == 8);
         uint16 v= icmph->checksum;
         icmph->checksum=0;
         uint16 ret= count_checksum16(reinterpret_cast<uint16*>(icmph), (len));
         icmph->checksum=v;
         return ret;
      }

      void icmp_transmit(struct ip_address ip_addr, struct Net::packet_t *p, uint8 type, uint8 code, uint32 data) {
         testif(p != null);
         testif(p->off >= sizeof(struct icmp_header));
         p->off -= sizeof(struct icmp_header);
         struct icmp_header *icmph = reinterpret_cast<struct icmp_header*>(&p->buf[p->off]);
         icmph->type = type;
         icmph->code = code;
         icmph->data = data;
         icmph->checksum=count_checksum16_icmph(icmph, p->end-p->off);

         Net::IP::ip_transmit(ip_addr, 0, 0x01, p);
      }

   }
}

void print(struct Net::ICMP::icmp_header icmph) {
   prin("(icmp-h: type=", icmph.type, " code=", icmph.code, " checksum=", Net::ntohs(icmph.checksum));
// nie da sie sprawdzic checksumy bez danych pakietu ?
//   uint16 v = Net::ICMP::count_checksum16_icmph(icmph);
//   if (v == icmph.checksum)
//      prin(" (correct)");
//   else
//      prin(" (should be ", v, ")");
   prin(" dt=", icmph.data,")");
}

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