#include <stdio.h>
#include <netdb.h>
#include <stdlib.h>
#include <strings.h>

#include "ip.h"
#include "main.h"
#include "tcp.h"
#include "util.h"
#include "vars.h"

int tcpconns = 0;

static const char *tcp_ports[65536];

static const char *portcache(int port)
{
 if (! tcp_ports[port])
  { struct servent *sp;
    sp = getservbyport(port,"tcp");
    if (sp)
     { char *tmp;
       tmp = malloc(1+strlen(sp->s_name)+1);
       sprintf(tmp,"=%s",sp->s_name);
       tcp_ports[port] = tmp;
     }
    else
     { tcp_ports[port] = "";
     }
  }
 return(tcp_ports[port]);
}

void dump_tcp(void)
{
 unsigned short int th_sport;
 unsigned short int th_dport;
 unsigned long int th_seq;
 unsigned long int th_ack;
 unsigned char th_off;
 unsigned char th_flags;
 unsigned short int th_win;
 unsigned short int th_sum;
 unsigned short int th_urp;
 int tcp_optlen;

 need(20,"minimum TCP header");
 printx(pkt,2);
 th_sport = get16(0);
 printf("th_sport [%d%s]\n",th_sport,portcache(th_sport));
 consume(2);
 printx(pkt,2);
 th_dport = get16(0);
 printf("th_dport [%d%s]\n",th_dport,portcache(th_dport));
 consume(2);
 printx(pkt,4);
 th_seq = get32(0);
 printf("th_seq\n");
 consume(4);
 printx(pkt,4);
 th_ack = get32(0);
 printf("th_ack\n");
 consume(4);
 printx(pkt,1);
 th_off = get8(0) >> 4;
 printf("th_off=%d\n",th_off);
 if (th_off < 5)
  { printf("*** Claimed header size too small\n");
    dumpabort();
  }
 if (get8(0) & 0x0f)
  { printf("*** Reserved bit(s) set\n");
    dumpabort();
  }
 consume(1);
 printx(pkt,1);
 th_flags = get8(0);
 printf("th_flags ");
  { static struct {
	     int bit;
	     const char *name;
	     } flags[] = { { 0x20, "URG" },
			   { 0x10, "ACK" },
			   { 0x08, "PSH" },
			   { 0x04, "RST" },
			   { 0x02, "SYN" },
			   { 0x01, "FIN" } };
    int i;
    char c;
    c = '[';
    for (i=0;i<(sizeof(flags)/sizeof(flags[0]));i++)
     { if (th_flags & flags[i].bit)
	{ printf("%c%s",c,flags[i].name);
	  c = '|';
	}
     }
    if (c == '[') printf("[");
  }
 printf("]\n");
 if (th_flags & 0xc0)
  { printf("*** Reserved bit(s) set\n");
    dumpabort();
  }
 consume(1);
 printx(pkt,2);
 th_win = get16(0);
 printf("th_win [%d]\n",th_win);
 consume(2);
 printx(pkt,2);
 th_sum = get16(0);
 printf("th_sum\n");
 consume(2);
 printx(pkt,2);
 th_urp = get16(0);
 printf("th_urp [%d]\n",th_urp);
 consume(2);
 tcp_optlen = (th_off - 5) * 4;
 need(tcp_optlen,"TCP options");
 while (tcp_optlen > 0)
  { int n;
    switch (get8(0))
     { case 0x00:
	  n = 1;
	  printx(pkt,1);
	  printf("TCP option: end-of-list\n");
	  break;
       case 0x01:
	  n = 1;
	  printx(pkt,1);
	  printf("TCP option: No-op\n");
	  break;
       case 0x02:
	  n = get8(1);
	  if (n > tcp_optlen)
	   { printx(pkt,2);
	     printf("...\n*** MSS option extends past end of options\n");
	     n = tcp_optlen;
	   }
	  else
	   { printx(pkt,n);
	     if (n != 4)
	      { printf("TCP option: MSS (bad length)\n");
	      }
	     else
	      { unsigned short int mss;
		mss = get16(2);
		printf("TCP option: MSS=%d\n",mss);
	      }
	   }
	  break;
       case 0x03:
	  n = get8(1);
	  if (n > tcp_optlen)
	   { printx(pkt,2);
	     printf("...\n*** WS option extends past end of options\n");
	     n = tcp_optlen;
	   }
	  else
	   { printx(pkt,n);
	     if (n != 3)
	      { printf("TCP option: WS (bad length)\n");
	      }
	     else
	      { unsigned char scl;
		scl = get8(2);
		printf("TCP option: WS=%d (factor %d)\n",scl,1<<scl);
	      }
	   }
	  break;
       case 0x04:
	  n = get8(1);
	  if (n > tcp_optlen)
	   { printx(pkt,2);
	     printf("...\n*** SACK-OK option extends past end of options\n");
	     n = tcp_optlen;
	   }
	  else
	   { printx(pkt,n);
	     if (n != 2)
	      { printf("TCP option: SACK-OK (bad length)\n");
	      }
	     else
	      { printf("TCP option: SACK-OK\n");
	      }
	   }
	  break;
       case 0x08:
	  n = get8(1);
	  if (n > tcp_optlen)
	   { printx(pkt,2);
	     printf("...\n*** TS option extends past end of options\n");
	     n = tcp_optlen;
	   }
	  else
	   { printx(pkt,n);
	     if (n != 10)
	      { printf("TCP option: TS (bad length)\n");
	      }
	     else
	      { unsigned long int val;
		unsigned long int ech;
		val = get32(2);
		ech = get32(6);
		printf("TCP option: TS val=%08lx",val);
		if (th_flags & 0x10/*ACK*/) printf(" ech=%08lx",ech);
		printf("\n");
	      }
	   }
	  break;
       default:
	  n = tcp_optlen;
	  need(n,"TCP option flush");
	  printx(pkt,n);
	  printf("Unrecognized TCP option(s)\n");
	  break;
     }
    consume(n);
    tcp_optlen -= n;
  }
 if (tcpconns && (pktleft > 0))
  { int i;
    printf("=TCP= %lu.%lu.%lu.%lu/%d -> %lu.%lu.%lu.%lu/%d %08lx %d:",ip_src>>24,(ip_src>>16)&0xff,(ip_src>>8)&0xff,ip_src&0xff,th_sport,ip_dst>>24,(ip_dst>>16)&0xff,(ip_dst>>8)&0xff,ip_dst&0xff,th_dport,th_seq,pktleft);
    for (i=0;i<pktleft;i++) printf(" %02x",pkt[i]);
    printf("\n");
  }
}