--- tcp.c.orig	Wed Nov 14 11:56:01 2001
+++ tcp.c.new	Wed Nov 14 12:03:52 2001
@@ -43,7 +43,6 @@
  struct arglist ret;
  if(arg_get_type(args, "ip")>=0)
  {
-  struct pseudohdr pseudoheader;
   u_char * pkt;
   struct ip * ip = arg_get_value(args, "ip");
   char * data = arg_get_value(args, "data");
@@ -81,14 +80,15 @@
    tcp->th_dport = htons((unsigned short)atoi(prompt(globals, "th_dport : ")));
    
   if((arg_get_type(args, "th_seq"))>=0)
-   tcp->th_seq  = htonl((u_long)atol(arg_get_value(args, "th_seq")));
+   tcp->th_seq  = htonl(strtoul(arg_get_value(args, "th_seq"), NULL, 0));
   else
-   tcp->th_seq = htonl((u_long)atol(prompt(globals, "th_seq : ")));
+   tcp->th_seq = htonl(strtoul(prompt(globals, "th_seq : "), NULL, 0));
    
   if((arg_get_type(args, "th_ack"))>=0)
-   tcp->th_ack = htonl((u_long)atol(arg_get_value(args, "th_ack")));
-  else
-   tcp->th_ack = htonl((u_long)atol(prompt(globals, "th_ack : ")));
+   tcp->th_ack  = htonl(strtoul(arg_get_value(args, "th_ack"), NULL, 0));
+  else {
+   tcp->th_ack = htonl(strtoul(prompt(globals, "th_ack : "), NULL, 0));
+  }
     
   if((arg_get_type(args, "th_x2"))>=0)
    tcp->th_x2 = (u_char)atoi(arg_get_value(args, "th_x2"));
@@ -126,7 +126,18 @@
 
   if(!tcp->th_sum)
   {
+   struct pseudohdr pseudoheader;
+   char * tcpsumdata = (char *)malloc( sizeof( struct pseudohdr ) +
+				  ( len % 2 ? len + 1 : 0 ) );
    struct in_addr source, dest;
+
+   if( tcpsumdata == NULL ) {
+     printf("forge_tcp_packet : Error : tcpsumdata malloc failed \n");
+     ret.value = NULL;
+     ret.type = 0;
+     return(ret);
+   }
+     
    source.s_addr = ip->ip_src.s_addr;
    dest.s_addr = ip->ip_dst.s_addr;
    
@@ -135,10 +146,13 @@
    pseudoheader.daddr.s_addr=dest.s_addr;
  
    pseudoheader.protocol=IPPROTO_TCP;
-   pseudoheader.length=htons(sizeof(struct tcphdr))+len;
+   pseudoheader.length=htons(sizeof(struct tcphdr)+len);
    bcopy((char *) tcp,(char *) &pseudoheader.tcpheader,sizeof(struct tcphdr));
-   tcp->th_sum = np_in_cksum((unsigned short *)&pseudoheader,12+sizeof(struct
-   tcphdr)+len);
+   /* fill tcpsumdata with data to checksum */
+   bcopy((char *) &pseudoheader, tcpsumdata ,sizeof(struct pseudohdr));
+   bcopy((char *) data, tcpsumdata + sizeof(struct pseudohdr), len );
+   tcp->th_sum = np_in_cksum((unsigned short *)tcpsumdata,12+sizeof(struct tcphdr) + len );
+   free( tcpsumdata );
   } 
   ret.type = VAR_PKT|PKT_IP|PKT_TCP;
   ret.value = pkt;