Ethereal-users: Re: [ethereal-users] One strange thing about the MS Netmon 2.x capture file

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From: Guy Harris <gharris@xxxxxxxxxxxx>
Date: Thu, 23 Mar 2000 02:24:45 -0800
> That's because it's using "strlen()" to figure out how much data there
> is, and that stops on a '\0'.
> 
> I'll look into making it not do so.

I have a patch to do so; I also got rid of some unnecessary temporary
string buffers, and cleaned it up some (in part so that I could figure
out what the temporary string buffers were doing, and to replace
references to them to references to the packet data itself).

The patch is attached.

Index: packet-telnet.c
===================================================================
RCS file: /usr/local/cvsroot/ethereal/packet-telnet.c,v
retrieving revision 1.8
diff -c -r1.8 packet-telnet.c
*** packet-telnet.c	2000/01/07 22:05:41	1.8
--- packet-telnet.c	2000/03/23 10:21:45
***************
*** 71,77 ****
  #define TN_SUSP  237
  #define TN_EOF   236
  
! char *options[] = {
    "Binary Transmission",
    "Echo",
    "Reconnection",
--- 71,77 ----
  #define TN_SUSP  237
  #define TN_EOF   236
  
! static const char *options[] = {
    "Binary Transmission",
    "Echo",
    "Reconnection",
***************
*** 115,321 ****
    "TN3270E"
  };
  
! void telnet_sub_option(proto_tree *telnet_tree, char *rr, int *i, int offset, int max_data)
  {
    proto_tree *ti, *option_tree;
!   int subneg_len, req, si1, not_found = 1;
!   volatile int i1;
!   char *opt, sub_opt_data[1500];
  
!   memset(sub_opt_data, '\0', sizeof(sub_opt_data));
  
    /* Figure out the option and type */
! 
!   opt = options[(unsigned int)rr[*i]];
!   req = (unsigned int)rr[*i + 1];
! 
!   i1 = *i + 2; si1 = i1;
!   while ((i1 < max_data) && (not_found)) {  
! 
!     if ((unsigned char)rr[i1] == (unsigned char)TN_IAC)
!       not_found = 0;
      else
!       i1++;
! 
    }
  
!   subneg_len = i1 - *i + 2;
  
!   ti = proto_tree_add_text(telnet_tree, offset, subneg_len, "Suboption Begin: %s", opt);
  
    option_tree = proto_item_add_subtree(ti, ett_telnet_subopt);
  
!   proto_tree_add_text(option_tree, offset + 2, subneg_len - 2, "%s %s", (req ? "Send your" : "Here's my"), opt);
  
    if (req == 0) {  /* Add the value */
! 
!     memcpy(sub_opt_data, rr + *i + 2, subneg_len - 2);
!     proto_tree_add_text(option_tree, offset + 4, subneg_len - 4, "Value: %s", format_text(sub_opt_data, subneg_len - 4));
!     *i += subneg_len - 2;
! 
    }
!   else {
  
!     *i += subneg_len - 2;
  
!   }
  }
  
! void telnet_command(proto_tree *telnet_tree, char *rr, int *i, int offset, int max_data) 
  {
!   char *opt;
    
!   switch((unsigned char)rr[*i]) {
  
    case TN_EOF:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: End of File");
!     (*i)++;
      break;
  
    case TN_SUSP:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Suspend Current Process");
!     (*i)++;
      break;
  
    case TN_ABORT:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Abort Process");
!     (*i)++;
      break;
  
    case TN_EOR:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: End of Record");
!     (*i)++;
      break;
  
    case TN_SE:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Suboption End");
!     (*i)++;
      break;
  
    case TN_NOP:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: No Operation");
!     (*i)++;
      break;
  
    case TN_DM:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Data Mark");
!     (*i)++;
      break;
  
    case TN_BRK:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Break");
!     (*i)++;
      break;
  
    case TN_IP:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Interrupt Process");
!     (*i)++;
      break;
  
    case TN_AO:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Abort Output");
!     (*i)++;
      break;
  
    case TN_AYT:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Are You There?");
!     (*i)++;
      break;
  
    case TN_EC:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Escape Character");
!     (*i)++;
      break;
  
    case TN_EL:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Erase Line");
!     (*i)++;
      break;
  
    case TN_GA:
! 
!     proto_tree_add_text(telnet_tree, offset, 2, "Command: Go Ahead");
!     (*i)++;
      break;
  
    case TN_SB:
! 
!     (*i)++;
!     telnet_sub_option(telnet_tree, rr, i, offset, max_data);
      break;
  
    case TN_WILL:
! 
!     if (rr[*i + 1] > (sizeof(options)/sizeof(char *)))
!       opt = "<unknown option>";
!     else
!       opt = options[(unsigned int)rr[*i + 1]];
! 		      
!     proto_tree_add_text(telnet_tree, offset, 3, "Command: Will %s", opt);
!     *i += 2; /* skip two chars */
      break;
  
    case TN_WONT:
! 
!     if (rr[*i + 1] > (sizeof(options)/sizeof(char *)))
!       opt = "<unknown option>";
!     else
!       opt = options[(unsigned int)rr[*i + 1]];
! 		      
!     proto_tree_add_text(telnet_tree, offset, 3, "Command: Won't %s", opt);
!     *i += 2; /* skip two chars */
      break;
  
    case TN_DO:
! 
!     if (rr[*i + 1] > (sizeof(options)/sizeof(char *)))
!       opt = "<unknown option>";
!     else
!       opt = options[(unsigned int)rr[*i + 1]];
! 		      
!     proto_tree_add_text(telnet_tree, offset, 3, "Command: Do %s", opt);
!     *i += 2; /* skip two chars */
      break;
  
    case TN_DONT:
! 
!     if (rr[*i + 1] > (sizeof(options)/sizeof(char *)))
!       opt = "<unknown option>";
!     else
!       opt = options[(unsigned int)rr[*i + 1]];
! 		      
!     proto_tree_add_text(telnet_tree, offset, 3, "Command: Don't %s", opt);
!     *i += 2; /* skip two chars */
      break;
- 
    }
  
  }
  
  void
  dissect_telnet(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
  {
          proto_tree      *telnet_tree, *ti;
- 	gchar           rr[1500];
- 	int i1;
- 	int i2;
  	int max_data = pi.captured_len - offset;
  
- 	memset(rr, '\0', sizeof(rr));
- 
  	if (check_col(fd, COL_PROTOCOL))
  		col_add_str(fd, COL_PROTOCOL, "TELNET");
  
--- 115,302 ----
    "TN3270E"
  };
  
! #define	NOPTIONS	(sizeof options / sizeof options[0])
! 
! static int
! telnet_sub_option(proto_tree *telnet_tree, const u_char *pd,
! 		int start_offset)
  {
    proto_tree *ti, *option_tree;
!   int offset = start_offset;
!   int subneg_len, req;
!   gboolean not_found = TRUE;
!   const u_char *opt;
  
!   offset += 2;	/* skip IAC and SB */
  
    /* Figure out the option and type */
!   if (pd[offset] > NOPTIONS)
!     opt = "<unknown option>";
!   else
!     opt = options[pd[offset]];
!   offset++;
!   req = pd[offset];
!   offset++;
! 
!   while (offset < pi.captured_len && not_found) {  
!     if (pd[offset] == TN_IAC)
!       not_found = FALSE;
      else
!       offset++;
    }
  
!   subneg_len = offset - start_offset;
  
!   ti = proto_tree_add_text(telnet_tree, start_offset, subneg_len,
! 			"Suboption Begin: %s", opt);
  
    option_tree = proto_item_add_subtree(ti, ett_telnet_subopt);
  
!   proto_tree_add_text(option_tree, start_offset + 2, 2,
! 			"%s %s", (req ? "Send your" : "Here's my"), opt);
  
    if (req == 0) {  /* Add the value */
!     proto_tree_add_text(option_tree, start_offset + 4, subneg_len - 4,
! 	"Value: %s", format_text(&pd[start_offset + 4], subneg_len - 4));
    }
!   return offset;
! }
  
! static int
! telnet_will_wont_do_dont(proto_tree *telnet_tree, const u_char *pd,
! 			int start_offset, char *type)
! {
!   int offset = start_offset;
!   const char *opt;
  
!   offset += 2;	/* skip IAC and WILL,WONT,DO,DONT} */
!   if (pd[offset] > NOPTIONS)
!     opt = "<unknown option>";
!   else
!     opt = options[pd[offset]];
!   offset++;
! 		      
!   proto_tree_add_text(telnet_tree, start_offset, 3,
! 			"Command: %s %s", type, opt);
!   return offset;
  }
  
! static int
! telnet_command(proto_tree *telnet_tree, const u_char *pd,
! 		int start_offset, int max_data) 
  {
!   int offset = start_offset;
!   u_char optcode;
    
!   offset += 1;	/* skip IAC */
!   optcode = pd[offset];
!   offset++;
!   switch(optcode) {
  
    case TN_EOF:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: End of File");
      break;
  
    case TN_SUSP:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Suspend Current Process");
      break;
  
    case TN_ABORT:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Abort Process");
      break;
  
    case TN_EOR:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: End of Record");
      break;
  
    case TN_SE:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Suboption End");
      break;
  
    case TN_NOP:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: No Operation");
      break;
  
    case TN_DM:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Data Mark");
      break;
  
    case TN_BRK:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Break");
      break;
  
    case TN_IP:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Interrupt Process");
      break;
  
    case TN_AO:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Abort Output");
      break;
  
    case TN_AYT:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Are You There?");
      break;
  
    case TN_EC:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Escape Character");
      break;
  
    case TN_EL:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Erase Line");
      break;
  
    case TN_GA:
!     proto_tree_add_text(telnet_tree, start_offset, 2,
! 			"Command: Go Ahead");
      break;
  
    case TN_SB:
!     offset = telnet_sub_option(telnet_tree, pd, start_offset);
      break;
  
    case TN_WILL:
!     offset = telnet_will_wont_do_dont(telnet_tree, pd, start_offset,
! 					"Will");
      break;
  
    case TN_WONT:
!     offset = telnet_will_wont_do_dont(telnet_tree, pd, start_offset,
! 					"Won't");
      break;
  
    case TN_DO:
!     offset = telnet_will_wont_do_dont(telnet_tree, pd, start_offset,
! 					"Do");
      break;
  
    case TN_DONT:
!     offset = telnet_will_wont_do_dont(telnet_tree, pd, start_offset,
! 					"Don't");
      break;
    }
  
+   return offset;
  }
  
  void
  dissect_telnet(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
  {
          proto_tree      *telnet_tree, *ti;
  	int max_data = pi.captured_len - offset;
  
  	if (check_col(fd, COL_PROTOCOL))
  		col_add_str(fd, COL_PROTOCOL, "TELNET");
  
***************
*** 326,379 ****
  	}
  
  	if (tree) {
  
- 	  char data[1500];
- 	  int i3;
- 
- 	  memset(data, '\0', sizeof(data));
- 
- 	  memcpy(rr, pd + offset, max_data);
- 
  	  ti = proto_tree_add_item(tree, proto_telnet, offset, END_OF_FRAME, NULL);
  	  telnet_tree = proto_item_add_subtree(ti, ett_telnet);
- 
- 	  i1 = i2 = i3 = 0;
- 
- 	  while (i1 < max_data) {
- 
- 	    if ((unsigned char)rr[i1] == (unsigned char)TN_IAC) {
  
! 	      if (strlen(data) > 0) {
  
! 		proto_tree_add_text(telnet_tree, offset + i2, strlen(data), "Data: %s", format_text(data, strlen(data)));
! 		memset(data, '\0', sizeof(data));
! 		i3 = 0;
! 
  	      }
  	      
! 	      i1++;
! 	      telnet_command(telnet_tree, rr, &i1, offset + i1 - 1, max_data);
! 	      i2 = i1;
! 
  	    }
  	    else {
! 
! 	      data[i3] = rr[i1];
! 	      i3++;
! 	      i1++;
! 
! 
  	    }
  	  }
- 
- 	  if (strlen(data) > 0) { /* Still some data to add */
  
! 	    proto_tree_add_text(telnet_tree, offset + i2, strlen(data), "Data: %s", format_text(data, strlen(data)));
! 
  	  }
- 
  	}
- 
  }
  
  void
--- 307,359 ----
  	}
  
  	if (tree) {
+ 	  int data_offset;
+ 	  int data_len;
  
  	  ti = proto_tree_add_item(tree, proto_telnet, offset, END_OF_FRAME, NULL);
  	  telnet_tree = proto_item_add_subtree(ti, ett_telnet);
  
! 	  data_offset = offset;
! 	  data_len = 0;
  
! 	  /*
! 	   * Scan through the buffer looking for an IAC byte.
! 	   */
! 	  while (offset < pi.captured_len) {
! 	    if (pd[offset] == TN_IAC) {
! 	      /*
! 	       * We found an IAC byte.
! 	       * If there's any data before it, add that data to the
! 	       * tree.
! 	       */
! 	      if (data_len > 0) {
! 		proto_tree_add_text(telnet_tree, data_offset, data_len,
! 			"Data: %s", format_text(&pd[data_offset], data_len));
! 		data_len = 0;
! 		data_offset = offset;
  	      }
  	      
! 	      /*
! 	       * Now interpret the command.
! 	       */
! 	      offset = telnet_command(telnet_tree, pd, offset, max_data);
! 	      data_offset = offset;
  	    }
  	    else {
! 	      data_len++;
! 	      offset++;
  	    }
  	  }
  
! 	  /*
! 	   * We've reached the end of the buffer.
! 	   * If there's any data left, add it to the tree.
! 	   */
! 	  if (data_len > 0) {
! 	    proto_tree_add_text(telnet_tree, data_offset, data_len, "Data: %s",
! 	    		format_text(&pd[data_offset], data_len));
  	  }
  	}
  }
  
  void