The Tcpdump Group git mirrors - tcpdump/blob - print-ssh.c

   1 /*
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that: (1) source code
   4  * distributions retain the above copyright notice and this paragraph
   5  * in its entirety, and (2) distributions including binary code include
   6  * the above copyright notice and this paragraph in its entirety in
   7  * the documentation or other materials provided with the distribution.
   8  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
   9  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  10  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  11  * FOR A PARTICULAR PURPOSE.
  12  */
  13
  14 /* \summary: Secure Shell (SSH) printer */
  15
  16 #ifdef HAVE_CONFIG_H
  17 #include <config.h>
  18 #endif
  19
  20 #include "netdissect-stdinc.h"
  21
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24
  25 #include "netdissect.h"
  26 #include "extract.h"
  27
  28 static int
  29 ssh_print_version(netdissect_options *ndo, const u_char *pptr, u_int len)
  30 {
  31         u_int idx = 0;
  32         const char *pnp;
  33
  34         if ( GET_U_1(pptr+idx) != 'S' )
  35                 return 0;
  36         idx++;
  37         if ( GET_U_1(pptr+idx) != 'S' )
  38                 return 0;
  39         idx++;
  40         if ( GET_U_1(pptr+idx) != 'H' )
  41                 return 0;
  42         idx++;
  43         if ( GET_U_1(pptr+idx) != '-' )
  44                 return 0;
  45         idx++;
  46
  47         while (idx < len) {
  48                 if (GET_U_1(pptr + idx) == '\n') {
  49                         /*
  50                          * LF without CR; end of line.
  51                          * Skip the LF and print the line, with the
  52                          * exception of the LF.
  53                          */
  54                         goto print;
  55                 } else if (GET_U_1(pptr + idx) == '\r') {
  56                         /* CR - any LF? */
  57                         if ((idx+1) >= len) {
  58                                 /* not in this packet */
  59                                 goto trunc;
  60                         }
  61                         if (GET_U_1(pptr + idx + 1) == '\n') {
  62                                 /*
  63                                  * CR-LF; end of line.
  64                                  * Skip the CR-LF and print the line, with
  65                                  * the exception of the CR-LF.
  66                                  */
  67                                 goto print;
  68                         }
  69
  70                         /*
  71                          * CR followed by something else; treat this as
  72                          * if it were binary data and don't print it.
  73                          */
  74                         goto trunc;
  75                 } else if (!isascii(GET_U_1(pptr + idx)) ||
  76                            !isprint(GET_U_1(pptr + idx)) ) {
  77                         /*
  78                          * Not a printable ASCII character; treat this
  79                          * as if it were binary data and don't print it.
  80                          */
  81                         goto trunc;
  82                 }
  83                 idx++;
  84         }
  85 trunc:
  86         return -1;
  87 print:
  88         ND_PRINT(": ");
  89         /* Capitalize the protocol name */
  90         for (pnp = ndo->ndo_protocol; *pnp != '\0'; pnp++)
  91                 ND_PRINT("%c", ND_TOUPPER((u_char)*pnp));
  92         ND_PRINT(": %.*s", (int)idx, pptr);
  93         return idx;
  94 }
  95
  96 void
  97 ssh_print(netdissect_options *ndo, const u_char *pptr, u_int len)
  98 {
  99         ndo->ndo_protocol = "ssh";
 100
 101         ssh_print_version(ndo, pptr, len);
 102 }