stap-find-servers

   1 #!/bin/bash
   2
   3 # Find compile servers for systemtap
   4 #
   5 # Copyright (C) 2008, 2009 Red Hat Inc.
   6 #
   7 # This file is part of systemtap, and is free software.  You can
   8 # redistribute it and/or modify it under the terms of the GNU General
   9 # Public License (GPL); either version 2, or (at your option) any
  10 # later version.
  11
  12 # This script uses avahi to find systemtap compile servers on the local
  13 # network. Information about each server found is printed to stdout.
  14
  15 # Deprecation warning.
  16 echo "WARNING: stap-find-servers is deprecated and will be removed in release 1.5" >&2
  17 echo "Please use 'stap --list-servers'. See stap(1) for more information" >&2
  18
  19 # Initialize the environment
  20 . ${PKGLIBEXECDIR}stap-env
  21
  22 #-----------------------------------------------------------------------------
  23 # Helper functions.
  24 #-----------------------------------------------------------------------------
  25 # function: initialization
  26 function initialization {
  27     rc=1 # not found yet
  28     if test "X$1" = "X--all"; then
  29         find_all=1
  30     else
  31         find_all=0
  32     fi
  33     timeout=20 # seconds
  34 }
  35
  36 # function: find_servers
  37 #
  38 # Find and establish connection with a compatible stap server.
  39 function find_servers {
  40     # Create a temp file for the list of servers. We do this instead
  41     # of using a pipe so that we can kill avahi-browse if it
  42     # takes too long.
  43     tmpfile=`mktemp -t stap-serversXXXXXX` || \
  44         fatal "Cannot create temporary file " $tmpfile
  45
  46     # Find servers
  47     avahi-browse $stap_avahi_service_tag --terminate -r > $tmpfile &
  48
  49     for ((attempt=0; $attempt < $timeout; ++attempt))
  50     do
  51         if ! jobs '%avahi-browse' >/dev/null 2>&1; then
  52             break
  53         fi
  54         sleep 1
  55     done
  56
  57     # Kill avahi-browse, if it's still running
  58     test $attempt = $timeout && kill -s SIGTERM '%avahi-browse' 2>/dev/null
  59
  60     match_server < $tmpfile
  61     rm -fr $tmpfile
  62 }
  63
  64 # function: match_server
  65 #
  66 # Find a suitable server using the avahi-browse output provided on stdin.
  67 function match_server {
  68     local server_ip
  69     local server_name
  70     local server_sysinfo
  71     local server_port
  72
  73     rc=1 # not found yet
  74
  75     # Loop over the avahi service descriptors.
  76     read -t $timeout || return
  77     while test "X$REPLY" != "X"
  78     do
  79         server_name=
  80         server_ip=
  81         server_port=
  82         server_sysinfo=
  83
  84         # Examine the next service descriptor
  85         # Is it a stap server?
  86         if ! echo $REPLY | grep -q "=.* .* IPv4 .*_stap"; then
  87             read -t $timeout || return
  88             continue
  89         fi
  90         REPLY=
  91
  92         # Get the details of the service
  93         local service_tag equal service_data
  94         while read -t $timeout service_tag equal service_data
  95         do
  96             case $service_tag in
  97                 hostname )
  98                     server_name=`expr "$service_data" : '\[\([^]]*\)\]'`
  99                     ;;
 100                 address )
 101                     # Sometimes (seems random), avahi-resolve-host-name resolves a local server to its
 102                     # hardware address rather than its ip address. Keep trying until we get
 103                     # an ip address.
 104                     server_ip=`expr "$service_data" : '\[\([^]]*\)\]'`
 105                     local attempt
 106                     for ((attempt=0; $attempt < 5; ++attempt))
 107                     do
 108                         server_ip=`expr "$server_ip" : '\([0-9]*\.[0-9]*\.[0-9]*\.[0-9]*\)$'`
 109                         if test "X$server_ip" != "X"; then
 110                             break
 111                         fi
 112                         # Resolve the server.domain to an ip address.
 113                         server_ip=`avahi-resolve-host-name $server_name`
 114                         server_ip=`expr "$server_ip" : '.*      \(.*\)$'`
 115                     done
 116                     ;;
 117                 port )
 118                     server_port=`expr "$service_data" : '\[\([^]]*\)\]'`
 119                     ;;
 120                 txt )
 121                     server_sysinfo=`expr "$service_data" : '\[.*\"\(sysinfo=[^]]*\)\"\]'`
 122                     ;;
 123                 * )
 124                     REPLY="$service_tag $equal $service_data"
 125                     break
 126                     ;;
 127             esac
 128         done
 129
 130         # It's an stap server, but is it compatible?
 131         if test $find_all = 0 -a "$server_sysinfo" != "`client_sysinfo`"; then
 132             continue
 133         fi
 134
 135         # It's compatible, or we're finding all servers. Print a summary line
 136         echo "$server_name $server_ip $server_port '$server_sysinfo'"
 137         rc=0
 138     done
 139 }
 140
 141 # function client_sysinfo
 142 #
 143 # Generate the client's sysinfo and echo it to stdout
 144 function client_sysinfo {
 145     if test "X$sysinfo_client" = "X"; then
 146         # Add some info from uname
 147         sysinfo_client="`uname -r` `stap_get_arch`"
 148     fi
 149     echo sysinfo=$sysinfo_client
 150 }
 151
 152 # function: fatal [ MESSAGE ]
 153 #
 154 # Fatal error
 155 # Prints its arguments to stderr and exits
 156 function fatal {
 157     echo "$0: ERROR:" "$@" >&2
 158     exit 1
 159 }
 160
 161 #-----------------------------------------------------------------------------
 162 # Beginning of main line execution.
 163 #-----------------------------------------------------------------------------
 164 initialization "$@"
 165 find_servers
 166
 167 exit $rc