Class: Vtysh::Diff

Inherits:
Object
  • Object
show all
Defined in:
lib/vtysh/diff.rb

Class Method Summary collapse

Class Method Details

.bgp_command_priority(cmd) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 150

def self.bgp_command_priority(cmd)
  case
  when cmd.include?('bgp router-id') then 1
  when cmd =~ /neighbor \S+ peer-group$/ then 2
  when cmd.include?('remote-as') then 3
  when cmd =~ /neighbor \S+ local-as/ then 4
  when cmd.include?('bgp listen range') then 5
  else 6
  end
end

.block_being_removed?(cmd, source_cmds, target_cmds) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/vtysh/diff.rb', line 130

def self.block_being_removed?(cmd, source_cmds, target_cmds)
  removals = source_cmds - target_cmds
  cmd[:context].any? { |ctx|
    is_block_command(ctx) && removals.any? { |r| r[:command] == ctx }
  }
end

.commands(source, target) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 3

def self.commands(source, target)
  source_cmds = parse_config(source)
  target_cmds = parse_config(target)

  if needs_bgp_recreation?(source_cmds, target_cmds)
    bgp_commands = handle_bgp_recreation(source_cmds, target_cmds)
    non_bgp_commands = handle_non_bgp_changes(source_cmds, target_cmds, skip_bgp_blocks: true)
    bgp_commands + non_bgp_commands
  else
    handle_non_bgp_changes(source_cmds, target_cmds) +
      handle_incremental_bgp_changes(source_cmds, target_cmds)
  end
end

.format_context_command(command, context) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 255

def self.format_context_command(command, context)
  parts = context.map { |ctx| ctx }
  vtysh_cmd(*parts, command)
end

.format_removal_command(cmd) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 251

def self.format_removal_command(cmd)
  vtysh_cmd("no #{cmd[:command]}")
end

.handle_bgp_recreation(source_cmds, target_cmds) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 72

def self.handle_bgp_recreation(source_cmds, target_cmds)
  source_asns = source_cmds.select { |c| c[:command].start_with?("router bgp") }.map { |c| c[:command].split[2] }
  target_asns = target_cmds.select { |c| c[:command].start_with?("router bgp") }.map { |c| c[:command].split[2] }

  commands = []

  (source_asns & target_asns).each do |asn|
    bgp_ctx = "router bgp #{asn}"

    # Step 1: Remove the old BGP block
    commands << vtysh_cmd("no #{bgp_ctx}")

    # Step 2: Create the new BGP block
    commands << vtysh_cmd(bgp_ctx)

    # Step 3: Add main BGP commands (not inside address-family)
    target_bgp = target_cmds.select { |c|
      c[:depth] > 0 &&
      c[:context].include?(bgp_ctx) &&
      !c[:context].any? { |ctx| ctx.start_with?("address-family") } &&
      !is_block_command(c[:command])  # skip block commands (router bgp, address-family)
    }

    target_bgp.sort_by { |c| bgp_command_priority(c[:command]) }.each do |cmd|
      commands << vtysh_cmd(bgp_ctx, cmd[:command])
    end

    # Step 4: Add address-family blocks
    af_contexts = target_cmds.select { |c|
      c[:command].start_with?("address-family") && c[:context].include?(bgp_ctx)
    }.map { |c| c[:command] }.uniq

    af_contexts.each do |af|
      commands << vtysh_cmd(bgp_ctx, af)

      af_cmds = target_cmds.select { |c|
        c[:depth] > 0 &&
        c[:context].include?(bgp_ctx) &&
        c[:context].include?(af) &&
        c[:command] != af  # skip the address-family command itself
      }

      af_cmds.each do |cmd|
        commands << vtysh_cmd(bgp_ctx, af, cmd[:command])
      end
    end
  end

  commands
end

.handle_incremental_bgp_changes(source_cmds, target_cmds) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 51

def self.handle_incremental_bgp_changes(source_cmds, target_cmds)
  commands = []

  # BGP removals
  (source_cmds - target_cmds).each do |cmd|
    next unless inside_bgp?(cmd)
    next if cmd[:command].start_with?("router bgp") # don't remove the block itself
    next if block_being_removed?(cmd, source_cmds, target_cmds)
    commands << format_context_command("no #{cmd[:command]}", cmd[:context])
  end

  # BGP additions
  (target_cmds - source_cmds).each do |cmd|
    next unless inside_bgp?(cmd)
    next if cmd[:command].start_with?("router bgp")
    commands << format_context_command(cmd[:command], cmd[:context])
  end

  reorder_bgp(commands)
end

.handle_non_bgp_changes(source_cmds, target_cmds, skip_bgp_blocks: false) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 19

def self.handle_non_bgp_changes(source_cmds, target_cmds, skip_bgp_blocks: false)
  commands = []

  # Removals (non-BGP, plus top-level BGP block removals when not recreating)
  (source_cmds - target_cmds).each do |cmd|
    next if inside_bgp?(cmd) && !cmd[:command].start_with?("router bgp")
    next if skip_bgp_blocks && cmd[:command].start_with?("router bgp")
    if is_block_command(cmd[:command])
      commands << format_removal_command(cmd)
    elsif cmd[:depth] > 0
      next if block_being_removed?(cmd, source_cmds, target_cmds)
      commands << format_context_command("no #{cmd[:command]}", cmd[:context])
    else
      commands << vtysh_cmd("no #{cmd[:command]}")
    end
  end

  # Non-BGP additions
  (target_cmds - source_cmds).each do |cmd|
    next if inside_bgp?(cmd)
    if is_block_command(cmd[:command])
      commands << vtysh_cmd(cmd[:command])
    elsif cmd[:depth] > 0
      commands << format_context_command(cmd[:command], cmd[:context])
    else
      commands << vtysh_cmd(cmd[:command])
    end
  end

  reorder_non_bgp(commands)
end

.inside_bgp?(cmd) ⇒ Boolean

--- Helpers ---

Returns:

  • (Boolean) 


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# File 'lib/vtysh/diff.rb', line 125

def self.inside_bgp?(cmd)
  cmd[:context].any? { |ctx| ctx.start_with?("router bgp") } ||
    cmd[:command].start_with?("router bgp")
end

.is_block_command(cmd) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 240

def self.is_block_command(cmd)
  cmd.start_with?('router ', 'interface ', 'route-map ', 'vrf ', 'address-family ')
end

.needs_bgp_recreation?(source_cmds, target_cmds) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/vtysh/diff.rb', line 137

def self.needs_bgp_recreation?(source_cmds, target_cmds)
  source_asns = source_cmds.select { |c| c[:command].start_with?("router bgp") }.map { |c| c[:command].split[2] }
  target_asns = target_cmds.select { |c| c[:command].start_with?("router bgp") }.map { |c| c[:command].split[2] }

  return false if source_asns != target_asns || source_asns.empty?

  source_asns.any? do |asn|
    src_rid = source_cmds.find { |c| c[:command].include?("bgp router-id") && c[:context].any? { |ctx| ctx.include?("router bgp #{asn}") } }
    tgt_rid = target_cmds.find { |c| c[:command].include?("bgp router-id") && c[:context].any? { |ctx| ctx.include?("router bgp #{asn}") } }
    src_rid && tgt_rid && src_rid[:command] != tgt_rid[:command]
  end
end

.parse_config(config) ⇒ Object

--- Parsing ---



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# File 'lib/vtysh/diff.rb', line 210

def self.parse_config(config)
  commands = []
  context_stack = []

  config.each_line do |line|
    line = line.strip
    next if line.empty? || line.start_with?('#', '!')
    next if line.start_with?('ip route ')       # managed by config_db STATIC_ROUTE
    next if line.start_with?('hostname ')      # managed by system hostname
    next if line == 'ip nht resolve-via-default'   # bgpcfgd managed
    next if line == 'ipv6 nht resolve-via-default' # bgpcfgd managed
    next if line == 'ip protocol bgp route-map RM_SET_SRC' # bgpcfgd managed
    next if line =~ /^(no )?set src /                      # bgpcfgd managed (inside RM_SET_SRC)
    next if line =~ /^frr (version|defaults)/ || line == 'no service integrated-vtysh-config' || line.start_with?('agentx')

    if line =~ /^exit(-address-family|-vrf)?$/
      context_stack.pop unless context_stack.empty?
    elsif line == 'end'
      context_stack = []
    elsif is_block_command(line)
      context_stack << line
      commands << { command: line, context: context_stack.dup, depth: context_stack.size }
    else
      commands << { command: line, context: context_stack.dup, depth: context_stack.size }
    end
  end

  commands
end

.reorder_bgp(commands) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 183

def self.reorder_bgp(commands)
  peer_groups = commands.select { |c| c =~ /neighbor \S+ peer-group"$/ && !c.include?("no ") }
  remote_as = commands.select { |c| c.include?("remote-as") && !c.include?("no ") }
  listen_range = commands.select { |c| c.include?("bgp listen range") && !c.include?("no ") }
  removals = commands.select { |c| c.include?("no ") }
  rest = commands - peer_groups - remote_as - listen_range - removals

  # A removal whose slot is reclaimed by an addition must run first, or FRR
  # rejects the addition as overlapping the value it supersedes.
  slots = (commands - removals).map { |c| slot_key(c) }.compact
  superseded, other = removals.partition { |c| slots.include?(slot_key(c)) }

  (peer_groups + remote_as + superseded + listen_range + rest + other).uniq
end

.reorder_non_bgp(commands) ⇒ Object 



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# File 'lib/vtysh/diff.rb', line 161

def self.reorder_non_bgp(commands)
  prefix_lists = commands.select { |c| c.include?("ip prefix-list") }
  # Only match route-map block creation (2 -c args), not commands inside route-maps
  route_maps = commands.select { |c| c.include?("route-map") && !c.include?("no ") && c.scan(/-c "/).count == 2 }
  top_level_removals = commands.select { |c| c.include?("no ") && c.scan(/-c "/).count <= 2 } - prefix_lists
  rest = commands - prefix_lists - route_maps - top_level_removals

  # Within context: group by context path, put removals before additions
  # so FRR replaces set/match statements correctly (remove old, then add new)
  rest = rest.group_by { |c|
    parts = c.scan(/-c "([^"]+)"/).flatten
    parts[0..-2].join("|")  # context = all but last -c arg
  }.flat_map { |_ctx, cmds|
    cmds.sort_by { |c|
      last_arg = c.scan(/-c "([^"]+)"/).flatten.last
      last_arg&.start_with?("no ") ? 0 : 1
    }
  }

  (prefix_lists + route_maps + rest + top_level_removals).uniq
end

.slot_key(command) ⇒ Object

Identifies commands that occupy one logical slot, so the "no" form and the form replacing it hash alike. Nil when the command owns no exclusive slot.



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# File 'lib/vtysh/diff.rb', line 200

def self.slot_key(command)
  parts = command.scan(/-c "([^"]+)"/).flatten
  slot = case parts.last.to_s.sub(/\Ano /, "")
         when /\Abgp listen range \S+ peer-group (\S+)\z/ then "listen-range:#{$1}"
         end
  slot && (parts[0..-2] + [slot]).join("|")
end

.vtysh_cmd(*parts) ⇒ Object

--- Formatting ---



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# File 'lib/vtysh/diff.rb', line 246

def self.vtysh_cmd(*parts)
  args = ["configure"] + parts
  "vtysh " + args.map { |p| "-c \"#{p}\"" }.join(" ")
end