neovim

_ssh.lua (5722B)

---

-- Converted into Lua from https://github.com/cyjake/ssh-config
-- TODO (siddhantdev): deal with include directives

local M = {}

local whitespace_pattern = '%s'
local line_break_pattern = '[\r\n]'

---@param param string
local function is_multi_value_directive(param)
 local multi_value_directives = {
   'globalknownhostsfile',
   'host',
   'ipqos',
   'sendenv',
   'userknownhostsfile',
   'proxycommand',
   'match',
   'canonicaldomains',
 }

 return vim.list_contains(multi_value_directives, param:lower())
end

---@param text string The ssh configuration which needs to be parsed
---@return string[] The parsed host names in the configuration
function M.parse_ssh_config(text)
 local i = 1
 local line = 1

 local function consume()
   if i <= #text then
     local char = text:sub(i, i)
     i = i + 1
     return char
   end
   return nil
 end

 local chr = consume()

 local function parse_spaces()
   local spaces = ''
   while chr and chr:match(whitespace_pattern) do
     spaces = spaces .. chr
     chr = consume()
   end
   return spaces
 end

 local function parse_linebreaks()
   local breaks = ''
   while chr and chr:match(line_break_pattern) do
     line = line + 1
     breaks = breaks .. chr
     chr = consume()
   end
   return breaks
 end

 local function parse_parameter_name()
   local param = ''
   while chr and not chr:match('[ \t=]') do
     param = param .. chr
     chr = consume()
   end
   return param
 end

 local function parse_separator()
   local sep = parse_spaces()
   if chr == '=' then
     sep = sep .. chr
     chr = consume()
   end
   return sep .. parse_spaces()
 end

 local function parse_value()
   local val = {}
   local quoted, escaped = false, false

   while chr and not chr:match(line_break_pattern) do
     if escaped then
       table.insert(val, chr == '"' and chr or '\\' .. chr)
       escaped = false
     elseif chr == '"' and (val == {} or quoted) then
       quoted = not quoted
     elseif chr == '\\' then
       escaped = true
     elseif chr == '#' and not quoted then
       break
     else
       table.insert(val, chr)
     end
     chr = consume()
   end

   if quoted or escaped then
     error('Unexpected line break at line ' .. line)
   end

   return vim.trim(table.concat(val))
 end

 local function parse_comment()
   while chr and not chr:match(line_break_pattern) do
     chr = consume()
   end
 end

 ---@return string[]
 local function parse_multiple_values()
   local results = {}
   local val = {}
   local quoted = false
   local escaped = false

   while chr and not chr:match(line_break_pattern) do
     if escaped then
       table.insert(val, chr == '"' and chr or '\\' .. chr)
       escaped = false
     elseif chr == '"' then
       quoted = not quoted
     elseif chr == '\\' then
       escaped = true
     elseif quoted then
       table.insert(val, chr)
     elseif chr:match('[ \t=]') then
       if val ~= {} then
         table.insert(results, vim.trim(table.concat(val)))
         val = {}
       end
     elseif chr == '#' and #results > 0 then
       break
     else
       table.insert(val, chr)
     end
     chr = consume()
   end

   if quoted or escaped then
     error('Unexpected line break at line ' .. line)
   end

   if val ~= {} then
     table.insert(results, vim.trim(table.concat(val)))
   end

   return results
 end

 local function parse_directive()
   local param = parse_parameter_name()
   local multiple = is_multi_value_directive(param)
   local _ = parse_separator()
   local value = multiple and parse_multiple_values() or parse_value()

   local result = {
     param = param,
     value = value,
   }

   return result
 end

 local function parse_line()
   local _ = parse_spaces()
   if chr == '#' then
     parse_comment()
     return nil
   end
   local node = parse_directive()
   local _ = parse_linebreaks()

   return node
 end

 local hostnames = {}

 ---@param value string
 local function is_valid(value)
   return not (value:find('[?*!]') or vim.list_contains(hostnames, value))
 end

 while chr do
   local node = parse_line()
   if node then
     -- This is done just to assign the type
     node.value = node.value ---@type string[]
     if node.param:lower() == 'match' and node.value then
       local current = nil
       for ind, val in ipairs(node.value) do
         if val:lower() == 'host' and ind + 1 <= #node.value and is_valid(node.value[ind + 1]) then
           current = node.value[ind + 1]
         end
       end
       if current then
         table.insert(hostnames, current)
       end
     elseif node.param:lower() == 'host' and node.value then
       for _, value in ipairs(node.value) do
         if is_valid(value) then
           table.insert(hostnames, value)
         end
       end
     end
   end
 end

 return hostnames
end

---@param filename string
---@return string[] The hostnames configured in the file located at filename
function M.parse_config(filename)
 local file = io.open(filename, 'r')
 if not file then
   error('Cannot read ssh configuration file')
 end
 local config_string = file:read('*a')
 file:close()

 return M.parse_ssh_config(config_string)
end

---@return string[] The hostnames configured in the ssh configuration file
---                 located at "~/.ssh/config".
---                 Note: This does not currently process `Include` directives in the
---                 configuration file.
function M.get_hosts()
 local config_path = vim.fs.normalize('~/.ssh/config') ---@type string

 return M.parse_config(config_path)
end

return M