feat(ssh): SSH configuration parser #35027

runtime/lua/vim/net/_ssh.lua

@@ -0,0 +1,237 @@
+-- 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