gbr-games/cmd/gbrgames/draftchecks.go

package main

import (
	"encoding/json"
	"fmt"
	"regexp"
	"sort"
	"strconv"
	"strings"
)

// Checks a booting draft can still fail: things that only go wrong once an owner changes a setting, so
// neither the validator nor a boot test with the defaults sees them.

// splitSettings finds text settings that reach the server's command line unquoted, so a value with spaces
// ("GBRHosting - My Server") arrives as several arguments and the game only sees the first word. Covers
// direct use (-name ${SERVER_NAME}) and the common ARGS="-name ${SERVER_NAME}"; ./server $ARGS, where the
// quotes in the assignment don't survive the unquoted $ARGS.
func splitSettings(game map[string]any) []string {
	startup, _ := game["defaultStartupCommand"].(string)
	if startup == "" {
		return nil
	}
	textVars := map[string]string{} // env name -> setting key
	for key, p := range schemaProperties(game) {
		if prop, _ := p.(map[string]any); prop["type"] == "string" {
			textVars[envName(key)] = key
		}
	}
	if len(textVars) == 0 {
		return nil
	}
	s := scanShell(unwrapShell(startup))

	split := map[string]string{} // setting key -> how it gets split
	var reach func(holder string, seen map[string]bool) []string
	reach = func(holder string, seen map[string]bool) []string {
		if seen[holder] {
			return nil
		}
		seen[holder] = true
		var out []string
		for _, v := range s.held[holder] {
			if _, ok := textVars[v]; ok {
				out = append(out, v)
			}
			out = append(out, reach(v, seen)...)
		}
		return out
	}
	for _, e := range s.uses {
		if e.quoted {
			continue
		}
		if key, ok := textVars[e.name]; ok {
			split[key] = "${" + e.name + "} is not in double quotes"
		}
		if len(s.held[e.name]) > 0 {
			for _, v := range reach(e.name, map[string]bool{}) {
				if _, done := split[textVars[v]]; !done {
					split[textVars[v]] = fmt.Sprintf("${%s} is inside $%s, which is used without double quotes", v, e.name)
				}
			}
		}
	}
	var problems []string
	for _, key := range sortedKeysString(split) {
		problems = append(problems, fmt.Sprintf("setting %s is split into words on the command line (%s): a value with spaces like "+
			"\"GBRHosting - My Server\" reaches the game as several arguments. Quote it where it is used (-name \"${%s}\"), or build "+
			"optional arguments in a bash array: args=(-name \"$%s\"); [ -n \"$X\" ] && args+=(-x \"$X\"); ./server \"${args[@]}\"",
			key, split[key], envName(key), envName(key)))
	}
	return problems
}

var shellWrap = regexp.MustCompile(`^\s*(?:ba)?sh\s+-c\s+'(.*)'\s*$`)

// unwrapShell looks inside a startup command that is one bash -c '...' (ARK's), which would otherwise be
// all single-quoted text.
func unwrapShell(cmd string) string {
	if m := shellWrap.FindStringSubmatch(cmd); m != nil && !strings.Contains(m[1], "'") {
		return m[1]
	}
	return cmd
}

type shellUse struct {
	name   string
	quoted bool
}

type shellScan struct {
	uses []shellUse          // expansions where the value is used: words, arguments
	held map[string][]string // variable -> variables its assigned value contains
}

var (
	assignWord = regexp.MustCompile(`^([A-Za-z_][A-Za-z0-9_]*)\+?=`)
	varName    = regexp.MustCompile(`^[A-Za-z_][A-Za-z0-9_]*`)
	nestedVar  = regexp.MustCompile(`\$\{?([A-Za-z_][A-Za-z0-9_]*)`)
)

// scanShell is just enough of a shell parser for splitSettings: quotes, $VAR / ${VAR...} expansions, and
// assignments (NAME=..., NAME+=..., NAME=(...) arrays).
func scanShell(cmd string) *shellScan {
	s := &shellScan{held: map[string][]string{}}
	var single, double, wordStart = false, false, true
	assign, inArray := "", false
	record := func(name string, quoted bool) {
		switch {
		case assign != "" && !inArray:
			// NAME="...$X..." : no splitting yet, but $NAME carries X along
			s.held[assign] = append(s.held[assign], name)
		case inArray && quoted:
			s.held[assign] = append(s.held[assign], name) // safe unless the array is expanded unquoted
		default:
			s.uses = append(s.uses, shellUse{name, quoted})
		}
	}
	for i := 0; i < len(cmd); i++ {
		c := cmd[i]
		if wordStart && !single && !double {
			if m := assignWord.FindString(cmd[i:]); m != "" {
				assign = strings.TrimRight(strings.TrimSuffix(m, "="), "+")
				i += len(m)
				if i < len(cmd) && cmd[i] == '(' {
					inArray = true
				} else {
					i--
				}
				wordStart = false
				continue
			}
		}
		wordStart = false
		switch {
		case c == '\\' && !single:
			i++
		case c == '\'' && !double:
			single = !single
		case c == '"' && !single:
			double = !double
		case c == '$' && !single && i+1 < len(cmd):
			if cmd[i+1] == '{' {
				end := matchingBrace(cmd, i+1)
				body := cmd[i+2 : end]
				name := varName.FindString(strings.TrimLeft(body, "#!"))
				if name != "" {
					record(name, double)
				}
				// Defaults can hold more expansions: ${A:-${B}}
				for _, m := range nestedVar.FindAllStringSubmatch(body[len(name):], -1) {
					record(m[1], double)
				}
				i = end
			} else if name := varName.FindString(cmd[i+1:]); name != "" {
				record(name, double)
				i += len(name)
			}
		case single || double:
		case inArray && c == ')':
			inArray, assign = false, ""
		case inArray:
		case c == ' ' || c == '\t' || c == '\n' || c == ';' || c == '&' || c == '|' || c == '(' || c == ')':
			assign, wordStart = "", true
		}
	}
	return s
}

func matchingBrace(s string, open int) int {
	depth := 0
	for i := open; i < len(s); i++ {
		switch s[i] {
		case '{':
			depth++
		case '}':
			depth--
			if depth == 0 {
				return i
			}
		}
	}
	return len(s) - 1
}

var (
	portSetting = regexp.MustCompile(`(?i)(port$|(^|_)port(_|$))`)
	notAPort    = regexp.MustCompile(`(?i)(sup|re|ex|im|trans)port$`)
	// Reached over the Docker network, never published (AUTHORING.md)
	internalPort = regexp.MustCompile(`(?i)rcon|rest|api|admin|telnet|web|http|metrics`)
)

// portSettings checks settings that set a port players connect to against defaultPorts. The node always
// publishes defaultPorts' container ports (moving only the host side when servers share a node), so a
// game listening anywhere else can't be reached: a default that isn't published is broken from the
// start, and an editable one breaks the moment an owner changes it.
func portSettings(game map[string]any) []string {
	published := map[int]bool{}
	ports, _ := game["defaultPorts"].([]any)
	for _, p := range ports {
		n, _ := strconv.Atoi(strings.Split(containerPort(fmt.Sprint(p)), "/")[0])
		published[n] = true
	}
	defaults, _ := game["defaultConfig"].(map[string]any)
	props := schemaProperties(game)
	var problems []string
	keys := make([]string, 0, len(defaults))
	for k := range defaults {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	for _, key := range keys {
		if !portSetting.MatchString(key) || notAPort.MatchString(key) || internalPort.MatchString(key) {
			continue
		}
		port, ok := portNumber(defaults[key])
		if !ok {
			continue // {PUBLIC_PORT_n} and other placeholders are filled per server
		}
		_, editable := props[key]
		switch {
		case !published[port]:
			problems = append(problems, fmt.Sprintf("setting %s defaults to port %d, which defaultPorts does not publish: players can't reach it. "+
				"Use one of the published ports, or add this port to defaultPorts if players connect to it", key, port))
		case editable:
			problems = append(problems, fmt.Sprintf("setting %s lets owners change the port, but the node always publishes container port %d "+
				"(defaultPorts), so any other value makes the server unreachable. Don't make it a setting: remove %s from "+
				"defaultConfig and configSchema and write %d directly in the startup command or config file. If the game must "+
				"announce the port players use, give it {PUBLIC_PORT_%d} instead", key, port, key, port, port))
		}
	}
	return problems
}

func portNumber(v any) (int, bool) {
	var s string
	switch n := v.(type) {
	case json.Number:
		s = n.String()
	case string:
		s = n
	case int, int64, float64:
		s = fmt.Sprint(n)
	default:
		return 0, false
	}
	p, err := strconv.Atoi(strings.TrimSpace(s))
	return p, err == nil && p > 0 && p < 65536
}