quirks.go

/* ipp-usb - HTTP reverse proxy, backed by IPP-over-USB connection to device
 *
 * Copyright (C) 2020 and up by Alexander Pevzner (pzz@apevzner.com)
 * See LICENSE for license terms and conditions
 *
 * Device-specific quirks
 */

package main

import (
	"fmt"
	"io"
	"io/ioutil"
	"math"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"time"
)

// Quirk represents a single quirk
type Quirk struct {
	Origin    string      // file:line of definition
	Match     string      // Match pattern
	Name      string      // Quirk name
	RawValue  string      // Quirk raw (not parsed) value
	Parsed    interface{} // Parsed Value
	LoadOrder int         // Incremented in order of loading
}

// Quirk names. Use these constants instead of literal strings,
// so compiler will catch a mistake:
const (
	QuirkNmBlacklist         = "blacklist"
	QuirkNmBuggyIppResponses = "buggy-ipp-responses"
	QuirkNmDisableFax        = "disable-fax"
	QuirkNmIgnoreIppStatus   = "ignore-ipp-status"
	QuirkNmInitDelay         = "init-delay"
	QuirkNmInitReset         = "init-reset"
	QuirkNmRequestDelay      = "request-delay"
	QuirkNmUsbMaxInterfaces  = "usb-max-interfaces"
)

// quirkParse maps quirk names into appropriate parsing methods,
// which defines value syntax and resulting type.
var quirkParse = map[string]func(*Quirk) error{
	QuirkNmBlacklist:         (*Quirk).parseBool,
	QuirkNmBuggyIppResponses: (*Quirk).parseQuirkBuggyIppRsp,
	QuirkNmDisableFax:        (*Quirk).parseBool,
	QuirkNmIgnoreIppStatus:   (*Quirk).parseBool,
	QuirkNmInitDelay:         (*Quirk).parseDuration,
	QuirkNmInitReset:         (*Quirk).parseQuirkResetMethod,
	QuirkNmRequestDelay:      (*Quirk).parseDuration,
	QuirkNmUsbMaxInterfaces:  (*Quirk).parseUint,
}

// quirkDefaultStrings contains default values for quirks, in
// a string form.
var quirkDefaultStrings = map[string]string{
	QuirkNmBlacklist:         "false",
	QuirkNmBuggyIppResponses: "reject",
	QuirkNmDisableFax:        "false",
	QuirkNmIgnoreIppStatus:   "false",
	QuirkNmInitDelay:         "0",
	QuirkNmInitReset:         "none",
	QuirkNmRequestDelay:      "0",
	QuirkNmUsbMaxInterfaces:  "0",
}

// quirkDefault contains default values for quirks, precompiled.
var quirkDefault = make(map[string]*Quirk)

// init populates quirkDefault using quirk values from quirkDefaultStrings.
func init() {
	for name, value := range quirkDefaultStrings {
		q := &Quirk{
			Origin:    "default",
			Match:     "*",
			Name:      name,
			RawValue:  value,
			LoadOrder: math.MaxInt,
		}

		parse := quirkParse[name]
		parse(q)
		quirkDefault[name] = q
	}
}

// parseBool parses and saves [Quirk.RawValue] as bool.
func (q *Quirk) parseBool() error {
	switch q.RawValue {
	case "true":
		q.Parsed = true
	case "false":
		q.Parsed = false
	default:
		return fmt.Errorf("%q: must be true or false", q.RawValue)
	}

	return nil
}

// parseUind parses [Quirk.RawValue] as bool.
func (q *Quirk) parseUint() error {
	v, err := strconv.ParseUint(q.RawValue, 10, 32)
	if err != nil {
		return fmt.Errorf("%q: invalid unsigned integer", q.RawValue)
	}

	q.Parsed = uint(v)
	return nil
}

// parseDuration parses [Quirk.RawValue] as time.Duration.
func (q *Quirk) parseDuration() error {
	ms, err := strconv.ParseUint(q.RawValue, 10, 32)
	if err != nil {
		return fmt.Errorf("%q: invalid duration", q.RawValue)
	}

	q.Parsed = time.Millisecond * time.Duration(ms)
	return nil
}

// parseQuirkBuggyIppRsp parses [Quirk.RawValue] as QuirkBuggyIppRsp.
func (q *Quirk) parseQuirkBuggyIppRsp() error {
	switch q.RawValue {
	case "allow":
		q.Parsed = QuirkBuggyIppRspAllow
	case "reject":
		q.Parsed = QuirkBuggyIppRspReject
	case "sanitize":
		q.Parsed = QuirkBuggyIppRspSanitize
	default:
		s := q.RawValue
		return fmt.Errorf("%q: must be allow, reject or sanitize", s)
	}

	return nil
}

// parseQuirkResetMethod parses [Quirk.RawValue] as QuirkResetMethod.
func (q *Quirk) parseQuirkResetMethod() error {
	switch q.RawValue {
	case "none":
		q.Parsed = QuirkResetNone
	case "soft":
		q.Parsed = QuirkResetSoft
	case "hard":
		q.Parsed = QuirkResetHard
	default:
		return fmt.Errorf("%q: must be none, soft or hard", q.RawValue)
	}

	return nil
}

// prioritize returns more prioritized Quirk, choosing between q and q2.
func (q *Quirk) prioritize(q2 *Quirk, model string) *Quirk {
	matchlen := GlobMatch(model, q.Match)
	matchlen2 := GlobMatch(model, q2.Match)

	switch {
	// Choose by match length (more specific match wins)
	case matchlen > matchlen2:
		return q
	case matchlen < matchlen2:
		return q2

	// Choose by load order (first loaded wins)
	case q.LoadOrder > q2.LoadOrder:
		return q
	}

	return q
}

// QuirkResetMethod represents how to reset a device
// during initialization
type QuirkResetMethod int

// QuirkResetUnset - reset method not specified
// QuirkResetNone  - don't reset device at all
// QuirkResetSoft  - use class-specific soft reset
// QuirkResetHard  - use USB hard reset
const (
	QuirkResetNone QuirkResetMethod = iota
	QuirkResetSoft
	QuirkResetHard
)

// String returns textual representation of QuirkResetMethod
func (m QuirkResetMethod) String() string {
	switch m {
	case QuirkResetNone:
		return "none"
	case QuirkResetSoft:
		return "soft"
	case QuirkResetHard:
		return "hard"
	}

	return fmt.Sprintf("unknown (%d)", int(m))
}

// QuirkBuggyIppRsp defines, how to handle buggy IPP responses
type QuirkBuggyIppRsp int

// QuirkBuggyIppRspReject   - ipp-usb will reject bad IPP responses
// QuirkBuggyIppRspAllow    - ipp-usb will allow bad IPP responses
// QuirkBuggyIppRspSanitize - bad ipp responses will be sanitized (fixed)
const (
	QuirkBuggyIppRspReject QuirkBuggyIppRsp = iota
	QuirkBuggyIppRspAllow
	QuirkBuggyIppRspSanitize
)

// String returns textual representation of QuirkBuggyIppRsp
func (m QuirkBuggyIppRsp) String() string {
	switch m {
	case QuirkBuggyIppRspReject:
		return "reject"
	case QuirkBuggyIppRspAllow:
		return "allow"
	case QuirkBuggyIppRspSanitize:
		return "sanitize"
	}

	return fmt.Sprintf("unknown (%d)", int(m))
}

// Quirks is the collection of Quirk-s.
type Quirks struct {
	byName      map[string]*Quirk // Quirks by name
	HTTPHeaders map[string]string // HTTP header override
}

// Get returns quirk by name.
func (quirks Quirks) Get(name string) *Quirk {
	q := quirks.byName[name]
	if q == nil {
		q = quirkDefault[name]
	}

	return q
}

// All returns all quirks in the collection. This method is
// intended mostly for diagnostic purposes (logging, dumping,
// testing and so on).
func (quirks Quirks) All() []*Quirk {
	qq := make([]*Quirk, 0, len(quirks.byName))
	for _, q := range quirks.byName {
		qq = append(qq, q)
	}

	sort.Slice(qq, func(i, j int) bool {
		return qq[i].Name < qq[j].Name
	})

	return qq
}

// GetBlacklist returns effective "blacklist" parameter,
// taking the whole set into consideration.
func (quirks Quirks) GetBlacklist() bool {
	return quirks.Get(QuirkNmBlacklist).Parsed.(bool)
}

// GetBuggyIppRsp returns effective "buggy-ipp-responses" parameter
// taking the whole set into consideration.
func (quirks Quirks) GetBuggyIppRsp() QuirkBuggyIppRsp {
	return quirks.Get(QuirkNmBuggyIppResponses).Parsed.(QuirkBuggyIppRsp)
}

// GetDisableFax returns effective "disable-fax" parameter,
// taking the whole set into consideration.
func (quirks Quirks) GetDisableFax() bool {
	return quirks.Get(QuirkNmDisableFax).Parsed.(bool)
}

// GetIgnoreIppStatus returns effective "ignore-ipp-status" parameter,
// taking the whole set into consideration.
func (quirks Quirks) GetIgnoreIppStatus() bool {
	return quirks.Get(QuirkNmIgnoreIppStatus).Parsed.(bool)
}

// GetInitDelay returns effective "init-delay" parameter
// taking the whole set into consideration.
func (quirks Quirks) GetInitDelay() time.Duration {
	return quirks.Get(QuirkNmInitDelay).Parsed.(time.Duration)
}

// GetInitReset returns effective "init-reset" parameter
// taking the whole set into consideration.
func (quirks Quirks) GetInitReset() QuirkResetMethod {
	return quirks.Get(QuirkNmInitReset).Parsed.(QuirkResetMethod)
}

// GetRequestDelay returns effective "request-delay" parameter
// taking the whole set into consideration.
func (quirks Quirks) GetRequestDelay() time.Duration {
	return quirks.Get(QuirkNmRequestDelay).Parsed.(time.Duration)
}

// GetUsbMaxInterfaces returns effective "usb-max-interfaces" parameter,
// taking the whole set into consideration.
func (quirks Quirks) GetUsbMaxInterfaces() uint {
	return quirks.Get(QuirkNmUsbMaxInterfaces).Parsed.(uint)
}

// QuirksSet represents collection of quirks
type QuirksSet []*Quirks

// LoadQuirksSet creates new QuirksSet and loads its content from a directory
func LoadQuirksSet(paths ...string) (QuirksSet, error) {
	qset := QuirksSet{}

	for _, path := range paths {
		err := qset.readDir(path)
		if err != nil {
			return nil, err
		}
	}

	return qset, nil
}

// readDir loads all Quirks from a directory
func (qset *QuirksSet) readDir(path string) error {
	files, err := ioutil.ReadDir(path)
	if err != nil {
		if os.IsNotExist(err) {
			err = nil
		}
		return err
	}

	for _, file := range files {
		if file.Mode().IsRegular() &&
			strings.HasSuffix(file.Name(), ".conf") {
			err = qset.readFile(filepath.Join(path, file.Name()))
			if err != nil {
				return err
			}
		}
	}

	return nil
}

// readFile reads all Quirks from a file
func (qset *QuirksSet) readFile(file string) error {
	// Open quirks file
	ini, err := OpenIniFileWithRecType(file)
	if err != nil {
		return err
	}

	defer ini.Close()

	// Load all quirks
	var quirks *Quirks
	var loadOrder int

	for err == nil {
		var rec *IniRecord
		rec, err = ini.Next()
		if err != nil {
			break
		}

		origin := fmt.Sprintf("%s:%d", rec.File, rec.Line)

		// Get Quirks structure
		if rec.Type == IniRecordSection {
			quirks = &Quirks{
				byName:      make(map[string]*Quirk),
				HTTPHeaders: make(map[string]string),
			}
			qset.Add(quirks)

			continue
		} else if quirks == nil {
			err = fmt.Errorf("%s: %q = %q out of any section",
				origin, rec.Key, rec.Value)
			break
		}

		if found := quirks.byName[rec.Key]; found != nil {
			err = fmt.Errorf("%s: %q already defined at %s",
				origin, rec.Key, found.Origin)
			return err
		}

		q := &Quirk{
			Origin:    origin,
			Match:     rec.Section,
			Name:      rec.Key,
			RawValue:  rec.Value,
			LoadOrder: loadOrder,
		}

		loadOrder++

		if strings.HasPrefix(rec.Key, "http-") {
			// Canonicalize HTTP header name
			q.Name = strings.ToLower(q.Name)
			q.Parsed = q.RawValue

			hdr := http.CanonicalHeaderKey(rec.Key[5:])
			quirks.HTTPHeaders[hdr] = q.RawValue
		} else {
			parse := quirkParse[rec.Key]
			if parse == nil {
				// Ignore unknown keys, it may be due to
				// downgrade of the ipp-usb
				continue
			}

			err := parse(q)
			if err != nil {
				err = fmt.Errorf("%s: %s", origin, err)
				return err
			}
		}

		quirks.byName[rec.Key] = q
	}

	if err == io.EOF {
		err = nil
	}

	return err
}

// Add appends Quirks to QuirksSet
func (qset *QuirksSet) Add(q *Quirks) {
	*qset = append(*qset, q)
}

// MatchByModelName returns collection of quirks, applicable for
// specific device, matched by model name.
func (qset QuirksSet) MatchByModelName(model string) Quirks {
	ret := Quirks{
		byName: make(map[string]*Quirk),
	}

	for _, quirks := range qset {
		for name, q := range quirks.byName {
			if GlobMatch(model, q.Match) >= 0 {
				q2 := ret.byName[name]
				if q2 != nil {
					q = q.prioritize(q2, model)
				}
				ret.byName[name] = q
			}
		}
	}

	return ret
}