path: root/Godeps/_workspace/src/github.com/huin/goupnp/ssdp/registry.go

package ssdp

import (
    "fmt"
    "log"
    "net/http"
    "net/url"
    "regexp"
    "strconv"
    "sync"
    "time"

    "github.com/huin/goupnp/httpu"
)

const (
    maxExpiryTimeSeconds = 24 * 60 * 60
)

var (
    maxAgeRx = regexp.MustCompile("max-age=([0-9]+)")
)

type Entry struct {
    // The address that the entry data was actually received from.
    RemoteAddr string
    // Unique Service Name. Identifies a unique instance of a device or service.
    USN string
    // Notfication Type. The type of device or service being announced.
    NT string
    // Server's self-identifying string.
    Server string
    Host   string
    // Location of the UPnP root device description.
    Location *url.URL

    // Despite BOOTID,CONFIGID being required fields, apparently they are not
    // always set by devices. Set to -1 if not present.

    BootID   int32
    ConfigID int32

    SearchPort uint16

    // When the last update was received for this entry identified by this USN.
    LastUpdate time.Time
    // When the last update's cached values are advised to expire.
    CacheExpiry time.Time
}

func newEntryFromRequest(r *http.Request) (*Entry, error) {
    now := time.Now()
    expiryDuration, err := parseCacheControlMaxAge(r.Header.Get("CACHE-CONTROL"))
    if err != nil {
        return nil, fmt.Errorf("ssdp: error parsing CACHE-CONTROL max age: %v", err)
    }

    loc, err := url.Parse(r.Header.Get("LOCATION"))
    if err != nil {
        return nil, fmt.Errorf("ssdp: error parsing entry Location URL: %v", err)
    }

    bootID, err := parseUpnpIntHeader(r.Header, "BOOTID.UPNP.ORG", -1)
    if err != nil {
        return nil, err
    }
    configID, err := parseUpnpIntHeader(r.Header, "CONFIGID.UPNP.ORG", -1)
    if err != nil {
        return nil, err
    }
    searchPort, err := parseUpnpIntHeader(r.Header, "SEARCHPORT.UPNP.ORG", ssdpSearchPort)
    if err != nil {
        return nil, err
    }

    if searchPort < 1 || searchPort > 65535 {
        return nil, fmt.Errorf("ssdp: search port %d is out of range", searchPort)
    }

    return &Entry{
        RemoteAddr:  r.RemoteAddr,
        USN:         r.Header.Get("USN"),
        NT:          r.Header.Get("NT"),
        Server:      r.Header.Get("SERVER"),
        Host:        r.Header.Get("HOST"),
        Location:    loc,
        BootID:      bootID,
        ConfigID:    configID,
        SearchPort:  uint16(searchPort),
        LastUpdate:  now,
        CacheExpiry: now.Add(expiryDuration),
    }, nil
}

func parseCacheControlMaxAge(cc string) (time.Duration, error) {
    matches := maxAgeRx.FindStringSubmatch(cc)
    if len(matches) != 2 {
        return 0, fmt.Errorf("did not find exactly one max-age in cache control header: %q", cc)
    }
    expirySeconds, err := strconv.ParseInt(matches[1], 10, 16)
    if err != nil {
        return 0, err
    }
    if expirySeconds < 1 || expirySeconds > maxExpiryTimeSeconds {
        return 0, fmt.Errorf("rejecting bad expiry time of %d seconds", expirySeconds)
    }
    return time.Duration(expirySeconds) * time.Second, nil
}

// parseUpnpIntHeader is intended to parse the
// {BOOT,CONFIGID,SEARCHPORT}.UPNP.ORG header fields. It returns the def if
// the head is empty or missing.
func parseUpnpIntHeader(headers http.Header, headerName string, def int32) (int32, error) {
    s := headers.Get(headerName)
    if s == "" {
        return def, nil
    }
    v, err := strconv.ParseInt(s, 10, 32)
    if err != nil {
        return 0, fmt.Errorf("ssdp: could not parse header %s: %v", headerName, err)
    }
    return int32(v), nil
}

var _ httpu.Handler = new(Registry)

// Registry maintains knowledge of discovered devices and services.
type Registry struct {
    lock  sync.Mutex
    byUSN map[string]*Entry
}

func NewRegistry() *Registry {
    return &Registry{
        byUSN: make(map[string]*Entry),
    }
}

// ServeMessage implements httpu.Handler, and uses SSDP NOTIFY requests to
// maintain the registry of devices and services.
func (reg *Registry) ServeMessage(r *http.Request) {
    if r.Method != methodNotify {
        return
    }

    nts := r.Header.Get("nts")

    var err error
    switch nts {
    case ntsAlive:
        err = reg.handleNTSAlive(r)
    case ntsUpdate:
        err = reg.handleNTSUpdate(r)
    case ntsByebye:
        err = reg.handleNTSByebye(r)
    default:
        err = fmt.Errorf("unknown NTS value: %q", nts)
    }
    log.Printf("In %s request from %s: %v", nts, r.RemoteAddr, err)
}

func (reg *Registry) handleNTSAlive(r *http.Request) error {
    entry, err := newEntryFromRequest(r)
    if err != nil {
        return err
    }

    reg.lock.Lock()
    defer reg.lock.Unlock()

    reg.byUSN[entry.USN] = entry

    return nil
}

func (reg *Registry) handleNTSUpdate(r *http.Request) error {
    entry, err := newEntryFromRequest(r)
    if err != nil {
        return err
    }
    nextBootID, err := parseUpnpIntHeader(r.Header, "NEXTBOOTID.UPNP.ORG", -1)
    if err != nil {
        return err
    }
    entry.BootID = nextBootID

    reg.lock.Lock()
    defer reg.lock.Unlock()

    reg.byUSN[entry.USN] = entry

    return nil
}

func (reg *Registry) handleNTSByebye(r *http.Request) error {
    reg.lock.Lock()
    defer reg.lock.Unlock()

    delete(reg.byUSN, r.Header.Get("USN"))

    return nil
}