begin prototyping mdns

Author: sevenrats

source/utils/misc.brs

@@ -1,4 +1,5 @@
 import "pkg:/source/utils/config.brs"
+import "pkg:/source/utils/resolver/resolver.brs"
 
 function isNodeEvent(msg, field as string) as boolean
     return type(msg) = "roSGNodeEvent" and msg.getField() = field
@@ -233,6 +234,9 @@ function urlCandidates(input as string)
     host = url[2]
     port = url[3]
     path = url[4]
+
+    host = resolve(host) ' /source/utils/resolver/resolver.brs
+
     protoCandidates = []
     supportedProtos = ["http:", "https:"] ' appending colons because the regex does
     if proto = "none:" ' the user did not declare a protocol

source/utils/resolver/resolver.brs

@@ -0,0 +1,24 @@
+
+import "pkg:/source/utils/resolver/resolvers/local.brs"
+
+' takes a string like "domain.tld",
+' determines if a stub resolver exists for tld
+' if it does, it attempts to resolve and return an ip
+' if resolution fails or no stub resolver exists,
+' returns the arguemnt it received.
+' we get around the tls problem with .local, since most interfaces
+' on the roku do not accept custom tls directives in 12.0
+' such as the Poster, the agent that fetches bif files, etc.
+' this means there is no way that the user has domain which both
+' requires one of these resolvers and has a globally
+' signed certificate. later, perhaps we can implement a custom
+' httpAgent and do our own per-resolver verification.
+function resolve(dn as string) as string
+    parts = dn.tokenize(".")
+    domain = parts[0]
+    tld = parts[1]
+    if tld = "local"
+        localResolve(domain)
+    end if
+    return dn
+end function

source/utils/resolver/resolvers/local.brs

@@ -0,0 +1,110 @@
+function localResolve(dn as string) as string
+    print ".local resolver received domain " dn
+    sendQuery(dn)
+    ts = CreateObject("roTimespan")
+    while ts.totalSeconds() < 10
+        msg = Wait(5000, m.mdns.port)
+        if msg <> invalid
+            print "Message: "
+            print msg
+            ProcessMDNSResponse(msg)
+            exit while
+        end if
+    end while
+    return ""
+end function
+
+function processMdnsResponse(message)
+    if Type(message) = "roSocketEvent"
+        if message.GetSocketId() = m.mdns.socket.GetId()
+            print "The status of the socket: " m.mdns.socket.eSuccess()
+            if m.mdns.socket.IsReadable()
+                response = CreateObject("roByteArray")
+                r = m.mdns.socket.Receive(response, 0, 4096)
+                print "Received MDNS response packet: "
+                print response
+                print r
+            else
+                print "m.mdns.socket is not readable"
+            end if
+        else
+            print "message is not from m.mdns.socket"
+        end if
+    else
+        print "message is not an roSocketEvent"
+    end if
+    return ""
+end function
+
+function rdRightShift(num as integer, count = 1 as integer) as integer
+    mult = 2 ^ count
+    summand = 1
+    total = 0
+    for i = count to 31
+        if num and summand * mult
+            total = total + summand
+        end if
+        summand = summand * 2
+    end for
+    return total
+end function
+
+function rdINTtoHEX(num as integer) as object
+    ba = CreateObject("roByteArray")
+    ba.setresize(4, false)
+    ba[0] = rdRightShift(num, 24)
+    ba[1] = rdRightShift(num, 16)
+    ba[2] = rdRightShift(num, 8)
+    ba[3] = num ' truncates
+    return ba.toHexString().Right(2)
+end function
+
+sub printTests()
+    print rdINTtoHEX(183)
+end sub
+
+function strToHex(name as string) as object
+    ba = CreateObject("roByteArray")
+    ba.FromAsciiString(name)
+    return ba.toHexString()
+end function
+
+function createPacket(name as string)
+    firstPart = "000000000001000000000000"
+    secondPart = rdINTtoHEX(len(name)) + strToHex(name)
+    lastPart = "056c6f63616c0000010001"
+    packet = CreateObject("roByteArray")
+    packet.fromHexString(firstPart + secondPart + lastPart)
+    return packet
+end function
+
+sub sendQuery(name)
+    m.mdns = {
+        port: CreateObject("roMessagePort"),
+        address: CreateObject("roSocketAddress"),
+        group: CreateObject("roSocketAddress"),
+        socket: CreateObject("roDatagramSocket"),
+        urlTransfer: CreateObject("roUrlTransfer")
+    }
+
+    m.mdns.address.SetAddress("224.0.0.251:5353")
+    m.mdns.group.SetAddress("224.0.0.251:5353")
+
+    print "Succesfully joined group:" m.mdns.socket.JoinGroup(m.mdns.group)
+    m.mdns.socket.SetBroadcast(false)
+    m.mdns.socket.setaddress(m.mdns.address)
+    m.mdns.socket.NotifyReadable(true)
+    print "THE MULTICAST TTL: " m.mdns.socket.getMulticastTTL()
+    m.mdns.socket.SetMessagePort(m.mdns.port)
+    m.mdns.urlTransfer.SetPort(m.mdns.port)
+    'm.mdns.socket.SetBroadcast(true)
+    'print "Broadcast enabled: " m.mdns.socket.GetBroadcast()
+    'print "Multicastloop: " m.mdns.socket.GetMulticastLoop()
+    m.mdns.socket.SetSendToAddress(m.mdns.address)
+
+    mdnsQueryPacket = createPacket(name)
+    groupJoinPacket = CreateObject("roByteArray")
+    groupJoinPacket.fromHexString("1100eeff00000000")
+    m.mdns.socket.Send(groupJoinPacket, 0, mdnsQueryPacket.count())
+    m.mdns.socket.Send(mdnsQueryPacket, 0, mdnsQueryPacket.count())
+end sub