From ff1fb155312b1c829beacf77e97996b58caf3159 Mon Sep 17 00:00:00 2001
From: dschmenk <dschmenk@sbcglobal.net>
Date: Sat, 31 Oct 2015 17:01:01 -0700
Subject: [PATCH] Working DNS resolution

---
 src/libsrc/dhcp.pla |   4 +-
 src/libsrc/inet.pla | 200 ++++++++++++++++++++++++++++++++++++++------
 2 files changed, 177 insertions(+), 27 deletions(-)

diff --git a/src/libsrc/dhcp.pla b/src/libsrc/dhcp.pla
index 6932c68..ff89ae1 100644
--- a/src/libsrc/dhcp.pla
+++ b/src/libsrc/dhcp.pla
@@ -255,7 +255,9 @@ loop
 iNet:closeUDP(portDHCP)
 iNet:setInterfaceIP(@localip, @localnet, @localgw)
 puts(@boundstr);putip(@localip);putc('/');putip(@localnet);putln
-iNet:setDNS(@localdns)
+if localdns:0 | localdns:2
+    iNet:setDNS(@localdns)
+fin
 puts(@dnsstr);putip(@localdns);putln
 
 done
diff --git a/src/libsrc/inet.pla b/src/libsrc/inet.pla
index e87cb78..73aa6b2 100644
--- a/src/libsrc/inet.pla
+++ b/src/libsrc/inet.pla
@@ -28,6 +28,17 @@ struc t_inet
     word resolveIP
 end
 //
+// DNS message
+//
+struc t_dnshdr
+    word dnsID
+    word dnsCode
+    word dnsQdCount
+    word dnsAnCount
+    word dnsNsCount
+    word dnsArCount
+end
+//
 // External interface to net class. Must be first.
 //
 export byte[t_inet] iNet
@@ -39,35 +50,56 @@ byte            = "UTHERNET"
 byte            = ""
 word driver = @netDrivers
 //
-// DNS address
+// DNS address (default to Google DNS)
 //
-byte[4] dns
-
-export def iNetInit
-    //
-    // Look for net hardware
-    //
-    while ^driver
-        //puts(driver);putln
-	if modexec(driver) >= 0
-            break
-	fin
-	driver = driver + ^driver + 1
-    loop
-    if !^driver
-        return 0
-    fin
-    //
-    // Get an IP address
-    //
-    modexec("DHCP")
-    return @iNet
-end
+byte[4] dns = 8,8,8,8
+const DNS_QUERY  = 1
+const DNS_ANSWER = 2
+byte stateDNS
 
 def iNetSetDNS(ipptr)
     return memcpy(@dns, ipptr, 4)
 end
 
+def putln
+    return putc($0D)
+end
+def putb(hexb)
+    return call($FDDA, hexb, 0, 0, 0)
+end
+def puth(hex)
+    return call($F941, hex >> 8, hex, 0, 0)
+end
+def puti(i)
+  if i < 0; putc('-'); i = -i; fin
+  if i < 10
+    putc(i + '0')
+  else
+    puti(i / 10)
+    putc(i % 10 + '0')
+  fin
+end
+def putip(ipptr)
+    byte i
+    
+    for i = 0 to 2
+        puti(ipptr->[i]); putc('.')
+    next
+    return puti(ipptr->[i])
+end
+def dumpbytes(buf, len)
+    word i
+    
+    for i = 0 to len - 1
+        putb(buf->[i])
+	if i & 7 == 7
+	    putln
+	else
+	    putc(' ')
+	fin
+    next
+end
+
 def parseIP(ipstr, ipaddr)
     byte i
     word endstr
@@ -86,21 +118,137 @@ def parseIP(ipstr, ipaddr)
     return i == 3
 end
 
+def parseDomain(domstr, msgptr)
+    byte i, l
+
+    l = 0
+    for i = 1 to ^domstr
+        if domstr->[i] == '.'
+	    msgptr->[l] = i - l - 1
+	    l = i
+	else
+	    msgptr->[i] = domstr->[i]
+	fin
+    next
+    msgptr->[l] = i - l - 1
+    msgptr  = msgptr + i
+    ^msgptr = 0 // Terminate label list
+    return msgptr + 1 
+end
+
+def recvDNS(remip, remport, pkt, len, ipaddr)
+    byte q, r
+    word resptr
+    
+    if pkt=>dnsID == $BEEF
+        q = pkt->dnsQdCount.1
+        r = pkt->dnsAnCount.1 + pkt->dnsNsCount.1 + pkt->dnsArCount.1
+	resptr = pkt + t_dnshdr
+	while q
+	    while ^resptr
+	        //puts(resptr); putc('.')
+		resptr = resptr + ^resptr + 1
+	    loop
+	    resptr = resptr + 1
+	    //putln; dumpbytes(resptr, 4); putln
+	    resptr = resptr + 4
+	    q = q - 1
+	loop
+	while r
+	    //dumpbytes(resptr, 40); putln
+	    if ^resptr & $C0 == $C0
+	        resptr = resptr + 2
+	    else
+	        while ^resptr
+	            //puts(resptr); putc('.')
+		    resptr = resptr + ^resptr + 1
+		loop
+		resptr = resptr + 1
+	    fin
+	    if resptr->1 == 1 and resptr->3 == 1 and resptr->9 == 4
+	        ipaddr=>0 = resptr=>10
+		ipaddr=>2 = resptr=>12
+	    fin
+	    //putln; dumpbytes(resptr, 10); putc(':'); putln
+	    resptr = resptr + 8
+	    //dumpbytes(resptr + 2, ^(resptr + 1))
+	    resptr = resptr + 2 + ^(resptr + 1); putln
+	    r = r - 1
+	loop
+    fin
+    stateDNS = DNS_ANSWER
+end
+
 def iNetResolve(namestr, ipaddr)
+    word dnspkt, msgptr, msglen
+    word portDNS, timeout
+    
     ipaddr=>0 = 0
     ipaddr=>2 = 0
     if not parseIP(namestr, ipaddr)
         //
 	// Query Domain Name Server for address
 	//
+	dnspkt             = heapmark // Use heap as working DNS query packet
+	msgptr             = dnspkt
+	msgptr=>dnsID      = $BEEF
+	msgptr=>dnsCode    = $0001 // RD (Recursion Desired)
+	msgptr=>dnsQdCount = $0100 // BE count = 1
+	msgptr=>dnsAnCount = 0
+	msgptr=>dnsNsCount = 0
+	msgptr=>dnsArCount = 0
+	msgptr             = parseDomain(namestr, msgptr + t_dnshdr)
+	msgptr=>0          = $0100 // BE TYPE  = Address
+	msgptr=>2          = $0100 // BE CLASS = INternet
+	msglen             = msgptr - dnspkt + 4
+	heapalloc(msglen)
+	//
+	// Prepare to receive DNS answer from server
+	//
+	portDNS = iNet:openUDP(3999, @recvDNS, ipaddr)
+	//
+	// Service IP
+	//
+	stateDNS = DNS_QUERY
+	iNet:sendUDP(portDNS, @dns, 53, dnspkt, msglen)
+	for timeout = 1 to 1000
+	    iNet:serviceIP()
+	    if stateDNS == DNS_ANSWER
+	        break
+	    fin
+	next
+	iNet:closeUDP(portDNS)
+	heaprelease(dnspkt)
     fin
-    return 1
+    return ipaddr=>0 <> 0 or ipaddr=>2 <> 0
+end
+
+export def iNetInit
+    //
+    // Look for net hardware
+    //
+    while ^driver
+        //puts(driver);putln
+	if modexec(driver) >= 0
+            break
+	fin
+	driver = driver + ^driver + 1
+    loop
+    if !^driver
+        return 0
+    fin
+    //
+    // Get an IP address
+    //
+    modexec("DHCP")
+    iNet:resolveIP = @iNetResolve
+    return @iNet
 end
 
 //
-// Fill iNet 
+// Fill iNet class
+//
 iNet:initIP    = @iNetInit
 iNet:setDNS    = @iNetSetDNS
-iNet:resolveIP = @iNetResolve
 
 done