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# Provide nice ways to do DNS resolution
# Spec: http://www.faqs.org/rfcs/rfc1035.html
<
{ ==err _ 0 lt { err ?? } rep } "+??" deffd
{ ==err ==actions _ 0 lt { actions err ??? } rep } "+???" deffd
# Uncomment to enable function ("deffd") tracing for this scope
# {
# -010 { " executing" cat dump }_ -01 ; -01 =*:
# }" /deffd deffd
bin .scan "->" via
bin .print "<-" via
bin .produce "<=" via
sys .linux "+" via
# 0 -> ascii ip address
# 0 <- ipv4 address as un32
{ [ -01 "^(\\d+)\\.(\\d+)\\.(\\d+)\\.(\\d+)$" regex not { "not an IPv4 address" die } rep ]
txt .consume .u reverse str .fromArray
} /parseIpv4 deffd
# 0 -> hostname
# 0 <- ipv4 address as un32
{ ==host
ensureResolvConf
resolvConf .nameserver parseIpv4 53 net .udp .sockaddrIpv4
+AFINET +SOCKDGRAM +IPPROTOUDP +socket +??io.net.socket _ ==s
-01 +connect +??io.net.connect --
s
host buildDnsQueryMessage
_ len
+write +??io.net.write -- # TODO: correctly handle non-full writes
1024 str .alloc ==buf
s
buf
_ len
+read +??io.net.read
buf str .inplacePrefix =buf
buf
->un16 ==id # expected to be zero
->u16 2 math .base ==bitfields
->un16 ==qdCount
->un16 ==anCount
->un16 ==nsCount # expected to be zero
->un16 ==arCount # expected to be zero
qdCount {
->u8 ==labelLength
{ labelLength } {
labelLength 64 ge {
"unexpected compression pointer in DNS reply" die
} {
labelLength -01 str .postfix
->u8 =labelLength
} ? *
} loop
->un16 ==qType
->un16 ==qClass
} rep
# _ |dump each
anCount {
->u8 ==labelLength
{ labelLength } {
labelLength 64 ge {
->u8 labelLength 63 band 256 mul add ==pointerTarget # TODO actually care for pointer target
0 =labelLength
} {
labelLength -01 str .postfix
->u8 =labelLength
} ? *
} loop
->un16 1 eq not { "Answer type field was not 'A'" die } rep
->un16 1 eq not { "Answer class field was not 'INET'" die } rep
->un32 -- # _ ==ttl "TTL: " dump dump
->un16 4 eq not { "Answer data length was not 4" die } rep
4 -01 str .inplacePrefix # 4 byte IP data to be returned
} {
"Answer did not contain any answer data" die
} ? *
} /resolveIpv4 deffd
# 0 -> hostname
# 0 <- dns query message
{ ==host
0 <=un16 # id
[ 1 0 0 0 0 0 0 0 ] 2 math .unbase <-u8 # QR Opcode*4 AA TC RD
[ 0 0 0 0 0 0 0 0 ] 2 math .unbase <-u8 # RA Z*3 RCODE*4
1 <-un16 # qdcount
0 <-un16 # ancount
0 <-un16 # nscount
0 <-un16 # arcount
==query
host { "^([^.]+)\\.?(.*)" regex } {
makeLabel query -01 cat =query
} loop
query
"\0" cat
1 <-un16 # "A" query
1 <-un16 # "Internet" QCLASS
} /buildDnsQueryMessage deffd
# 0 -> string
# 0 <- string with u8 length prepended
{ _ len <=u8 -01 cat } /makeLabel deffd
# 0 -> dns message
# 0 <- dns message with tcp transport header prepended
{ _ len <=u16 -01 cat } /prepareTcpMessage deffd
<
0 ==?loaded
{ defv }' /put deffd
> /resolvConf defvd
# ensure resolv.conf is parsed
{
resolvConf .loaded not {
{ [
{ _ "^[ ]*nameserver[ ]+(.*)" regex } { /nameserver resolvConf .put }
] conds -- }
"/etc/resolv.conf" sys .file ":" via :open :eachLine :close
1 /loaded resolvConf .put
} rep
} /ensureResolvConf deffd
> /dns net .defv
# vim: syn=elymas
|
