ref: 91a715bcdfdd2c762c700b45591e74f42c4a0626
dir: /lib/std/resolve+posixy.myr/
use sys
use "alloc"
use "chartype"
use "die"
use "endian"
use "extremum"
use "hashfuncs"
use "htab"
use "ipparse"
use "option"
use "result"
use "slcp"
use "sldup"
use "sleq"
use "slpush"
use "slurp"
use "strfind"
use "strsplit"
use "strstrip"
use "threadhooks"
use "types"
use "utf"
use "fmt"
pkg std =
type rectype = union
`DnsA /* host address */
`DnsNS /* authoritative name server */
`DnsCNAME /* canonical name for an alias */
`DnsSOA /* marks the start of a zone of authority */
`DnsWKS /* well known service description */
`DnsPTR /* domain name pointer */
`DnsHINFO /* host information */
`DnsMINFO /* mailbox or mail list information */
`DnsMX /* mail exchange */
`DnsTXT /* text strings */
`DnsAAAA /* ipv6 host address */
;;
type resolveerr = union
`Badconn
`Badhost
`Badsrv
`Badquery
`Badresp
;;
type hostinfo = struct
fam : sys.sockfam
stype : sys.socktype
ttl : uint32
addr : netaddr
;;
const resolve : (host : byte[:] -> result(hostinfo[:], resolveerr))
const resolvemx : (host : byte[:] -> result(hostinfo[:], resolveerr))
const resolverec : (host : byte[:], t : rectype -> result(hostinfo[:], resolveerr))
;;
const Hostfile = "/etc/hosts"
const Resolvfile = "/etc/resolv.conf"
var hostmap : htab(byte[:], hostinfo)#
var search : byte[:][:]
var nameservers : netaddr[:]
const __init__ = {
hostmap = mkht(strhash, streq)
loadhosts()
loadresolv()
}
const resolve = {host
-> resolverec(host, `DnsA)
}
const resolvemx = {host
-> resolverec(host, `DnsMX)
}
const resolverec = {host, t
match hostfind(host)
| `Some hinf:
-> `Ok sldup([hinf][:])
| `None:
-> dnsresolve(host, rectype(`DnsA))
;;
}
const hostfind = {host
var h
lock(netlck)
h = htget(hostmap, host)
unlock(netlck)
-> h
}
const loadhosts = {
var h
var lines
match slurp(Hostfile)
| `Ok d: h = d
| `Err m: -> void
;;
lines = strsplit(h, "\n")
for l in lines
/* trim comment */
match strfind(l, "#")
| `Some idx: l = l[:idx]
| `None: /* whole line */
;;
match word(l)
| `Some (ip, rest):
match ipparse(ip)
| `Some addr:
lock(netlck)
addhosts(addr, ip, rest)
unlock(netlck)
| `None:
/*
invalid addresses are ignored: we don't want to break stuff
with invalid or unsupported addresses
*/
;;
| `None:
;;
;;
slfree(lines)
slfree(h)
}
const addhosts = {addr, as, str
var hinf
var fam
match addr
| `Ipv4 _: fam = sys.Afinet
| `Ipv6 _: fam = sys.Afinet6
;;
while true
match word(str)
| `Some (name, rest):
str = rest
if hthas(hostmap, name)
continue
;;
unlock(netlck)
hinf = [
.fam=fam,
.stype = 0,
.ttl = 0,
.addr = addr
]
htput(hostmap, sldup(name), hinf)
| `None:
-> void
;;
;;
}
const loadresolv = {
var h
var lines
lock(netlck)
match slurp(Resolvfile)
| `Ok d: h = d
| `Err m: -> void
;;
lines = strsplit(h, "\n")
for l in lines
match strfind(l, "#")
| `Some _idx: l = l[:_idx]
| `None:
;;
match word(l)
| `Some ("nameserver", srv):
addns(srv)
| `Some (_, rest):
/* invalid or unrecognized commands */
| `None:
/* unrecognized lines */
;;
;;
slfree(lines)
slfree(h)
unlock(netlck)
}
const addns = {rest
match word(rest)
| `Some (name, _):
match ipparse(name)
| `Some addr:
slpush(&nameservers, addr)
| `None:
/* nothing */
;;
| `None:
/* nothing */
;;
}
const word = {s
var c, len
len = 0
s = strfstrip(s)
for c = decode(s[len:]); c != Badchar && !isblank(c); c = decode(s[len:])
len += charlen(c)
;;
if len == 0
-> `None
else
-> `Some (s[:len], s[len:])
;;
}
const dnsresolve = {host, rt
var nsrv, r
if !valid(host)
-> `Err (`Badhost)
;;
lock(netlck)
for ns in nameservers
nsrv = dnsconnect(ns)
if nsrv >= 0
r = dnsquery(nsrv, host, rt)
sys.close(nsrv)
unlock(netlck)
-> r
;;
;;
unlock(netlck)
-> `Err (`Badsrv)
}
const dnsconnect = {ns
match ns
| `Ipv4 addr: -> dnsconnectv4(addr)
| `Ipv6 addr: die("don't support ipv6 yet\n")
;;
}
const dnsconnectv4 = {addr
var sa : sys.sockaddr_in
var s
var status
s = sys.socket(sys.Afinet, sys.Sockdgram, 0)
if s < 0
-> -1
;;
sa = [
.fam = sys.Afinet,
.port = hosttonet(53),
.addr = addr,
]
status = sys.connect(s, (&sa : sys.sockaddr#), sizeof(sys.sockaddr_in))
if status < 0
-> -1
;;
-> s
}
const dnsquery = {srv, host, t
var id
var r
id = tquery(srv, host, t)
r = rquery(srv, id)
-> r
}
const Qr : uint16 = 1 << 0
const Aa : uint16 = 1 << 5
const Tc : uint16 = 1 << 6
const Rd : uint16 = 1 << 7
const Ra : uint16 = 1 << 8
var nextid : uint16 = 42
const tquery = {srv, host, t
var pkt : byte[512] /* big enough */
var off : size
/* header */
off = 0
nextid++
off += pack16(pkt[:], off, nextid) /* id */
off += pack16(pkt[:], off, Ra) /* flags */
off += pack16(pkt[:], off, 1) /* qdcount */
off += pack16(pkt[:], off, 0) /* ancount */
off += pack16(pkt[:], off, 0) /* nscount */
off += pack16(pkt[:], off, 0) /* arcount */
/* query */
off += packname(pkt[:], off, host) /* host */
off += pack16(pkt[:], off, (t : uint16)) /* qtype: a record */
off += pack16(pkt[:], off, 0x1) /* qclass: inet4 */
sys.write(srv, pkt[:off])
-> nextid
}
const rquery = {srv, id
var pktbuf : byte[1024]
var pkt
var n
n = sys.read(srv, pktbuf[:])
if n < 0
-> `Err `Badconn
;;
pkt = pktbuf[:n]
-> hosts(pkt, id)
}
const hosts = {pkt, id : uint16
var off
var v, q, a
var hinf : hostinfo[:]
off = 0
/* parse header */
(v, off) = unpack16(pkt, off) /* id */
if v != id
-> `Err `Badresp
;;
(v, off) = unpack16(pkt, off) /* flags */
(q, off) = unpack16(pkt, off) /* qdcount */
(a, off) = unpack16(pkt, off) /* ancount */
(v, off) = unpack16(pkt, off) /* nscount */
(v, off) = unpack16(pkt, off) /* arcount */
/* skip past query records */
for var i = 0; i < q; i++
off = skipname(pkt, off) /* name */
(v, off) = unpack16(pkt, off) /* type */
(v, off) = unpack16(pkt, off) /* class */
;;
/* parse answer records */
hinf = slalloc((a : size))
for var i = 0; i < a; i++
off = skipname(pkt, off) /* name */
(v, off) = unpack16(pkt, off) /* type */
(v, off) = unpack16(pkt, off) /* class */
(hinf[i].ttl, off) = unpack32(pkt, off) /* ttl */
(v, off) = unpack16(pkt, off) /* rdatalen */
/* the thing we're interested in: our IP address */
hinf[i].addr = `Ipv4 [pkt[off], pkt[off+1], pkt[off+2], pkt[off+3]]
off += 4;
;;
-> `Ok hinf
}
const skipname = {pkt, off
var sz
for sz = (pkt[off] : size); sz != 0; sz = (pkt[off] : size)
/* ptr is 2 bytes */
if sz & 0xC0 == 0xC0
-> off + 2
else
off += sz + 1
;;
;;
-> off + 1
}
const pack16 = {buf, off, v
buf[off] = ((v & 0xff00) >> 8 : byte)
buf[off+1] = ((v & 0x00ff) >> 0 : byte)
-> sizeof(uint16) /* we always write one uint16 */
}
const unpack16 = {buf, off
var v
v = 0
v |= (buf[off + 0] : uint16) << 8
v |= (buf[off + 1] : uint16) << 0
-> (v, off+sizeof(uint16))
}
const unpack32 = {buf, off
var v
v = (buf[off] : uint32) << 24
v |= (buf[off+1] : uint32) << 32
v |= (buf[off+2] : uint32) << 8
v |= (buf[off+3] : uint32)
-> (v, off+sizeof(uint32))
}
const packname = {buf, off : size, host
var start
var last
start = off
last = 0
for var i = 0; i < host.len; i++
if host[i] == ('.' : byte)
off += addseg(buf, off, host[last:i])
last = i + 1
;;
;;
if host[host.len - 1] != ('.' : byte)
off += addseg(buf, off, host[last:])
;;
off += addseg(buf, off, "") /* null terminating segment */
-> off - start
}
const addseg = {buf, off, str
buf[off] = (str.len : byte)
slcp(buf[off + 1 : off + str.len + 1], str)
-> str.len + 1
}
const valid = {host : byte[:]
var i
var seglen
/* maximum length: 255 chars */
if host.len > 255
-> false
;;
seglen = 0
for i = 0; i < host.len; i++
if host[i] == ('.' : byte)
seglen = 0
;;
if seglen > 63
-> false
;;
if host[i] & 0x80 != 0
-> false
;;
;;
-> true
}
const rectype = {rtype
match rtype
| `DnsA: -> 1 /* host address */
| `DnsNS: -> 2 /* authoritative name server */
| `DnsCNAME: -> 5 /* canonical name for an alias */
| `DnsSOA: -> 6 /* marks the start of a zone of authority */
| `DnsWKS: -> 11 /* well known service description */
| `DnsPTR: -> 12 /* domain name pointer */
| `DnsHINFO: -> 13 /* host information */
| `DnsMINFO: -> 14 /* mailbox or mail list information */
| `DnsMX: -> 15 /* mail exchange */
| `DnsTXT: -> 16 /* text strings */
| `DnsAAAA: -> 28 /* ipv6 host address */
;;
}