X-Git-Url: https://git.distorted.org.uk/~mdw/tripe/blobdiff_plain/6f48da4ac71b5944d0464dd940ced3baf0d4311b..ad36789130f4756ba2a27ed9bb8b5ab62a21ce7d:/peerdb/tripe-newpeers.in?ds=sidebyside diff --git a/peerdb/tripe-newpeers.in b/peerdb/tripe-newpeers.in index 0ba9cb61..202cea8c 100644 --- a/peerdb/tripe-newpeers.in +++ b/peerdb/tripe-newpeers.in @@ -34,6 +34,7 @@ import cdb as CDB from sys import stdin, stdout, exit, argv import re as RX import os as OS +import socket as S from cStringIO import StringIO ###-------------------------------------------------------------------------- @@ -48,17 +49,64 @@ class CDBFake (object): def finish(me): pass +class ExpectedError (Exception): pass + ###-------------------------------------------------------------------------- ### A bulk DNS resolver. -class ResolverFailure (Exception): +class ResolverFailure (ExpectedError): def __init__(me, host, msg): me.host = host me.msg = msg def __str__(me): return "failed to resolve `%s': %s" % (me.host, me.msg) -class BulkResolver (object): +class ResolvingHost (object): + """ + A host name which is being looked up by a bulk-resolver instance. + + Most notably, this is where the flag-handling logic lives for the + $FLAGS[HOSTNAME] syntax. + """ + + def __init__(me, name): + """Make a new resolving-host object for the host NAME.""" + me.name = name + me.addr = { 'INET': [], 'INET6': [] } + me.failure = None + + def addaddr(me, af, addr): + """ + Add the address ADDR with address family AF. + + The address family may be `INET' or `INET6'. + """ + me.addr[af].append(addr) + + def failed(me, msg): + """ + Report that resolution of this host failed, with a human-readable MSG. + """ + me.failure = msg + + def get(me, flags): + """Return a list of addresses according to the FLAGS string.""" + if me.failure is not None: raise ResolverFailure(me.name, me.failure) + aa = [] + a4 = me.addr['INET'] + a6 = me.addr['INET6'] + all, any = False, False + for ch in flags: + if ch == '*': all = True + elif ch == '4': aa += a4; any = True + elif ch == '6': aa += a6; any = True + else: raise ValueError("unknown address-resolution flag `%s'" % ch) + if not any: aa = a4 + a6 + if not aa: raise ResolverFailure(me.name, 'no matching addresses found') + if not all: aa = [aa[0]] + return aa + +class BaseBulkResolver (object): """ Resolve a number of DNS names in parallel. @@ -76,36 +124,62 @@ class BulkResolver (object): def __init__(me): """Initialize the resolver.""" - me._resolvers = {} me._namemap = {} - def prepare(me, host): - """Prime the resolver to resolve the name HOST.""" - if host not in me._resolvers: - me._resolvers[host] = M.SelResolveByName \ - (host, - lambda name, alias, addr: - me._resolved(host, addr[0]), - lambda: me._resolved(host, None)) + def prepare(me, name): + """Prime the resolver to resolve the given host NAME.""" + if name not in me._namemap: + me._namemap[name] = host = ResolvingHost(name) + try: + ailist = S.getaddrinfo(name, None, S.AF_UNSPEC, S.SOCK_DGRAM, 0, + S.AI_NUMERICHOST | S.AI_NUMERICSERV) + except S.gaierror: + me._prepare(host, name) + else: + for af, skty, proto, cname, sa in ailist: + if af == S.AF_INET: host.addaddr('INET', sa[0]) + elif af == S.AF_INET6: host.addaddr('INET6', sa[0]) + + def lookup(me, name, flags): + """Fetch the address corresponding to the host NAME.""" + return me._namemap[name].get(flags) + +class BresBulkResolver (BaseBulkResolver): + """ + A BulkResolver using mLib's `bres' background resolver. + + This is always available (and might use ADNS), but only does IPv4. + """ + + def __init__(me): + super(BresBulkResolver, me).__init__() + """Initialize the resolver.""" + me._noutstand = 0 + + def _prepare(me, host, name): + """Arrange to resolve a NAME, reporting the results to HOST.""" + host._resolv = M.SelResolveByName( + name, + lambda cname, alias, addr: me._resolved(host, cname, addr), + lambda: me._resolved(host, None, [])) + me._noutstand += 1 def run(me): """Run the background DNS resolver until it's finished.""" - while me._resolvers: - M.select() + while me._noutstand: M.select() - def lookup(me, host): - """ - Fetch the address corresponding to HOST. - """ - addr = me._namemap[host] - if addr is None: - raise ResolverFailure(host, '(unknown failure)') - return addr + def _resolved(me, host, cname, addr): + """Callback function: remember that ADDRs are the addresses for HOST.""" + if not addr: + host.failed('(unknown failure)') + else: + if cname is not None: host.name = cname + for a in addr: host.addaddr('INET', a) + host._resolv = None + me._noutstand -= 1 - def _resolved(me, host, addr): - """Callback function: remember that ADDR is the address for HOST.""" - me._namemap[host] = addr - del me._resolvers[host] +## Select a bulk resolver. Currently, there's only one choice. +BulkResolver = BresBulkResolver ###-------------------------------------------------------------------------- ### The configuration parser. @@ -131,10 +205,11 @@ RX_CONT = RX.compile(r'''(?x) ^ \s+ ## Match a $(VAR) configuration variable reference; group 1 is the VAR. RX_REF = RX.compile(r'(?x) \$ \( ([^)]+) \)') -## Match a $[HOST] name resolution reference; group 1 is the HOST. -RX_RESOLVE = RX.compile(r'(?x) \$ \[ ([^]]+) \]') +## Match a $FLAGS[HOST] name resolution reference; group 1 are the flags; +## group 2 is the HOST. +RX_RESOLVE = RX.compile(r'(?x) \$ ([46*]*) \[ ([^]]+) \]') -class ConfigSyntaxError (Exception): +class ConfigSyntaxError (ExpectedError): def __init__(me, fname, lno, msg): me.fname = fname me.lno = lno @@ -145,7 +220,7 @@ class ConfigSyntaxError (Exception): def _fmt_path(path): return ' -> '.join(["`%s'" % hop for hop in path]) -class AmbiguousOptionError (Exception): +class AmbiguousOptionError (ExpectedError): def __init__(me, key, patha, vala, pathb, valb): me.key = key me.patha, me.vala = patha, vala @@ -155,7 +230,7 @@ class AmbiguousOptionError (Exception): "path %s yields `%s' but %s yields `%s'" % \ (me.key, _fmt_path(me.patha), me.vala, _fmt_path(me.pathb), me.valb) -class InheritanceCycleError (Exception): +class InheritanceCycleError (ExpectedError): def __init__(me, key, path): me.key = key me.path = path @@ -163,13 +238,13 @@ class InheritanceCycleError (Exception): return "Found a cycle %s looking up key `%s'" % \ (_fmt_path(me.path), me.key) -class MissingSectionException (Exception): +class MissingSectionException (ExpectedError): def __init__(me, sec): - me.key = key + me.sec = sec def __str__(me): return "Section `%s' not found" % (me.sec) -class MissingKeyException (Exception): +class MissingKeyException (ExpectedError): def __init__(me, sec, key): me.sec = sec me.key = key @@ -210,17 +285,17 @@ class ConfigSection (object): def _expand(me, string, resolvep): """ - Expands $(...) and (optionally) $[...] placeholders in STRING. + Expands $(...) and (optionally) $FLAGS[...] placeholders in STRING. RESOLVEP is a boolean switch: do we bother to tax the resolver or not? This is turned off by MyConfigParser's resolve() method while it's collecting hostnames to be resolved. """ - string = RX_REF.sub \ - (lambda m: me.get(m.group(1), resolvep), string) + string = RX_REF.sub(lambda m: me.get(m.group(1), resolvep), string) if resolvep: - string = RX_RESOLVE.sub(lambda m: me._cp._resolver.lookup(m.group(1)), - string) + string = RX_RESOLVE.sub( + lambda m: ' '.join(me._cp._resolver.lookup(m.group(2), m.group(1))), + string) return string def _parents(me): @@ -350,8 +425,10 @@ class MyConfigParser (object): * It recognizes `$(VAR)' references to configuration variables during expansion and processes them correctly. - * It recognizes `$[HOST]' name-resolver requests and handles them - correctly. + * It recognizes `$FLAGS[HOST]' name-resolver requests and handles them + correctly. FLAGS consists of characters `4' (IPv4 addresses), `6' + (IPv6 addresses), and `*' (all, space-separated, rather than just the + first). * Its parsing behaviour is well-defined. @@ -464,7 +541,7 @@ class MyConfigParser (object): for key in sec.items(): value = sec.get(key, resolvep = False) for match in RX_RESOLVE.finditer(value): - me._resolver.prepare(match.group(1)) + me._resolver.prepare(match.group(2)) me._resolver.run() ###-------------------------------------------------------------------------- @@ -562,8 +639,12 @@ def main(): cdb = CDB.cdbmake(opts.cdbfile, opts.cdbfile + '.new') else: cdb = CDBFake() - conf = getconf(args[1:]) - output(conf, cdb) + try: + conf = getconf(args[1:]) + output(conf, cdb) + except ExpectedError, e: + M.moan(str(e)) + exit(2) if __name__ == '__main__': main()