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Code Issues Releases Wiki Activity

ircd::net::dns::resolver: Question must match or this is the mist of a packet spray.

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This commit is contained in:
Jason Volk 2022-08-14 18:55:42 -07:00
parent 7469c09130
commit 31c1e834bd
2 changed files with 39 additions and 31 deletions
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2
include/ircd/net/dns_resolver.h
View file

@ -66,7 +66,7 @@ ircd::net::dns::resolver
// reception
bool handle_error(const header &, tag &);
void handle_reply(const header &, const const_buffer &body, tag &);
void handle_reply(const header &, const_buffer, tag &);
void handle_reply(const ipport &, const header &, const const_buffer &body);
void handle(const ipport &, const mutable_buffer &);
void handle_interrupt(ctx::ctx *const &) noexcept;

68
ircd/net_dns_resolver.cc
View file

@ -680,6 +680,42 @@ ircd::net::dns::resolver::handle_reply(const ipport &from,
header.arcount,
};
if(unlikely(header.qr != 1))
throw rfc1035::error
{
"Response header is marked as 'Query' and not 'Response'"
};
if(header.qdcount > MAX_COUNT || header.ancount > MAX_COUNT)
throw error
{
"Response contains too many sections..."
};
if(header.qdcount < 1)
throw error
{
"Response does not contain the question."
};
const_buffer buffer
{
body
};
// Questions are regurgitated back to us so they must be parsed first
thread_local std::array<rfc1035::question, MAX_COUNT> qd;
for(size_t i(0); i < header.qdcount; ++i)
consume(buffer, size(qd.at(i).parse(buffer)));
// Question must match or this is the mist of a packet spray with
// matching tag and source ip.
if(unlikely(!has(qd.at(0).name, host(tag.hp))))
throw error
{
"Response contains the wrong question."
};
// Handle ServFail as a special case here. We can try again without
// handling this tag or propagating this error any further yet.
if(header.rcode == 2 && tag.tries < size_t(server.size()))
@ -711,33 +747,15 @@ ircd::net::dns::resolver::handle_reply(const ipport &from,
assert(tag.tries > 0);
tag.last = steady_point::min(); // tag ignored by the timeout worker during handling.
tag.rcode = header.rcode;
handle_reply(header, body, tag);
handle_reply(header, buffer, tag);
}
void
ircd::net::dns::resolver::handle_reply(const header &header,
const const_buffer &body,
const_buffer buffer,
tag &tag)
try
{
if(unlikely(header.qr != 1))
throw rfc1035::error
{
"Response header is marked as 'Query' and not 'Response'"
};
if(header.qdcount > MAX_COUNT || header.ancount > MAX_COUNT)
throw error
{
"Response contains too many sections..."
};
if(header.qdcount < 1)
throw error
{
"Response does not contain the question."
};
if(!handle_error(header, tag))
throw rfc1035::error
{
@ -746,16 +764,6 @@ try
rfc1035::rcode.at(header.rcode)
};
const_buffer buffer
{
body
};
// Questions are regurgitated back to us so they must be parsed first
thread_local std::array<rfc1035::question, MAX_COUNT> qd;
for(size_t i(0); i < header.qdcount; ++i)
consume(buffer, size(qd.at(i).parse(buffer)));
// Answers are parsed into this buffer
thread_local std::array<rfc1035::answer, MAX_COUNT> an;
for(size_t i(0); i < header.ancount; ++i)