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Fix multiple vulnerabilities in the resolver #4872

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merged 1 commit into from
Feb 23, 2025
Merged

Fix multiple vulnerabilities in the resolver #4872

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30 changes: 21 additions & 9 deletions core/net/dns.odin
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Original file line number Diff line number Diff line change
Expand Up @@ -7,23 +7,26 @@ package net
*/

/*
Copyright 2022 Tetralux <[email protected]>
Copyright 2022 Colin Davidson <[email protected]>
Copyright 2022 Jeroen van Rijn <[email protected]>.
Copyright 2024 Feoramund <[email protected]>.
Copyright 2022 Tetralux <[email protected]>
Copyright 2022 Colin Davidson <[email protected]>
Copyright 2022 Jeroen van Rijn <[email protected]>.
Copyright 2024 Feoramund <[email protected]>.
Copyright 2025 Christiano Haesbaert <[email protected]>.
Made available under Odin's BSD-3 license.

List of contributors:
Tetralux: Initial implementation
Colin Davidson: Linux platform code, OSX platform code, Odin-native DNS resolver
Jeroen van Rijn: Cross platform unification, code style, documentation
Feoramund: FreeBSD platform code
Haesbaert: Security fixes
*/

import "core:mem"
import "core:strings"
import "core:time"
import "core:os"
import "core:math/rand"
/*
Default configuration for DNS resolution.
*/
Expand Down Expand Up @@ -227,7 +230,7 @@ get_dns_records_from_nameservers :: proc(hostname: string, type: DNS_Record_Type
}

hdr := DNS_Header{
id = 0,
id = u16be(rand.uint32()),
is_response = false,
opcode = 0,
is_authoritative = false,
Expand Down Expand Up @@ -272,17 +275,23 @@ get_dns_records_from_nameservers :: proc(hostname: string, type: DNS_Record_Type
return nil, .Connection_Error
}

recv_sz, _ := recv_udp(conn, dns_response_buf[:]) or_continue
recv_sz, src := recv_udp(conn, dns_response_buf[:]) or_continue
if recv_sz == 0 {
continue
}
if src != name_server {
continue
}

dns_response = dns_response_buf[:recv_sz]

rsp, _ok := parse_response(dns_response, type)
rsp, xid, _ok := parse_response(dns_response, type)
if !_ok {
return nil, .Server_Error
}
if id != xid {
continue
}

if len(rsp) == 0 {
continue
Expand Down Expand Up @@ -803,7 +812,7 @@ parse_record :: proc(packet: []u8, cur_off: ^int, filter: DNS_Record_Type = nil)
- Data[]
*/

parse_response :: proc(response: []u8, filter: DNS_Record_Type = nil, allocator := context.allocator) -> (records: []DNS_Record, ok: bool) {
parse_response :: proc(response: []u8, filter: DNS_Record_Type = nil, allocator := context.allocator) -> (records: []DNS_Record, xid: u16be, ok: bool) {
context.allocator = allocator

HEADER_SIZE_BYTES :: 12
Expand All @@ -816,11 +825,13 @@ parse_response :: proc(response: []u8, filter: DNS_Record_Type = nil, allocator
dns_hdr_chunks := mem.slice_data_cast([]u16be, response[:HEADER_SIZE_BYTES])
hdr := unpack_dns_header(dns_hdr_chunks[0], dns_hdr_chunks[1])
if !hdr.is_response {
delete(_records)
return
}

question_count := int(dns_hdr_chunks[2])
if question_count != 1 {
delete(_records)
return
}
answer_count := int(dns_hdr_chunks[3])
Expand Down Expand Up @@ -872,6 +883,7 @@ parse_response :: proc(response: []u8, filter: DNS_Record_Type = nil, allocator
append(&_records, rec)
}
}
xid = hdr.id

return _records[:], true
return _records[:], xid, true
}