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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,86 @@ | ||
| /* | ||
| * Copyright (c) 2022 DuckDuckGo | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
|
|
||
| package main | ||
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|
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| // #include <android/log.h> | ||
| import "C" | ||
|
|
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| import ( | ||
| "fmt" | ||
| "strings" | ||
|
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| "github.com/miekg/dns" | ||
| ) | ||
|
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| // parseDNSResponse parses the raw DNS response from a byte slice. | ||
| func parseDNSResponse(data []byte) *dns.Msg { | ||
| tag := cstring("WireGuard/GoBackend/parseDNSResponse") | ||
| // Create a new DNS message structure | ||
| dnsMsg := new(dns.Msg) | ||
|
|
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| // Unpack the DNS message from the raw data | ||
| err := dnsMsg.Unpack(data) | ||
| if err != nil { | ||
| C.__android_log_write(C.ANDROID_LOG_DEBUG, tag, cstring(fmt.Sprintf("Failed to unpack DNS message: %v", err))) | ||
| return nil | ||
| } | ||
|
|
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| // Check if this is a DNS response (QR bit set) | ||
| if dnsMsg.Response { | ||
| return dnsMsg | ||
| } | ||
|
|
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| // If not a response, return nil | ||
| return nil | ||
| } | ||
|
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|
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| /* | ||
| * WasDNSMalwareBlocked checks if the DNS packet contains a "blocked:m" TXT | ||
| * record under the "explanation.invalid" domain. If such a record is found, | ||
| * it returns true along with the domain being blocked. | ||
| * That record is found when our the DDG (malware) DNS server blocks domains that | ||
| * serve malware | ||
| */ | ||
| func WasDNSMalwareBlocked(dnsData []byte) (bool, string) { | ||
| dnsResponse := parseDNSResponse(dnsData) | ||
| if dnsResponse == nil { | ||
| return false, "" | ||
| } | ||
|
|
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| // Look for "explanation.invalid" in the additional section | ||
| for _, rr := range dnsResponse.Extra { | ||
| if txtRecord, ok := rr.(*dns.TXT); ok { | ||
| if txtRecord.Hdr.Name == "explanation.invalid." { | ||
| for _, txt := range txtRecord.Txt { | ||
| if txt == "blocked:m" { | ||
| // If there is a matching TXT record, return the blocked domain | ||
| if len(dnsResponse.Question) > 0 { | ||
| blockedDomain := dnsResponse.Question[0].Name | ||
| // remove the trailing dot (FQDN) if present | ||
| blockedDomain = strings.TrimSuffix(blockedDomain, ".") | ||
| return true, blockedDomain | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
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| return false, "" | ||
| } |
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