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LookupServer: Only interpret A records as 32-bit IPv4 addresses.

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This fixes a bug where CNAME records would be interpreted as if they were
IP addresses, causing much confusion.
This commit is contained in:
Andreas Kling 2019-04-02 20:39:12 +02:00
parent 17e02e7450
commit ff93d3f362
1 changed files with 12 additions and 8 deletions
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20
Servers/LookupServer/main.cpp
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@ -186,7 +186,7 @@ Vector<IPv4Address> lookup(const String& hostname, bool& did_timeout)
dst_addr.sin_family = AF_INET; dst_addr.sin_family = AF_INET;
dst_addr.sin_port = htons(53); dst_addr.sin_port = htons(53);
rc = inet_pton(AF_INET, "172.20.10.1", &dst_addr.sin_addr); rc = inet_pton(AF_INET, "127.0.0.53", &dst_addr.sin_addr);
int nsent = sendto(fd, buffer.pointer(), buffer.size(), 0,(const struct sockaddr *)&dst_addr, sizeof(dst_addr)); int nsent = sendto(fd, buffer.pointer(), buffer.size(), 0,(const struct sockaddr *)&dst_addr, sizeof(dst_addr));
if (nsent < 0) { if (nsent < 0) {
@ -218,11 +218,11 @@ Vector<IPv4Address> lookup(const String& hostname, bool& did_timeout)
} }
auto& response_header = *(DNSPacket*)(response_buffer); auto& response_header = *(DNSPacket*)(response_buffer);
printf("Got response (ID: %u)\n", response_header.id()); dbgprintf("Got response (ID: %u)\n", response_header.id());
//printf(" Question count: %u\n", response_header.question_count()); dbgprintf(" Question count: %u\n", response_header.question_count());
printf(" Answer count: %u\n", response_header.answer_count()); dbgprintf(" Answer count: %u\n", response_header.answer_count());
//printf(" Authority count: %u\n", response_header.authority_count()); dbgprintf(" Authority count: %u\n", response_header.authority_count());
//printf("Additional count: %u\n", response_header.additional_count()); dbgprintf("Additional count: %u\n", response_header.additional_count());
if (response_header.id() != request_header.id()) { if (response_header.id() != request_header.id()) {
dbgprintf("LookupServer: ID mismatch (%u vs %u) :(\n", response_header.id(), request_header.id()); dbgprintf("LookupServer: ID mismatch (%u vs %u) :(\n", response_header.id(), request_header.id());
@ -246,15 +246,18 @@ Vector<IPv4Address> lookup(const String& hostname, bool& did_timeout)
for (word i = 0; i < response_header.answer_count(); ++i) { for (word i = 0; i < response_header.answer_count(); ++i) {
auto& record = *(const DNSRecord*)(&((const byte*)response_header.payload())[offset]); auto& record = *(const DNSRecord*)(&((const byte*)response_header.payload())[offset]);
auto ipv4_address = IPv4Address((const byte*)record.data()); auto ipv4_address = IPv4Address((const byte*)record.data());
dbgprintf("LookupServer: Answer #%u: (question: %s), ttl=%u, length=%u, data=%s\n", dbgprintf("LookupServer: Answer #%u: (question: %s), type=%u, ttl=%u, length=%u, data=%s\n",
i, i,
question.characters(), question.characters(),
record.type(),
record.ttl(), record.ttl(),
record.data_length(), record.data_length(),
ipv4_address.to_string().characters()); ipv4_address.to_string().characters());
offset += sizeof(DNSRecord) + record.data_length(); offset += sizeof(DNSRecord) + record.data_length();
addresses.append(ipv4_address); if (record.type() == T_A)
addresses.append(ipv4_address);
// FIXME: Parse some other record types perhaps?
} }
return addresses; return addresses;
@ -270,6 +273,7 @@ static String parse_dns_name(const byte* data, int& offset, int max_offset)
break; break;
} }
if ((ch & 0xc0) == 0xc0) { if ((ch & 0xc0) == 0xc0) {
ASSERT_NOT_REACHED();
// FIXME: Parse referential names. // FIXME: Parse referential names.
offset += 2; offset += 2;
} }