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hostsutils.c
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hostsutils.c
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#include "hostsutils.h"
#include "ipchunk.h"
#include "dnsgenerator.h"
#include "goodiplist.h"
#define CONTEXT_DATA_LENGTH 2048
static int HostsUtils_GetCName_Callback(int Number,
HostsRecordType Type,
const char *Data,
char *Buffer
)
{
strcpy(Buffer, Data);
return 0;
}
int HostsUtils_GetCName(const char *Domain,
char *Buffer,
HostsContainer *Container
)
{
return Container->Find(Container,
Domain,
HOSTS_TYPE_CNAME,
(HostsFindFunc)HostsUtils_GetCName_Callback,
Buffer
)
== NULL;
}
BOOL HostsUtils_TypeExisting(HostsContainer *Container,
const char *Domain,
HostsRecordType Type
)
{
return Container->Find(Container,
Domain,
Type,
NULL,
NULL
)
!= NULL;
}
static int HostsUtils_Generate(int Number,
HostsRecordType Type,
const void *Data,
DnsGenerator *g /* Inited */
)
{
switch( Type )
{
case HOSTS_TYPE_CNAME:
if( g->CName(g, "a", Data, 60) != 0 )
{
return -26;
}
break;
case HOSTS_TYPE_A:
if( g->RawData(g,
"a",
DNS_TYPE_A,
DNS_CLASS_IN,
(const char *)(((IpAddr *)Data)->Addr + 12),
4,
60
)
!= 0 )
{
return -41;
}
break;
case HOSTS_TYPE_AAAA:
if( g->RawData(g,
"a",
DNS_TYPE_AAAA,
DNS_CLASS_IN,
(const char *)(((IpAddr *)Data)->Addr),
16,
60
)
!= 0 )
{
return -56;
}
break;
case HOSTS_TYPE_GOOD_IP_LIST:
{
const char *ActuallData;
ActuallData = GoodIpList_Get(Data);
if( ActuallData == NULL )
{
return -96;
}
if( g->RawData(g,
"a",
DNS_TYPE_A,
DNS_CLASS_IN,
ActuallData,
4,
60
)
!= 0 )
{
return -109;
}
}
break;
default:
return -61;
break;
}
return 0;
}
HostsUtilsTryResult HostsUtils_Try(MsgContext *MsgCtx,
int BufferLength,
HostsContainer *Container
)
{
IHeader *Header = (IHeader *)MsgCtx;
char *RequestEntity = (char *)(Header + 1);
const char *MatchState;
HostsRecordType Type;
if( Header->Type != DNS_TYPE_CNAME &&
HostsUtils_TypeExisting(Container, Header->Domain, HOSTS_TYPE_CNAME)
)
{
return HOSTSUTILS_TRY_RECURSED;
}
switch( Header->Type )
{
case DNS_TYPE_CNAME:
Type = HOSTS_TYPE_CNAME;
MatchState = Container->Find(Container,
Header->Domain,
HOSTS_TYPE_CNAME,
NULL,
NULL
);
break;
case DNS_TYPE_A:
MatchState = Container->Find(Container,
Header->Domain,
HOSTS_TYPE_A,
NULL,
NULL
);
if( MatchState != NULL )
{
Type = HOSTS_TYPE_A;
} else {
Type = HOSTS_TYPE_GOOD_IP_LIST;
MatchState = Container->Find(Container,
Header->Domain,
HOSTS_TYPE_GOOD_IP_LIST,
NULL,
NULL
);
}
break;
case DNS_TYPE_AAAA:
Type = HOSTS_TYPE_AAAA;
MatchState = Container->Find(Container,
Header->Domain,
HOSTS_TYPE_AAAA,
NULL,
NULL
);
break;
default:
return HOSTSUTILS_TRY_NONE;
break;
}
if( MatchState != NULL )
{
DnsGenerator g;
char *HereToGenerate = RequestEntity + Header->EntityLength;
int LeftBufferLength =
BufferLength - sizeof(IHeader) - Header->EntityLength;
int ResultLength;
if( DnsGenerator_Init(&g,
HereToGenerate,
LeftBufferLength,
RequestEntity,
Header->EntityLength,
TRUE
)
!= 0)
{
return HOSTSUTILS_TRY_NONE;
}
g.Header->Flags.Direction = 1;
g.Header->Flags.AuthoritativeAnswer = 0;
g.Header->Flags.RecursionAvailable = 1;
g.Header->Flags.ResponseCode = 0;
g.Header->Flags.Type = 0;
if( g.NextPurpose(&g) != DNS_RECORD_PURPOSE_ANSWER )
{
return HOSTSUTILS_TRY_NONE;
}
if( Container->Find(Container,
Header->Domain,
Type,
(HostsFindFunc)HostsUtils_Generate,
&g
)
== NULL )
{
return HOSTSUTILS_TRY_NONE;
}
if( Header->EDNSEnabled )
{
while( g.NextPurpose(&g) != DNS_RECORD_PURPOSE_ADDITIONAL );
if( g.EDns(&g, 1280) != 0 )
{
return HOSTSUTILS_TRY_NONE;
}
}
/* g will no longer be needed, and can be crapped */
ResultLength = DNSCompress(HereToGenerate, g.Length(&g));
if( ResultLength < 0 )
{
return HOSTSUTILS_TRY_NONE;
}
Header->EntityLength = ResultLength;
memmove(RequestEntity, HereToGenerate, ResultLength);
MsgContext_SendBack(MsgCtx);
return HOSTSUTILS_TRY_OK;
} else {
return HOSTSUTILS_TRY_NONE;
}
}
int HostsUtils_GenerateQuery(char *RequestBuffer,
int BufferLength,
SOCKET Socket, /* Both for sending and receiving */
Address_Type *BackAddress,
BOOL RequestTcp,
uint16_t Identifier,
const char *Name,
DNSRecordType Type
)
{
static const char DNSHeader[DNS_HEADER_LENGTH] = {
00, 00, /* QueryIdentifier */
01, 00, /* Flags */
00, 00, /* QuestionCount */
00, 00, /* AnswerCount */
00, 00, /* NameServerCount */
00, 00, /* AdditionalCount */
};
IHeader *Header = (IHeader *)RequestBuffer;
char *RequestEntity = RequestBuffer + sizeof(IHeader);
DnsGenerator g;
if( DnsGenerator_Init(&g,
RequestEntity,
BufferLength - sizeof(IHeader),
DNSHeader,
DNS_HEADER_LENGTH,
FALSE
)
!= 0 )
{
return -323;
}
g.SetIdentifier(&g, Identifier);
if( g.Question(&g, Name, Type, DNS_CLASS_IN) != 0 )
{
return -328;
}
if( IHeader_Fill(Header,
TRUE,
RequestEntity,
g.Length(&g),
(struct sockaddr *)&(BackAddress->Addr),
Socket,
BackAddress->family,
"CNameRedirect"
)
!= 0 )
{
return -309;
}
Header->RequestTcp = RequestTcp;
return 0;
}
/* Error code returned */
int HostsUtils_CombineRecursedResponse(MsgContext *Buffer,
int Bufferlength,
char *RecursedEntity,
int EntityLength,
const char *RecursedDomain
)
{
IHeader *NewHeader = (IHeader *)Buffer;
char *NewEntity = (char *)(NewHeader + 1);
DnsSimpleParser p;
DnsSimpleParserIterator i;
DnsGenerator g;
uint16_t OriginalIdentifier = DNSGetQueryIdentifier(NewEntity);
int CompressedLength;
if( DnsSimpleParser_Init(&p,
RecursedEntity,
EntityLength,
FALSE
) != 0
)
{
return -268;
}
if( DnsSimpleParserIterator_Init(&i, &p) != 0 )
{
return -273;
}
if( DnsGenerator_Init(&g,
NewEntity,
Bufferlength - sizeof(IHeader),
NULL,
0,
FALSE
)
!= 0 )
{
return -285;
}
g.CopyHeader(&g, RecursedEntity, FALSE);
g.SetIdentifier(&g, OriginalIdentifier);
if( g.Question(&g,
NewHeader->Domain,
NewHeader->Type,
DNS_CLASS_IN
)
!= 0 )
{
return -298;
}
if( g.NextPurpose(&g) != DNS_RECORD_PURPOSE_ANSWER )
{
return -303;
}
if( g.CName(&g, NewHeader->Domain, RecursedDomain, 60) != 0 )
{
return -309;
}
i.GotoAnswers(&i);
while( i.Next(&i) != NULL && i.Purpose == DNS_RECORD_PURPOSE_ANSWER )
{
switch( i.Type )
{
case DNS_TYPE_CNAME:
if( g.CopyCName(&g, &i) != 0 )
{
return -321;
}
break;
case DNS_TYPE_A:
if( g.CopyA(&g, &i) != 0 )
{
return -328;
}
break;
case DNS_TYPE_AAAA:
if( g.CopyAAAA(&g, &i) != 0 )
{
return -335;
}
break;
default:
break;
}
}
if( NewHeader->EDNSEnabled )
{
while( g.NextPurpose(&g) != DNS_RECORD_PURPOSE_ADDITIONAL );
if( g.EDns(&g, 1280) != 0 )
{
return -351;
}
}
CompressedLength = DNSCompress(g.Buffer, g.Length(&g));
if( CompressedLength < 0 )
{
return -343;
}
NewHeader->EntityLength = CompressedLength;
return 0;
}