How do you do a DNS lookup, like nslookup?

Is there a way to do this easily? I can't seem to get this to work.

Anyone have any clue on how to do this? I have an IP address and I want to get back the domain piece...

It seems I want gethostbyaddress() from the ws32_32 API but I don't quite grasp the syntax of the System pluging.

It uses parameters lists to pass pack and forth between NSIS and System32 DLL variables. I appologize, I am new to the Windows world (I'm aUNIX guy).

Alright, the gethostbyaddress() from what I gather can take a string for an IP and return the DNS name (what I want). I realize it has been deprecated by gethostentry() but anyway...

Can someone give me a quick example and EXPLAIN the syntax?

Based on the doc:

System::Call 'CondMgr::CmGetHotSyncExecPath(t, *i) i(.r0, r1r1).r2'

This says CmGetHostSyncExecPath takes a pointer to a string, pointer to an int returns an int. The t is address of r0 with no input/output passing, the *i comes from r1 and whatever is returned in r1 after the call completes and the return value should be placed in r2. Right?

So by that logic for gethostbyaddress() I should have

System::Call 'ws32_32::gethostbyaddress(t) t($IPADDRESS).r5'

Pass a string which is my variable IPADDRESS and the return value (the string I presume) place it in r5. This barfs miserably. Obviously its pilot error but can I get a quick explanation? Maybe I'm looking at the wrong API doc on MSDN...

Whooops...looks like I am looking at the wrong API doc...arrghhh..

System::Call 'ws2_32::WSAStartup(i 514, i r2) i .r3'
# Convert IP to proper format
System::Call 'ws2_32::inet_addr(t "$IPADDRESS") l .r5'
System::Call 'ws2_32::gethostbyaddr(t r5, i 4, i 2) *i .r6'

The above crashes on the gethostbyaddr call. What am I doing wrong? I would think the pointer to the hostent structure would be returned in R6, right?

Again, any help would be much appreciated (I'm starting to get the SystemDLL plugin).

Where is $IPADDRESS coming from, or have you not posted all your code?

-Stu

The first command should be

System::Call 'ws2_32::WSAStartup(i 514, *i .r2) i .r3'

(note the * and the . before r2). It is a pointer (hence the *) and you are getting it out of the function (hence the .).
Your code will give an error since the first call fails to initiallize the WS2_32 process.

I think that the 3rd call is also wrong. Maybe try to allocate the hostent structure instead of pointing $6 to it:

System::Call '*(t,t,i,i,t)i.s'

Pop $6

System::Call 'ws2_32::gethostbyaddr(t r5, i 4, i ${AF_INET}) i r6'

I am not also sure about the 't r5' on the third call. You get an unsigned long from the second call to $5 and then you place this as a 't' on the third call?

I'll try to look at this as soon as I get to work.

CF

This code works:

!define AF_INET 2

!define strhostent '(t,t,i,i,t)i'

StrCpy $IPADDRESS "aaa.xxx.yyy.zzz" ; put your address here

System::Call 'Ws2_32::WSAStartup(i 514, *i .r2) i .r3'

System::Call 'Ws2_32::inet_addr(t "$IPADRESS") l .r5'

System::Call 'Ws2_32::gethostbyaddr(*l r5, i 4, i ${AF_INET}) i .r6'

System::Call '*$6${strhostent}(.R1,,,,)'

DetailPrint 'The full DNS name of "$IPADDRESS" is "$R1"'

System::Call 'Ws2_32::WSACleanup()i.R9'

System::Free $6

This gives you the full domain name. For example if $IPADDRESS is '205.188.229.57' $R1 will be 'waforumweb-dtc1l-0.stream.aol.com'

🙂
CF

Originally posted by CancerFace
This code works:

!define AF_INET 2

!define strhostent '(t,t,i,i,t)i'

StrCpy $IPADDRESS "aaa.xxx.yyy.zzz" ; put your address here

System::Call 'Ws2_32::WSAStartup(i 514, *i .r2) i .r3'

System::Call 'Ws2_32::inet_addr(t "$IPADRESS") l .r5'

System::Call 'Ws2_32::gethostbyaddr(*l r5, i 4, i ${AF_INET}) i .r6'

System::Call '*$6${strhostent}(.R1,,,,)'

DetailPrint 'The full DNS name of "$IPADDRESS" is "$R1"'

System::Call 'Ws2_32::WSACleanup()i.R9'

System::Free $6

This gives you the full domain name. For example if $IPADDRESS is '205.188.229.57' $R1 will be 'waforumweb-dtc1l-0.stream.aol.com'

🙂
CF

Thanks dude. I'm sorry for not getting back to you, I'm on vacation!

This works for me though I had to make some changes. I was still confused about the *l r5 over the t r5 and the gethostname thread I believe is wrong since its not allocating a buffer to store the name (I had to combine the two).

Anyway, I'm starting to get a hand of the System syntax - its still awkward though!

and the gethostname thread I believe is wrong since its not allocating a buffer to store the name (I had to combine the two).

🧟
You lost me there ... The above code works for me for a given IP in $IPADDRESS. There is no reason to allocate space for the name as it will be allocated by the system (in $6)...

CF