[fakuivan]

How do I perform a DNS Lookup from a plugin to get an IP address?

[Powerlord]

I don't think SourceMod has the ability to do this built in.

Probably needs an extension to do it. Not sure how hard that would be to write, but it should just need to wrap the various OS's inet_pton and gethostbyname/getnameinfo calls.

[fakuivan]

Originally Posted by Powerlord I don't think SourceMod has the ability to do this built in. Probably needs an extension to do it. Not sure how hard that would be to write, but it should just need to wrap the various OS's inet_pton and gethostbyname/getnameinfo calls.

I scrapped an extension (I've never coded extensions but I am quite familiar with c++). It only works on linux afaik. Any recomendations?

extension.cpp

PHP Code:

#include <netdb.h>
#include <arpa/inet.h>

/**
 * @file extension.cpp
 * @brief Implement extension code here.
 */

FQDN_to_IP g_FQDN_to_IP;        /**< Global singleton for extension's main interface */

SMEXT_LINK(&g_FQDN_to_IP);

cell_t to_IP(IPluginContext *pContext, const cell_t *params)
{
    char * pHostName;
    pContext->LocalToString(params[1], &pHostName);
    struct hostent * pHostData;
    if ((pHostData = gethostbyname(pHostName)) == NULL)
    {
        return 0;
    }
    return *((unsigned long *)pHostData->h_addr);
}

const sp_nativeinfo_t MyNatives[] =
{
    { "FQDN_to_IP",                to_IP },
    { NULL,                        NULL },
};

void FQDN_to_IP::SDK_OnAllLoaded()
{
    sharesys->AddNatives(myself, MyNatives);
} 


include

PHP Code:

/**
 * Resolves a FQDN into an IP address, to its binary form.
 * 
 * @param s_fqdn        The FQDN to query.
 * @return                IP address in binary form.
 */
native int FQDN_to_IP(char s_fqdn[255])

stock int IntToIP(int i_IP, char s_IP[18])
{
    int i_octet[4];
    i_octet[3] = (i_IP >> 24) & 0xFF; 
    i_octet[2] = (i_IP >> 16) & 0xFF; 
    i_octet[1] = (i_IP >> 8 ) & 0xFF; 
    i_octet[0] =  i_IP        & 0xFF;
    return Format(s_IP, sizeof(s_IP), "%d.%d.%d.%d", i_octet[0], i_octet[1], i_octet[2], i_octet[3]);
} 


Test plugin

PHP Code:

public void OnPluginStart()
{
    RegAdminCmd("test_fqdn_to_ip_resolve", Command_Resolve, ADMFLAG_RCON, "Resolves a FQDN into an IP address.");
}

public Action Command_Resolve(int i_client, int i_args)
{
    if (i_args != 1)
    {
        ReplyToCommand(i_client, "[SM-TEST] test_fqdn_to_ip_resolve <fqdn>")
        return Plugin_Handled;
    }
    char s_fqdn[255];
    GetCmdArg(1, s_fqdn, sizeof(s_fqdn));
    char s_IP[18];
    int i_IP = FQDN_to_IP(s_fqdn);
    IntToIP(i_IP, s_IP);
    ReplyToCommand(i_client, "[SM-TEST] Returned: %d | %s", i_IP, s_IP);
    return Plugin_Handled;
} 


Testing:

test_fqdn_to_ip_resolve "forums.alliedmods.net"
[SM-TEST] Returned: 197007720 | 104.25.190.11

[Powerlord]

I think the include for gethostbyname is different on windows. Let me check...

Yeah, it appears to be in winsock2.h on Windows.

I know SourceMod has ifdefs for Linux versus Windows but I don't remember what they are off the top of my head.

[Impact123]

It's probably a good idea to make this callback based so you don't block the game server.

[fakuivan]

Originally Posted by Powerlord I think the include for gethostbyname is different on windows. Let me check... Yeah, it appears to be in winsock2.h on Windows. I know SourceMod has ifdefs for Linux versus Windows but I don't remember what they are off the top of my head.

I don't plan to offer windows support any time soon, maybe on a pre release state. (I appreciate any kind of help tho)

Originally Posted by Impact123 It's probably a good idea to make this callback based so you don't block the game server.

I plan on doing so, but I think that gethostbyname is not thread safe :/.