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/*
* DNS plugin. $Id: dns.c 377 2007-03-12 20:48:05Z bortz $
*/
#define IN_PLUGIN
#include "../../echoping.h"
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
struct addrinfo name_server;
poptContext dns_poptcon;
char *request;
int type;
char *type_name = NULL;
boolean use_tcp = FALSE;
boolean no_recurse = FALSE;
/* nsError stolen from Liu & Albitz check_soa (in their book "DNS and BIND") */
/****************************************************************
* nsError -- Print an error message from h_errno for a failure *
* looking up NS records. res_query() converts the DNS *
* packet return code to a smaller list of errors and *
* places the error value in h_errno. There is a routine *
* called herror() for printing out strings from h_errno *
* like perror() does for errno. Unfortunately, the *
* herror() messages assume you are looking up address *
* records for hosts. In this program, we are looking up *
* NS records for domains, so we need our own list of error *
* strings. *
****************************************************************/
int
nsError(error, domain)
int error;
char *domain;
{
switch (error) {
case HOST_NOT_FOUND:
err_ret("Unknown domain: %s\n", domain);
return -1;
case NO_DATA:
err_ret("No records of type %s for %s in the Answer section\n",
to_upper(type_name), domain);
return -1;
case TRY_AGAIN:
err_ret("No response for query\n");
return -2;
default:
err_ret("Unexpected error\n");
return -1;
}
}
void
dns_usage(const char *msg)
{
if (msg) {
fprintf(stderr, "Error: %s\n", msg);
}
poptPrintUsage(dns_poptcon, stderr, 0);
fprintf(stderr, " request\n");
exit(1);
}
char *
init(const int argc, const char **argv)
{
int value;
char *hostname;
char *msg = malloc(256);
char *upper_type_name = NULL;
/* popt variables */
struct poptOption options[] = {
{"type", 't', POPT_ARG_STRING, &type_name, 0,
"Type of resources queried (A, MX, SOA, etc)",
"type"},
{"tcp", (char) NULL, POPT_ARG_NONE, &use_tcp, 0,
"Use TCP for the request (virtual circuit)",
"tcp"},
{"no-recurse", (char) NULL, POPT_ARG_NONE, &no_recurse, 0,
"Do not ask recursion",
"no-recurse"},
POPT_AUTOHELP POPT_TABLEEND
};
dns_poptcon = poptGetContext(NULL, argc,
argv, options, POPT_CONTEXT_KEEP_FIRST);
while ((value = poptGetNextOpt(dns_poptcon)) > 0) {
}
if (value < -1) {
sprintf(msg, "%s: %s",
poptBadOption(dns_poptcon, POPT_BADOPTION_NOALIAS),
poptStrerror(value));
dns_usage(msg);
}
hostname = (char *) poptGetArg(dns_poptcon); /* Not used */
request = (char *) poptGetArg(dns_poptcon);
if (request == NULL)
dns_usage("Mandatory request missing");
if ((type_name == NULL) || !strcmp(type_name, "")) {
type = T_A;
type_name = "A";
} else {
upper_type_name = (char *) to_upper(type_name);
/*
* TODO: a better algorithm. Use dns_rdatatype_fromtext in
* BIND ?
*/
if (!strcmp(upper_type_name, "A"))
type = T_A;
else if (!strcmp(upper_type_name, "AAAA"))
type = T_AAAA;
else if (!strcmp(upper_type_name, "NS"))
type = T_NS;
else if (!strcmp(upper_type_name, "SOA"))
type = T_SOA;
else if (!strcmp(upper_type_name, "MX"))
type = T_MX;
else if (!strcmp(upper_type_name, "SRV"))
type = T_SRV;
else if (!strcmp(upper_type_name, "CNAME"))
type = T_CNAME;
else if (!strcmp(upper_type_name, "PTR"))
type = T_PTR;
else if (!strcmp(upper_type_name, "TXT"))
type = T_TXT;
else if (!strcmp(upper_type_name, "ANY"))
type = T_ANY;
else
dns_usage("Unknown type");
}
return "domain";
}
void
start(struct addrinfo *res)
{
struct sockaddr name_server_sockaddr;
struct sockaddr_in name_server_sockaddr_in;
struct sockaddr_in6 name_server_sockaddr_in6;
name_server = *res;
name_server_sockaddr = *name_server.ai_addr;
if (name_server_sockaddr.sa_family == AF_INET) {
/* Converts a generic sockaddr to an IPv4 sockaddr_in */
(void) memcpy((void *) &name_server_sockaddr_in,
&name_server_sockaddr, sizeof(struct sockaddr));
} else if (name_server_sockaddr.sa_family == AF_INET6) {
#ifdef HAVE_RES_EXT
/* TODO: the code for IPv6 servers is hopelessly broken. Start again
*/
fprintf(stderr,
"WARNING: IPv6 nameservers not really supported yet (experts may apply). Falling back to IPv4 and the default server. You may use -4, too\n");
/* Converts a generic sockaddr to an IPv6 sockaddr_in6 */
(void) memcpy((void *) &name_server_sockaddr_in6,
&name_server_sockaddr, sizeof(struct sockaddr));
#else
err_quit
("IPv6 name servers not supported on this platform, may be you should use the -4 option");
#endif
} else {
err_quit("Unknown family for address of the server");
}
if (res_init() < 0)
err_sys("res_init");
if (name_server_sockaddr.sa_family == AF_INET) {
_res.nsaddr_list[0] = name_server_sockaddr_in;
} else if (name_server_sockaddr.sa_family == AF_INET6) {
#ifdef HAVE_RES_EXT
/* TODO: completely broken, dioes not work. Check in Stevens */
(void) memcpy(_res_ext.nsaddr_list, &name_server_sockaddr_in6,
sizeof(struct sockaddr_in6));
#endif
}
_res.nscount = 1;
_res.options &= ~(RES_DNSRCH | RES_DEFNAMES | RES_NOALIASES);
if (use_tcp) {
_res.options |= RES_USEVC;
}
if (no_recurse) {
_res.options &= ~RES_RECURSE;
}
}
int
execute()
{
union {
HEADER hdr; /* defined in resolv.h */
u_char buf[PACKETSZ]; /* defined in arpa/nameser.h */
} response; /* response buffers */
int response_length; /* buffer length */
if ((response_length = res_query(request, /* the domain we care about */
C_IN, /* Internet class records */
type, (u_char *) & response, /* response
* buffer */
sizeof(response))) /* buffer size */
<0) { /* If negative */
nsError(h_errno, request); /* report the error */
if (h_errno == TRY_AGAIN)
return -1; /* More luck next time? */
else
return -2; /* Give in */
}
/*
* TODO: better analysis of the replies. For instance, replies can be
* in the authority section (delegation info)
*/
return 0;
}
void
terminate()
{
}
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