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/* udns_init.c
resolver initialisation stuff
Copyright (C) 2006 Michael Tokarev <mjt@corpit.ru>
This file is part of UDNS library, an async DNS stub resolver.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library, in file named COPYING.LGPL; if not,
write to the Free Software Foundation, Inc., 59 Temple Place,
Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#ifdef __MINGW32__
# include <winsock2.h> /* includes <windows.h> */
# include <iphlpapi.h> /* for dns server addresses etc */
#else
# include <sys/types.h>
# include <unistd.h>
# include <fcntl.h>
#endif /* !__MINGW32__ */
#include <stdlib.h>
#include <string.h>
#include "udns.h"
#define ISSPACE(x) (x == ' ' || x == '\t' || x == '\r' || x == '\n')
static const char space[] = " \t\r\n";
static void dns_set_serv_internal(struct dns_ctx *ctx, char *serv) {
dns_add_serv(ctx, NULL);
for(serv = strtok(serv, space); serv; serv = strtok(NULL, space))
dns_add_serv(ctx, serv);
}
static void dns_set_srch_internal(struct dns_ctx *ctx, char *srch) {
dns_add_srch(ctx, NULL);
for(srch = strtok(srch, space); srch; srch = strtok(NULL, space))
dns_add_srch(ctx, srch);
}
#ifdef __MINGW32__
#define NO_IPHLPAPI
#ifndef NO_IPHLPAPI
/* Apparently, some systems does not have proper headers for IPHLPAIP to work.
* The best is to upgrade headers, but here's another, ugly workaround for
* this: compile with -DNO_IPHLPAPI.
*/
typedef DWORD (WINAPI *GetAdaptersAddressesFunc)(
ULONG Family, DWORD Flags, PVOID Reserved,
PIP_ADAPTER_ADDRESSES pAdapterAddresses,
PULONG pOutBufLen);
static int dns_initns_iphlpapi(struct dns_ctx *ctx) {
HANDLE h_iphlpapi;
GetAdaptersAddressesFunc pfnGetAdAddrs;
PIP_ADAPTER_ADDRESSES pAddr, pAddrBuf;
PIP_ADAPTER_DNS_SERVER_ADDRESS pDnsAddr;
ULONG ulOutBufLen;
DWORD dwRetVal;
int ret = -1;
h_iphlpapi = LoadLibrary("iphlpapi.dll");
if (!h_iphlpapi)
return -1;
pfnGetAdAddrs = (GetAdaptersAddressesFunc)
GetProcAddress(h_iphlpapi, "GetAdaptersAddresses");
if (!pfnGetAdAddrs) goto freelib;
ulOutBufLen = 0;
dwRetVal = pfnGetAdAddrs(AF_UNSPEC, 0, NULL, NULL, &ulOutBufLen);
if (dwRetVal != ERROR_BUFFER_OVERFLOW) goto freelib;
pAddrBuf = malloc(ulOutBufLen);
if (!pAddrBuf) goto freelib;
dwRetVal = pfnGetAdAddrs(AF_UNSPEC, 0, NULL, pAddrBuf, &ulOutBufLen);
if (dwRetVal != ERROR_SUCCESS) goto freemem;
for (pAddr = pAddrBuf; pAddr; pAddr = pAddr->Next)
for (pDnsAddr = pAddr->FirstDnsServerAddress;
pDnsAddr;
pDnsAddr = pDnsAddr->Next)
dns_add_serv_s(ctx, pDnsAddr->Address.lpSockaddr);
ret = 0;
freemem:
free(pAddrBuf);
freelib:
FreeLibrary(h_iphlpapi);
return ret;
}
#else /* NO_IPHLPAPI */
#define dns_initns_iphlpapi(ctx) (-1)
#endif /* NO_IPHLPAPI */
static int dns_initns_registry(struct dns_ctx *ctx) {
LONG res;
HKEY hk;
DWORD type = REG_EXPAND_SZ | REG_SZ;
DWORD len;
char valBuf[1024];
#define REGKEY_WINNT "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters"
#define REGKEY_WIN9x "SYSTEM\\CurrentControlSet\\Services\\VxD\\MSTCP"
res = RegOpenKeyEx(HKEY_LOCAL_MACHINE, REGKEY_WINNT, 0, KEY_QUERY_VALUE, &hk);
if (res != ERROR_SUCCESS)
res = RegOpenKeyEx(HKEY_LOCAL_MACHINE, REGKEY_WIN9x,
0, KEY_QUERY_VALUE, &hk);
if (res != ERROR_SUCCESS)
return -1;
len = sizeof(valBuf) - 1;
res = RegQueryValueEx(hk, "NameServer", NULL, &type, (BYTE*)valBuf, &len);
if (res != ERROR_SUCCESS || !len || !valBuf[0]) {
len = sizeof(valBuf) - 1;
res = RegQueryValueEx(hk, "DhcpNameServer", NULL, &type,
(BYTE*)valBuf, &len);
}
RegCloseKey(hk);
if (res != ERROR_SUCCESS || !len || !valBuf[0])
return -1;
valBuf[len] = '\0';
/* nameservers are stored as a whitespace-seperate list:
* "192.168.1.1 123.21.32.12" */
dns_set_serv_internal(ctx, valBuf);
return 0;
}
#else /* !__MINGW32__ */
static int dns_init_resolvconf(struct dns_ctx *ctx) {
char *v;
char buf[2049]; /* this buffer is used to hold /etc/resolv.conf */
int has_srch = 0;
/* read resolv.conf... */
{ int fd = open("/etc/resolv.conf", O_RDONLY);
if (fd >= 0) {
int l = read(fd, buf, sizeof(buf) - 1);
close(fd);
buf[l < 0 ? 0 : l] = '\0';
}
else
buf[0] = '\0';
}
if (buf[0]) { /* ...and parse it */
char *line, *nextline;
line = buf;
do {
nextline = strchr(line, '\n');
if (nextline) *nextline++ = '\0';
v = line;
while(*v && !ISSPACE(*v)) ++v;
if (!*v) continue;
*v++ = '\0';
while(ISSPACE(*v)) ++v;
if (!*v) continue;
if (strcmp(line, "domain") == 0) {
dns_set_srch_internal(ctx, strtok(v, space));
has_srch = 1;
}
else if (strcmp(line, "search") == 0) {
dns_set_srch_internal(ctx, v);
has_srch = 1;
}
else if (strcmp(line, "nameserver") == 0)
dns_add_serv(ctx, strtok(v, space));
else if (strcmp(line, "options") == 0)
dns_set_opts(ctx, v);
} while((line = nextline) != NULL);
}
buf[sizeof(buf)-1] = '\0';
/* get list of nameservers from env. vars. */
if ((v = getenv("NSCACHEIP")) != NULL ||
(v = getenv("NAMESERVERS")) != NULL) {
strncpy(buf, v, sizeof(buf) - 1);
dns_set_serv_internal(ctx, buf);
}
/* if $LOCALDOMAIN is set, use it for search list */
if ((v = getenv("LOCALDOMAIN")) != NULL) {
strncpy(buf, v, sizeof(buf) - 1);
dns_set_srch_internal(ctx, buf);
has_srch = 1;
}
if ((v = getenv("RES_OPTIONS")) != NULL)
dns_set_opts(ctx, v);
/* if still no search list, use local domain name */
if (has_srch &&
gethostname(buf, sizeof(buf) - 1) == 0 &&
(v = strchr(buf, '.')) != NULL &&
*++v != '\0')
dns_add_srch(ctx, v);
return 0;
}
#endif /* !__MINGW32__ */
int dns_init(struct dns_ctx *ctx, int do_open) {
if (!ctx)
ctx = &dns_defctx;
dns_reset(ctx);
#ifdef __MINGW32__
if (dns_initns_iphlpapi(ctx) != 0)
dns_initns_registry(ctx);
/*XXX __MINGW32__: probably good to get default domain and search list too...
* And options. Something is in registry. */
/*XXX __MINGW32__: maybe environment variables are also useful? */
#else
dns_init_resolvconf(ctx);
#endif
return do_open ? dns_open(ctx) : 0;
}