Chiebot-Mirror
/
c-ares
mirror of https://github.com/c-ares/c-ares.git
8
0
Fork 0
Code Issues Projects Releases Wiki Activity

ares_init.c: Further refactoring of Windows system's DNS fetching code

Browse Source
pull/14/head
Yang Tse 13 years ago
parent 05346c25cb
commit 7ce8fe781a
1 changed files with 369 additions and 181 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 550
      ares_init.c

550
ares_init.c
Unescape View File

@ -546,74 +546,331 @@ static int init_by_environment(ares_channel channel)
#ifdef WIN32
/*
* Warning: returns a dynamically allocated buffer, the user MUST
* use free() if the function returns 1
* get_REG_SZ()
*
* Given a 'hKey' handle to an open registry key and a 'leafKeyName' pointer
* to the name of the registry leaf key to be queried, fetch it's string
* value and return a pointer in *outptr to a newly allocated memory area
* holding it as a null-terminated string.
*
* Returns 0 and nullifies *outptr upon inability to return a string value.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*
* Supported on Windows NT 3.5 and newer.
*/
static int get_res_nt(HKEY hKey, const char *subkey, char **obuf)
static int get_REG_SZ(HKEY hKey, const char *leafKeyName, char **outptr)
{
/* Test for the size we need */
DWORD size = 0;
int result;
int res;
*outptr = NULL;
result = RegQueryValueEx(hKey, subkey, 0, NULL, NULL, &size);
if ((result != ERROR_SUCCESS && result != ERROR_MORE_DATA) || !size)
/* Find out size of string stored in registry */
res = RegQueryValueEx(hKey, leafKeyName, 0, NULL, NULL, &size);
if ((res != ERROR_SUCCESS && res != ERROR_MORE_DATA) || !size)
return 0;
*obuf = malloc(size+1);
if (!*obuf)
/* Allocate buffer of indicated size plus one given that string
might have been stored without null termination */
*outptr = malloc(size+1);
if (!*outptr)
return 0;
if (RegQueryValueEx(hKey, subkey, 0, NULL,
(LPBYTE)*obuf, &size) != ERROR_SUCCESS)
/* Get the value for real */
res = RegQueryValueEx(hKey, leafKeyName, 0, NULL,
(unsigned char *)*outptr, &size);
if ((res != ERROR_SUCCESS) || (size == 1))
{
free(*obuf);
free(*outptr);
*outptr = NULL;
return 0;
}
if (size == 1)
/* Null terminate buffer allways */
*(*outptr + size) = '\0';
return 1;
}
/*
* get_REG_SZ_9X()
*
* Functionally identical to get_REG_SZ()
*
* Supported on Windows 95, 98 and ME.
*/
static int get_REG_SZ_9X(HKEY hKey, const char *leafKeyName, char **outptr)
{
DWORD dataType = 0;
DWORD size = 0;
int res;
*outptr = NULL;
/* Find out size of string stored in registry */
res = RegQueryValueEx(hKey, leafKeyName, 0, &dataType, NULL, &size);
if ((res != ERROR_SUCCESS && res != ERROR_MORE_DATA) || !size)
return 0;
/* Allocate buffer of indicated size plus one given that string
might have been stored without null termination */
*outptr = malloc(size+1);
if (!*outptr)
return 0;
/* Get the value for real */
res = RegQueryValueEx(hKey, leafKeyName, 0, &dataType,
(unsigned char *)*outptr, &size);
if ((res != ERROR_SUCCESS) || (size == 1))
{
free(*obuf);
free(*outptr);
*outptr = NULL;
return 0;
}
/* Null terminate buffer allways */
*(*outptr + size) = '\0';
return 1;
}
static int get_res_interfaces_nt(HKEY hKey, const char *subkey, char **obuf)
/*
* get_enum_REG_SZ()
*
* Given a 'hKeyParent' handle to an open registry key and a 'leafKeyName'
* pointer to the name of the registry leaf key to be queried, parent key
* is enumerated searching in child keys for given leaf key name and its
* associated string value. When located, this returns a pointer in *outptr
* to a newly allocated memory area holding it as a null-terminated string.
*
* Returns 0 and nullifies *outptr upon inability to return a string value.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*
* Supported on Windows NT 3.5 and newer.
*/
static int get_enum_REG_SZ(HKEY hKeyParent, const char *leafKeyName,
char **outptr)
{
char enumbuf[39]; /* GUIDs are 38 chars + 1 for NULL */
DWORD enum_size = 39;
int idx = 0;
HKEY hVal;
char enumKeyName[256];
DWORD enumKeyNameBuffSize;
DWORD enumKeyIdx = 0;
HKEY hKeyEnum;
int gotString;
int res;
while (RegEnumKeyEx(hKey, idx++, enumbuf, &enum_size, 0,
NULL, NULL, NULL) != ERROR_NO_MORE_ITEMS)
{
int rc;
*outptr = NULL;
enum_size = 39;
if (RegOpenKeyEx(hKey, enumbuf, 0, KEY_QUERY_VALUE, &hVal) !=
ERROR_SUCCESS)
for(;;)
{
enumKeyNameBuffSize = sizeof(enumKeyName);
res = RegEnumKeyEx(hKeyParent, enumKeyIdx++, enumKeyName,
&enumKeyNameBuffSize, 0, NULL, NULL, NULL);
if (res != ERROR_SUCCESS)
break;
res = RegOpenKeyEx(hKeyParent, enumKeyName, 0, KEY_QUERY_VALUE,
&hKeyEnum);
if (res != ERROR_SUCCESS)
continue;
rc = get_res_nt(hVal, subkey, obuf);
RegCloseKey(hVal);
if (rc)
return 1;
}
return 0;
gotString = get_REG_SZ(hKeyEnum, leafKeyName, outptr);
RegCloseKey(hKeyEnum);
if (gotString)
break;
}
if (!*outptr)
return 0;
return 1;
}
/* get_iphlpapi_dns_classic() is supported on W98 and newer */
static int get_iphlpapi_dns_classic(char *ret_buf, size_t ret_size)
/*
* get_DNS_Registry_9X()
*
* Functionally identical to get_DNS_Registry()
*
* Implementation supports Windows 95, 98 and ME.
*/
static int get_DNS_Registry_9X(char **outptr)
{
HKEY hKey_VxD_MStcp;
int gotString;
int res;
*outptr = NULL;
res = RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_9X, 0, KEY_READ,
&hKey_VxD_MStcp);
if (res != ERROR_SUCCESS)
return 0;
gotString = get_REG_SZ_9X(hKey_VxD_MStcp, NAMESERVER, outptr);
RegCloseKey(hKey_VxD_MStcp);
if (!gotString || !*outptr)
return 0;
return 1;
}
/*
* get_DNS_Registry_NT()
*
* Functionally identical to get_DNS_Registry()
*
* Refs: Microsoft Knowledge Base articles KB120642 and KB314053.
*
* Implementation supports Windows NT 3.5 and newer.
*/
static int get_DNS_Registry_NT(char **outptr)
{
HKEY hKey_Interfaces = NULL;
HKEY hKey_Tcpip_Parameters;
int gotString;
int res;
*outptr = NULL;
res = RegOpenKeyEx(HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0, KEY_READ,
&hKey_Tcpip_Parameters);
if (res != ERROR_SUCCESS)
return 0;
/*
** Global DNS settings override adapter specific parameters when both
** are set. Additionally static DNS settings override DHCP-configured
** parameters when both are set.
*/
/* Global DNS static parameters */
gotString = get_REG_SZ(hKey_Tcpip_Parameters, NAMESERVER, outptr);
if (gotString)
goto done;
/* Global DNS DHCP-configured parameters */
gotString = get_REG_SZ(hKey_Tcpip_Parameters, DHCPNAMESERVER, outptr);
if (gotString)
goto done;
/* Try adapter specific parameters */
res = RegOpenKeyEx(hKey_Tcpip_Parameters, "Interfaces", 0,
KEY_QUERY_VALUE | KEY_ENUMERATE_SUB_KEYS,
&hKey_Interfaces);
if (res != ERROR_SUCCESS)
{
hKey_Interfaces = NULL;
goto done;
}
/* Adapter specific DNS static parameters */
gotString = get_enum_REG_SZ(hKey_Interfaces, NAMESERVER, outptr);
if (gotString)
goto done;
/* Adapter specific DNS DHCP-configured parameters */
gotString = get_enum_REG_SZ(hKey_Interfaces, DHCPNAMESERVER, outptr);
done:
if (hKey_Interfaces)
RegCloseKey(hKey_Interfaces);
RegCloseKey(hKey_Tcpip_Parameters);
if (!gotString || !*outptr)
return 0;
return 1;
}
/*
* get_DNS_Registry()
*
* Locates DNS info in the registry. When located, this returns a pointer
* in *outptr to a newly allocated memory area holding a null-terminated
* string with a space or comma seperated list of DNS IP addresses.
*
* Returns 0 and nullifies *outptr upon inability to return DNSes string.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*/
static int get_DNS_Registry(char **outptr)
{
win_platform platform;
int gotString = 0;
*outptr = NULL;
platform = ares__getplatform();
if (platform == WIN_NT)
gotString = get_DNS_Registry_NT(outptr);
else if (platform == WIN_9X)
gotString = get_DNS_Registry_9X(outptr);
if (!gotString)
return 0;
return 1;
}
/*
* commajoin()
*
* RTF code.
*/
static void commajoin(char **dst, const char *src)
{
char *tmp;
if (*dst)
{
tmp = malloc(strlen(*dst) + strlen(src) + 2);
if (!tmp)
return;
sprintf(tmp, "%s,%s", *dst, src);
free(*dst);
*dst = tmp;
}
else
{
*dst = malloc(strlen(src) + 1);
if (!*dst)
return;
strcpy(*dst, src);
}
}
/*
* get_DNS_NetworkParams()
*
* Locates DNS info using GetNetworkParams() function from the Internet
* Protocol Helper (IP Helper) API. When located, this returns a pointer
* in *outptr to a newly allocated memory area holding a null-terminated
* string with a space or comma seperated list of DNS IP addresses.
*
* Returns 0 and nullifies *outptr upon inability to return DNSes string.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*
* Implementation supports Windows 98 and newer.
*
* Note: Ancient PSDK required in order to build a W98 target.
*/
static int get_DNS_NetworkParams(char **outptr)
{
FIXED_INFO *fi, *newfi;
struct ares_addr namesrvr;
char *txtaddr;
IP_ADDR_STRING *ipAddr;
size_t txtlen;
HRESULT res;
int res;
DWORD size = sizeof (*fi);
char *endptr = ret_buf;
int count = 0;
*endptr = '\0';
*outptr = NULL;
/* Verify run-time availability of GetNetworkParams() */
if (ares_fpGetNetworkParams == ZERO_NULL)
return 0;
fi = malloc(size);
if (!fi)
@ -621,16 +878,16 @@ static int get_iphlpapi_dns_classic(char *ret_buf, size_t ret_size)
res = (*ares_fpGetNetworkParams) (fi, &size);
if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
goto quit;
goto done;
newfi = realloc(fi, size);
if (!newfi)
goto quit;
goto done;
fi = newfi;
res = (*ares_fpGetNetworkParams) (fi, &size);
if (res != ERROR_SUCCESS)
goto quit;
goto done;
for (ipAddr = &fi->DnsServerList; ipAddr; ipAddr = ipAddr->Next)
{
@ -652,39 +909,47 @@ static int get_iphlpapi_dns_classic(char *ret_buf, size_t ret_size)
else
continue;
txtlen = strlen(txtaddr);
if (ret_size >= strlen(ret_buf) + txtlen + 2)
{
sprintf(endptr, "%s,", txtaddr);
endptr += txtlen + 1;
count++;
}
commajoin(outptr, txtaddr);
if (!*outptr)
break;
}
quit:
done:
if (fi)
free(fi);
if (endptr != ret_buf)
*(endptr - 1) = '\0';
if (!*outptr)
return 0;
return count;
return 1;
}
/*
* get_DNS_AdaptersAddresses()
*
* Locates DNS info using GetAdaptersAddresses() function from the Internet
* Protocol Helper (IP Helper) API. When located, this returns a pointer
* in *outptr to a newly allocated memory area holding a null-terminated
* string with a space or comma seperated list of DNS IP addresses.
*
* Returns 0 and nullifies *outptr upon inability to return DNSes string.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*
* Implementation supports Windows XP and newer.
*/
#define IPAA_INITIAL_BUF_SZ 15 * 1024
#define IPAA_MAX_TRIES 3
static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
static int get_DNS_AdaptersAddresses(char **outptr)
{
IP_ADAPTER_DNS_SERVER_ADDRESS *ipaDNSAddr;
IP_ADAPTER_ADDRESSES *ipaa, *newipaa, *ipaaEntry;
ULONG res;
ULONG ReqBufsz = IPAA_INITIAL_BUF_SZ;
ULONG Bufsz = IPAA_INITIAL_BUF_SZ;
ULONG AddrFlags = 0;
char *endptr = ret_buf;
int trying = IPAA_MAX_TRIES;
int count = 0;
int res;
union {
struct sockaddr *sa;
@ -693,13 +958,12 @@ static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
} namesrvr;
char txtaddr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
size_t txtlen;
/* Unless GetAdaptersAddresses is available, use GetNetworkParams */
if (ares_fpGetAdaptersAddresses == ZERO_NULL)
return get_iphlpapi_dns_classic(ret_buf, ret_size);
*outptr = NULL;
*endptr = '\0';
/* Verify run-time availability of GetAdaptersAddresses() */
if (ares_fpGetAdaptersAddresses == ZERO_NULL)
return 0;
ipaa = malloc(Bufsz);
if (!ipaa)
@ -709,7 +973,7 @@ static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
res = (*ares_fpGetAdaptersAddresses) (AF_UNSPEC, AddrFlags, NULL,
ipaa, &ReqBufsz);
if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
goto quit;
goto done;
while ((res == ERROR_BUFFER_OVERFLOW) && (--trying))
{
@ -717,7 +981,7 @@ static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
{
newipaa = realloc(ipaa, ReqBufsz);
if (!newipaa)
goto quit;
goto done;
Bufsz = ReqBufsz;
ipaa = newipaa;
}
@ -727,7 +991,7 @@ static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
break;
}
if (res != ERROR_SUCCESS)
goto quit;
goto done;
for (ipaaEntry = ipaa; ipaaEntry; ipaaEntry = ipaaEntry->Next)
{
@ -758,24 +1022,49 @@ static int get_iphlpapi_dns_info(char *ret_buf, size_t ret_size)
else
continue;
txtlen = strlen(txtaddr);
if (ret_size >= strlen(ret_buf) + txtlen + 2)
{
sprintf(endptr, "%s,", txtaddr);
endptr += txtlen + 1;
count++;
}
commajoin(outptr, txtaddr);
if (!*outptr)
goto done;
}
}
quit:
done:
if (ipaa)
free(ipaa);
if (endptr != ret_buf)
*(endptr - 1) = '\0';
if (!*outptr)
return 0;
return 1;
}
/*
* get_DNS_Windows()
*
* Locates DNS info from Windows employing most suitable methods available at
* run-time no matter which Windows version it is. When located, this returns
* a pointer in *outptr to a newly allocated memory area holding a string with
* a space or comma seperated list of DNS IP addresses, null-terminated.
*
* Returns 0 and nullifies *outptr upon inability to return DNSes string.
*
* Returns 1 and sets *outptr when returning a dynamically allocated string.
*
* Implementation supports Windows 95 and newer.
*/
static int get_DNS_Windows(char **outptr)
{
/* Try using IP helper API GetAdaptersAddresses() */
if (get_DNS_AdaptersAddresses(outptr))
return 1;
return count;
/* Try using IP helper API GetNetworkParams() */
if (get_DNS_NetworkParams(outptr))
return 1;
/* Fall-back to registry information */
return get_DNS_Registry(outptr);
}
#endif
@ -790,111 +1079,13 @@ static int init_by_resolv_conf(ares_channel channel)
#ifdef WIN32
/*
NameServer info via IPHLPAPI (IP helper API):
GetNetworkParams() should be the trusted source for this.
Available in Win-98/2000 and later. If that fail, fall-back to
registry information.
NameServer Registry:
On Windows 9X, the DNS server can be found in:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP\NameServer
On Windows NT/2000/XP/2003:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\NameServer
or
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DhcpNameServer
or
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\{AdapterID}\
NameServer
or
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\{AdapterID}\
DhcpNameServer
*/
HKEY mykey;
HKEY subkey;
DWORD data_type;
DWORD bytes;
DWORD result;
char buf[512];
win_platform platform;
if (channel->nservers > -1) /* don't override ARES_OPT_SERVER */
return ARES_SUCCESS;
if (get_iphlpapi_dns_info(buf,sizeof(buf)) > 0)
if (get_DNS_Windows(&line))
{
status = config_nameserver(&servers, &nservers, buf);
if (status == ARES_SUCCESS)
goto okay;
}
platform = ares__getplatform();
if (platform == WIN_NT)
{
if (RegOpenKeyEx(
HKEY_LOCAL_MACHINE, WIN_NS_NT_KEY, 0,
KEY_READ, &mykey
) == ERROR_SUCCESS)
{
RegOpenKeyEx(mykey, "Interfaces", 0,
KEY_QUERY_VALUE|KEY_ENUMERATE_SUB_KEYS, &subkey);
if (get_res_nt(mykey, NAMESERVER, &line))
{
status = config_nameserver(&servers, &nservers, line);
free(line);
}
else if (get_res_nt(mykey, DHCPNAMESERVER, &line))
{
status = config_nameserver(&servers, &nservers, line);
free(line);
}
/* Try the interfaces */
else if (get_res_interfaces_nt(subkey, NAMESERVER, &line))
{
status = config_nameserver(&servers, &nservers, line);
free(line);
}
else if (get_res_interfaces_nt(subkey, DHCPNAMESERVER, &line))
{
status = config_nameserver(&servers, &nservers, line);
free(line);
}
RegCloseKey(subkey);
RegCloseKey(mykey);
}
}
else if (platform == WIN_9X)
{
if (RegOpenKeyEx(
HKEY_LOCAL_MACHINE, WIN_NS_9X, 0,
KEY_READ, &mykey
) == ERROR_SUCCESS)
{
if ((result = RegQueryValueEx(
mykey, NAMESERVER, NULL, &data_type,
NULL, &bytes
)
) == ERROR_SUCCESS ||
result == ERROR_MORE_DATA)
{
if (bytes)
{
line = malloc(bytes+1);
if (RegQueryValueEx(mykey, NAMESERVER, NULL, &data_type,
(unsigned char *)line, &bytes) ==
ERROR_SUCCESS)
{
status = config_nameserver(&servers, &nservers, line);
}
free(line);
}
}
}
RegCloseKey(mykey);
status = config_nameserver(&servers, &nservers, line);
free(line);
}
if (status == ARES_SUCCESS)
@ -1128,9 +1319,6 @@ DhcpNameServer
}
/* If we got any name server entries, fill them in. */
#ifdef WIN32
okay:
#endif
if (servers)
{
channel->servers = servers;

Write Preview
Loading…
Cancel
Save