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https://frontier.innolan.net/rainlance/c-ares.git
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IPv6-on-windows: find DNS servers correctly
This commit is contained in:
David Stuart
committed by
Daniel Stenberg
Daniel Stenberg
parent
d60f07d094
commit
6518b56a5e
237
ares_init.c
237
ares_init.c
@ -69,6 +69,7 @@
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#include "ares_nowarn.h"
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#include "ares_platform.h"
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#include "ares_private.h"
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#include "inet_ntop.h"
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#ifdef ANDROID
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#include <sys/system_properties.h>
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@ -595,73 +596,195 @@ static int get_res_interfaces_nt(HKEY hKey, const char *subkey, char **obuf)
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return 0;
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}
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/**
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* The desired output for this method is that we set "ret_buf" to
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* something like:
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*
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* 192.168.0.1,dns01.my.domain,fe80::200:f8ff:fe21:67cf
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*
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* The only ordering requirement is that primary servers are listed
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* before secondary. There is no requirement that IPv4 addresses should
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* necessarily be before IPv6.
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*
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* Note that ret_size should ideally be big enough to hold around
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* 2-3 IPv4 and 2-3 IPv6 addresses.
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*
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* Finally, we need to return the total number of DNS servers located.
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*/
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static int get_iphlpapi_dns_info (char *ret_buf, size_t ret_size)
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{
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FIXED_INFO *fi, *newfi;
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DWORD size = sizeof (*fi);
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IP_ADDR_STRING *ipAddr;
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int i, count = 0;
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int debug = 0;
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size_t ip_size = sizeof("255.255.255.255,")-1;
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size_t left = ret_size;
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char *ret = ret_buf;
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HRESULT res;
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const size_t ipv4_size = INET_ADDRSTRLEN + 1; /* +1 for ',' at end */
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const size_t ipv6_size = INET6_ADDRSTRLEN + 12; /* +12 for "%0123456789," at end */
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size_t left = ret_size;
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char *ret = ret_buf;
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int count = 0;
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fi = malloc(size);
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if (!fi)
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return 0;
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res = (*ares_fpGetNetworkParams) (fi, &size);
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if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
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goto quit;
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newfi = realloc(fi, size);
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if (!newfi)
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goto quit;
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fi = newfi;
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res = (*ares_fpGetNetworkParams) (fi, &size);
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if (res != ERROR_SUCCESS)
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goto quit;
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if (debug)
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/* Use the GetAdaptersAddresses method if it's available, otherwise
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fall back to GetNetworkParams. */
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if (ares_fpGetAdaptersAddresses != ZERO_NULL)
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{
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printf ("Host Name: %s\n", fi->HostName);
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printf ("Domain Name: %s\n", fi->DomainName);
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printf ("DNS Servers:\n"
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" %s (primary)\n", fi->DnsServerList.IpAddress.String);
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}
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if (strlen(fi->DnsServerList.IpAddress.String) > 0 &&
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inet_addr(fi->DnsServerList.IpAddress.String) != INADDR_NONE &&
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left > ip_size)
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{
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ret += sprintf (ret, "%s,", fi->DnsServerList.IpAddress.String);
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left -= ret - ret_buf;
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count++;
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}
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const ULONG working_buf_size = 15000;
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IP_ADAPTER_ADDRESSES *pFirstEntry = NULL;
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IP_ADAPTER_ADDRESSES *pEntry = NULL;
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ULONG bufSize = 0;
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ULONG result = 0;
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for (i = 0, ipAddr = fi->DnsServerList.Next; ipAddr && left > ip_size;
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ipAddr = ipAddr->Next, i++)
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{
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if (inet_addr(ipAddr->IpAddress.String) != INADDR_NONE)
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/* According to MSDN, the recommended way to do this is to use a temporary
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buffer of 15K, to "dramatically reduce the chance that the GetAdaptersAddresses
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method returns ERROR_BUFFER_OVERFLOW" */
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pFirstEntry = ( IP_ADAPTER_ADDRESSES * ) malloc( working_buf_size );
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bufSize = working_buf_size;
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if( !pFirstEntry )
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return 0;
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/* Call the method one time */
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result = ( *ares_fpGetAdaptersAddresses )( AF_UNSPEC, 0, 0, pFirstEntry, &bufSize );
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if( result == ERROR_BUFFER_OVERFLOW )
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{
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ret += sprintf (ret, "%s,", ipAddr->IpAddress.String);
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left -= ret - ret_buf;
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count++;
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/* Reallocate, bufSize should now be set to the required size */
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pFirstEntry = ( IP_ADAPTER_ADDRESSES * ) realloc( pFirstEntry, bufSize );
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if( !pFirstEntry )
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return 0;
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/* Call the method a second time */
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result = ( *ares_fpGetAdaptersAddresses )( AF_UNSPEC, 0, 0, pFirstEntry, &bufSize );
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if( result == ERROR_BUFFER_OVERFLOW )
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{
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/* Reallocate, bufSize should now be set to the required size */
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pFirstEntry = ( IP_ADAPTER_ADDRESSES * ) realloc( pFirstEntry, bufSize );
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if( !pFirstEntry )
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return 0;
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/* Call the method a third time. The maximum number of times we're going to do
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this is 3. Three shall be the number thou shalt count, and the number of the
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counting shall be three. Five is right out. */
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result = ( *ares_fpGetAdaptersAddresses )( AF_UNSPEC, 0, 0, pFirstEntry, &bufSize );
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}
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}
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if (debug)
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printf (" %s (secondary %d)\n", ipAddr->IpAddress.String, i+1);
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/* Check the current result for failure */
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if( result != ERROR_SUCCESS )
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{
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free( pFirstEntry );
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return 0;
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}
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/* process the results */
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for( pEntry = pFirstEntry ; pEntry != NULL ; pEntry = pEntry->Next )
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{
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IP_ADAPTER_DNS_SERVER_ADDRESS* pDNSAddr = pEntry->FirstDnsServerAddress;
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for( ; pDNSAddr != NULL ; pDNSAddr = pDNSAddr->Next )
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{
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struct sockaddr *pGenericAddr = pDNSAddr->Address.lpSockaddr;
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int stringlen = 0;
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if( pGenericAddr->sa_family == AF_INET && left > ipv4_size )
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{
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/* Handle the v4 case */
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struct sockaddr_in *pIPv4Addr = ( struct sockaddr_in * ) pGenericAddr;
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ares_inet_ntop( AF_INET, &pIPv4Addr->sin_addr, ret, ipv4_size - 1 ); /* -1 for comma */
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/* Append a comma to the end, THEN NULL. Should be OK because we
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already tested the size at the top of the if statement. */
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stringlen = strlen( ret );
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ret[ stringlen ] = ',';
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ret[ stringlen + 1 ] = '\0';
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ret += stringlen + 1;
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left -= ret - ret_buf;
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++count;
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}
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else if( pGenericAddr->sa_family == AF_INET6 && left > ipv6_size )
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{
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/* Handle the v6 case */
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struct sockaddr_in6 *pIPv6Addr = ( struct sockaddr_in6 * ) pGenericAddr;
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ares_inet_ntop( AF_INET6, &pIPv6Addr->sin6_addr, ret, ipv6_size - 1 ); /* -1 for comma */
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/* Append a comma to the end, THEN NULL. Should be OK because we
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already tested the size at the top of the if statement. */
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stringlen = strlen( ret );
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ret[ stringlen ] = ',';
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ret[ stringlen + 1 ] = '\0';
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ret += stringlen + 1;
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left -= ret - ret_buf;
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++count;
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/* NB on Windows this also returns stuff in the fec0::/10 range,
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seems to be hard-coded somehow. Do we need to ignore them? */
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}
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}
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}
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if( pFirstEntry )
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free( pFirstEntry );
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if (ret > ret_buf)
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ret[-1] = '\0';
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return count;
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}
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else
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{
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FIXED_INFO *fi, *newfi;
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DWORD size = sizeof (*fi);
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IP_ADDR_STRING *ipAddr;
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int i;
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int debug = 0;
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HRESULT res;
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fi = malloc(size);
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if (!fi)
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return 0;
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res = (*ares_fpGetNetworkParams) (fi, &size);
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if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
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goto quit;
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newfi = realloc(fi, size);
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if (!newfi)
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goto quit;
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fi = newfi;
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res = (*ares_fpGetNetworkParams) (fi, &size);
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if (res != ERROR_SUCCESS)
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goto quit;
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if (debug)
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{
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printf ("Host Name: %s\n", fi->HostName);
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printf ("Domain Name: %s\n", fi->DomainName);
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printf ("DNS Servers:\n"
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" %s (primary)\n", fi->DnsServerList.IpAddress.String);
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}
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if (strlen(fi->DnsServerList.IpAddress.String) > 0 &&
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inet_addr(fi->DnsServerList.IpAddress.String) != INADDR_NONE &&
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left > ipv4_size)
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{
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ret += sprintf (ret, "%s,", fi->DnsServerList.IpAddress.String);
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left -= ret - ret_buf;
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++count;
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}
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for (i = 0, ipAddr = fi->DnsServerList.Next; ipAddr && left > ipv4_size;
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ipAddr = ipAddr->Next, i++)
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{
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if (inet_addr(ipAddr->IpAddress.String) != INADDR_NONE)
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{
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ret += sprintf (ret, "%s,", ipAddr->IpAddress.String);
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left -= ret - ret_buf;
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++count;
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}
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if (debug)
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printf (" %s (secondary %d)\n", ipAddr->IpAddress.String, i+1);
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}
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quit:
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if (fi)
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free(fi);
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if (fi)
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free(fi);
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if (debug && left <= ip_size)
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printf ("Too many nameservers. Truncating to %d addressess", count);
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if (ret > ret_buf)
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ret[-1] = '\0';
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return count;
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if (debug && left <= ipv4_size)
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printf ("Too many nameservers. Truncating to %d addressess", count);
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if (ret > ret_buf)
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ret[-1] = '\0';
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return count;
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}
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}
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#endif
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@ -704,7 +827,7 @@ DhcpNameServer
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DWORD data_type;
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DWORD bytes;
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DWORD result;
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char buf[256];
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char buf[512];
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win_platform platform;
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if (channel->nservers > -1) /* don't override ARES_OPT_SERVER */
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