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ares_init.c: get_iphlpapi_dns_info() refactoring

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pull/8/merge
Yang Tse 13 years ago
parent 8b79584e01
commit 4980cc99e2
1 changed files with 157 additions and 177 deletions
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  1. 288
      ares_init.c

288
ares_init.c
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@ -65,11 +65,11 @@
#endif #endif
#include "ares.h" #include "ares.h"
#include "inet_ntop.h"
#include "inet_net_pton.h" #include "inet_net_pton.h"
#include "ares_library_init.h" #include "ares_library_init.h"
#include "ares_nowarn.h" #include "ares_nowarn.h"
#include "ares_platform.h" #include "ares_platform.h"
#include "inet_ntop.h"
#include "ares_private.h" #include "ares_private.h"
#ifdef WATT32 #ifdef WATT32
@ -598,203 +598,183 @@ static int get_res_interfaces_nt(HKEY hKey, const char *subkey, char **obuf)
return 0; return 0;
} }
/** /* get_iphlpapi_dns_classic() is supported on W98 and newer */
* The desired output for this method is that we set "ret_buf" to static int get_iphlpapi_dns_classic(char *ret_buf, size_t ret_size)
* something like:
*
* 192.168.0.1,dns01.my.domain,fe80::200:f8ff:fe21:67cf
*
* The only ordering requirement is that primary servers are listed
* before secondary. There is no requirement that IPv4 addresses should
* necessarily be before IPv6.
*
* Note that ret_size should ideally be big enough to hold around
* 2-3 IPv4 and 2-3 IPv6 addresses.
*
* Finally, we need to return the total number of DNS servers located.
*/
static int get_iphlpapi_dns_info (char *ret_buf, size_t ret_size)
{ {
const size_t ipv4_size = INET_ADDRSTRLEN + 1; /* +1 for ',' at end */ FIXED_INFO *fi, *newfi;
const size_t ipv6_size = INET6_ADDRSTRLEN + 12; /* +12 for "%0123456789," */ struct ares_addr namesrvr;
long left = ret_size; char *txtaddr;
char *ret = ret_buf; IP_ADDR_STRING *ipAddr;
size_t txtlen;
HRESULT res;
DWORD size = sizeof (*fi);
char *endptr = ret_buf;
int count = 0; int count = 0;
/* Use the GetAdaptersAddresses method if it's available, otherwise *endptr = '\0';
fall back to GetNetworkParams. */
if (ares_fpGetAdaptersAddresses != ZERO_NULL)
{
const ULONG working_buf_size = 15000;
IP_ADAPTER_ADDRESSES *pFirstEntry = NULL;
IP_ADAPTER_ADDRESSES *pEntry = NULL;
ULONG bufSize = 0;
ULONG result = 0;
/* According to MSDN, the recommended way to do this is to use a temporary
buffer of 15K, to "dramatically reduce the chance that the
GetAdaptersAddresses method returns ERROR_BUFFER_OVERFLOW" */
pFirstEntry = (IP_ADAPTER_ADDRESSES *) malloc(working_buf_size);
bufSize = working_buf_size;
if(!pFirstEntry)
return 0;
/* Call the method one time */ fi = malloc(size);
result = (*ares_fpGetAdaptersAddresses)(AF_UNSPEC, 0, 0, pFirstEntry, if (!fi)
&bufSize);
if(result == ERROR_BUFFER_OVERFLOW)
{
/* Reallocate, bufSize should now be set to the required size */
pFirstEntry = (IP_ADAPTER_ADDRESSES *) realloc(pFirstEntry, bufSize);
if(!pFirstEntry)
return 0; return 0;
/* Call the method a second time */ res = (*ares_fpGetNetworkParams) (fi, &size);
result = (*ares_fpGetAdaptersAddresses)(AF_UNSPEC, 0, 0, pFirstEntry, if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
&bufSize); goto quit;
if(result == ERROR_BUFFER_OVERFLOW)
{
/* Reallocate, bufSize should now be set to the required size */
pFirstEntry = (IP_ADAPTER_ADDRESSES *)realloc(pFirstEntry, bufSize);
if(!pFirstEntry)
return 0;
/* Call the method a third time. The maximum number of times we're newfi = realloc(fi, size);
going to do this is 3. Three shall be the number thou shalt count, if (!newfi)
and the number of the counting shall be three. Five is right goto quit;
out. */
result = (*ares_fpGetAdaptersAddresses)(AF_UNSPEC, 0, 0, pFirstEntry,
&bufSize);
}
}
/* Check the current result for failure */ fi = newfi;
if(result != ERROR_SUCCESS) res = (*ares_fpGetNetworkParams) (fi, &size);
{ if (res != ERROR_SUCCESS)
free(pFirstEntry); goto quit;
return 0;
}
/* process the results */ for (ipAddr = &fi->DnsServerList; ipAddr; ipAddr = ipAddr->Next)
for(pEntry = pFirstEntry ; pEntry != NULL ; pEntry = pEntry->Next)
{
IP_ADAPTER_DNS_SERVER_ADDRESS* pDNSAddr = pEntry->FirstDnsServerAddress;
for(; pDNSAddr != NULL ; pDNSAddr = pDNSAddr->Next)
{ {
struct sockaddr *pGenericAddr = pDNSAddr->Address.lpSockaddr; txtaddr = &ipAddr->IpAddress.String[0];
size_t stringlen = 0;
if(pGenericAddr->sa_family == AF_INET && left > ipv4_size) /* Validate converting textual address to binary format. */
if (ares_inet_pton(AF_INET, txtaddr, &namesrvr.addrV4) == 1)
{ {
/* Handle the v4 case */ if ((namesrvr.addrV4.S_un.S_addr == INADDR_ANY) ||
struct sockaddr_in *pIPv4Addr = (struct sockaddr_in *) pGenericAddr; (namesrvr.addrV4.S_un.S_addr == INADDR_NONE))
continue;
ares_inet_ntop(AF_INET, &pIPv4Addr->sin_addr, ret,
ipv4_size - 1); /* -1 for comma */
/* Append a comma to the end, THEN NULL. Should be OK because we
already tested the size at the top of the if statement. */
stringlen = strlen(ret);
ret[ stringlen ] = ',';
ret[ stringlen + 1 ] = '\0';
ret += stringlen + 1;
left -= stringlen + 1;
++count;
} }
else if(pGenericAddr->sa_family == AF_INET6 && left > ipv6_size) else if (ares_inet_pton(AF_INET6, txtaddr, &namesrvr.addrV6) == 1)
{ {
/* Handle the v6 case */ if (memcmp(&namesrvr.addrV6, &ares_in6addr_any,
struct sockaddr_in6 *pIPv6Addr = (struct sockaddr_in6 *)pGenericAddr; sizeof(namesrvr.addrV6)) == 0)
ares_inet_ntop(AF_INET6, &pIPv6Addr->sin6_addr, ret, continue;
ipv6_size - 1); /* -1 for comma */
/* Append a comma to the end, THEN NULL. Should be OK because we
already tested the size at the top of the if statement. */
stringlen = strlen(ret);
ret[ stringlen ] = ',';
ret[ stringlen + 1 ] = '\0';
ret += stringlen + 1;
left -= stringlen + 1;
++count;
/* NB on Windows this also returns stuff in the fec0::/10 range,
seems to be hard-coded somehow. Do we need to ignore them? */
} }
else
continue;
txtlen = strlen(txtaddr);
if (ret_size >= strlen(ret_buf) + txtlen + 2)
{
sprintf(endptr, "%s,", txtaddr);
endptr += txtlen + 1;
count++;
} }
} }
if(pFirstEntry) quit:
free(pFirstEntry); if (fi)
if (ret > ret_buf) free(fi);
ret[-1] = '\0';
if (endptr != ret_buf)
*(endptr - 1) = '\0';
return count; return count;
} }
else
#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)
{ {
FIXED_INFO *fi, *newfi; IP_ADAPTER_DNS_SERVER_ADDRESS *ipaDNSAddr;
DWORD size = sizeof (*fi); IP_ADAPTER_ADDRESSES *ipaa, *newipaa, *ipaaEntry;
IP_ADDR_STRING *ipAddr; ULONG res;
int i; ULONG ReqBufsz = IPAA_INITIAL_BUF_SZ;
int debug = 0; ULONG Bufsz = IPAA_INITIAL_BUF_SZ;
HRESULT res; ULONG AddrFlags = 0;
char *endptr = ret_buf;
int trying = IPAA_MAX_TRIES;
int count = 0;
fi = malloc(size); union {
if (!fi) struct sockaddr *sa;
struct sockaddr_in *sa4;
struct sockaddr_in6 *sa6;
} 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);
*endptr = '\0';
ipaa = malloc(Bufsz);
if (!ipaa)
return 0; return 0;
res = (*ares_fpGetNetworkParams) (fi, &size); /* Usually this call suceeds with initial buffer size */
res = (*ares_fpGetAdaptersAddresses) (AF_UNSPEC, AddrFlags, NULL,
ipaa, &ReqBufsz);
if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS)) if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
goto quit; goto quit;
newfi = realloc(fi, size); while ((res == ERROR_BUFFER_OVERFLOW) && (--trying))
if (!newfi) {
if (Bufsz < ReqBufsz)
{
newipaa = realloc(ipaa, ReqBufsz);
if (!newipaa)
goto quit; goto quit;
Bufsz = ReqBufsz;
fi = newfi; ipaa = newipaa;
res = (*ares_fpGetNetworkParams) (fi, &size); }
res = (*ares_fpGetAdaptersAddresses) (AF_UNSPEC, AddrFlags, NULL,
ipaa, &ReqBufsz);
if (res == ERROR_SUCCESS)
break;
}
if (res != ERROR_SUCCESS) if (res != ERROR_SUCCESS)
goto quit; goto quit;
if (debug) for (ipaaEntry = ipaa; ipaaEntry; ipaaEntry = ipaaEntry->Next)
{
for (ipaDNSAddr = ipaaEntry->FirstDnsServerAddress;
ipaDNSAddr;
ipaDNSAddr = ipaDNSAddr->Next)
{ {
printf ("Host Name: %s\n", fi->HostName); namesrvr.sa = ipaDNSAddr->Address.lpSockaddr;
printf ("Domain Name: %s\n", fi->DomainName);
printf ("DNS Servers:\n" if (namesrvr.sa->sa_family == AF_INET)
" %s (primary)\n", fi->DnsServerList.IpAddress.String); {
if ((namesrvr.sa4->sin_addr.S_un.S_addr == INADDR_ANY) ||
(namesrvr.sa4->sin_addr.S_un.S_addr == INADDR_NONE))
continue;
if (! ares_inet_ntop(AF_INET, &namesrvr.sa4->sin_addr,
txtaddr, sizeof(txtaddr)))
continue;
} }
if (strlen(fi->DnsServerList.IpAddress.String) > 0 && else if (namesrvr.sa->sa_family == AF_INET6)
inet_addr(fi->DnsServerList.IpAddress.String) != INADDR_NONE &&
left > ipv4_size)
{ {
ret += sprintf (ret, "%s,", fi->DnsServerList.IpAddress.String); if (memcmp(&namesrvr.sa6->sin6_addr, &ares_in6addr_any,
left -= ret - ret_buf; sizeof(namesrvr.sa6->sin6_addr)) == 0)
++count; continue;
if (! ares_inet_ntop(AF_INET, &namesrvr.sa6->sin6_addr,
txtaddr, sizeof(txtaddr)))
continue;
} }
else
continue;
for (i = 0, ipAddr = fi->DnsServerList.Next; ipAddr && left > ipv4_size; txtlen = strlen(txtaddr);
ipAddr = ipAddr->Next, i++) if (ret_size >= strlen(ret_buf) + txtlen + 2)
{
if (inet_addr(ipAddr->IpAddress.String) != INADDR_NONE)
{ {
ret += sprintf (ret, "%s,", ipAddr->IpAddress.String); sprintf(endptr, "%s,", txtaddr);
left -= ret - ret_buf; endptr += txtlen + 1;
++count; count++;
}
} }
if (debug)
printf (" %s (secondary %d)\n", ipAddr->IpAddress.String, i+1);
} }
quit: quit:
if (fi) if (ipaa)
free(fi); free(ipaa);
if (endptr != ret_buf)
*(endptr - 1) = '\0';
if (debug && left <= ipv4_size)
printf ("Too many nameservers. Truncating to %d addressess", count);
if (ret > ret_buf)
ret[-1] = '\0';
return count; return count;
} }
}
#endif #endif
static int init_by_resolv_conf(ares_channel channel) static int init_by_resolv_conf(ares_channel channel)

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