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ares_init.c: get_iphlpapi_dns_info() refactoring
This commit is contained in:
Yang Tse
342
ares_init.c
342
ares_init.c
@ -65,11 +65,11 @@
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#endif
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#include "ares.h"
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#include "inet_ntop.h"
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#include "inet_net_pton.h"
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#include "ares_library_init.h"
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#include "ares_nowarn.h"
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#include "ares_platform.h"
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#include "inet_ntop.h"
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#include "ares_private.h"
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#ifdef WATT32
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@ -598,202 +598,182 @@ 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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/* get_iphlpapi_dns_classic() is supported on W98 and newer */
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static int get_iphlpapi_dns_classic(char *ret_buf, size_t ret_size)
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{
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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," */
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long left = ret_size;
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char *ret = ret_buf;
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int count = 0;
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FIXED_INFO *fi, *newfi;
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struct ares_addr namesrvr;
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char *txtaddr;
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IP_ADDR_STRING *ipAddr;
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size_t txtlen;
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HRESULT res;
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DWORD size = sizeof (*fi);
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char *endptr = ret_buf;
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int count = 0;
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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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*endptr = '\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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for (ipAddr = &fi->DnsServerList; ipAddr; ipAddr = ipAddr->Next)
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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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txtaddr = &ipAddr->IpAddress.String[0];
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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
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GetAdaptersAddresses 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,
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&bufSize);
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if(result == ERROR_BUFFER_OVERFLOW)
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/* Validate converting textual address to binary format. */
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if (ares_inet_pton(AF_INET, txtaddr, &namesrvr.addrV4) == 1)
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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 second time */
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result = (*ares_fpGetAdaptersAddresses)(AF_UNSPEC, 0, 0, pFirstEntry,
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&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
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going to do this is 3. Three shall be the number thou shalt count,
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and the number of the counting shall be three. Five is right
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out. */
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result = (*ares_fpGetAdaptersAddresses)(AF_UNSPEC, 0, 0, pFirstEntry,
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&bufSize);
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}
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if ((namesrvr.addrV4.S_un.S_addr == INADDR_ANY) ||
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(namesrvr.addrV4.S_un.S_addr == INADDR_NONE))
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continue;
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}
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/* Check the current result for failure */
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if(result != ERROR_SUCCESS)
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else if (ares_inet_pton(AF_INET6, txtaddr, &namesrvr.addrV6) == 1)
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{
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free(pFirstEntry);
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return 0;
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if (memcmp(&namesrvr.addrV6, &ares_in6addr_any,
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sizeof(namesrvr.addrV6)) == 0)
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continue;
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}
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else
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continue;
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/* process the results */
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for(pEntry = pFirstEntry ; pEntry != NULL ; pEntry = pEntry->Next)
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txtlen = strlen(txtaddr);
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if (ret_size >= strlen(ret_buf) + txtlen + 2)
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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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size_t 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,
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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 -= stringlen + 1;
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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,
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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 -= stringlen + 1;
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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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sprintf(endptr, "%s,", txtaddr);
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endptr += txtlen + 1;
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count++;
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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 <= 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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if (endptr != ret_buf)
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*(endptr - 1) = '\0';
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return count;
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}
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#define IPAA_INITIAL_BUF_SZ 15 * 1024
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#define IPAA_MAX_TRIES 3
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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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IP_ADAPTER_DNS_SERVER_ADDRESS *ipaDNSAddr;
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IP_ADAPTER_ADDRESSES *ipaa, *newipaa, *ipaaEntry;
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ULONG res;
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ULONG ReqBufsz = IPAA_INITIAL_BUF_SZ;
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ULONG Bufsz = IPAA_INITIAL_BUF_SZ;
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ULONG AddrFlags = 0;
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char *endptr = ret_buf;
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int trying = IPAA_MAX_TRIES;
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int count = 0;
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union {
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struct sockaddr *sa;
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struct sockaddr_in *sa4;
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struct sockaddr_in6 *sa6;
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} namesrvr;
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char txtaddr[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:255.255.255.255")];
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size_t txtlen;
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/* Unless GetAdaptersAddresses is available, use GetNetworkParams */
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if (ares_fpGetAdaptersAddresses == ZERO_NULL)
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return get_iphlpapi_dns_classic(ret_buf, ret_size);
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*endptr = '\0';
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ipaa = malloc(Bufsz);
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if (!ipaa)
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return 0;
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/* Usually this call suceeds with initial buffer size */
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res = (*ares_fpGetAdaptersAddresses) (AF_UNSPEC, AddrFlags, NULL,
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ipaa, &ReqBufsz);
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if ((res != ERROR_BUFFER_OVERFLOW) && (res != ERROR_SUCCESS))
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goto quit;
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while ((res == ERROR_BUFFER_OVERFLOW) && (--trying))
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{
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if (Bufsz < ReqBufsz)
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{
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newipaa = realloc(ipaa, ReqBufsz);
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if (!newipaa)
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goto quit;
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Bufsz = ReqBufsz;
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ipaa = newipaa;
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}
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res = (*ares_fpGetAdaptersAddresses) (AF_UNSPEC, AddrFlags, NULL,
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ipaa, &ReqBufsz);
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if (res == ERROR_SUCCESS)
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break;
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}
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if (res != ERROR_SUCCESS)
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goto quit;
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for (ipaaEntry = ipaa; ipaaEntry; ipaaEntry = ipaaEntry->Next)
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{
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for (ipaDNSAddr = ipaaEntry->FirstDnsServerAddress;
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ipaDNSAddr;
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ipaDNSAddr = ipaDNSAddr->Next)
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{
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namesrvr.sa = ipaDNSAddr->Address.lpSockaddr;
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if (namesrvr.sa->sa_family == AF_INET)
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{
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if ((namesrvr.sa4->sin_addr.S_un.S_addr == INADDR_ANY) ||
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(namesrvr.sa4->sin_addr.S_un.S_addr == INADDR_NONE))
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continue;
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if (! ares_inet_ntop(AF_INET, &namesrvr.sa4->sin_addr,
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txtaddr, sizeof(txtaddr)))
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continue;
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}
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else if (namesrvr.sa->sa_family == AF_INET6)
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{
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if (memcmp(&namesrvr.sa6->sin6_addr, &ares_in6addr_any,
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sizeof(namesrvr.sa6->sin6_addr)) == 0)
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continue;
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if (! ares_inet_ntop(AF_INET, &namesrvr.sa6->sin6_addr,
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txtaddr, sizeof(txtaddr)))
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continue;
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}
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else
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continue;
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txtlen = strlen(txtaddr);
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if (ret_size >= strlen(ret_buf) + txtlen + 2)
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{
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sprintf(endptr, "%s,", txtaddr);
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endptr += txtlen + 1;
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count++;
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}
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}
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}
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quit:
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if (ipaa)
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free(ipaa);
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if (endptr != ret_buf)
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*(endptr - 1) = '\0';
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return count;
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}
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#endif
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