--- /dev/null
+
+/* Copyright 1998 by the Massachusetts Institute of Technology.
+ *
+ * Permission to use, copy, modify, and distribute this
+ * software and its documentation for any purpose and without
+ * fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting
+ * documentation, and that the name of M.I.T. not be used in
+ * advertising or publicity pertaining to distribution of the
+ * software without specific, written prior permission.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose. It is provided "as is"
+ * without express or implied warranty.
+ */
+
+#include "ares_setup.h"
+
+#ifdef HAVE_NETINET_IN_H
+# include <netinet/in.h>
+#endif
+#ifdef HAVE_NETDB_H
+# include <netdb.h>
+#endif
+#ifdef HAVE_ARPA_NAMESER_H
+# include <arpa/nameser.h>
+#else
+# include "nameser.h"
+#endif
+#ifdef HAVE_ARPA_NAMESER_COMPAT_H
+# include <arpa/nameser_compat.h>
+#endif
+
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif
+
+#include "ares.h"
+#include "ares_dns.h"
+#include "ares_nowarn.h"
+#include "ares_private.h"
+
+int ares_parse_ptr_reply(const unsigned char *abuf, int alen, const void *addr,
+ int addrlen, int family, struct hostent **host)
+{
+ unsigned int qdcount, ancount;
+ int status, i, rr_type, rr_class, rr_len;
+ long len;
+ const unsigned char *aptr;
+ char *ptrname, *hostname, *rr_name, *rr_data;
+ struct hostent *hostent;
+ int aliascnt = 0;
+ int alias_alloc = 8;
+ char ** aliases;
+ size_t rr_data_len;
+
+ /* Set *host to NULL for all failure cases. */
+ *host = NULL;
+
+ /* Give up if abuf doesn't have room for a header. */
+ if (alen < HFIXEDSZ)
+ return ARES_EBADRESP;
+
+ /* Fetch the question and answer count from the header. */
+ qdcount = DNS_HEADER_QDCOUNT(abuf);
+ ancount = DNS_HEADER_ANCOUNT(abuf);
+ if (qdcount != 1)
+ return ARES_EBADRESP;
+
+ /* Expand the name from the question, and skip past the question. */
+ aptr = abuf + HFIXEDSZ;
+ status = ares__expand_name_for_response(aptr, abuf, alen, &ptrname, &len);
+ if (status != ARES_SUCCESS)
+ return status;
+ if (aptr + len + QFIXEDSZ > abuf + alen)
+ {
+ ares_free(ptrname);
+ return ARES_EBADRESP;
+ }
+ aptr += len + QFIXEDSZ;
+
+ /* Examine each answer resource record (RR) in turn. */
+ hostname = NULL;
+ aliases = ares_malloc(alias_alloc * sizeof(char *));
+ if (!aliases)
+ {
+ ares_free(ptrname);
+ return ARES_ENOMEM;
+ }
+ for (i = 0; i < (int)ancount; i++)
+ {
+ /* Decode the RR up to the data field. */
+ status = ares__expand_name_for_response(aptr, abuf, alen, &rr_name, &len);
+ if (status != ARES_SUCCESS)
+ break;
+ aptr += len;
+ if (aptr + RRFIXEDSZ > abuf + alen)
+ {
+ ares_free(rr_name);
+ status = ARES_EBADRESP;
+ break;
+ }
+ rr_type = DNS_RR_TYPE(aptr);
+ rr_class = DNS_RR_CLASS(aptr);
+ rr_len = DNS_RR_LEN(aptr);
+ aptr += RRFIXEDSZ;
+ if (aptr + rr_len > abuf + alen)
+ {
+ ares_free(rr_name);
+ status = ARES_EBADRESP;
+ break;
+ }
+
+ if (rr_class == C_IN && rr_type == T_PTR
+ && strcasecmp(rr_name, ptrname) == 0)
+ {
+ /* Decode the RR data and set hostname to it. */
+ status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
+ &len);
+ if (status != ARES_SUCCESS)
+ {
+ ares_free(rr_name);
+ break;
+ }
+ if (hostname)
+ ares_free(hostname);
+ hostname = rr_data;
+ rr_data_len = strlen(rr_data)+1;
+ aliases[aliascnt] = ares_malloc(rr_data_len * sizeof(char));
+ if (!aliases[aliascnt])
+ {
+ ares_free(rr_name);
+ status = ARES_ENOMEM;
+ break;
+ }
+ strncpy(aliases[aliascnt], rr_data, rr_data_len);
+ aliascnt++;
+ if (aliascnt >= alias_alloc) {
+ char **ptr;
+ alias_alloc *= 2;
+ ptr = ares_realloc(aliases, alias_alloc * sizeof(char *));
+ if(!ptr) {
+ ares_free(rr_name);
+ status = ARES_ENOMEM;
+ break;
+ }
+ aliases = ptr;
+ }
+ }
+
+ if (rr_class == C_IN && rr_type == T_CNAME)
+ {
+ /* Decode the RR data and replace ptrname with it. */
+ status = ares__expand_name_for_response(aptr, abuf, alen, &rr_data,
+ &len);
+ if (status != ARES_SUCCESS)
+ {
+ ares_free(rr_name);
+ break;
+ }
+ ares_free(ptrname);
+ ptrname = rr_data;
+ }
+
+ ares_free(rr_name);
+ aptr += rr_len;
+ if (aptr > abuf + alen)
+ { /* LCOV_EXCL_START: already checked above */
+ status = ARES_EBADRESP;
+ break;
+ } /* LCOV_EXCL_STOP */
+ }
+
+ if (status == ARES_SUCCESS && !hostname)
+ status = ARES_ENODATA;
+ if (status == ARES_SUCCESS)
+ {
+ /* We got our answer. Allocate memory to build the host entry. */
+ hostent = ares_malloc(sizeof(struct hostent));
+ if (hostent)
+ {
+ hostent->h_addr_list = ares_malloc(2 * sizeof(char *));
+ if (hostent->h_addr_list)
+ {
+ hostent->h_addr_list[0] = ares_malloc(addrlen);
+ if (hostent->h_addr_list[0])
+ {
+ hostent->h_aliases = ares_malloc((aliascnt+1) * sizeof (char *));
+ if (hostent->h_aliases)
+ {
+ /* Fill in the hostent and return successfully. */
+ hostent->h_name = hostname;
+ for (i=0 ; i<aliascnt ; i++)
+ hostent->h_aliases[i] = aliases[i];
+ hostent->h_aliases[aliascnt] = NULL;
+ hostent->h_addrtype = aresx_sitoss(family);
+ hostent->h_length = aresx_sitoss(addrlen);
+ memcpy(hostent->h_addr_list[0], addr, addrlen);
+ hostent->h_addr_list[1] = NULL;
+ *host = hostent;
+ ares_free(aliases);
+ ares_free(ptrname);
+ return ARES_SUCCESS;
+ }
+ ares_free(hostent->h_addr_list[0]);
+ }
+ ares_free(hostent->h_addr_list);
+ }
+ ares_free(hostent);
+ }
+ status = ARES_ENOMEM;
+ }
+ for (i=0 ; i<aliascnt ; i++)
+ if (aliases[i])
+ ares_free(aliases[i]);
+ ares_free(aliases);
+ if (hostname)
+ ares_free(hostname);
+ ares_free(ptrname);
+ return status;
+}
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