diff options
Diffstat (limited to 'ares_parse_ptr_reply.c')
| -rw-r--r-- | ares_parse_ptr_reply.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/ares_parse_ptr_reply.c b/ares_parse_ptr_reply.c new file mode 100644 index 0000000..2ebca24 --- /dev/null +++ b/ares_parse_ptr_reply.c @@ -0,0 +1,159 @@ +/* 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. + */ + +static const char rcsid[] = "$Id$"; + +#include <sys/types.h> + +#ifdef WIN32 +#include "nameser.h" +#else +#include <sys/socket.h> +#include <netinet/in.h> +#include <netdb.h> +#include <arpa/nameser.h> +#endif + +#include <stdlib.h> +#include <string.h> +#include "ares.h" +#include "ares_dns.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, len, rr_type, rr_class, rr_len; + const unsigned char *aptr; + char *ptrname, *hostname, *rr_name, *rr_data; + struct hostent *hostent; + + /* 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(aptr, abuf, alen, &ptrname, &len); + if (status != ARES_SUCCESS) + return status; + if (aptr + len + QFIXEDSZ > abuf + alen) + { + free(ptrname); + return ARES_EBADRESP; + } + aptr += len + QFIXEDSZ; + + /* Examine each answer resource record (RR) in turn. */ + hostname = NULL; + for (i = 0; i < ancount; i++) + { + /* Decode the RR up to the data field. */ + status = ares_expand_name(aptr, abuf, alen, &rr_name, &len); + if (status != ARES_SUCCESS) + break; + aptr += len; + if (aptr + RRFIXEDSZ > abuf + alen) + { + 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 (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(aptr, abuf, alen, &rr_data, &len); + if (status != ARES_SUCCESS) + break; + if (hostname) + free(hostname); + hostname = rr_data; + } + + if (rr_class == C_IN && rr_type == T_CNAME) + { + /* Decode the RR data and replace ptrname with it. */ + status = ares_expand_name(aptr, abuf, alen, &rr_data, &len); + if (status != ARES_SUCCESS) + break; + free(ptrname); + ptrname = rr_data; + } + + free(rr_name); + aptr += rr_len; + if (aptr > abuf + alen) + { + status = ARES_EBADRESP; + break; + } + } + + if (status == ARES_SUCCESS && !hostname) + status = ARES_ENODATA; + if (status == ARES_SUCCESS) + { + /* We got our answer. Allocate memory to build the host entry. */ + hostent = malloc(sizeof(struct hostent)); + if (hostent) + { + hostent->h_addr_list = malloc(2 * sizeof(char *)); + if (hostent->h_addr_list) + { + hostent->h_addr_list[0] = malloc(addrlen); + if (hostent->h_addr_list[0]) + { + hostent->h_aliases = malloc(sizeof (char *)); + if (hostent->h_aliases) + { + /* Fill in the hostent and return successfully. */ + hostent->h_name = hostname; + hostent->h_aliases[0] = NULL; + hostent->h_addrtype = family; + hostent->h_length = addrlen; + memcpy(hostent->h_addr_list[0], addr, addrlen); + hostent->h_addr_list[1] = NULL; + *host = hostent; + free(ptrname); + return ARES_SUCCESS; + } + free(hostent->h_addr_list[0]); + } + free(hostent->h_addr_list); + } + free(hostent); + } + status = ARES_ENOMEM; + } + if (hostname) + free(hostname); + free(ptrname); + return status; +} |