diff options
Diffstat (limited to 'src/c-ares/ares_parse_txt_reply.c')
| -rw-r--r-- | src/c-ares/ares_parse_txt_reply.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/c-ares/ares_parse_txt_reply.c b/src/c-ares/ares_parse_txt_reply.c new file mode 100644 index 000000000..4856b4cea --- /dev/null +++ b/src/c-ares/ares_parse_txt_reply.c @@ -0,0 +1,220 @@ + +/* Copyright 1998 by the Massachusetts Institute of Technology. + * Copyright (C) 2009 by Jakub Hrozek <jhrozek@redhat.com> + * + * 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_INET_H +# include <arpa/inet.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_data.h" +#include "ares_private.h" + +static int +ares__parse_txt_reply (const unsigned char *abuf, int alen, + int ex, void **txt_out) +{ + size_t substr_len; + unsigned int qdcount, ancount, i; + const unsigned char *aptr; + const unsigned char *strptr; + int status, rr_type, rr_class, rr_len; + long len; + char *hostname = NULL, *rr_name = NULL; + struct ares_txt_ext *txt_head = NULL; + struct ares_txt_ext *txt_last = NULL; + struct ares_txt_ext *txt_curr; + + /* Set *txt_out to NULL for all failure cases. */ + *txt_out = 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; + if (ancount == 0) + return ARES_ENODATA; + + /* Expand the name from the question, and skip past the question. */ + aptr = abuf + HFIXEDSZ; + status = ares_expand_name (aptr, abuf, alen, &hostname, &len); + if (status != ARES_SUCCESS) + return status; + + if (aptr + len + QFIXEDSZ > abuf + alen) + { + ares_free (hostname); + return ARES_EBADRESP; + } + aptr += len + QFIXEDSZ; + + /* Examine each answer resource record (RR) in turn. */ + 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 (aptr + rr_len > abuf + alen) + { + status = ARES_EBADRESP; + break; + } + + /* Check if we are really looking at a TXT record */ + if (rr_class == C_IN && rr_type == T_TXT) + { + /* + * There may be multiple substrings in a single TXT record. Each + * substring may be up to 255 characters in length, with a + * "length byte" indicating the size of the substring payload. + * RDATA contains both the length-bytes and payloads of all + * substrings contained therein. + */ + + strptr = aptr; + while (strptr < (aptr + rr_len)) + { + substr_len = (unsigned char)*strptr; + if (strptr + substr_len + 1 > aptr + rr_len) + { + status = ARES_EBADRESP; + break; + } + + /* Allocate storage for this TXT answer appending it to the list */ + txt_curr = ares_malloc_data(ex ? ARES_DATATYPE_TXT_EXT : + ARES_DATATYPE_TXT_REPLY); + if (!txt_curr) + { + status = ARES_ENOMEM; + break; + } + if (txt_last) + { + txt_last->next = txt_curr; + } + else + { + txt_head = txt_curr; + } + txt_last = txt_curr; + + if (ex) + txt_curr->record_start = (strptr == aptr); + txt_curr->length = substr_len; + txt_curr->txt = ares_malloc (substr_len + 1/* Including null byte */); + if (txt_curr->txt == NULL) + { + status = ARES_ENOMEM; + break; + } + + ++strptr; + memcpy ((char *) txt_curr->txt, strptr, substr_len); + + /* Make sure we NULL-terminate */ + txt_curr->txt[substr_len] = 0; + + strptr += substr_len; + } + } + + /* Propagate any failures */ + if (status != ARES_SUCCESS) + { + break; + } + + /* Don't lose memory in the next iteration */ + ares_free (rr_name); + rr_name = NULL; + + /* Move on to the next record */ + aptr += rr_len; + } + + if (hostname) + ares_free (hostname); + if (rr_name) + ares_free (rr_name); + + /* clean up on error */ + if (status != ARES_SUCCESS) + { + if (txt_head) + ares_free_data (txt_head); + return status; + } + + /* everything looks fine, return the data */ + *txt_out = txt_head; + + return ARES_SUCCESS; +} + +int +ares_parse_txt_reply (const unsigned char *abuf, int alen, + struct ares_txt_reply **txt_out) +{ + return ares__parse_txt_reply(abuf, alen, 0, (void **) txt_out); +} + + +int +ares_parse_txt_reply_ext (const unsigned char *abuf, int alen, + struct ares_txt_ext **txt_out) +{ + return ares__parse_txt_reply(abuf, alen, 1, (void **) txt_out); +} |