/* Copyright 1998 by the Massachusetts Institute of Technology. * Copyright (C) 2009 by Jakub Hrozek * * 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_SYS_SOCKET_H # include #endif #ifdef HAVE_NETINET_IN_H # include #endif #ifdef HAVE_NETDB_H # include #endif #ifdef HAVE_ARPA_INET_H # include #endif #ifdef HAVE_ARPA_NAMESER_H # include #else # include "nameser.h" #endif #ifdef HAVE_ARPA_NAMESER_COMPAT_H # include #endif #include "ares.h" #include "ares_dns.h" #include "ares_data.h" #include "ares_private.h" /* AIX portability check */ #ifndef T_SRV # define T_SRV 33 /* server selection */ #endif int ares_parse_srv_reply (const unsigned char *abuf, int alen, struct ares_srv_reply **srv_out) { unsigned int qdcount, ancount, i; const unsigned char *aptr, *vptr; int status, rr_type, rr_class, rr_len; long len; char *hostname = NULL, *rr_name = NULL; struct ares_srv_reply *srv_head = NULL; struct ares_srv_reply *srv_last = NULL; struct ares_srv_reply *srv_curr; /* Set *srv_out to NULL for all failure cases. */ *srv_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) { 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; /* Check if we are really looking at a SRV record */ if (rr_class == C_IN && rr_type == T_SRV) { /* parse the SRV record itself */ if (rr_len < 6) { status = ARES_EBADRESP; break; } /* Allocate storage for this SRV answer appending it to the list */ srv_curr = ares_malloc_data(ARES_DATATYPE_SRV_REPLY); if (!srv_curr) { status = ARES_ENOMEM; break; } if (srv_last) { srv_last->next = srv_curr; } else { srv_head = srv_curr; } srv_last = srv_curr; vptr = aptr; srv_curr->priority = DNS__16BIT(vptr); vptr += sizeof(unsigned short); srv_curr->weight = DNS__16BIT(vptr); vptr += sizeof(unsigned short); srv_curr->port = DNS__16BIT(vptr); vptr += sizeof(unsigned short); status = ares_expand_name (vptr, abuf, alen, &srv_curr->host, &len); if (status != ARES_SUCCESS) break; } /* Don't lose memory in the next iteration */ free (rr_name); rr_name = NULL; /* Move on to the next record */ aptr += rr_len; } if (hostname) free (hostname); if (rr_name) free (rr_name); /* clean up on error */ if (status != ARES_SUCCESS) { if (srv_head) ares_free_data (srv_head); return status; } /* everything looks fine, return the data */ *srv_out = srv_head; return ARES_SUCCESS; }