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-rw-r--r--resolv/res_mkquery.c46
1 files changed, 46 insertions, 0 deletions
diff --git a/resolv/res_mkquery.c b/resolv/res_mkquery.c
index fd80569fe2..3fa597fecd 100644
--- a/resolv/res_mkquery.c
+++ b/resolv/res_mkquery.c
@@ -208,3 +208,49 @@ res_nmkquery(res_state statp,
return (cp - buf);
}
libresolv_hidden_def (res_nmkquery)
+
+
+/* attach OPT pseudo-RR, as documented in RFC2671 (EDNS0). */
+#ifndef T_OPT
+#define T_OPT 41
+#endif
+
+int
+__res_nopt(res_state statp,
+ int n0, /* current offset in buffer */
+ u_char *buf, /* buffer to put query */
+ int buflen, /* size of buffer */
+ int anslen) /* UDP answer buffer size */
+{
+ u_int16_t flags = 0;
+
+#ifdef DEBUG
+ if ((statp->options & RES_DEBUG) != 0U)
+ printf(";; res_nopt()\n");
+#endif
+
+ HEADER *hp = (HEADER *) buf;
+ u_char *cp = buf + n0;
+ u_char *ep = buf + buflen;
+
+ if ((ep - cp) < 1 + RRFIXEDSZ)
+ return -1;
+
+ *cp++ = 0; /* "." */
+
+ ns_put16(T_OPT, cp); /* TYPE */
+ cp += INT16SZ;
+ ns_put16(anslen & 0xffff, cp); /* CLASS = UDP payload size */
+ cp += INT16SZ;
+ *cp++ = NOERROR; /* extended RCODE */
+ *cp++ = 0; /* EDNS version */
+ /* XXX Once we support DNSSEC we change the flag value here. */
+ ns_put16(flags, cp);
+ cp += INT16SZ;
+ ns_put16(0, cp); /* RDLEN */
+ cp += INT16SZ;
+ hp->arcount = htons(ntohs(hp->arcount) + 1);
+
+ return cp - buf;
+}
+libresolv_hidden_def (__res_nopt)