YAML escape EDNS EDE option EXTRA-TEXT value

The description in the EXTRA-TEXT field of the EDE option needs
to be escaped to ensure that the emitted message is valid YAML.

bin/tests/system/digdelv/tests.sh

@@ -748,6 +748,19 @@ if [ -x "$DIG" ]; then
   if [ $ret -ne 0 ]; then echo_i "failed"; fi
   status=$((status + ret))
 
+  if [ $HAS_PYYAML -ne 0 ]; then
+    n=$((n + 1))
+    echo_i "check that Extended DNS Error 0 is printed correctly +yaml ($n)"
+    ret=0
+    # add specials '"' and '\'
+    dig_with_opts @10.53.0.3 +yaml +ednsopt=ede:0000666f6f225c a.example +qr >dig.out.test$n 2>&1 || ret=1
+    $PYTHON yamlget.py dig.out.test$n 0 message query_message_data OPT_PSEUDOSECTION EDNS EDE EXTRA-TEXT >yamlget.out.test$n 2>&1 || ret=1
+    read -r value <yamlget.out.test$n
+    [ "$value" = 'foo"\' ] || ret=1
+    if [ $ret -ne 0 ]; then echo_i "failed"; fi
+    status=$((status + ret))
+  fi
+
   n=$((n + 1))
   echo_i "check that Extended DNS Error 24 is printed correctly ($n)"
   ret=0

lib/dns/message.c

@@ -3900,19 +3900,32 @@ dns_message_pseudosectiontoyaml(dns_message_t *msg, dns_pseudosection_t section,
 				} else {
 					ADD_STRING(target, "\"");
 				}
-				if (isc_buffer_availablelength(target) < optlen)
-				{
-					result = ISC_R_NOSPACE;
-					goto cleanup;
-				}
 				for (i = 0; i < optlen; i++) {
 					if (isprint(optdata[i]) ||
 					    (utf8ok && optdata[i] > 127))
 					{
+						/*
+						 * We are emitting a yaml '"'
+						 * delimited string so we need
+						 * to escape '"' and '\'.
+						 */
+						if (extra_text &&
+						    (optdata[i] == '"' ||
+						     optdata[i] == '\\'))
+						{
+							ADD_STRING(target,
+								   "\\");
+						}
+						if (isc_buffer_availablelength(
+							    target) < 1)
+						{
+							result = ISC_R_NOSPACE;
+							goto cleanup;
+						}
 						isc_buffer_putmem(
 							target, &optdata[i], 1);
 					} else {
-						isc_buffer_putstr(target, ".");
+						ADD_STRING(target, ".");
 					}
 				}
 				if (!extra_text) {