- Merge #911 from natalie-reece: Exclude EDE before other EDNS options when

there isn't enough space.
- For #911: Try to trim EXTRA-TEXT (and LDNS_EDE_OTHER options
  altogether) before giving up on attaching EDE options.

doc/Changelog

@@ -1,3 +1,9 @@
+1 August 2023: George
+	- Merge #911 from natalie-reece: Exclude EDE before other EDNS options
+	  when there isn't enough space.
+	- For #911: Try to trim EXTRA-TEXT (and LDNS_EDE_OTHER options
+	  altogether) before giving up on attaching EDE options.
+
 31 July 2023: George
 	- Merge #790 from Tom Carpay: Add support for EDE caching in cachedb
 	  and subnetcache.

testcode/unitmain.c

@@ -839,6 +839,218 @@ static void respip_test(void)
 	respip_conf_actions_test();
 }
 
+#include "util/regional.h"
+#include "sldns/sbuffer.h"
+#include "util/data/dname.h"
+#include "util/data/msgreply.h"
+#include "util/data/msgencode.h"
+#include "sldns/str2wire.h"
+
+static void edns_ede_encode_setup(struct edns_data* edns,
+	struct regional* region)
+{
+	memset(edns, 0, sizeof(*edns));
+	edns->edns_present = 1;
+	edns->edns_version = EDNS_ADVERTISED_VERSION;
+	edns->udp_size = EDNS_ADVERTISED_SIZE;
+	edns->bits &= EDNS_DO;
+	/* Fill up opt_list_out with EDEs */
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_BLOCKED, "Too long blocked text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_BLOCKED, "Too long blocked text"));
+	/* Fill up opt_list_inplace_cb_out with EDEs */
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_BLOCKED, "Too long blocked text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_BLOCKED, "Too long blocked text"));
+	/* append another EDNS option to both lists */
+	unit_assert(
+		edns_opt_list_append(&edns->opt_list_out,
+		LDNS_EDNS_UNBOUND_CACHEDB_TESTFRAME_TEST, 0, NULL, region));
+	unit_assert(
+		edns_opt_list_append(&edns->opt_list_inplace_cb_out,
+		LDNS_EDNS_UNBOUND_CACHEDB_TESTFRAME_TEST, 0, NULL, region));
+	/* append LDNS_EDE_OTHER at the end of both lists */
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+	unit_assert(
+		edns_opt_list_append_ede(&edns->opt_list_inplace_cb_out, region,
+		LDNS_EDE_OTHER, "Too long other text"));
+}
+
+static void edns_ede_encode_encodedecode(struct query_info* qinfo,
+	struct reply_info* rep, struct regional* region,
+	struct edns_data* edns, sldns_buffer* pkt)
+{
+	/* encode */
+	unit_assert(
+		reply_info_answer_encode(qinfo, rep, 1, rep->flags, pkt,
+		0, 0, region, 65535, edns, 0, 0));
+	/* buffer ready for reading; skip after the question section */
+	sldns_buffer_skip(pkt, LDNS_HEADER_SIZE);
+	(void)query_dname_len(pkt);
+	sldns_buffer_skip(pkt, 2 + 2);
+	/* decode */
+	unit_assert(
+		parse_edns_from_query_pkt(pkt, edns, NULL, NULL, region)==0);
+}
+
+static void edns_ede_encode_check(struct edns_data* edns, int* found_ede,
+	int* found_ede_other, int* found_ede_txt, int* found_other_edns)
+{
+	struct edns_option* opt;
+	for(opt = edns->opt_list_in; opt; opt = opt->next) {
+		if(opt->opt_code == LDNS_EDNS_EDE) {
+			(*found_ede)++;
+			if(opt->opt_len > 2)
+				(*found_ede_txt)++;
+			if(opt->opt_len >= 2 && sldns_read_uint16(
+				opt->opt_data) == LDNS_EDE_OTHER)
+				(*found_ede_other)++;
+		} else {
+			(*found_other_edns)++;
+		}
+	}
+
+}
+
+static void edns_ede_encode_fit_test(struct query_info* qinfo,
+	struct reply_info* rep, struct regional* region)
+{
+	struct edns_data edns;
+	int found_ede = 0, found_ede_other = 0, found_ede_txt = 0;
+	int found_other_edns = 0;
+	sldns_buffer* pkt = sldns_buffer_new(65535);
+	unit_assert(pkt);
+	edns_ede_encode_setup(&edns, region);
+	/* leave the pkt buffer as is; everything should fit */
+	edns_ede_encode_encodedecode(qinfo, rep, region, &edns, pkt);
+	edns_ede_encode_check(&edns, &found_ede, &found_ede_other,
+		&found_ede_txt, &found_other_edns);
+	unit_assert(found_ede == 12);
+	unit_assert(found_ede_other == 8);
+	unit_assert(found_ede_txt == 12);
+	unit_assert(found_other_edns == 2);
+	/* cleanup */
+	sldns_buffer_free(pkt);
+}
+
+static void edns_ede_encode_notxt_fit_test( struct query_info* qinfo,
+	struct reply_info* rep, struct regional* region)
+{
+	struct edns_data edns;
+	sldns_buffer* pkt;
+	uint16_t edns_field_size, ede_txt_size;
+	int found_ede = 0, found_ede_other = 0, found_ede_txt = 0;
+	int found_other_edns = 0;
+	edns_ede_encode_setup(&edns, region);
+	/* pkt buffer should fit everything if the ede txt is cropped.
+	 * OTHER EDE should not be there since it is useless without text. */
+	edns_field_size = calc_edns_field_size(&edns);
+	(void)calc_ede_option_size(&edns, &ede_txt_size);
+	pkt = sldns_buffer_new(LDNS_HEADER_SIZE
+		+ qinfo->qname_len
+		+ 2 + 2 /* qtype + qclass */
+		+ 11 /* opt record */
+		+ edns_field_size
+		- ede_txt_size);
+	unit_assert(pkt);
+	edns_ede_encode_encodedecode(qinfo, rep, region, &edns, pkt);
+	edns_ede_encode_check(&edns, &found_ede, &found_ede_other,
+		&found_ede_txt, &found_other_edns);
+	unit_assert(found_ede == 4);
+	unit_assert(found_ede_other == 0);
+	unit_assert(found_ede_txt == 0);
+	unit_assert(found_other_edns == 2);
+	/* cleanup */
+	sldns_buffer_free(pkt);
+}
+
+static void edns_ede_encode_no_fit_test( struct query_info* qinfo,
+	struct reply_info* rep, struct regional* region)
+{
+	struct edns_data edns;
+	sldns_buffer* pkt;
+	uint16_t edns_field_size, ede_size, ede_txt_size;
+	int found_ede = 0, found_ede_other = 0, found_ede_txt = 0;
+	int found_other_edns = 0;
+	edns_ede_encode_setup(&edns, region);
+	/* pkt buffer should fit only non-EDE options. */
+	edns_field_size = calc_edns_field_size(&edns);
+	ede_size = calc_ede_option_size(&edns, &ede_txt_size);
+	pkt = sldns_buffer_new(LDNS_HEADER_SIZE
+		+ qinfo->qname_len
+		+ 2 + 2 /* qtype + qclass */
+		+ 11 /* opt record */
+		+ edns_field_size
+		- ede_size);
+	unit_assert(pkt);
+	edns_ede_encode_encodedecode(qinfo, rep, region, &edns, pkt);
+	edns_ede_encode_check(&edns, &found_ede, &found_ede_other,
+		&found_ede_txt, &found_other_edns);
+	unit_assert(found_ede == 0);
+	unit_assert(found_ede_other == 0);
+	unit_assert(found_ede_txt == 0);
+	unit_assert(found_other_edns == 2);
+	/* cleanup */
+	sldns_buffer_free(pkt);
+}
+
+/** test optional EDE encoding with various buffer
+ *  available sizes */
+static void edns_ede_answer_encode_test(void)
+{
+	struct regional* region = regional_create();
+	struct reply_info* rep;
+	struct query_info qinfo;
+	unit_show_feature("edns ede optional encoding");
+	unit_assert(region);
+	rep = construct_reply_info_base(region,
+		LDNS_RCODE_NOERROR | BIT_QR, 1,
+		3600, 3600, 3600,
+		0, 0, 0, 0,
+		sec_status_unchecked, LDNS_EDE_NONE);
+	unit_assert(rep);
+	memset(&qinfo, 0, sizeof(qinfo));
+	qinfo.qname = sldns_str2wire_dname("encode.ede.", &qinfo.qname_len);
+	unit_assert(qinfo.qname);
+	qinfo.qtype = LDNS_RR_TYPE_TXT;
+	qinfo.qclass = LDNS_RR_CLASS_IN;
+
+	edns_ede_encode_fit_test(&qinfo, rep, region);
+	edns_ede_encode_notxt_fit_test(&qinfo, rep, region);
+	edns_ede_encode_no_fit_test(&qinfo, rep, region);
+
+	/* cleanup */
+	free(qinfo.qname);
+	regional_free_all(region);
+	regional_destroy(region);
+}
+
 void unit_show_func(const char* file, const char* func)
 {
 	printf("test %s:%s\n", file, func);
@@ -852,6 +1064,7 @@ void unit_show_feature(const char* feature)
 #ifdef USE_ECDSA_EVP_WORKAROUND
 void ecdsa_evp_workaround_init(void);
 #endif
+
 /**
  * Main unit test program. Setup, teardown and report errors.
  * @param argc: arg count.
@@ -909,6 +1122,7 @@ main(int argc, char* argv[])
 	zonemd_test();
 	tcpreuse_test();
 	msgparse_test();
+	edns_ede_answer_encode_test();
 #ifdef CLIENT_SUBNET
 	ecs_test();
 #endif /* CLIENT_SUBNET */

util/data/msgencode.c

@@ -806,6 +806,93 @@ calc_edns_field_size(struct edns_data* edns)
 	return 1 + 2 + 2 + 4 + 2 + rdatalen;
 }
 
+uint16_t
+calc_edns_option_size(struct edns_data* edns, uint16_t code)
+{
+	size_t rdatalen = 0;
+	struct edns_option* opt;
+	if(!edns || !edns->edns_present)
+		return 0;
+	for(opt = edns->opt_list_inplace_cb_out; opt; opt = opt->next) {
+		if(opt->opt_code == code)
+			rdatalen += 4 + opt->opt_len;
+	}
+	for(opt = edns->opt_list_out; opt; opt = opt->next) {
+		if(opt->opt_code == code)
+			rdatalen += 4 + opt->opt_len;
+	}
+	return rdatalen;
+}
+
+uint16_t
+calc_ede_option_size(struct edns_data* edns, uint16_t* txt_size)
+{
+	size_t rdatalen = 0;
+	struct edns_option* opt;
+	*txt_size = 0;
+	if(!edns || !edns->edns_present)
+		return 0;
+	for(opt = edns->opt_list_inplace_cb_out; opt; opt = opt->next) {
+		if(opt->opt_code == LDNS_EDNS_EDE)
+			rdatalen += 4 + opt->opt_len;
+			if(opt->opt_len > 2)
+				*txt_size += opt->opt_len - 2;
+			if(opt->opt_len >= 2 && sldns_read_uint16(
+				opt->opt_data) == LDNS_EDE_OTHER)
+				*txt_size += 4 + 2;
+	}
+	for(opt = edns->opt_list_out; opt; opt = opt->next) {
+		if(opt->opt_code == LDNS_EDNS_EDE)
+			rdatalen += 4 + opt->opt_len;
+			if(opt->opt_len > 2)
+				*txt_size += opt->opt_len - 2;
+			if(opt->opt_len >= 2 && sldns_read_uint16(
+				opt->opt_data) == LDNS_EDE_OTHER)
+				*txt_size += 4 + 2;
+	}
+	return rdatalen;
+}
+
+/* Trims the EDE OPTION-DATA to not include any EXTRA-TEXT data.
+ * Also removes any LDNS_EDE_OTHER options from the list since they are useless
+ * without the extra text. */
+static void
+ede_trim_text(struct edns_option** list)
+{
+	struct edns_option* curr, *prev = NULL;
+	if(!list || !(*list)) return;
+	/* Unlink and repoint if LDNS_EDE_OTHER are first in list */
+	while(list && *list && (*list)->opt_code == LDNS_EDNS_EDE
+		&& (*list)->opt_len >= 2
+		&& sldns_read_uint16((*list)->opt_data) == LDNS_EDE_OTHER ) {
+		*list = (*list)->next;
+	}
+	if(!list || !(*list)) return;
+	curr = *list;
+	while(curr) {
+		if(curr->opt_code == LDNS_EDNS_EDE) {
+			if(curr->opt_len >= 2 && sldns_read_uint16(
+				curr->opt_data) == LDNS_EDE_OTHER) {
+				/* LDNS_EDE_OTHER cannot be the first option in
+				 * this while, so prev is always initialized at
+				 * this point from the other branches;
+				 * cut this option off */
+				prev->next = curr->next;
+				curr = curr->next;
+			} else if(curr->opt_len > 2) {
+				/* trim this option's EXTRA-TEXT */
+				curr->opt_len = 2;
+				prev = curr;
+				curr = curr->next;
+			}
+		} else {
+			/* continue */
+			prev = curr;
+			curr = curr->next;
+		}
+	}
+}
+
 static void
 attach_edns_record_max_msg_sz(sldns_buffer* pkt, struct edns_data* edns,
 	uint16_t max_msg_sz)
@@ -894,6 +981,7 @@ reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
 {
 	uint16_t flags;
 	unsigned int attach_edns = 0;
+	uint16_t edns_field_size, ede_size, ede_txt_size;
 
 	if(!cached || rep->authoritative) {
 		/* original flags, copy RD and CD bits from query. */
@@ -916,25 +1004,39 @@ reply_info_answer_encode(struct query_info* qinf, struct reply_info* rep,
 	log_assert(flags & BIT_QR); /* QR bit must be on in our replies */
 	if(udpsize < LDNS_HEADER_SIZE)
 		return 0;
+	/* currently edns does not change during calculations;
+	 * calculate sizes once here */
+	edns_field_size = calc_edns_field_size(edns);
+	ede_size = calc_ede_option_size(edns, &ede_txt_size);
 	if(sldns_buffer_capacity(pkt) < udpsize)
 		udpsize = sldns_buffer_capacity(pkt);
-	if(udpsize < LDNS_HEADER_SIZE + calc_edns_field_size(edns)) {
+	/* EDEs are optional, try to fit anything else before them */
+	if(udpsize < LDNS_HEADER_SIZE + edns_field_size - ede_size) {
 		/* packet too small to contain edns, omit it. */
 		attach_edns = 0;
 	} else {
 		/* reserve space for edns record */
-		attach_edns = (unsigned int)calc_edns_field_size(edns);
-		udpsize -= attach_edns;
+		attach_edns = (unsigned int)edns_field_size - ede_size;
 	}
 
 	if(!reply_info_encode(qinf, rep, id, flags, pkt, timenow, region,
-		udpsize, dnssec, MINIMAL_RESPONSES)) {
+		udpsize - attach_edns, dnssec, MINIMAL_RESPONSES)) {
 		log_err("reply encode: out of memory");
 		return 0;
 	}
-	if(attach_edns && sldns_buffer_capacity(pkt) >=
-		sldns_buffer_limit(pkt)+attach_edns)
-		attach_edns_record_max_msg_sz(pkt, edns, udpsize+attach_edns);
+	if(attach_edns) {
+		if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size)
+			attach_edns_record_max_msg_sz(pkt, edns, udpsize);
+		else if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size - ede_txt_size) {
+			ede_trim_text(&edns->opt_list_inplace_cb_out);
+			ede_trim_text(&edns->opt_list_out);
+			attach_edns_record_max_msg_sz(pkt, edns, udpsize);
+		} else if(udpsize >= sldns_buffer_limit(pkt) + edns_field_size - ede_size) {
+			edns_opt_list_remove(&edns->opt_list_inplace_cb_out, LDNS_EDNS_EDE);
+			edns_opt_list_remove(&edns->opt_list_out, LDNS_EDNS_EDE);
+			attach_edns_record_max_msg_sz(pkt, edns, udpsize);
+		}
+	}
 	return 1;
 }
 
@@ -996,8 +1098,14 @@ error_encode(sldns_buffer* buf, int r, struct query_info* qinfo,
 		es.ext_rcode = 0;
 		es.bits &= EDNS_DO;
 		if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
-			edns->udp_size)
+			edns->udp_size) {
+			edns_opt_list_remove(&es.opt_list_inplace_cb_out, LDNS_EDNS_EDE);
+			edns_opt_list_remove(&es.opt_list_out, LDNS_EDNS_EDE);
+			if(sldns_buffer_limit(buf) + calc_edns_field_size(&es) >
+				edns->udp_size) {
 				return;
+			}
+		}
 		attach_edns_record(buf, &es);
 	}
 }

util/data/msgencode.h

@@ -108,6 +108,27 @@ void qinfo_query_encode(struct sldns_buffer* pkt, struct query_info* qinfo);
  */
 uint16_t calc_edns_field_size(struct edns_data* edns);
 
+/**
+ * Calculate the size of a specific EDNS option in packet.
+ * @param edns: edns data or NULL.
+ * @param code: the opt code to get the size of.
+ * @return octets the option will take up.
+ */
+uint16_t calc_edns_option_size(struct edns_data* edns, uint16_t code);
+
+/**
+ * Calculate the size of the EDE option(s) in packet. Also calculate seperately
+ * the size of the EXTRA-TEXT field(s) in case we can trim them to fit.
+ * In this case include any LDNS_EDE_OTHER options in their entirety since they
+ * are useless without extra text.
+ * @param edns: edns data or NULL.
+ * @param txt_size: the size of the EXTRA-TEXT field(s); this includes
+ *	LDNS_EDE_OTHER in their entirety since they are useless without
+ *	extra text.
+ * @return octets the option will take up.
+ */
+uint16_t calc_ede_option_size(struct edns_data* edns, uint16_t* txt_size);
+
 /**
  * Attach EDNS record to buffer. Buffer has complete packet. There must
  * be enough room left for the EDNS record.