P2P: Relax Bonjour SD query matching

The DNS Name is allowed to use or not use domain name compression. To
handle both cases, check human readable DNS Name match if binary
matching does not show a hit.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/p2p_supplicant.c

@@ -1234,6 +1234,135 @@ static int wpas_send_probe_resp(void *ctx, const struct wpabuf *buf)
 }
 
 
+/*
+ * DNS Header section is used only to calculate compression pointers, so the
+ * contents of this data does not matter, but the length needs to be reserved
+ * in the virtual packet.
+ */
+#define DNS_HEADER_LEN 12
+
+/*
+ * 27-octet in-memory packet from P2P specification containing two implied
+ * queries for _tcp.lcoal. PTR IN and _udp.local. PTR IN
+ */
+#define P2P_SD_IN_MEMORY_LEN 27
+
+static int p2p_sd_dns_uncompress_label(char **upos, char *uend, u8 *start,
+				       u8 **spos, const u8 *end)
+{
+	while (*spos < end) {
+		u8 val = ((*spos)[0] & 0xc0) >> 6;
+		int len;
+
+		if (val == 1 || val == 2) {
+			/* These are reserved values in RFC 1035 */
+			wpa_printf(MSG_DEBUG, "P2P: Invalid domain name "
+				   "sequence starting with 0x%x", val);
+			return -1;
+		}
+
+		if (val == 3) {
+			u16 offset;
+			u8 *spos_tmp;
+
+			/* Offset */
+			if (*spos + 2 > end) {
+				wpa_printf(MSG_DEBUG, "P2P: No room for full "
+					   "DNS offset field");
+				return -1;
+			}
+
+			offset = (((*spos)[0] & 0x3f) << 8) | (*spos)[1];
+			if (offset >= *spos - start) {
+				wpa_printf(MSG_DEBUG, "P2P: Invalid DNS "
+					   "pointer offset %u", offset);
+				return -1;
+			}
+
+			(*spos) += 2;
+			spos_tmp = start + offset;
+			return p2p_sd_dns_uncompress_label(upos, uend, start,
+							   &spos_tmp,
+							   *spos - 2);
+		}
+
+		/* Label */
+		len = (*spos)[0] & 0x3f;
+		if (len == 0)
+			return 0;
+
+		(*spos)++;
+		if (*spos + len > end) {
+			wpa_printf(MSG_DEBUG, "P2P: Invalid domain name "
+				   "sequence - no room for label with length "
+				   "%u", len);
+			return -1;
+		}
+
+		if (*upos + len + 2 > uend)
+			return -2;
+
+		os_memcpy(*upos, *spos, len);
+		*spos += len;
+		*upos += len;
+		(*upos)[0] = '.';
+		(*upos)++;
+		(*upos)[0] = '\0';
+	}
+
+	return 0;
+}
+
+
+/* Uncompress domain names per RFC 1035 using the P2P SD in-memory packet.
+ * Returns -1 on parsing error (invalid input sequence), -2 if output buffer is
+ * not large enough */
+static int p2p_sd_dns_uncompress(char *buf, size_t buf_len, const u8 *msg,
+				 size_t msg_len, size_t offset)
+{
+	/* 27-octet in-memory packet from P2P specification */
+	const char *prefix = "\x04_tcp\x05local\x00\x00\x0C\x00\x01"
+		"\x04_udp\xC0\x11\x00\x0C\x00\x01";
+	u8 *tmp, *end, *spos;
+	char *upos, *uend;
+	int ret = 0;
+
+	if (buf_len < 2)
+		return -1;
+	if (offset > msg_len)
+		return -1;
+
+	tmp = os_malloc(DNS_HEADER_LEN + P2P_SD_IN_MEMORY_LEN + msg_len);
+	if (tmp == NULL)
+		return -1;
+	spos = tmp + DNS_HEADER_LEN + P2P_SD_IN_MEMORY_LEN;
+	end = spos + msg_len;
+	spos += offset;
+
+	os_memset(tmp, 0, DNS_HEADER_LEN);
+	os_memcpy(tmp + DNS_HEADER_LEN, prefix, P2P_SD_IN_MEMORY_LEN);
+	os_memcpy(tmp + DNS_HEADER_LEN + P2P_SD_IN_MEMORY_LEN, msg, msg_len);
+
+	upos = buf;
+	uend = buf + buf_len;
+
+	ret = p2p_sd_dns_uncompress_label(&upos, uend, tmp, &spos, end);
+	if (ret) {
+		os_free(tmp);
+		return ret;
+	}
+
+	if (upos == buf) {
+		upos[0] = '.';
+		upos[1] = '\0';
+	} else if (upos[-1] == '.')
+		upos[-1] = '\0';
+
+	os_free(tmp);
+	return 0;
+}
+
+
 static struct p2p_srv_bonjour *
 wpas_p2p_service_get_bonjour(struct wpa_supplicant *wpa_s,
 			     const struct wpabuf *query)
@@ -1324,6 +1453,33 @@ static void wpas_sd_all_bonjour(struct wpa_supplicant *wpa_s,
 }
 
 
+static int match_bonjour_query(struct p2p_srv_bonjour *bsrv, const u8 *query,
+			       size_t query_len)
+{
+	char str_rx[256], str_srv[256];
+
+	if (query_len < 3 || wpabuf_len(bsrv->query) < 3)
+		return 0; /* Too short to include DNS Type and Version */
+	if (os_memcmp(query + query_len - 3,
+		      wpabuf_head_u8(bsrv->query) + wpabuf_len(bsrv->query) - 3,
+		      3) != 0)
+		return 0; /* Mismatch in DNS Type or Version */
+	if (query_len == wpabuf_len(bsrv->query) &&
+	    os_memcmp(query, wpabuf_head(bsrv->query), query_len - 3) == 0)
+		return 1; /* Binary match */
+
+	if (p2p_sd_dns_uncompress(str_rx, sizeof(str_rx), query, query_len - 3,
+				  0))
+		return 0; /* Failed to uncompress query */
+	if (p2p_sd_dns_uncompress(str_srv, sizeof(str_srv),
+				  wpabuf_head(bsrv->query),
+				  wpabuf_len(bsrv->query) - 3, 0))
+		return 0; /* Failed to uncompress service */
+
+	return os_strcmp(str_rx, str_srv) == 0;
+}
+
+
 static void wpas_sd_req_bonjour(struct wpa_supplicant *wpa_s,
 				struct wpabuf *resp, u8 srv_trans_id,
 				const u8 *query, size_t query_len)
@@ -1348,8 +1504,7 @@ static void wpas_sd_req_bonjour(struct wpa_supplicant *wpa_s,
 
 	dl_list_for_each(bsrv, &wpa_s->global->p2p_srv_bonjour,
 			 struct p2p_srv_bonjour, list) {
-		if (query_len != wpabuf_len(bsrv->query) ||
-		    os_memcmp(query, wpabuf_head(bsrv->query), query_len) != 0)
+		if (!match_bonjour_query(bsrv, query, query_len))
 			continue;
 
 		if (wpabuf_tailroom(resp) <