Issue #419: Escape backslashes when printing json

Thanks boB Rudis

ChangeLog

@@ -1,3 +1,7 @@
+* 2019-??-??: Version 1.?.?
+  * Issue #419: Escape backslashed when printing in JSON format.
+    Thanks boB Rudis
+
 * 2019-01-11: Version 1.5.1
   * Introduce proof of concept GnuTLS implementation. Incomplete support
     for Trust Anchor validation. Requires GnuTLS DANE library. Currently

src/dict.c

@@ -782,13 +782,31 @@ getdns_pp_bindata(gldns_buffer *buf, getdns_bindata *bindata,
 
 	if (bindata->size > 0 && i == bindata->size) {     /* all printable? */
 
-		if (json)
+		if (json) {
-			(void)snprintf(spc, sizeof(spc), "\"%%.%ds\"", (int)i);
+			const uint8_t *s = bindata->data;
-		else
+			const uint8_t *e = s + bindata->size;
+			const uint8_t *b;
+
+			if (!gldns_buffer_reserve(buf, (e - s) + 2))
+				return -1;
+			gldns_buffer_write_u8(buf, '"');
+			while ((b = memchr(s, '\\', e - s))) {
+				if (!gldns_buffer_reserve(buf, (b - s) + 3))
+					return -1;
+				gldns_buffer_write(buf, s, b - s);
+				gldns_buffer_write_u8(buf, '\\');
+				gldns_buffer_write_u8(buf, '\\');
+				s = b + 1;
+			}
+			if (s < e)
+			       	gldns_buffer_write(buf, s, e - s);
+			gldns_buffer_write_u8(buf, '"');
+		} else {
 			(void)snprintf(spc, sizeof(spc), "of \"%%.%ds\"%s>",
 			    (int)(i > 32 ? 32 : i), (i > 32 ? "..." : ""));
-		if (gldns_buffer_printf(buf, spc, bindata->data) < 0)
+			if (gldns_buffer_printf(buf, spc, bindata->data) < 0)
-			return -1;
+				return -1;
+		}
 
 	} else if (bindata->size > 1 &&         /* null terminated printable */
 	    i == bindata->size - 1 && bindata->data[i] == 0) {

src/gldns/gbuffer.c

@@ -106,6 +106,8 @@ int
 gldns_buffer_reserve(gldns_buffer *buffer, size_t amount)
 {
 	gldns_buffer_invariant(buffer);
+	if (buffer->_vfixed)
+		return 1;
 	assert(!buffer->_fixed);
 	if (buffer->_capacity < buffer->_position + amount) {
 		size_t new_capacity = buffer->_capacity * 3 / 2;