add dohpath parsing

sldns/str2wire.c

@@ -1150,6 +1150,11 @@ sldns_str2wire_svcparam_key_lookup(const char *key, size_t key_len)
 			return SVCB_KEY_IPV6HINT;
 		break;
 
+	case sizeof("dohpath")-1:
+		if (!strncmp(key, "dohpath", sizeof("dohpath")-1))
+			return SVCB_KEY_DOHPATH;
+		break;
+
 	case sizeof("ech")-1:
 		if (!strncmp(key, "ech", sizeof("ech")-1))
 			return SVCB_KEY_ECH;
@@ -1515,6 +1520,40 @@ sldns_str2wire_svcbparam_alpn_value(const char* val,
 	return LDNS_WIREPARSE_ERR_OK;
 }
 
+static int
+sldns_str2wire_svcbparam_dohpath_value(const char* val,
+	uint8_t* rd, size_t* rd_len)
+{
+	size_t val_len;
+
+	/* RFC6570#section-2.1
+	 * "The characters outside of expressions in a URI Template string are
+	 * intended to be copied literally"
+	 * Practically this means we do not have to look for "double escapes"
+	 * like in the alpn value list.
+	 */
+
+	val_len = strlen(val);
+
+	if (*rd_len < 4 + val_len) {
+		return LDNS_WIREPARSE_ERR_BUFFER_TOO_SMALL;
+	}
+
+	/* draft-ietf-add-svcb-dns-06#section-5.1
+	 * The URI Template MUST contain a "dns" variable
+	 */
+	if (!(strstr(val, "?dns"))) {
+		return LDNS_WIREPARSE_ERR_SVCB_NO_DNS_VAR_IN_DOHPATH;
+	}
+
+	sldns_write_uint16(rd, SVCB_KEY_DOHPATH);
+	sldns_write_uint16(rd + 2, val_len);
+	memcpy(rd + 4, val, val_len);
+	*rd_len = 4 + val_len;
+
+	return LDNS_WIREPARSE_ERR_OK;
+}
+
 static int
 sldns_str2wire_svcparam_value(const char *key, size_t key_len,
 	const char *val, uint8_t* rd, size_t* rd_len)
@@ -1535,6 +1574,7 @@ sldns_str2wire_svcparam_value(const char *key, size_t key_len,
 		case SVCB_KEY_PORT:
 		case SVCB_KEY_IPV4HINT:
 		case SVCB_KEY_IPV6HINT:
+		case SVCB_KEY_DOHPATH:
 			return LDNS_WIREPARSE_ERR_SVCB_MISSING_PARAM;
 #endif
 		default:
@@ -1566,6 +1606,8 @@ sldns_str2wire_svcparam_value(const char *key, size_t key_len,
 		return sldns_str2wire_svcbparam_ech_value(val, rd, rd_len);
 	case SVCB_KEY_ALPN:
 		return sldns_str2wire_svcbparam_alpn_value(val, rd, rd_len);
+	case SVCB_KEY_DOHPATH:
+		return sldns_str2wire_svcbparam_dohpath_value(val, rd, rd_len);
 	default:
 		str_len = strlen(val);
 		if (*rd_len < 4 + str_len)

sldns/str2wire.h

@@ -38,7 +38,8 @@ struct sldns_struct_lookup_table;
 #define SVCB_KEY_IPV4HINT		4
 #define SVCB_KEY_ECH			5
 #define SVCB_KEY_IPV6HINT		6
-#define SVCPARAMKEY_COUNT		7
+#define SVCB_KEY_DOHPATH		7
+#define SVCPARAMKEY_COUNT		8
 
 #define MAX_NUMBER_OF_SVCPARAMS	64
 
@@ -234,7 +235,9 @@ uint8_t* sldns_wirerr_get_rdatawl(uint8_t* rr, size_t len, size_t dname_len);
 #define LDNS_WIREPARSE_ERR_SVCB_IPV6_TOO_MANY_ADDRESSES 383
 #define LDNS_WIREPARSE_ERR_SVCB_ALPN_KEY_TOO_LARGE 384
 #define LDNS_WIREPARSE_ERR_SVCB_NO_DEFAULT_ALPN_VALUE 385
-#define LDNS_WIREPARSE_ERR_SVCPARAM_BROKEN_RDATA 386
+#define LDNS_WIREPARSE_ERR_SVCB_NO_DNS_VAR_IN_DOHPATH 386
+#define LDNS_WIREPARSE_ERR_SVCPARAM_BROKEN_RDATA 387
+
 
 /**
  * Get reference to a constant string for the (parse) error.

sldns/wire2str.c

@@ -171,6 +171,8 @@ static sldns_lookup_table sldns_wireparse_errors_data[] = {
 		"Alpn strings need to be smaller than 255 chars"},
 	{ LDNS_WIREPARSE_ERR_SVCB_NO_DEFAULT_ALPN_VALUE,
 		"No-default-alpn should not have a value" },
+	{ LDNS_WIREPARSE_ERR_SVCB_NO_DNS_VAR_IN_DOHPATH,
+		"Dohpath must have '?dns' in the URI template variable" },
 	{ LDNS_WIREPARSE_ERR_SVCPARAM_BROKEN_RDATA,
 		"General SVCParam error" },
 	{ 0, NULL }
@@ -224,7 +226,7 @@ sldns_lookup_table* sldns_tsig_errors = sldns_tsig_errors_data;
 /* draft-ietf-dnsop-svcb-https-06: 6. Initial SvcParamKeys */
 const char *svcparamkey_strs[] = {
 	"mandatory", "alpn", "no-default-alpn", "port",
-	"ipv4hint", "ech", "ipv6hint"
+	"ipv4hint", "ech", "ipv6hint", "dohpath"
 };
 
 char* sldns_wire2str_pkt(uint8_t* data, size_t len)
@@ -1144,6 +1146,29 @@ static int sldns_wire2str_svcparam_ech2str(char** s,
 	return w + size;
 }
 
+static int sldns_wire2str_svcparam_dohpath2str(char** s,
+	size_t* slen, uint16_t data_len, uint8_t* data)
+{
+	int w = 0;
+	uint16_t i;
+
+	assert(data_len > 0); /* Guaranteed by sldns_wire2str_svcparam_scan */
+
+	w += sldns_str_print(s, slen, "=\"");
+
+	/* RC6570#section-2.1 specifies that the '\' (and other non-letter
+	 * characters in the URI) are "intended to be copied literally" */
+	for (i = 0; i < data_len; i++) {
+		// @TODO do a check like isprint()?
+
+		w += sldns_str_print(s, slen, "%c", data[i]);
+	}
+
+	w += sldns_str_print(s, slen, "\"");
+
+	return w;
+}
+
 int sldns_wire2str_svcparam_scan(uint8_t** d, size_t* dlen, char** s, size_t* slen)
 {
 	uint8_t ch;
@@ -1174,6 +1199,7 @@ int sldns_wire2str_svcparam_scan(uint8_t** d, size_t* dlen, char** s, size_t* sl
 	 	case SVCB_KEY_IPV4HINT:
 	 	case SVCB_KEY_IPV6HINT:
 	 	case SVCB_KEY_MANDATORY:
+	 	case SVCB_KEY_DOHPATH:
 	 		return -1;
 	 	default:
 	 		return written_chars;
@@ -1201,6 +1227,9 @@ int sldns_wire2str_svcparam_scan(uint8_t** d, size_t* dlen, char** s, size_t* sl
 	case SVCB_KEY_ECH:
 		r = sldns_wire2str_svcparam_ech2str(s, slen, data_len, *d);
 		break;
+	case SVCB_KEY_DOHPATH:
+		r = sldns_wire2str_svcparam_dohpath2str(s, slen, data_len, *d);
+		break;
 	default:
 		r = sldns_str_print(s, slen, "=\"");