edns-buffer-size option.

git-svn-id: file:///svn/unbound/trunk@1881 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -1,5 +1,6 @@
 29 October 2009: Wouter
 	- iana portlist updated.
+	- edns-buffer-size option, default 4096.
 
 28 October 2009: Wouter
 	- removed abort on prealloc failure, error still printed but softfail.

doc/example.conf.in

@@ -77,6 +77,10 @@ server:
 	# 0 is system default.  Use 4m to catch query spikes for busy servers.
 	# so-rcvbuf: 0
 
+	# EDNS reassembly buffer to advertise to UDP peers (the actual buffer
+	# is set with msg-buffer-size). 1480 can solve fragmentation (timeouts).
+	# edns-buffer-size: 4096
+
 	# buffer size for handling DNS data. No messages larger than this
 	# size can be sent or received, by UDP or TCP. In bytes.
 	# msg-buffer-size: 65552

doc/unbound.conf.5.in

@@ -165,6 +165,17 @@ to 0, or if do_tcp is "no", no TCP queries to authoritative servers are done.
 Number of incoming TCP buffers to allocate per thread. Default is 10. If set
 to 0, or if do_tcp is "no", no TCP queries from clients are accepted.
 .TP
+.B edns\-buffer\-size: \fI<number>
+Number of bytes size to advertise as the EDNS reassembly buffer size.
+This is the value put into datagrams over UDP towards peers.  The actual
+buffer size is determined by msg\-buffer\-size (both for TCP and UDP).  Do
+not set lower than that value.  Default is 4096 which is RFC recommended.
+If you have fragmentation reassembly problems, usually seen as timeouts,
+then a value of 1480 can fix it.  Setting to 512 bypasses even the most
+stringent path MTU problems, but is seen as extreme, since the amount
+of TCP fallback generated is excessive (probably also for this resolver,
+consider tuning the outgoing tcp number).
+.TP
 .B msg\-buffer\-size: \fI<number>
 Number of bytes size of the message buffers. Default is 65552 bytes, enough
 for 64 Kb packets, the maximum DNS message size. No message larger than this

smallapp/unbound-checkconf.c

@@ -135,6 +135,7 @@ print_option(struct config_file* cfg, const char* opt)
 	else O_DEC(opt, "outgoing-range", outgoing_num_ports)
 	else O_DEC(opt, "outgoing-num-tcp", outgoing_num_tcp)
 	else O_DEC(opt, "incoming-num-tcp", incoming_num_tcp)
+	else O_DEC(opt, "edns-buffer-size", edns_buffer_size)
 	else O_DEC(opt, "msg-buffer-size", msg_buffer_size)
 	else O_MEM(opt, "msg-cache-size", msg_cache_size)
 	else O_DEC(opt, "msg-cache-slabs", msg_cache_slabs)
@@ -442,6 +443,9 @@ morechecks(struct config_file* cfg, const char* fname)
 		fatal_exit("ip4 and ip6 are both disabled, pointless");
 	if(!cfg->do_udp && !cfg->do_tcp)
 		fatal_exit("udp and tcp are both disabled, pointless");
+	if(cfg->edns_buffer_size > cfg->msg_buffer_size)
+		fatal_exit("edns-buffer-size larger than msg-buffer-size, "
+			"answers will not fit in processing buffer");
 
 	if(cfg->chrootdir && cfg->chrootdir[0] && 
 		cfg->chrootdir[strlen(cfg->chrootdir)-1] == '/')

util/config_file.c

@@ -95,6 +95,7 @@ config_create()
 	cfg->outgoing_num_tcp = 2; /* leaves 64-52=12 for: 4if,1stop,thread4 */
 	cfg->incoming_num_tcp = 2; 
 #endif
+	cfg->edns_buffer_size = 4096; /* 4k from rfc recommendation */
 	cfg->msg_buffer_size = 65552; /* 64 k + a small margin */
 	cfg->msg_cache_size = 4 * 1024 * 1024;
 	cfg->msg_cache_slabs = 4;
@@ -277,6 +278,9 @@ int config_set_option(struct config_file* cfg, const char* opt,
 	} else if(strcmp(opt, "incoming-num-tcp:") == 0) {
 		IS_NUMBER_OR_ZERO;
 		cfg->incoming_num_tcp = (size_t)atoi(val);
+	} else if(strcmp(opt, "edns-buffer-size:") == 0) {
+		IS_NONZERO_NUMBER;
+		cfg->edns_buffer_size = (size_t)atoi(val);
 	} else if(strcmp(opt, "msg-buffer-size:") == 0) {
 		IS_NONZERO_NUMBER;
 		cfg->msg_buffer_size = (size_t)atoi(val);
@@ -850,6 +854,7 @@ config_apply(struct config_file* config)
 {
 	MAX_TTL = (uint32_t)config->max_ttl;
 	MIN_TTL = (uint32_t)config->min_ttl;
+	EDNS_ADVERTISED_SIZE = (uint16_t)config->edns_buffer_size;
 	log_set_time_asc(config->log_time_ascii);
 }
 

util/config_file.h

@@ -86,6 +86,8 @@ struct config_file {
 	/** allowed udp port numbers, array with 0 if not allowed */
 	int* outgoing_avail_ports;
 
+	/** EDNS buffer size to use */
+	size_t edns_buffer_size;
 	/** number of bytes buffer size for DNS messages */
 	size_t msg_buffer_size;
 	/** size of the message cache */

util/configlexer.lex

@@ -149,6 +149,7 @@ directory{COLON}		{ YDVAR(1, VAR_DIRECTORY) }
 logfile{COLON}			{ YDVAR(1, VAR_LOGFILE) }
 pidfile{COLON}			{ YDVAR(1, VAR_PIDFILE) }
 root-hints{COLON}		{ YDVAR(1, VAR_ROOT_HINTS) }
+edns-buffer-size{COLON}		{ YDVAR(1, VAR_EDNS_BUFFER_SIZE) }
 msg-buffer-size{COLON}		{ YDVAR(1, VAR_MSG_BUFFER_SIZE) }
 msg-cache-size{COLON}		{ YDVAR(1, VAR_MSG_CACHE_SIZE) }
 msg-cache-slabs{COLON}		{ YDVAR(1, VAR_MSG_CACHE_SLABS) }

util/configparser.h

@@ -149,7 +149,8 @@
      VAR_KEEP_MISSING = 365,
      VAR_ADD_HOLDDOWN = 366,
      VAR_DEL_HOLDDOWN = 367,
-     VAR_SO_RCVBUF = 368
+     VAR_SO_RCVBUF = 368,
+     VAR_EDNS_BUFFER_SIZE = 369
    };
 #endif
 /* Tokens.  */
@@ -264,6 +265,7 @@
 #define VAR_ADD_HOLDDOWN 366
 #define VAR_DEL_HOLDDOWN 367
 #define VAR_SO_RCVBUF 368
+#define VAR_EDNS_BUFFER_SIZE 369
 
 
 
@@ -280,7 +282,7 @@ typedef union YYSTYPE
 
 
 /* Line 1676 of yacc.c  */
-#line 284 "util/configparser.h"
+#line 286 "util/configparser.h"
 } YYSTYPE;
 # define YYSTYPE_IS_TRIVIAL 1
 # define yystype YYSTYPE /* obsolescent; will be withdrawn */

util/configparser.y

@@ -100,7 +100,7 @@ extern struct config_parser_state* cfg_parser;
 %token VAR_DOMAIN_INSECURE VAR_PYTHON VAR_PYTHON_SCRIPT VAR_VAL_SIG_SKEW_MIN
 %token VAR_VAL_SIG_SKEW_MAX VAR_CACHE_MIN_TTL VAR_VAL_LOG_LEVEL
 %token VAR_AUTO_TRUST_ANCHOR_FILE VAR_KEEP_MISSING VAR_ADD_HOLDDOWN 
-%token VAR_DEL_HOLDDOWN VAR_SO_RCVBUF
+%token VAR_DEL_HOLDDOWN VAR_SO_RCVBUF VAR_EDNS_BUFFER_SIZE
 
 %%
 toplevelvars: /* empty */ | toplevelvars toplevelvar ;
@@ -152,7 +152,8 @@ content_server: server_num_threads | server_verbosity | server_port |
 	server_domain_insecure | server_val_sig_skew_min | 
 	server_val_sig_skew_max | server_cache_min_ttl | server_val_log_level |
 	server_auto_trust_anchor_file | server_add_holddown | 
-	server_del_holddown | server_keep_missing | server_so_rcvbuf
+	server_del_holddown | server_keep_missing | server_so_rcvbuf |
+	server_edns_buffer_size
 	;
 stubstart: VAR_STUB_ZONE
 	{
@@ -527,6 +528,19 @@ server_so_rcvbuf: VAR_SO_RCVBUF STRING_ARG
 		free($2);
 	}
 	;
+server_edns_buffer_size: VAR_EDNS_BUFFER_SIZE STRING_ARG
+	{
+		OUTYY(("P(server_edns_buffer_size:%s)\n", $2));
+		if(atoi($2) == 0)
+			yyerror("number expected");
+		else if (atoi($2) < 12)
+			yyerror("edns buffer size too small");
+		else if (atoi($2) > 65535)
+			cfg_parser->cfg->edns_buffer_size = 65535;
+		else cfg_parser->cfg->edns_buffer_size = atoi($2);
+		free($2);
+	}
+	;
 server_msg_buffer_size: VAR_MSG_BUFFER_SIZE STRING_ARG
 	{
 		OUTYY(("P(server_msg_buffer_size:%s)\n", $2));

util/net_help.c

@@ -47,6 +47,8 @@
 
 /** max length of an IP address (the address portion) that we allow */
 #define MAX_ADDR_STRLEN 128 /* characters */
+/** default value for EDNS ADVERTISED size */
+uint16_t EDNS_ADVERTISED_SIZE = 4096;
 
 /* returns true is string addr is an ip6 specced address */
 int

util/net_help.h

@@ -80,7 +80,7 @@ struct regional;
 /** Advertised version of EDNS capabilities */
 #define EDNS_ADVERTISED_VERSION         0
 /** Advertised size of EDNS capabilities */
-#define EDNS_ADVERTISED_SIZE    4096
+extern uint16_t EDNS_ADVERTISED_SIZE;
 /** bits for EDNS bitfield */
 #define EDNS_DO 0x8000 /* Dnssec Ok */
 /** byte size of ip4 address */