MT#55283 add "control-pmtu" option

Change-Id: I4c7319f69dc5242bd6a35ab13a9aa72f394b5d5c

daemon/control_ng.c

@@ -21,6 +21,7 @@
 #include "streambuf.h"
 #include "str.h"
 #include "tcp_listener.h"
+#include "main.h"
 
 mutex_t rtpe_cngs_lock;
 mutex_t tcp_connections_lock;
@@ -544,6 +545,9 @@ struct control_ng *control_ng_new(struct poller *p, endpoint_t *ep, unsigned cha
 		goto fail2;
 	if (tos)
 		set_tos(&c->udp_listener, tos);
+	if (rtpe_config.control_pmtu)
+		set_pmtu_disc(&c->udp_listener,
+				rtpe_config.control_pmtu == PMTU_DISC_WANT ? IP_PMTUDISC_WANT : IP_PMTUDISC_DONT);
 	return c;
 
 fail2:

daemon/main.c

@@ -451,6 +451,7 @@ static void options(int *argc, char ***argv) {
 	AUTO_CLEANUP_GBUF(mos);
 	AUTO_CLEANUP_GBUF(dcc);
 	AUTO_CLEANUP_GBUF(use_audio_player);
+	AUTO_CLEANUP_GBUF(control_pmtu);
 
 	rwlock_lock_w(&rtpe_config.config_lock);
 
@@ -471,6 +472,7 @@ static void options(int *argc, char ***argv) {
 		{ "graphite-timeout", 0, 0, G_OPTION_ARG_INT, &rtpe_config.graphite_timeout, "Graphite socket timeout interval in seconds", "INT" },
 		{ "tos",	'T', 0, G_OPTION_ARG_INT,	&rtpe_config.default_tos,		"Default TOS value to set on streams",	"INT"		},
 		{ "control-tos",0 , 0, G_OPTION_ARG_INT,	&rtpe_config.control_tos,		"Default TOS value to set on control-ng",	"INT"		},
+		{ "control-pmtu", 0,0,	G_OPTION_ARG_STRING,	&control_pmtu,	"Path MTU discovery behaviour on UDP control sockets",	"want|dont"		},
 		{ "timeout",	'o', 0, G_OPTION_ARG_INT,	&rtpe_config.timeout,	"RTP timeout",			"SECS"		},
 		{ "silent-timeout",'s',0,G_OPTION_ARG_INT,	&rtpe_config.silent_timeout,"RTP timeout for muted",	"SECS"		},
 		{ "final-timeout",'a',0,G_OPTION_ARG_INT,	&rtpe_config.final_timeout,	"Call timeout",			"SECS"		},
@@ -903,6 +905,17 @@ static void options(int *argc, char ***argv) {
 			die("Invalid --dtls-cert-cipher option ('%s')", dcc);
 	}
 
+	if (control_pmtu) {
+		if (!strcasecmp(control_pmtu, "want"))
+			rtpe_config.control_pmtu = PMTU_DISC_WANT;
+		else if (!strcasecmp(control_pmtu, "dont"))
+			rtpe_config.control_pmtu = PMTU_DISC_DONT;
+		else if (!strcasecmp(control_pmtu, "don't"))
+			rtpe_config.control_pmtu = PMTU_DISC_DONT;
+		else
+			die("Invalid --control-pmtu option ('%s')", control_pmtu);
+	}
+
 	rwlock_unlock_w(&rtpe_config.config_lock);
 }
 

daemon/rtpengine.pod

@@ -162,6 +162,20 @@ should be set in the control-ng interface packets.
 The default is to leave the TOS field untouched.
 This parameter can also be set or listed via B<rtpengine-ctl>.
 
+=item B<--control-pmtu=>B<want>|B<dont>
+
+Forces a specific PMTU discovery behaviour on IPv4 UDP control sockets,
+overriding the system-wide default. If set to B<want> then path MTU discovery
+is performed, initially enabling the DF (don't fragment) bit on outgoing IPv4
+packets until the path MTU has been discovered through reception of a
+"fragmentation needed" ICMP packet. If set to B<dont> then path MTU discovery
+is disabled, leaving the DF bit unset, and relying on the routers within the
+network path to perform any necessary fragmentation.
+
+The setting of B<dont> is useful in broken IPv4 environments without
+functioning PMTU discovery, for example in networks which unconditionally block
+all ICMP.
+
 =item B<-o>, B<--timeout=>I<SECS>
 
 Takes the number of seconds as argument after which a media stream should

etc/rtpengine.conf

@@ -34,6 +34,7 @@ timeout = 60
 silent-timeout = 3600
 tos = 184
 # control-tos = 184
+# control-pmtu = dont
 # delete-delay = 30
 # final-timeout = 10800
 # endpoint-learning = heuristic

include/main.h

@@ -45,6 +45,11 @@ struct rtpengine_config {
 	char			*b2b_url;
 	int			default_tos;
 	int			control_tos;
+	enum {
+		PMTU_DISC_DEFAULT = 0,
+		PMTU_DISC_WANT,
+		PMTU_DISC_DONT,
+	}			control_pmtu;
 	enum xmlrpc_format	fmt;
 	enum log_format		log_format;
 	endpoint_t		graphite_ep;

lib/socket.c

@@ -40,6 +40,7 @@ static ssize_t __ip_sendto(socket_t *s, const void *buf, size_t len, const endpo
 static int __ip4_tos(socket_t *, unsigned int);
 static int __ip6_tos(socket_t *, unsigned int);
 static int __ip_error(socket_t *s);
+static void __ip4_pmtu_disc(socket_t *, int);
 static void __ip4_endpoint2kernel(struct re_address *, const endpoint_t *);
 static void __ip6_endpoint2kernel(struct re_address *, const endpoint_t *);
 static void __ip4_kernel2endpoint(endpoint_t *ep, const struct re_address *ra);
@@ -86,6 +87,7 @@ static struct socket_family __socket_families[__SF_LAST] = {
 		.sendto			= __ip_sendto,
 		.tos			= __ip4_tos,
 		.error			= __ip_error,
+		.pmtu_disc		= __ip4_pmtu_disc,
 		.endpoint2kernel	= __ip4_endpoint2kernel,
 		.kernel2endpoint	= __ip4_kernel2endpoint,
 		.packet_header		= __ip4_packet_header,
@@ -379,6 +381,10 @@ static int __ip_error(socket_t *s) {
 		return -1;
 	return optval;
 }
+static void __ip4_pmtu_disc(socket_t *s, int opt) {
+	if (setsockopt(s->fd, IPPROTO_IP, IP_MTU_DISCOVER, &opt, sizeof(opt)))
+		ilog(LOG_ERR, "Failed to set PMTU discovery option on IPv4 socket: %s", strerror(errno));
+}
 static int __ip_timestamping(socket_t *s) {
 	int one = 1;
 	if (setsockopt(s->fd, SOL_SOCKET, SO_TIMESTAMP, &one, sizeof(one)))

lib/socket.h

@@ -77,6 +77,7 @@ struct socket_family {
 	ssize_t				(*sendmsg)(socket_t *, struct msghdr *, const endpoint_t *);
 	ssize_t				(*sendto)(socket_t *, const void *, size_t, const endpoint_t *);
 	int				(*tos)(socket_t *, unsigned int);
+	void				(*pmtu_disc)(socket_t *, int);
 	int				(*error)(socket_t *);
 	void				(*endpoint2kernel)(struct re_address *, const endpoint_t *);
 	void				(*kernel2endpoint)(endpoint_t *, const struct re_address *);
@@ -294,6 +295,10 @@ INLINE int ipv46_any_convert(endpoint_t *ep) {
 INLINE void set_tos(socket_t *s, unsigned int tos) {
 	s->family->tos(s, tos);
 }
+INLINE void set_pmtu_disc(socket_t *s, int opt) {
+	if (s->family->pmtu_disc)
+		s->family->pmtu_disc(s, opt);
+}
 
 socktype_t *get_socket_type(const str *s);
 socktype_t *get_socket_type_c(const char *s);