MINOR: protocol: add get_src() and get_dst() at the protocol level

Right now the proto_fam descriptor provides a family-specific
get_src() and get_dst() pair of calls to retrieve a socket's source
or destination address. However this only works for connected mode
sockets. QUIC provides its own stream protocol, which relies on a
datagram protocol underneath, so the get_src()/get_dst() at that
protocol's family will not work, and QUIC would need to provide its
own.

This patch implements get_src() and get_dst() at the protocol level
from a connection, and makes sure that conn_get_src()/conn_get_dst()
will automatically use them if defined before falling back to the
family's pair of functions.

include/haproxy/connection.h

@@ -354,6 +354,11 @@ static inline int conn_get_src(struct connection *conn)
 	if (!sockaddr_alloc(&conn->src, NULL, 0))
 		goto fail;
 
+	/* some stream protocols may provide their own get_src/dst functions */
+	if (conn->ctrl->get_src &&
+	    conn->ctrl->get_src(conn, (struct sockaddr *)conn->src, sizeof(*conn->src)) != -1)
+		goto done;
+
 	if (conn->ctrl->proto_type != PROTO_TYPE_STREAM)
 		goto fail;
 
@@ -388,6 +393,11 @@ static inline int conn_get_dst(struct connection *conn)
 	if (!sockaddr_alloc(&conn->dst, NULL, 0))
 		goto fail;
 
+	/* some stream protocols may provide their own get_src/dst functions */
+	if (conn->ctrl->get_dst &&
+	    conn->ctrl->get_dst(conn, (struct sockaddr *)conn->dst, sizeof(*conn->dst)) != -1)
+		goto done;
+
 	if (conn->ctrl->proto_type != PROTO_TYPE_STREAM)
 		goto fail;
 

include/haproxy/protocol-t.h

@@ -75,8 +75,8 @@ struct proto_fam {
 	int l3_addrlen;					/* layer3 address length, used by hashes */
 	int (*addrcmp)(const struct sockaddr_storage *, const struct sockaddr_storage *); /* compare addresses (like memcmp) */
 	int (*bind)(struct receiver *rx, char **errmsg); /* bind a receiver */
-	int (*get_src)(int fd, struct sockaddr *, socklen_t, int dir); /* syscall used to retrieve src addr */
+	int (*get_src)(int fd, struct sockaddr *, socklen_t, int dir); /* syscall used to retrieve connection's src addr */
-	int (*get_dst)(int fd, struct sockaddr *, socklen_t, int dir); /* syscall used to retrieve dst addr */
+	int (*get_dst)(int fd, struct sockaddr *, socklen_t, int dir); /* syscall used to retrieve connection's dst addr */
 	void (*set_port)(struct sockaddr_storage *, int port);  /* set the port on the address; NULL if not implemented */
 };
 
@@ -103,6 +103,7 @@ struct protocol {
 	int (*suspend)(struct listener *l);             /* try to suspend the listener */
 	int (*resume)(struct listener *l);              /* try to resume a suspended listener */
 	struct connection *(*accept_conn)(struct listener *l, int *status); /* accept a new connection */
+
 	/* functions acting on connections */
 	void (*ctrl_init)(struct connection *);         /* completes initialization of the connection */
 	void (*ctrl_close)(struct connection *);        /* completes release of the connection */
@@ -110,6 +111,8 @@ struct protocol {
 	int (*drain)(struct connection *);              /* drain pending data; 0=failed, >0=success */
 	int (*check_events)(struct connection *conn, int event_type);  /* subscribe to socket events */
 	void (*ignore_events)(struct connection *conn, int event_type);  /* unsubscribe from socket events */
+	int (*get_src)(struct connection *conn, struct sockaddr *, socklen_t); /* retrieve connection's source address; -1=fail */
+	int (*get_dst)(struct connection *conn, struct sockaddr *, socklen_t); /* retrieve connection's dest address; -1=fail */
 
 	/* functions acting on the receiver */
 	int (*rx_suspend)(struct receiver *rx);         /* temporarily suspend this receiver for a soft restart */