routing: Added simple IRC library based on io_loop

The IRC library can login and keep its connection alive by replying to
PING messages. It also exposes a callback that handles PRIVMSG commands
and can inject messages from outside, e.g., based on a timer or a
lightning event.

irc.h

@@ -0,0 +1,67 @@
+#ifndef LIGHTNING_IRC_H
+#define LIGHTNING_IRC_H
+
+#include <stdio.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <ccan/io/io.h>
+#include <ccan/short_types/short_types.h>
+#include <ccan/str/str.h>
+#include <ccan/tal/str/str.h>
+#include <ccan/time/time.h>
+#include <ccan/timer/timer.h>
+
+#include "daemon/lightningd.h"
+
+struct irccommand {
+	struct list_node list;
+	const char *prefix;
+	const char *command;
+	const char *params;
+};
+
+struct privmsg {
+	const char *channel;
+	const char *sender;
+	const char *msg;
+};
+
+struct ircstate {
+	/* Meta information */
+	const char *nick;
+	const char *server;
+
+	/* Connection and reading */
+	struct io_conn *conn;
+	char buffer[512];
+	size_t readlen;
+	size_t buffered;
+
+	/* Write queue related */
+	struct list_head writequeue;
+	char *writebuffer;
+
+	/* Pointer to external state, making it available to callbacks */
+	struct lightningd_state *dstate;
+
+	struct log *log;
+
+	/* Are we currently connected? */
+	bool connected;
+
+	/* Time to wait after getting disconnected before reconnecting. */
+	struct timerel reconnect_timeout;
+};
+
+/* Callback to register for incoming messages */
+extern void (*irc_privmsg_cb)(struct ircstate *, const struct privmsg *);
+extern void (*irc_disconnect_cb)(struct ircstate *);
+
+/* Send messages to IRC */
+bool irc_send(struct ircstate *state, const char *command, const char *fmt, ...) PRINTF_FMT(3,4);
+bool irc_send_msg(struct ircstate *state, struct privmsg *m);
+
+/* Register IRC connection with io */
+void irc_connect(struct ircstate *state);
+
+#endif /* LIGHTNING_IRC_H */