+/* Userland defines for Linux DCCP support. */
+
+#ifndef IPPROTO_DCCP
+#define IPPROTO_DCCP 33 /**< IANA assigned value. */
+#endif
+
+#ifndef SOCK_DCCP
+#define SOCK_DCCP 6 /**< Linux socket type. */
+#endif
+
+#ifndef DCCP_SOCKOPT_RX_CCID
+/** Per-connection CCID support (set/get the RX CCID, since v2.6.30-rc1). */
+#define DCCP_SOCKOPT_RX_CCID 15
+#endif
+
+#ifndef SOL_DCCP
+#define SOL_DCCP 269 /**< Linux socket level. */
+#endif
+
+#ifndef DCCP_SOCKOPT_AVAILABLE_CCIDS
+#define DCCP_SOCKOPT_AVAILABLE_CCIDS 12 /**< List of supported CCIDs. */
+#endif
+
+#ifndef DCCP_SOCKOPT_CCID
+#define DCCP_SOCKOPT_CCID 13 /**< Sets both TX/RX CCID. */
+#endif
+
+#ifndef DCCP_SOCKOPT_TX_CCID
+#define DCCP_SOCKOPT_TX_CCID 14 /**< Set/get the TX CCID. */
+#endif
+
+/**
+ * Flowopts: Transport-layer independent encapsulation of socket options
+ * that need to be registered prior to setting up a connection.
+ */
+struct flowopts;
+
+extern struct flowopts *flowopt_new(void);
+extern void flowopt_add(struct flowopts *fo, int level, int opt,
+ char *name, const void *val, int len);
+extern void flowopt_add_bool(struct flowopts *fo, int lev, int opt,
+ char *optname, bool on_or_off);
+/** Flowopt shortcut macros */
+#define OPT_ADD(fo, lev, opt, val, len) flowopt_add(fo, lev, opt, #opt, val, len)
+#define OPT_ENABLE(fo, lev, opt) flowopt_add_bool(fo, lev, opt, #opt, 1)
+#define OPT_DISABLE(fo, lev, opt) flowopt_add_bool(fo, lev, opt, #opt, 0)
+
+/**
+ * Functions to parse and validate (parts of) URLs.
+ */
+extern char *parse_cidr(const char *cidr,
+ char *addr, ssize_t addrlen, int32_t *netmask);
+extern char *parse_url(const char *url,
+ char *host, ssize_t hostlen, int32_t *port);
+extern const char *stringify_port(int port, const char *transport);
+/**
+ * Ensure that string conforms to the IPv4 address format.
+ *
+ * \param address The address string to check.
+ *
+ * \return 1 if \a address conforms to the IPv4 address format, else 0.
+ */
+_static_inline_ bool is_valid_ipv4_address(const char *address)
+{
+ struct in_addr test_it;
+
+ return inet_pton(AF_INET, address, &test_it) != 0;
+}
+
+/**
+ * Ensure that string conforms to IPv6 address format.
+ *
+ * \param address The address string to check.
+ *
+ * \return 1 if string has a valid IPv6 address syntax, 0 if not.
+ * \sa RFC 4291
+ */
+_static_inline_ bool is_valid_ipv6_address(const char *address)
+{
+ struct in6_addr test_it;
+
+ return inet_pton(AF_INET6, address, &test_it) != 0;
+}
+
+/**
+ * Generic socket creation (passive and active sockets).
+ */
+extern int makesock(unsigned l4type, bool passive,
+ const char *host, uint16_t port_number,
+ struct flowopts *fo);
+
+static inline int para_connect_simple(unsigned l4type,
+ const char *host, uint16_t port)
+{
+ return makesock(l4type, 0, host, port, NULL);
+}
+
+extern struct in_addr extract_v4_addr(const struct sockaddr_storage *ss);
+
+/**
+ * Functions to support listening sockets.
+ */
+/** How many pending connections queue of a listening server will hold. */
+#define BACKLOG 10
+extern int para_listen(unsigned l4type, uint16_t port, struct flowopts *fo);
+
+static inline int para_listen_simple(unsigned l4type, uint16_t port)
+{
+ return para_listen(l4type, port, NULL);
+}
+
+/** Pretty-printing of IPv4/6 socket addresses */
+extern char *local_name(int sockfd);
+extern char *remote_name(int sockfd);