+ * Determine IPv4/v6 socket address length.
+ * \param sa Container of IPv4 or IPv6 address.
+ * \return Address-family dependent address length.
+ */
+static socklen_t salen(const struct sockaddr *sa)
+{
+ assert(sa->sa_family == AF_INET || sa->sa_family == AF_INET6);
+
+ return sa->sa_family == AF_INET6
+ ? sizeof(struct sockaddr_in6)
+ : sizeof(struct sockaddr_in);
+}
+
+/**
+ * Process IPv4/v6 address, turn v6-mapped-v4 address into normal IPv4 address.
+ * \param ss Container of IPv4/6 address.
+ * \return Pointer to normalized address (may be static storage).
+ *
+ * \sa RFC 3493
+ */
+static const struct sockaddr *
+normalize_ip_address(const struct sockaddr_storage *ss)
+{
+ const struct sockaddr_in6 *ia6 = (const struct sockaddr_in6 *)ss;
+
+ assert(ss->ss_family == AF_INET || ss->ss_family == AF_INET6);
+
+ if (ss->ss_family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&ia6->sin6_addr)) {
+ static struct sockaddr_in ia;
+
+ ia.sin_family = AF_INET;
+ ia.sin_port = ia6->sin6_port;
+ memcpy(&ia.sin_addr.s_addr, &(ia6->sin6_addr.s6_addr[12]), 4);
+ return (const struct sockaddr *)&ia;
+ }
+ return (const struct sockaddr *)ss;
+}
+
+/**
+ * Print numeric host and port number (beware - uses static char).
+ *
+ * \param sa The IPv4/IPv6 socket address to use.
+ *
+ * \sa getnameinfo(3), services(5), nsswitch.conf(5)
+ */
+static char *host_and_port(const struct sockaddr_storage *ss)
+{
+ const struct sockaddr *sa = normalize_ip_address(ss);
+ char hbuf[NI_MAXHOST], sbuf[NI_MAXSERV];
+ static char output[sizeof(hbuf) + sizeof(sbuf) + 2];
+ int ret;
+
+ ret = getnameinfo(sa, salen(sa),
+ hbuf, sizeof(hbuf),
+ sbuf, sizeof(sbuf),
+ NI_NUMERICHOST);
+ if (ret == 0) {
+ snprintf(output, sizeof(output), "%s#%s", hbuf, sbuf);
+ } else {
+ snprintf(output, sizeof(output), "(unknown)");
+ PARA_WARNING_LOG("hostname lookup error (%s).\n",
+ gai_strerror(ret));
+ }
+ return output;
+}
+
+/**
+ * Look up the local or remote side of a connected socket structure.
+ *
+ * \param fd The socket descriptor of the connected socket.
+ * \param getname Either \p getsockname() for local, or \p getpeername() for
+ * remote side.
+ *
+ * \return A static character string identifying hostname and port of the
+ * chosen side.
+ *
+ * \sa getsockname(2), getpeername(2).
+ */
+static char *__get_sock_name(int fd, int (*getname)(int, struct sockaddr*,
+ socklen_t *))
+{
+ struct sockaddr_storage ss;
+ socklen_t sslen = sizeof(ss);
+
+ if (getname(fd, (struct sockaddr *)&ss, &sslen) < 0) {
+ static char *dont_know = "(don't know)";
+ PARA_ERROR_LOG("can not determine address from fd %d: %s\n",
+ fd, strerror(errno));
+ return dont_know;
+ }
+ return host_and_port(&ss);
+}
+
+/**
+ * Look up the local side of a connected socket structure.
+ *
+ * \param sockfd The file descriptor of the socket.
+ *
+ * \return A pointer to a static buffer containing hostname an port. This
+ * buffer must not be freed by the caller.
+ *
+ * \sa remote_name().
+ */
+char *local_name(int sockfd)
+{
+ return __get_sock_name(sockfd, getsockname);
+}
+
+/**
+ * Look up the remote side of a connected socket structure.
+ *
+ * \param sockfd The file descriptor of the socket.
+ *
+ * \return Analogous to the return value of \ref local_name() but for the
+ * remote side.
+ *
+ * \sa local_name().
+ */
+char *remote_name(int sockfd)
+{
+ return __get_sock_name(sockfd, getpeername);
+}
+
+/**
+ * Extract IPv4 or IPv6-mapped-IPv4 address from sockaddr_storage.
+ * \param ss Container of IPv4/6 address
+ * \return Extracted IPv4 address (different from 0) or 0 if unsuccessful.
+ *
+ * \sa RFC 3493
+ */
+struct in_addr extract_v4_addr(const struct sockaddr_storage *ss)
+{
+ struct in_addr ia = {.s_addr = 0};
+ const struct sockaddr *sa = normalize_ip_address(ss);
+
+ if (sa->sa_family == AF_INET)
+ ia = ((struct sockaddr_in *)sa)->sin_addr;
+ return ia;
+}
+
+/**
+ * Send a binary buffer.