From 7f9340341574044e16e1ffc30f856f13d1e3ba6c Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Fri, 30 Nov 2007 10:23:51 +0100
Subject: [PATCH] 02_Reverse-lookup-support.diff

In some parts of the code a reverse-lookup (e.g. "connection from xxx") is used.
An address-family independent reverse-lookup function is provided by this patch,
exploiting that a socket is described by {src addr, src port, dst addr, dst port}:
 * host_and_port(): prints host and port number of given socket,
 * local_name():    pretty-prints src-addr/src-port,
 * remote_name():   pretty-prints dst-addr/dst-port;

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
---
 net.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 net.h |  5 +++++
 2 files changed, 62 insertions(+)

diff --git a/net.c b/net.c
index 3de57f28..8860312b 100644
--- a/net.c
+++ b/net.c
@@ -265,6 +265,63 @@ int para_listen(unsigned l3type, unsigned l4type, unsigned short port)
 	return fd;
 }
 
+/**
+ * Print numeric host and port number (beware - uses static char).
+ * \param sa	The IPv4/IPv6 socket address to use.
+ * \param len	The length of \p sa.
+ *
+ * \sa getnameinfo(3)
+ */
+char *host_and_port(struct sockaddr *sa, socklen_t len)
+{
+	static char	output[NI_MAXHOST + NI_MAXSERV + 2];
+	char		hbuf[NI_MAXHOST],
+			sbuf[NI_MAXSERV];
+	int		ret;
+
+	ret = getnameinfo(sa, len, hbuf, sizeof(hbuf), sbuf, sizeof(sbuf),
+			  NI_NUMERICHOST | NI_NUMERICSERV);
+	if (ret)	{
+		PARA_WARNING_LOG("hostname lookup error (%s).\n", gai_strerror(ret));
+		sprintf(output, "(unknown)");
+	} else {
+		sprintf(output, "%s#%s", hbuf, sbuf);
+	}
+	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 \fn getsockname() for local, or \fn 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((struct sockaddr *)&ss, sslen);
+}
+
+char  *local_name(int sockfd)
+{
+	return __get_sock_name(sockfd, getsockname);
+}
+
+char *remote_name(int sockfd)
+{
+	return __get_sock_name(sockfd, getpeername);
+}
+
 /*
  * Send out a buffer, resend on short writes.
  *
diff --git a/net.h b/net.h
index e78b7629..965273a8 100644
--- a/net.h
+++ b/net.h
@@ -37,6 +37,11 @@ extern int makesock(unsigned l3type, unsigned l4type, int passive,
 #define BACKLOG	10
 extern int para_listen(unsigned l3type, unsigned l4type, unsigned short port);
 
+/** Pretty-printing of IPv4/6 socket addresses */
+extern char *host_and_port(struct sockaddr *sa, socklen_t len);
+extern char *local_name(int sockfd);
+extern char *remote_name(int sockfd);
+
 /** used to crypt the communication between para_server and para_client */
 typedef void crypt_function(unsigned long len,
 	const unsigned char *indata, unsigned char *outdata, void *private_data);
-- 
2.39.5