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>

diff --git a/net.c b/net.c
index 3de57f281d7090c1bd5e4d8fbe9c01d8372548cd..8860312bf531b225bed615d2fa90d10b1f469534 100644 (file)
--- 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 e78b7629348bde49831ccc31a2f660719ad3d16d..965273a86073ff82d4533794093e0aa7aedb916c 100644 (file)
--- 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);