Hi,
On Wed, Aug 15, 2012 at 11:08:16AM +0200, Andrea Bonomi wrote:
> Hello, I developed a small patch for displaying the network address
> (IPv4 or IPv6) of a selected network interface in the agetty issue
> file. The name of network interface (default eth0) can be
> configured through a command line option. I use this feature on my
> virtual machines, so I can know the addresses without login. I hope
> this can be useful for someone else. Have a nice day, Andrea Bonomi
I did some changes to the patch -- see below. I don't like the
hardcoded interface names and I guess that on many machines is more
important just machine IP (based on hostname) rather than interface
IP. So:
\4 and \6 print IP address as returned by getaddrinfo() *or* if
--interface command line option is specified then interface IP is
printed.
It means that --interface is optional and probably unnecessary in many
cases.
Objections?
Karel
>From ca2fda5f40440f4f7686716d76f93c302f1b2e67 Mon Sep 17 00:00:00 2001
From: Andrea Bonomi <a.bonomi@xxxxxxxxxx>
Date: Wed, 15 Aug 2012 11:10:19 +0200
Subject: [PATCH] agetty: display network address in issue
Signed-off-by: Andrea Bonomi <a.bonomi@xxxxxxxxxx>
Signed-off-by: Karel Zak <kzak@xxxxxxxxxx>
---
term-utils/agetty.8 | 18 +++++++++-
term-utils/agetty.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++-
2 files changed, 111 insertions(+), 3 deletions(-)
diff --git a/term-utils/agetty.8 b/term-utils/agetty.8
index ebfdb96..bbf65d0 100644
--- a/term-utils/agetty.8
+++ b/term-utils/agetty.8
@@ -3,7 +3,7 @@
agetty \- alternative Linux getty
.SH SYNOPSIS
-.BR "agetty " [\-8chiLmnsUw]
+.BR "agetty " [\-8chiLmnsUwx]
.RI "[\-a " user ]
.RI "[\-f " issue_file ]
.RI "[\-H " login_host ]
@@ -198,6 +198,10 @@ Wait for the user or the modem to send a carriage-return or a
linefeed character before sending the \fI/etc/issue\fP (or other) file
and the login prompt. Very useful in connection with the \-I option.
.TP
+\-x, \-\-interface \fIinterface_name\fP
+The IPv4 and IPv6 addresses of a network interface can be displayed in
+the issue. The name of the network is configured by this option.
+.TP
\-\-noclear
Do not clear the screen before prompting for the login name
(the screen is normally cleared).
@@ -269,6 +273,18 @@ time etc. All escape codes consist of a backslash (\\) immediately
followed by one of the letters explained below.
.TP
+4
+Insert the IPv4 address of the machine hostname or IPv4 address the configured
+network interface if the \fB\-\-interface\fP command line option is specified.
+.TP
+6
+Insert the IPv6 address of the machine hostname or IPv6 address the configured
+network interface if the \fB\-\-interface\fP command line option is specified.
+.TP
+x
+Name of the configured network interface (configured by the \fB\-\-interface\fP
+command line option).
+.TP
b
Insert the baudrate of the current line.
.TP
diff --git a/term-utils/agetty.c b/term-utils/agetty.c
index 43243f9..71c7da3 100644
--- a/term-utils/agetty.c
+++ b/term-utils/agetty.c
@@ -31,6 +31,9 @@
#include <netdb.h>
#include <langinfo.h>
#include <grp.h>
+#include <arpa/inet.h>
+#include <netdb.h>
+#include <ifaddrs.h>
#include "strutils.h"
#include "all-io.h"
@@ -145,6 +148,7 @@ struct options {
int nice; /* Run login with this priority */
int numspeed; /* number of baud rates to try */
speed_t speeds[MAX_SPEED]; /* baud rates to be tried */
+ char *interface; /* name of the network interface displayed in issue */
};
#define F_PARSE (1<<0) /* process modem status messages */
@@ -169,6 +173,7 @@ struct options {
#define F_LONGHNAME (1<<19) /* Show Full qualified hostname */
#define F_NOHINTS (1<<20) /* Don't print hints */
#define F_REMOTE (1<<21) /* Add '-h fakehost' to login(1) command line */
+#define F_INTERFACE (1<<22) /* Name of the network interface displayed in issue */
#define serial_tty_option(opt, flag) \
(((opt)->flags & (F_VCONSOLE|(flag))) == (flag))
@@ -280,7 +285,7 @@ int main(int argc, char **argv)
.login = _PATH_LOGIN, /* default login program */
.tty = "tty1", /* default tty line */
.term = DEFAULT_VCTERM, /* terminal type */
- .issue = ISSUE /* default issue file */
+ .issue = ISSUE, /* default issue file */
};
char *login_argv[LOGIN_ARGV_MAX + 1];
int login_argc = 0;
@@ -569,6 +574,7 @@ static void parse_args(int argc, char **argv, struct options *op)
{ "timeout", required_argument, 0, 't' },
{ "detect-case", no_argument, 0, 'U' },
{ "wait-cr", no_argument, 0, 'w' },
+ { "interface", required_argument, 0, 'x' },
{ "nohints", no_argument, 0, NOHINTS_OPTION },
{ "nohostname", no_argument, 0, NOHOSTNAME_OPTION },
{ "long-hostname", no_argument, 0, LONGHOSTNAME_OPTION },
@@ -578,7 +584,7 @@ static void parse_args(int argc, char **argv, struct options *op)
};
while ((c = getopt_long(argc, argv,
- "8a:cC:d:Ef:hH:iI:Jl:LmnNo:pP:r:Rst:Uw", longopts,
+ "8a:cC:d:Ef:hH:iI:Jl:LmnNo:pP:r:Rst:Uwx:", longopts,
NULL)) != -1) {
switch (c) {
case '8':
@@ -659,6 +665,10 @@ static void parse_args(int argc, char **argv, struct options *op)
case 'w':
op->flags |= F_WAITCRLF;
break;
+ case 'x':
+ op->flags |= F_INTERFACE;
+ op->interface = optarg;
+ break;
case NOHINTS_OPTION:
op->flags |= F_NOHINTS;
break;
@@ -1696,6 +1706,68 @@ static void log_warn(const char *fmt, ...)
va_end(ap);
}
+static void output_iface_ip(struct ifaddrs *addrs, const char *iface, sa_family_t family)
+{
+ if (!iface)
+ return;
+
+ if (addrs->ifa_name
+ && strcmp(addrs->ifa_name, iface) == 0
+ && addrs->ifa_addr
+ && addrs->ifa_addr->sa_family == family) {
+
+ void *addr = NULL;
+ char buff[INET6_ADDRSTRLEN + 1];
+
+ switch (addrs->ifa_addr->sa_family) {
+ case AF_INET:
+ addr = &((struct sockaddr_in *) addrs->ifa_addr)->sin_addr;
+ break;
+ case AF_INET6:
+ addr = &((struct sockaddr_in6 *) addrs->ifa_addr)->sin6_addr;
+ break;
+ }
+ if (addr) {
+ inet_ntop(addrs->ifa_addr->sa_family, addr, buff, sizeof(buff));
+ printf("%s", buff);
+ }
+
+ } else if (addrs->ifa_next)
+ output_iface_ip(addrs->ifa_next, iface, family);
+}
+
+static void output_ip(sa_family_t family)
+{
+ char host[MAXHOSTNAMELEN + 1];
+ struct addrinfo hints, *info = NULL;
+
+ memset(&hints, 0, sizeof(hints));
+ hints.ai_family = family;
+ if (family == AF_INET6)
+ hints.ai_flags = AI_V4MAPPED;
+
+ if (gethostname(host, sizeof(host)) == 0
+ && getaddrinfo(host, NULL, &hints, &info) == 0
+ && info) {
+
+ void *addr = NULL;
+ char buff[INET6_ADDRSTRLEN + 1];
+
+ switch (info->ai_family) {
+ case AF_INET:
+ addr = &((struct sockaddr_in *) info->ai_addr)->sin_addr;
+ break;
+ case AF_INET6:
+ addr = &((struct sockaddr_in6 *) info->ai_addr)->sin6_addr;
+ break;
+ }
+ inet_ntop(info->ai_family, (void *) addr, buff, sizeof(buff));
+ printf("%s", buff);
+
+ freeaddrinfo(info);
+ }
+}
+
static void output_special_char(unsigned char c, struct options *op,
struct termios *tp)
{
@@ -1808,6 +1880,26 @@ static void output_special_char(unsigned char c, struct options *op,
printf((users == 1) ? _("user") : _("users"));
break;
}
+ case 'x':
+ if (op->interface) /* interface name */
+ printf("%s", op->interface);
+ break;
+ case '4':
+ case '6':
+ {
+ sa_family_t family = c == '4' ? AF_INET : AF_INET6;
+
+ if (op->interface) { /* interface IP */
+ struct ifaddrs *addrs;
+ int status = getifaddrs(&addrs);
+ if (status != 0)
+ break;
+ output_iface_ip(addrs, op->interface, family);
+ freeifaddrs(addrs);
+ } else /* host IP */
+ output_ip(family);
+ break;
+ }
default:
putchar(c);
break;
--
1.7.7.6
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