Hi, good idea, much better without the hardcoded interface name. I think that the --interface option is useful for the machine with a dynamic IP address. (in my experience, the getaddrinfo based on the hostname returns the loopback address) Another idea will be to add the interface name after the \4 or \6, something like: \4eth0 (or similar…) to get the IPv4 address of the interface eth0 So the user can specify the interface name directly in the issue file. What do you think? Andrea :: e n d i a n :: security with passion :: andrea bonomi :: senior software engineer :: http://www.endian.com :: a.bonomi@xxxxxxxxxx On 12/set/2012, at 11:37, Karel Zak wrote: > > 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 > -- To unsubscribe from this list: send the line "unsubscribe util-linux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
