- Added a configuration function, 'gethostname()', which calls the system

  function of the same name and presents the results as a data expression.
  This function can be used to incorporate the system level hostname of
  the system the DHCP software is operating on in responses or queries (such
  as including a failover partner's hostname in a dhcp message or binding
  scope, or having a DHCP client send any system hostname in the host-name or
  FQDN options by default).  [ISC-Bugs #17351]

9 files changed, 101 insertions, 7 deletions

diff --git a/RELNOTES b/RELNOTES
index aa1fa1bf..0a6237f9 100644
--- a/RELNOTES
+++ b/RELNOTES
@@ -58,6 +58,14 @@ work on other platforms. Please report any problems and suggested fixes to
   please carefully review the documentation of this parameter in the
   dhcpd.conf(5) manpage before determining to use it yourself.
 
+- Added a configuration function, 'gethostname()', which calls the system
+  function of the same name and presents the results as a data expression.
+  This function can be used to incorporate the system level hostname of
+  the system the DHCP software is operating on in responses or queries (such
+  as including a failover partner's hostname in a dhcp message or binding
+  scope, or having a DHCP client send any system hostname in the host-name or
+  FQDN options by default).
+
 			Changes since 4.1.0 (bug fixes)
 
 - Remove infinite loop in token_print_indent_concat().
diff --git a/client/dhclient.conf b/client/dhclient.conf
index 147e0045..64c6ce11 100644
--- a/client/dhclient.conf
+++ b/client/dhclient.conf
@@ -1,4 +1,4 @@
-send host-name "andare.fugue.com";
+send host-name = pick-first-value(gethostname(), "ISC-dhclient");
 send dhcp-client-identifier 1:0:a0:24:ab:fb:9c;
 send dhcp-lease-time 3600;
 supersede domain-name "fugue.com home.vix.com";
diff --git a/common/conflex.c b/common/conflex.c
index 2ce94840..41edb89a 100644
--- a/common/conflex.c
+++ b/common/conflex.c
@@ -984,12 +984,17 @@ intern(char *atom, enum dhcp_token dfv) {
 			return TOKEN_FREE;
 		break;
 	      case 'g':
+		if (!strncasecmp(atom + 1, "et", 2)) {
+			if (!strcasecmp(atom + 3, "-lease-hostnames"))
+				return GET_LEASE_HOSTNAMES;
+			if (!strcasecmp(atom + 3, "hostname"))
+				return GETHOSTNAME;
+			break;
+		}
 		if (!strcasecmp (atom + 1, "iaddr"))
 			return GIADDR;
 		if (!strcasecmp (atom + 1, "roup"))
 			return GROUP;
-		if (!strcasecmp (atom + 1, "et-lease-hostnames"))
-			return GET_LEASE_HOSTNAMES;
 		break;
 	      case 'h':
 		if (!strcasecmp(atom + 1, "ash"))
diff --git a/common/dhcp-eval.5 b/common/dhcp-eval.5
index 1bde0b2b..d497da9d 100644
--- a/common/dhcp-eval.5
+++ b/common/dhcp-eval.5
@@ -1,4 +1,4 @@
-.\"	$Id: dhcp-eval.5,v 1.27 2007/06/07 15:52:29 dhankins Exp $
+.\"	$Id: dhcp-eval.5,v 1.28 2009/07/06 23:29:51 dhankins Exp $
 .\"
 .\" Copyright (c) 2004,2007 by Internet Systems Consortium, Inc. ("ISC")
 .\" Copyright (c) 1996-2003 by Internet Software Consortium
@@ -247,6 +247,16 @@ The \fBconfig-option\fR operator returns the value for the specified option
 that the DHCP client or server has been configured to send.
 .RE
 .PP
+.B gethostname()
+.PP
+.RS 0.25i
+The \fBgethostname()\fR function returns a data string whose contents are a
+character string, the results of calling gethostname() on the local
+system with a size limit of 255 bytes (not including NULL terminator).  This
+can be used for example to configure dhclient to send the local hostname
+without knowing the local hostname at the time dhclient.conf is written.
+.RE
+.PP
 .B hardware
 .PP
 .RS 0.25i
diff --git a/common/parse.c b/common/parse.c
index d2842b48..feaec7df 100644
--- a/common/parse.c
+++ b/common/parse.c
@@ -4503,6 +4503,22 @@ int parse_non_binary (expr, cfile, lose, context)
 			goto norparen;
 		break;
 
+		/* This parses 'gethostname()'. */
+	      case GETHOSTNAME:
+		token = next_token(&val, NULL, cfile);
+		if (!expression_allocate(expr, MDL))
+			log_fatal("can't allocate expression");
+		(*expr)->op = expr_gethostname;
+
+		token = next_token(NULL, NULL, cfile);
+		if (token != LPAREN)
+			goto nolparen;
+
+		token = next_token(NULL, NULL, cfile);
+		if (token != RPAREN)
+			goto norparen;
+		break;
+
 		/* Not a valid start to an expression... */
 	      default:
 		if (token != NAME && token != NUMBER_OR_NAME)
diff --git a/common/print.c b/common/print.c
index a95198d7..6592b889 100644
--- a/common/print.c
+++ b/common/print.c
@@ -1062,6 +1062,13 @@ static unsigned print_subexpression (expr, buf, len)
 			return rv;
 		}
 
+	      case expr_gethostname:
+		if (len > 13) {
+			strcpy(buf, "(gethostname)");
+			return 13;
+		}
+		break;
+
 	      default:
 		log_fatal("Impossible case at %s:%d (undefined expression "
 			  "%d).", MDL, expr->op);
diff --git a/common/tree.c b/common/tree.c
index 5244a196..2e4616f3 100644
--- a/common/tree.c
+++ b/common/tree.c
@@ -951,6 +951,7 @@ int evaluate_dns_expression (result, packet, lease, client_state, in_options,
 	      case expr_config_option:
 	      case expr_leased_address:
 	      case expr_null:
+	      case expr_gethostname:
 		log_error ("Data opcode in evaluate_dns_expression: %d",
 		      expr -> op);
 		return 0;
@@ -1376,6 +1377,7 @@ int evaluate_boolean_expression (result, packet, lease, client_state,
 	      case expr_null:
 	      case expr_filename:
 	      case expr_sname:
+	      case expr_gethostname:
 		log_error ("Data opcode in evaluate_boolean_expression: %d",
 		      expr -> op);
 		return 0;
@@ -2299,6 +2301,39 @@ int evaluate_data_expression (result, packet, lease, client_state,
 #endif
 		return s0;
 
+		/* Provide the system's local hostname as a return value. */
+	      case expr_gethostname:
+		/*
+		 * Allocate a buffer to return.
+		 *
+		 * The largest valid hostname is maybe 64 octets at a single
+		 * label, or 255 octets if you think a hostname is allowed
+		 * to contain labels (plus termination).
+		 */
+		memset(result, 0, sizeof(*result));
+		if (!buffer_allocate(&result->buffer, 255, file, line)) {
+			log_error("data: gethostname(): no memory for buffer");
+			return 0;
+		}
+		result->data = result->buffer->data;
+
+		/*
+		 * On successful completion, gethostname() resturns 0.  It may
+		 * not null-terminate the string if there was insufficient
+		 * space.
+		 */
+		if (!gethostname((char *)result->buffer->data, 255)) {
+			if (result->buffer->data[255] == '\0')
+				result->len =
+					strlen((char *)result->buffer->data);
+			else
+				result->len = 255;
+			return 1;
+		}
+
+		data_string_forget(result, MDL);
+		return 0;
+
 	      case expr_check:
 	      case expr_equal:
 	      case expr_not_equal:
@@ -2420,6 +2455,7 @@ int evaluate_numeric_expression (result, packet, lease, client_state,
 	      case expr_config_option:
 	      case expr_leased_address:
 	      case expr_null:
+	      case expr_gethostname:
 		log_error ("Data opcode in evaluate_numeric_expression: %d",
 		      expr -> op);
 		return 0;
@@ -3202,6 +3238,7 @@ void expression_dereference (eptr, file, line)
 	      case expr_exists:
 	      case expr_known:
 	      case expr_null:
+	      case expr_gethostname:
 		break;
 
 	      default:
@@ -3261,7 +3298,8 @@ int is_data_expression (expr)
 		expr->op == expr_host_decl_name ||
 		expr->op == expr_leased_address ||
 		expr->op == expr_config_option ||
-		expr->op == expr_null);
+		expr->op == expr_null ||
+		expr->op == expr_gethostname);
 }
 
 int is_numeric_expression (expr)
@@ -3364,6 +3402,7 @@ static int op_val (op)
 	      case expr_binary_or:
 	      case expr_binary_xor:
 	      case expr_client_state:
+	      case expr_gethostname:
 		return 100;
 
 	      case expr_equal:
@@ -3457,6 +3496,7 @@ enum expression_context op_context (op)
 	      case expr_arg:
 	      case expr_funcall:
 	      case expr_function:
+	      case expr_gethostname:
 		return context_any;
 
 	      case expr_equal:
@@ -3988,6 +4028,11 @@ int write_expression (file, expr, col, indent, firstp)
 		col = token_print_indent (file, col, indent, "", "", ")");
 		break;
 
+	      case expr_gethostname:
+		col = token_print_indent(file, col, indent, "", "",
+					 "gethostname()");
+		break;
+
 	      default:
 		log_fatal ("invalid expression type in print_expression: %d",
 			   expr -> op);
@@ -4241,6 +4286,7 @@ int data_subexpression_length (int *rv,
 	      case expr_binary_or:
 	      case expr_binary_xor:
 	      case expr_client_state:
+	      case expr_gethostname:
 		return 0;
 	}
 	return 0;
diff --git a/includes/dhctoken.h b/includes/dhctoken.h
index 01ed1303..d47506a0 100644
--- a/includes/dhctoken.h
+++ b/includes/dhctoken.h
@@ -355,7 +355,8 @@ enum dhcp_token {
 	FIXED_PREFIX6 = 658,
 	ANYCAST_MAC = 659,
 	CONFLICT_DONE = 660,
-	AUTO_PARTNER_DOWN = 661
+	AUTO_PARTNER_DOWN = 661,
+	GETHOSTNAME = 662
 };
 
 #define is_identifier(x)	((x) >= FIRST_TOKEN &&	\
diff --git a/includes/tree.h b/includes/tree.h
index e7bde430..9c37bcc5 100644
--- a/includes/tree.h
+++ b/includes/tree.h
@@ -197,7 +197,8 @@ enum expr_op {
 	expr_ucase,
 	expr_lcase,
 	expr_regex_match,
-	expr_iregex_match
+	expr_iregex_match,
+	expr_gethostname
 };
 
 struct expression {