discover: Support DHCP "pathprefix" configuration option

This change implements support for the DHCP "pathprefix" option. We use
the following logic:

 - If pathprefix is present and a full URL, we base the config file
   location on pathprefix + conffile

 - If pathprefix is present but not a full URL, we use it as the path
   component of the URL, and pick up the host from other parameters in
   the DHCP response

 - If no pathprefix is present, we determine the configuration prefix
   from the DHCP bootfile parameter.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

7 files changed, 177 insertions, 37 deletions

diff --git a/discover/network.c b/discover/network.c
index 8cc0183..2857076 100644
--- a/discover/network.c
+++ b/discover/network.c
@@ -220,6 +220,7 @@ static void configure_interface_dhcp(struct interface *interface)
 		"-R",
 		"-n",
 		"-O", "pxeconffile",
+		"-O", "pxepathprefix",
 		"-p", pidfile,
 		"-i", interface->name,
 		NULL,
diff --git a/discover/user-event.c b/discover/user-event.c
index 11a54df..7acd237 100644
--- a/discover/user-event.c
+++ b/discover/user-event.c
@@ -232,61 +232,82 @@ static char *parse_ip_addr(struct discover_context *ctx, const char *ip)
 struct pb_url *user_event_parse_conf_url(struct discover_context *ctx,
 		struct event *event, bool *is_complete)
 {
-	const char *conffile, *host, *bootfile;
+	const char *conffile, *pathprefix, *host, *bootfile;
 	char *p, *basedir, *url_str;
 	struct pb_url *url;
 
 	conffile = event_get_param(event, "pxeconffile");
-	if (conffile) {
-		if (is_url(conffile)) {
-			url = pb_url_parse(ctx, conffile);
-		} else {
-			host = parse_host_addr(event);
-			if (!host) {
-				pb_log("%s: host address not found\n",
-						__func__);
-				return NULL;
-			}
-
-			url_str = talloc_asprintf(ctx, "%s%s/%s", "tftp://",
-					host, conffile);
-			url = pb_url_parse(ctx, url_str);
+	pathprefix = event_get_param(event, "pxepathprefix");
+	bootfile = event_get_param(event, "bootfile");
+
+	/* If we're given a conf file, we're able to generate a complete URL to
+	 * the configuration file, and the parser doesn't need to do any
+	 * further autodiscovery */
+	*is_complete = !!conffile;
+
+	/* if conffile is a URL, that's all we need */
+	if (conffile && is_url(conffile)) {
+		url = pb_url_parse(ctx, conffile);
+		return url;
+	}
 
+	/* If we can create a URL from pathprefix (optionally with
+	 * conffile appended to create a complete URL), use that */
+	if (pathprefix && is_url(pathprefix)) {
+		if (conffile) {
+			url_str = talloc_asprintf(ctx, "%s%s",
+					pathprefix, conffile);
+			url = pb_url_parse(ctx, url_str);
 			talloc_free(url_str);
+		} else {
+			url = pb_url_parse(ctx, pathprefix);
 		}
 
-		*is_complete = true;
-	} else {
-		host = parse_host_addr(event);
-		if (!host) {
-			pb_log("%s: host address not found\n", __func__);
-			return NULL;
-		}
+		return url;
+	}
 
-		bootfile = event_get_param(event, "bootfile");
-		if (!bootfile) {
-			pb_log("%s: bootfile param not found\n", __func__);
-			return NULL;
-		}
+	host = parse_host_addr(event);
+	if (!host) {
+		pb_log("%s: host address not found\n", __func__);
+		return NULL;
+	}
+
+	url_str = talloc_asprintf(ctx, "tftp://%s/", host);
+
+	/* if we have a pathprefix, use that directly.. */
+	if (pathprefix) {
+		/* strip leading slashes */
+		while (pathprefix[0] == '/')
+			pathprefix++;
+		url_str = talloc_asprintf_append(url_str, "%s", pathprefix);
+
+	/* ... otherwise, add a path based on the bootfile name, but only
+	 * if conffile isn't an absolute path itself */
+	} else if (bootfile && !(conffile && conffile[0] == '/')) {
 
 		basedir = talloc_strdup(ctx, bootfile);
-		p = strchr(basedir, '/');
+
+		/* strip filename from the bootfile path, leaving only a
+		 * directory */
+		p = strrchr(basedir, '/');
 		if (p)
 			*p = '\0';
 
-		if (!strcmp(basedir,"") || !strcmp(basedir, "."))
-			url_str = talloc_asprintf(ctx, "%s%s/", "tftp://",host);
-		else
-			url_str = talloc_asprintf(ctx, "%s%s/%s/", "tftp://",host,
+		if (strlen(basedir))
+			url_str = talloc_asprintf_append(url_str, "%s/",
 					basedir);
 
-		url = pb_url_parse(ctx, url_str);
-
-		talloc_free(url_str);
 		talloc_free(basedir);
-		*is_complete = false;
 	}
 
+	/* finally, append conffile */
+	if (conffile)
+		url_str = talloc_asprintf_append(url_str, "%s", conffile);
+
+	url = pb_url_parse(ctx, url_str);
+
+	talloc_free(url_str);
+
 	return url;
 }
 
diff --git a/test/parser/Makefile.am b/test/parser/Makefile.am
index 47fd458..fdc53e3 100644
--- a/test/parser/Makefile.am
+++ b/test/parser/Makefile.am
@@ -62,6 +62,9 @@ TESTS = \
 	test-pxe-ip-without-conf \
 	test-pxe-non-url-conf \
 	test-pxe-local \
+	test-pxe-pathprefix-with-conf \
+	test-pxe-non-url-pathprefix-with-conf \
+	test-pxe-pathprefix-discover \
 	test-unresolved-remove
 
 $(TESTS): %: %.embedded-config.o
diff --git a/test/parser/test-pxe-non-url-pathprefix-with-conf.c b/test/parser/test-pxe-non-url-pathprefix-with-conf.c
new file mode 100644
index 0000000..36d4726
--- /dev/null
+++ b/test/parser/test-pxe-non-url-pathprefix-with-conf.c
@@ -0,0 +1,38 @@
+
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+default linux
+
+label linux
+kernel ./kernel
+append command line
+initrd /initrd
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_read_conf_embedded_url(test, "tftp://host/path/to/conf.txt");
+
+	test_set_event_source(test);
+	test_set_event_param(test->ctx->event, "tftp", "host");
+	test_set_event_param(test->ctx->event, "pxepathprefix", "/path/to/");
+	test_set_event_param(test->ctx->event, "pxeconffile", "conf.txt");
+
+	test_run_parser(test, "pxe");
+
+	ctx = test->ctx;
+
+	check_boot_option_count(ctx, 1);
+	opt = get_boot_option(ctx, 0);
+
+	check_name(opt, "linux");
+	check_args(opt, "command line");
+
+	check_resolved_url_resource(opt->boot_image,
+			"tftp://host/path/to/./kernel");
+	check_resolved_url_resource(opt->initrd, "tftp://host/initrd");
+}
diff --git a/test/parser/test-pxe-pathprefix-discover.c b/test/parser/test-pxe-pathprefix-discover.c
new file mode 100644
index 0000000..de2feac
--- /dev/null
+++ b/test/parser/test-pxe-pathprefix-discover.c
@@ -0,0 +1,38 @@
+
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+default linux
+
+label linux
+kernel ./kernel
+append command line
+initrd /initrd
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_read_conf_embedded_url(test, "tftp://host/path/to/C0A8");
+
+	test_set_event_source(test);
+	test_set_event_param(test->ctx->event, "ip", "192.168.0.1");
+	test_set_event_param(test->ctx->event, "pxepathprefix",
+			"tftp://host/path/to/");
+
+	test_run_parser(test, "pxe");
+
+	ctx = test->ctx;
+
+	check_boot_option_count(ctx, 1);
+	opt = get_boot_option(ctx, 0);
+
+	check_name(opt, "linux");
+	check_args(opt, "command line");
+
+	check_resolved_url_resource(opt->boot_image,
+			"tftp://host/path/to/./kernel");
+	check_resolved_url_resource(opt->initrd, "tftp://host/initrd");
+}
diff --git a/test/parser/test-pxe-pathprefix-with-conf.c b/test/parser/test-pxe-pathprefix-with-conf.c
new file mode 100644
index 0000000..57f942d
--- /dev/null
+++ b/test/parser/test-pxe-pathprefix-with-conf.c
@@ -0,0 +1,38 @@
+
+#include "parser-test.h"
+
+#if 0 /* PARSER_EMBEDDED_CONFIG */
+default linux
+
+label linux
+kernel ./kernel
+append command line
+initrd /initrd
+#endif
+
+void run_test(struct parser_test *test)
+{
+	struct discover_boot_option *opt;
+	struct discover_context *ctx;
+
+	test_read_conf_embedded_url(test, "tftp://host/path/to/conf.txt");
+
+	test_set_event_source(test);
+	test_set_event_param(test->ctx->event, "pxepathprefix",
+			"tftp://host/path/to/");
+	test_set_event_param(test->ctx->event, "pxeconffile", "conf.txt");
+
+	test_run_parser(test, "pxe");
+
+	ctx = test->ctx;
+
+	check_boot_option_count(ctx, 1);
+	opt = get_boot_option(ctx, 0);
+
+	check_name(opt, "linux");
+	check_args(opt, "command line");
+
+	check_resolved_url_resource(opt->boot_image,
+			"tftp://host/path/to/./kernel");
+	check_resolved_url_resource(opt->initrd, "tftp://host/initrd");
+}
diff --git a/utils/pb-udhcpc b/utils/pb-udhcpc
index 4ff0dcf..714d5b4 100644
--- a/utils/pb-udhcpc
+++ b/utils/pb-udhcpc
@@ -18,7 +18,8 @@ pb_add () {
 	paramstr=''
 
 	# Collect relevant DHCP response parameters into $paramstr
-	for name in pxeconffile bootfile mac ip siaddr serverid tftp
+	for name in pxeconffile pxepathprefix bootfile mac ip siaddr \
+		serverid tftp
 	do
 		value=$(eval "echo \${$name}")
 		[ -n "$value" ] || continue;