pem: refactor to expose pem iterator privately

This patch introduces a new extended format for settings files. This new format allows raw data to be provided under a given group rather than key/value pairs. A group using an extended format will contain both the extended type and group name in the format, for example:

[@pem(a)certificate]

Where 'pem' is the type and 'certificate' is the name. The type of format requires an extension specific parser implementation in settings as the parser must know when to start/stop parsing data. This allows for any textual characters to be present after the group is declared, including special characters like [] (its completely up to the parser to decide whats valid and what is not).

Three new l_settings APIs were added:

l_settings_has_embedded_group
l_settings_get_embedded_groups
l_settings_get_embedded_value

In this patch, the 'pem' extension type is also introduced, and for now is the only extended type. The pem extended type expects a base64 encoded PEM (or list of PEMs) after the group. The pem parser will stop after the last PEM is found. Examples can be found in unit/test-settings.c

---
  ell/ell.sym    |   3 +
  ell/settings.c | 234 ++++++++++++++++++++++++++++++++++++++++++++++---
  ell/settings.h |   7 ++
  3 files changed, 233 insertions(+), 11 deletions(-)

(quoted diff) +0 -1

-v5:
  * Updated to use endp instead of len out parameter

ell/ell.sym +3 -0

index e02f0fe..32d94f5 100644
@@ -425,6 +425,9 @@ global:
  	l_settings_set_float;
  	l_settings_remove_group;
  	l_settings_remove_key;
+	l_settings_has_embedded_group;
+	l_settings_get_embedded_groups;
+	l_settings_get_embedded_value;
  	/* signal */
  	l_signal_create;
  	l_signal_remove;

ell/settings.c +1 -0

index 98f0cfd..457d3ec 100644
@@ -48,15 +48,23 @@
  #include "settings.h"
  #include "private.h"
  #include "missing.h"
+#include "pem-private.h"
 
  struct setting_data {
  	char *key;
  	char *value;
  };
 

ell/settings.c +5 -1

  };
 
  struct l_settings {

@@ -81,7 +89,11 @@ static void group_destroy(void *data)
  	struct group_data *group = data;
 
  	l_free(group->name);
-	l_queue_destroy(group->settings, setting_destroy);
+
+	if (group->settings)
+		l_queue_destroy(group->settings, setting_destroy);
+	else
+		l_free(group->embedded_data);
 
  	l_free(group);
  }

ell/settings.c +41 -0

+	size_t count = 0;
+
+	ptr = data;
+	end = data + len;
+
+	while (ptr && ptr < end) {
+		const char *pem_start = ptr;
+
+		if (!pem_next(ptr, len, NULL, NULL, &ptr, true)) {
+			if (ptr)
+				return -EINVAL;
+
+			break;
+		}
+
+		len -= ptr - pem_start;
+		count += ptr - pem_start;
+	}
+
+	return count;
+}
+
+struct group_extension {
+	char *name;
+	ssize_t (*parse)(const char *data, size_t len);
+};
+
+static struct group_extension pem_extension = {
+	.name = "pem",
+	.parse = parse_pem,
+};
+
+struct group_extension *extensions[] = {
+	&pem_extension,
+	NULL
+};
+
+static struct group_extension *find_group_extension(const char *type)
+{
+	unsigned int i;
+

ell/settings.c +13 -0

+	group->embedded_data->len = bytes;
+	memcpy(group->embedded_data->data, ptr1 + 2, bytes);
+	group->embedded_data->data[bytes] = '\0';
+
+	l_queue_push_tail(setting->groups, group);
+
+	return bytes;
+
+free_name:
+	l_free(name);
+	return -EINVAL;
+}
+
  static bool parse_group(struct l_settings *settings, const char *data,
  			size_t len, size_t line)
  {

ell/settings.c +4 -2

@@ -552,24 +708,24 @@ static void gather_groups(void *data, void *user_data)
  	struct group_data *group_data = data;
  	struct gather_data *gather = user_data;
 
-	gather->v[gather->cur++] = l_strdup(group_data->name);
+	if (!group_data->settings)
+		return;
+
+	gather->v = l_strv_append(gather->v, group_data->name);
  }
 
  LIB_EXPORT char **l_settings_get_groups(const struct l_settings *settings)
  {
-	char **ret;

ell/settings.c +28 -1

  	l_queue_foreach(settings->groups, gather_groups, &gather);
 
-	return ret;
+	return gather.v;
  }
 
  LIB_EXPORT bool l_settings_has_group(const struct l_settings *settings,

@@ -1176,3 +1332,59 @@ LIB_EXPORT bool l_settings_remove_key(struct l_settings *settings,
 
  	return true;
  }
+
+static void gather_embedded_groups(void *data, void *user_data)
+{
+	struct group_data *group_data = data;
+	struct gather_data *gather = user_data;
+
+	if (!group_data->embedded_data)
+		return;
+
+	gather->v = l_strv_append(gather->v, group_data->name);
+}
+
+LIB_EXPORT char **l_settings_get_embedded_groups(struct l_settings *settings)
+{
+	struct gather_data gather;
+
+	if (unlikely(!settings))
+		return NULL;
+
+	gather.v = l_strv_new();
+
+	l_queue_foreach(settings->groups, gather_embedded_groups, &gather);
+
+	return gather.v;
+}
+
+LIB_EXPORT bool l_settings_has_embedded_group(struct l_settings *settings,

ell/settings.c +6 -0

+}
+
+LIB_EXPORT const char *l_settings_get_embedded_value(struct l_settings *settings,
+							const char *group_name,
+							const char **out_type)
+{

This refactors pem.c to expose a new internal API, pem_next. This API will allow iteration/parsing of PEM(s). Other APIs in pem.c were updated to use pem_next.

pem_next behaves similar to pem_load_buffer, except it does not do any base64 decoding. Instead it just returns the start of the base64 data and the caller must decode it. This allows simple PEM iteration loops. Strictly for pem.c usage we decode the base64 string in the loop, but settings.c will need this for parsing PEMs from settings files and returning the PEM as a full string, including the start/end tags.

---
  ell/pem-private.h | 32 +++++++++++++++++++
  ell/pem.c         | 78 ++++++++++++++++++++++++++++++-----------------
  2 files changed, 82 insertions(+), 28 deletions(-)

create mode 100644 ell/pem-private.h

-v5:
* Fixed incorrect commit description (return start of base64 data)
* Removed len out parameter in pem_next, endp can be used instead
* Fixed base64_len off by one error.
* Fixed misleading comment, and removed unused error handling code