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Subject[PATCH 12/16] X.509: Add utility functions to render OIDs as strings
Date
Add a pair of utility functions to render OIDs as strings.  The first takes an
encoded OID and turns it into a "a.b.c.d" form string:

int sprint_oid(const void *data, size_t datasize,
char *buffer, size_t bufsize);

The second takes an OID enum index and calls the first on the data held
therein:

int sprint_OID(enum OID oid, char *buffer, size_t bufsize);

Signed-off-by: David Howells <dhowells@redhat.com>
---

include/linux/oid_registry.h | 2 +
lib/oid_registry.c | 81 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 83 insertions(+)


diff --git a/include/linux/oid_registry.h b/include/linux/oid_registry.h
index 5928546..6926db7 100644
--- a/include/linux/oid_registry.h
+++ b/include/linux/oid_registry.h
@@ -86,5 +86,7 @@ enum OID {
};

extern enum OID look_up_OID(const void *data, size_t datasize);
+extern int sprint_oid(const void *, size_t, char *, size_t);
+extern int sprint_OID(enum OID, char *, size_t);

#endif /* _LINUX_OID_REGISTRY_H */
diff --git a/lib/oid_registry.c b/lib/oid_registry.c
index 33cfd17..d8de11f 100644
--- a/lib/oid_registry.c
+++ b/lib/oid_registry.c
@@ -11,6 +11,9 @@

#include <linux/export.h>
#include <linux/oid_registry.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/bug.h>
#include "oid_registry_data.c"

/**
@@ -87,3 +90,81 @@ enum OID look_up_OID(const void *data, size_t datasize)
return OID__NR;
}
EXPORT_SYMBOL_GPL(look_up_OID);
+
+/*
+ * sprint_OID - Print an Object Identifier into a buffer
+ * @data: The encoded OID to print
+ * @datasize: The size of the encoded OID
+ * @buffer: The buffer to render into
+ * @bufsize: The size of the buffer
+ *
+ * The OID is rendered into the buffer in "a.b.c.d" format and the number of
+ * bytes is returned. -EBADMSG is returned if the data could not be intepreted
+ * and -ENOBUFS if the buffer was too small.
+ */
+int sprint_oid(const void *data, size_t datasize, char *buffer, size_t bufsize)
+{
+ const unsigned char *v = data, *end = v + datasize;
+ unsigned long num;
+ unsigned char n;
+ size_t ret;
+ int count;
+
+ if (v >= end)
+ return -EBADMSG;
+
+ n = *v++;
+ ret = count = snprintf(buffer, bufsize, "%u.%u", n / 40, n % 40);
+ buffer += count;
+ bufsize -= count;
+ if (bufsize == 0)
+ return -ENOBUFS;
+
+ while (v < end) {
+ num = 0;
+ n = *v++;
+ if (!(n & 0x80)) {
+ num = n;
+ } else {
+ num = n & 0x7f;
+ do {
+ if (v >= end)
+ return -EBADMSG;
+ n = *v++;
+ num <<= 7;
+ num |= n & 0x7f;
+ } while (n & 0x80);
+ }
+ ret += count = snprintf(buffer, bufsize, ".%lu", num);
+ buffer += count;
+ bufsize -= count;
+ if (bufsize == 0)
+ return -ENOBUFS;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(sprint_oid);
+
+/**
+ * sprint_OID - Print an Object Identifier into a buffer
+ * @oid: The OID to print
+ * @buffer: The buffer to render into
+ * @bufsize: The size of the buffer
+ *
+ * The OID is rendered into the buffer in "a.b.c.d" format and the number of
+ * bytes is returned.
+ */
+int sprint_OID(enum OID oid, char *buffer, size_t bufsize)
+{
+ int ret;
+
+ BUG_ON(oid >= OID__NR);
+
+ ret = sprint_oid(oid_data + oid_index[oid],
+ oid_index[oid + 1] - oid_index[oid],
+ buffer, bufsize);
+ BUG_ON(ret == -EBADMSG);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(sprint_OID);


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