1 files changed, 167 insertions, 0 deletions
diff --git a/lib/libavb/avb_property_descriptor.c b/lib/libavb/avb_property_descriptor.c
new file mode 100644
index 0000000000..2627cd0d64
--- /dev/null
+++ b/lib/libavb/avb_property_descriptor.c
@@ -0,0 +1,167 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * SPDX-License-Identifier:	MIT
+ */
+
+#include "avb_property_descriptor.h"
+#include "avb_util.h"
+
+bool avb_property_descriptor_validate_and_byteswap(
+    const AvbPropertyDescriptor* src, AvbPropertyDescriptor* dest) {
+  uint64_t expected_size;
+
+  avb_memcpy(dest, src, sizeof(AvbPropertyDescriptor));
+
+  if (!avb_descriptor_validate_and_byteswap((const AvbDescriptor*)src,
+                                            (AvbDescriptor*)dest))
+    return false;
+
+  if (dest->parent_descriptor.tag != AVB_DESCRIPTOR_TAG_PROPERTY) {
+    avb_error("Invalid tag for property descriptor.\n");
+    return false;
+  }
+
+  dest->key_num_bytes = avb_be64toh(dest->key_num_bytes);
+  dest->value_num_bytes = avb_be64toh(dest->value_num_bytes);
+
+  /* Check that key and value are fully contained. */
+  expected_size = sizeof(AvbPropertyDescriptor) - sizeof(AvbDescriptor) + 2;
+  if (!avb_safe_add_to(&expected_size, dest->key_num_bytes) ||
+      !avb_safe_add_to(&expected_size, dest->value_num_bytes)) {
+    avb_error("Overflow while adding up sizes.\n");
+    return false;
+  }
+  if (expected_size > dest->parent_descriptor.num_bytes_following) {
+    avb_error("Descriptor payload size overflow.\n");
+    return false;
+  }
+
+  return true;
+}
+
+typedef struct {
+  const char* key;
+  size_t key_size;
+  const char* ret_value;
+  size_t ret_value_size;
+} PropertyIteratorData;
+
+static bool property_lookup_desc_foreach(const AvbDescriptor* header,
+                                         void* user_data) {
+  PropertyIteratorData* data = (PropertyIteratorData*)user_data;
+  AvbPropertyDescriptor prop_desc;
+  const uint8_t* p;
+  bool ret = true;
+
+  if (header->tag != AVB_DESCRIPTOR_TAG_PROPERTY) {
+    goto out;
+  }
+
+  if (!avb_property_descriptor_validate_and_byteswap(
+          (const AvbPropertyDescriptor*)header, &prop_desc)) {
+    goto out;
+  }
+
+  p = (const uint8_t*)header;
+  if (p[sizeof(AvbPropertyDescriptor) + prop_desc.key_num_bytes] != 0) {
+    avb_error("No terminating NUL byte in key.\n");
+    goto out;
+  }
+
+  if (data->key_size == prop_desc.key_num_bytes) {
+    if (avb_memcmp(p + sizeof(AvbPropertyDescriptor),
+                   data->key,
+                   data->key_size) == 0) {
+      data->ret_value = (const char*)(p + sizeof(AvbPropertyDescriptor) +
+                                      prop_desc.key_num_bytes + 1);
+      data->ret_value_size = prop_desc.value_num_bytes;
+      /* Stop iterating. */
+      ret = false;
+      goto out;
+    }
+  }
+
+out:
+  return ret;
+}
+
+const char* avb_property_lookup(const uint8_t* image_data,
+                                size_t image_size,
+                                const char* key,
+                                size_t key_size,
+                                size_t* out_value_size) {
+  PropertyIteratorData data;
+
+  if (key_size == 0) {
+    key_size = avb_strlen(key);
+  }
+
+  data.key = key;
+  data.key_size = key_size;
+
+  if (avb_descriptor_foreach(
+          image_data, image_size, property_lookup_desc_foreach, &data) == 0) {
+    if (out_value_size != NULL) {
+      *out_value_size = data.ret_value_size;
+    }
+    return data.ret_value;
+  }
+
+  if (out_value_size != NULL) {
+    *out_value_size = 0;
+  }
+  return NULL;
+}
+
+bool avb_property_lookup_uint64(const uint8_t* image_data,
+                                size_t image_size,
+                                const char* key,
+                                size_t key_size,
+                                uint64_t* out_value) {
+  const char* value;
+  bool ret = false;
+  uint64_t parsed_val;
+  int base;
+  int n;
+
+  value = avb_property_lookup(image_data, image_size, key, key_size, NULL);
+  if (value == NULL) {
+    goto out;
+  }
+
+  base = 10;
+  if (avb_memcmp(value, "0x", 2) == 0) {
+    base = 16;
+    value += 2;
+  }
+
+  parsed_val = 0;
+  for (n = 0; value[n] != '\0'; n++) {
+    int c = value[n];
+    int digit;
+
+    parsed_val *= base;
+
+    if (c >= '0' && c <= '9') {
+      digit = c - '0';
+    } else if (base == 16 && c >= 'a' && c <= 'f') {
+      digit = c - 'a' + 10;
+    } else if (base == 16 && c >= 'A' && c <= 'F') {
+      digit = c - 'A' + 10;
+    } else {
+      avb_error("Invalid digit.\n");
+      goto out;
+    }
+
+    parsed_val += digit;
+  }
+
+  ret = true;
+  if (out_value != NULL) {
+    *out_value = parsed_val;
+  }
+
+out:
+  return ret;
+}