From a50b6746c097dad1a21f4f5a7e686a37a601c821 Mon Sep 17 00:00:00 2001
From: Hendrik Sauer <hendrik-sauer@mailbox.org>
Date: Tue, 7 Dec 2021 17:57:50 +0100
Subject: [PATCH] Implement functions to work with exposure keys

---
 src/extract_keys.c | 103 +++++++++++++++++++++++++++++++++++++++++++++
 src/extract_keys.h |  10 +++++
 2 files changed, 113 insertions(+)

diff --git a/src/extract_keys.c b/src/extract_keys.c
index 9b11af0..b29595a 100644
--- a/src/extract_keys.c
+++ b/src/extract_keys.c
@@ -1,2 +1,105 @@
+#include <stdlib.h>
+#include <string.h>
+#include <sys/printk.h>
+#include <zephyr.h>
+
+#include <protobuf-c.h>
+
+#include "export.pb-c.h"
 #include "extract_keys.h"
 
+
+#define KEY_SIZE 8
+#ifndef PROTOBUF_BLOCK_SIZE
+#define PROTOBUF_BLOCK_SIZE 0
+#endif
+#define EXPORT_BUFFER_SIZE 100000
+
+void process_key(TemporaryExposureKey* key) {
+    printk("Attempting to process key\n");
+    // #if !COVID_MEASURE_PERFORMANCE
+    if (key) {
+        if (key->has_key_data) {
+            int len = (key->key_data.len) + 1;
+            char data[len + 1];
+            memcpy(data, key->key_data.data, len - 1);
+            data[len] = 0;
+            printk("New key: %s\n", data);
+        }
+    }
+    // #endif
+}
+
+size_t generate_keys(uint8_t** buffer_pointer, size_t max_size, int num_keys) {
+    TemporaryExposureKeyExport export = {};
+    temporary_exposure_key_export__init(&export);
+    TemporaryExposureKey** key_ptrs = (TemporaryExposureKey**) k_malloc(sizeof(TemporaryExposureKey*) * num_keys);
+    if (key_ptrs == NULL) {
+        printk("Could not allocate memory for pointers\n");
+        return 0;
+    }
+    // TemporaryExposureKey* key_ptrs[num_keys];
+    uint8_t key_data[KEY_SIZE];
+    for (int i = 0; i < KEY_SIZE; i++) {
+        key_data[i] = 0xFF;
+    }
+    TemporaryExposureKey key;
+    temporary_exposure_key__init(&key);
+    key.key_data.data = key_data;
+    key.key_data.len = KEY_SIZE;
+    key.has_key_data = true;
+    for (int i = 0; i < num_keys; i++) {
+        key_ptrs[i] = &key;
+    }
+    export.keys = key_ptrs;
+    export.n_keys = num_keys;
+    size_t required_buffer = temporary_exposure_key_export__get_packed_size(&export);
+    uint8_t* buffer = (uint8_t*) k_malloc(required_buffer);
+    if (buffer == NULL) {
+        printk("Could not allocate memory for buffer\n");
+        return 0;
+    }
+    *buffer_pointer = buffer;
+    if (buffer != NULL) {
+        size_t buf_size = temporary_exposure_key_export__pack(&export, buffer);
+        free(key_ptrs);
+        return buf_size;
+    } else {
+        printk("Buffer too small to serialize %d keys. %d bytes necessary\n", num_keys, required_buffer);
+        return 0;
+    }
+}
+
+int unpack_keys(uint8_t* buf, size_t buf_size) {
+    // Unpack protocol buffer
+    printk("Buf size: %d\n", buf_size);
+    TemporaryExposureKeyExport* export = temporary_exposure_key_export__unpack(NULL, buf_size, buf);
+    if (export == NULL) {
+        printk("error unpacking incoming message\n");
+        return -2;
+    }
+
+    // Iterate over new keys
+    for (int i = 0; i < export->n_keys; i++) {
+        TemporaryExposureKey* key = export->keys[i];
+        process_key(key);
+    }
+
+    // Iterate over revised keys
+    for (int i = 0; i < export->n_revised_keys; i++) {
+        TemporaryExposureKey* key = export->revised_keys[i];
+        process_key(key);
+    }
+    return 0;
+}
+
+int test_unpacking(int num_keys) {
+    uint8_t* buffer;
+    printk("Test unpacking %d keys\n", num_keys);
+    size_t buffer_size = generate_keys(&buffer, EXPORT_BUFFER_SIZE, num_keys);
+    if (buffer_size) {
+        unpack_keys(buffer, buffer_size);
+    }
+    k_free(buffer);
+    return 0;
+}
\ No newline at end of file
diff --git a/src/extract_keys.h b/src/extract_keys.h
index a10c5e5..36114f5 100644
--- a/src/extract_keys.h
+++ b/src/extract_keys.h
@@ -1,4 +1,14 @@
 #ifndef EXTRACT_KEYS_H
 #define EXTRACT_KEYS_H
 
+#include "export.pb-c.h"
+
+void process_key(TemporaryExposureKey*);
+
+size_t generate_keys(uint8_t**, size_t, int);
+
+int unpack_keys(uint8_t*, size_t) ;
+
+int test_unpacking(int);
+
 #endif
\ No newline at end of file