lib: net: Add message frame handling

Signed-off-by: Ian Moffett <ian@osmora.org>

2 files changed, 119 insertions, 0 deletions

diff --git a/lib/include/net/stpsession.h b/lib/include/net/stpsession.h
index 351be26..773d57b 100644
--- a/lib/include/net/stpsession.h
+++ b/lib/include/net/stpsession.h
@@ -91,4 +91,10 @@ struct msg_frame {
     uint16_t len;
     uint8_t payload[MESSAGE_SIZE];
 };
+
+int send_frame(int client_fd, void *data, size_t len,
+    const unsigned char *session_key);
+int recv_frame(int client_fd, size_t len, const unsigned char *session_key,
+    void *res);
+
 #endif  /* STP_SESSION_H_ */
diff --git a/lib/net/frame.c b/lib/net/frame.c
new file mode 100644
index 0000000..d8bba5e
--- /dev/null
+++ b/lib/net/frame.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <net/stpsession.h>
+#include <crypto/aes.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+static int
+decrypt_frame(const struct msg_frame *frame, const unsigned char *key, size_t len,
+    void *res)
+{
+    struct aes_message am;
+    unsigned char *tmp;
+    int error;
+
+    /* Construct an AES message with the message frame */
+    am.ciphertext = (unsigned char *)frame->payload;
+    am.ciphertext_len = frame->len;
+    memcpy(am.tag, frame->tag, AES_GCM_TAG_SIZE);
+    memcpy(am.iv, frame->iv, AES_IV_SIZE);
+    memcpy(am.ciphertext, frame->payload, frame->len);
+
+    /* Decrypt and deserialize the frame payload */
+    if ((error = aes256_decrypt(&am, key, &tmp)) < 0) {
+        return error;
+    }
+    memcpy(res, tmp, len);
+    free(tmp);
+    return 0;
+}
+
+int
+send_frame(int client_fd, void *data, size_t len, const unsigned char *session_key)
+{
+    struct aes_message am;
+    struct msg_frame msg_frame;
+    int error;
+
+    error = aes256_encrypt((void *)data, len, session_key, &am);
+    if (error < 0) {
+        printf("send_frame: Failed to encrypt data\n");
+        return error;
+    }
+
+    memcpy(msg_frame.iv, am.iv, AES_IV_SIZE);
+    memcpy(msg_frame.tag, am.tag, AES_GCM_TAG_SIZE);
+    memcpy(msg_frame.payload, am.ciphertext, am.ciphertext_len);
+    msg_frame.len = am.ciphertext_len;
+
+    /* Send in the message frame */
+    error = send(client_fd, &msg_frame, sizeof(msg_frame), 0);
+    if (error < 0) {
+        printf("send_frame: Failed sending frame to server\n");
+        aes256_free_msg(&am);
+        return error;
+    }
+    return 0;
+}
+
+int
+recv_frame(int client_fd, size_t len, const unsigned char *session_key, void *res)
+{
+    struct msg_frame frame;
+    int error, ret;
+
+    /* Get the message frame over the network */
+    ret = recv(client_fd, &frame, sizeof(struct msg_frame), MSG_WAITALL);
+    if (ret < 0) {
+        printf("Failed to get frame payload from peer\n");
+        return error;
+    }
+    if (ret == 0) {
+        printf("Connection closed by peer\n");
+        return -1;
+    }
+
+    /* Decrypt the payload */
+    if ((error = decrypt_frame(&frame, session_key, len, res)) < 0) {
+        printf("Failed to decrypt frame payload, rejecting...\n");
+        return error;
+    }
+
+    return ret;
+}