From e34b3151c45e0a767d667dccc6725cdecb04c424 Mon Sep 17 00:00:00 2001
From: Vlad Badoiu <vlad_andrei.badoiu@upb.ro>
Date: Sun, 19 Feb 2023 22:28:29 +0200
Subject: [PATCH] lab2: Update skeleton to match text
---
lab2/README.md | 26 +++++++++++++++++++-------
lab2/common.h | 10 ++++++++++
lab2/recv.c | 32 ++++++++++++++++++++++++--------
lab2/send.c | 36 ++++++++++++++++++++++++++++--------
4 files changed, 81 insertions(+), 23 deletions(-)
diff --git a/lab2/README.md b/lab2/README.md
index 8644dd8..496fd77 100644
--- a/lab2/README.md
+++ b/lab2/README.md
@@ -1,20 +1,29 @@
-Physical layer simulator.
+Physical layer simulator. We have **two separate programs**, the sender and the receiver.
+
+Normally, we would implement our protocol as a library, but to make things
+easier, we implement part of the protocol in send.c, and the receving code in
+recv.c.
``send.c`` - the code that the sender will execute
``recv.c`` - the code that the receiver on the other end of the wire will execute
-``common.h`` - header where we define the `Frame` structure
+``common.h`` - header where we define the `Frame` structure and the API that the physical layers exports
Overview of the architecture
```
-sender receiver
- | |
- |______________________|
- Physical (wire)
+ sender receiver
+ | |
+ Physical layer Physical layer
+ protocol protocol
+ |______________________|
+ Physical (wire)
```
-Note, if you want to use C++, simply change the extension of the `send.c` and `recv.c` to `.cpp` and update the Makefile.
+## C++
+
+Note, if you want to use C++, simply change the extension of the `send.c` and
+`recv.c` to `.cpp` and update the Makefile to use `g++`.
## API
```
@@ -30,3 +39,6 @@ make
```
We will run the sender and receiver in parallel using ``run_experiment.sh``.
+This scripts first runs the receiver binary and then runs the sender binary.
+There are several parameters that can be used to modify the characteristics of
+the link, but we don't need them for this lab.
diff --git a/lab2/common.h b/lab2/common.h
index 4d15161..9cfd562 100644
--- a/lab2/common.h
+++ b/lab2/common.h
@@ -1,9 +1,19 @@
+#define DLE (char)0
+#define STX (char)2
+#define ETX (char)3
+
/* Atributul este folosit pentru a anunta compilatorul sa nu alinieze structura */
__attribute__((packed))
/* DELIM | DATE | DELIM */
struct Frame {
char frame_delim_start[2]; /* DEL STX */
+ /* TODO 2: Add source and destination */
char payload[30]; /* Datele pe care vrem sa le transmitem */
char frame_delim_end[2]; /* DEL ETX */
};
+/* Sends one character to the other end via the Physical layer */
+int send_byte(char c);
+/* Receives one character from the other end, if nothing is sent by the other end, returns a random character */
+char recv_byte();
+
diff --git a/lab2/recv.c b/lab2/recv.c
index 95f7fa8..99dba5d 100644
--- a/lab2/recv.c
+++ b/lab2/recv.c
@@ -5,17 +5,34 @@
#include <fcntl.h>
#include "link_emulator/lib.h"
+/* Do not touch these two */
#define HOST "127.0.0.1"
#define PORT 10001
#include "common.h"
-#define DLE (char)0
-#define STX (char)2
-#define ETX (char)3
-/* TODO 2: write recv_frame function */
+/* Our unqiue layer 2 ID */
+static int ID = 123131;
+
+/* Function which our protocol implementation will provide to the upper layer. */
+int recv_frame(char *buf, int size)
+{
+ /* TODO 1.1: Call recv_byte() until we receive the frame start
+ * delimitator. This operation makes this function blocking until it
+ * receives a frame. */
+
+ /* TODO 2.1: The first two 2 * sizeof(int) bytes represent sender and receiver ID */
+
+ /* TODO 2.2: Check that the frame was sent to me */
+
+ /* TODO 1.2: Read bytes and copy them to buff until we receive the end of the frame */
+
+ /* If everything went well return the number of bytes received */
+ return 0;
+}
int main(int argc,char** argv){
+ /* Do not touch this */
init(HOST,PORT);
@@ -52,12 +69,11 @@ int main(int argc,char** argv){
c = recv_byte();
printf("%c\n", c);
+ /* TODO 1.0: Allocate a buffer and call recv_frame */
- /* TODO 2: Run the receiver until you receive the frame DONE */
-
- /* TODO 3: receive a frame with a structure of type Pa */
- /* TODO 4: Measure latency in a while loop for any frame that contains a timestamp we receive, print frame_size and latency */
+ /* TODO 3: Measure latency in a while loop for any frame that contains
+ * a timestamp we receive, print frame_size and latency */
printf("[RECEIVER] Finished transmission\n");
return 0;
diff --git a/lab2/send.c b/lab2/send.c
index d8b1d4b..e6c35a4 100644
--- a/lab2/send.c
+++ b/lab2/send.c
@@ -13,13 +13,29 @@
/* Here we have the Frame structure */
#include "common.h"
-#define DLE (char)0
-#define STX (char)2
-#define ETX (char)3
-/* TODO 2: implement send_frame function */
+/* Our unqiue layer 2 ID */
+static int ID = 123131;
+
+/* Function which our protocol implementation will provide to the upper layer. */
+int send_frame(char *buf, int size)
+{
+
+ /* TODO 1.1: Create a new frame. */
+
+ /* TODO 1.2: Copy the data from buffer to our frame structure */
+
+ /* TODO 2.1: Set the destination and source */
+
+ /* TODO 1.3: We can cast the frame to a char *, and iterate through sizeof(struct Frame) bytes
+ calling send_bytes. */
+
+ /* if all went all right, return 0 */
+ return 0;
+}
int main(int argc,char** argv){
+ // Don't touch this
init(HOST,PORT);
/* Send Hello */
@@ -31,12 +47,16 @@ int main(int argc,char** argv){
send_byte('l');
send_byte('o');
send_byte('!');
+ send_byte(DLE);
+ send_byte(ETX);
+
+ /* TODO 1.0: Get some input in a buffer and call send_frame with it */
+
+ /* TODO 3.1: Get a timestamp of the current time copy it in the the payload */
- /* TODO 2: call send_frame function with a given string input */
+ /* TODO 3.0: Upload the maximum size of the payload in Frame to 100, send the frame */
- /* TODO 3: use send_frame to send a structure of type Packet */
+ /* TODO 3.0: Upload the maximum size of the payload in Frame to 300, send the frame */
- /* TODO 4: send 100 bytes, send 300 bytes, append a timestamp to these frames */
-
return 0;
}
--
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