From 6491f22ec5e41c4d6e03a0f41972f72e002cc977 Mon Sep 17 00:00:00 2001
From: Teodor Adrian Miron <teodormiron75@gmail.com>
Date: Wed, 19 Mar 2025 10:23:25 +0200
Subject: [PATCH] lab2 and 3 finished
---
common/link_emulator/link | Bin 0 -> 54664 bytes
lab2/common.h | 4 +-
lab2/recv.c | 113 +++++++++++++++++++++-----------------
lab2/send.c | 53 ++++++++++--------
lab3/common.c | 27 +++++----
lab3/link_emulator.err | 0
lab3/link_emulator.out | 0
lab3/recv.c | 31 +++++++++--
lab3/send.c | 31 +++++++++--
9 files changed, 165 insertions(+), 94 deletions(-)
create mode 100755 common/link_emulator/link
create mode 100644 lab3/link_emulator.err
create mode 100644 lab3/link_emulator.out
diff --git a/common/link_emulator/link b/common/link_emulator/link
new file mode 100755
index 0000000000000000000000000000000000000000..84cca1b8ed57ab973d6eeb5bcc1cd92ed980a4e4
GIT binary patch
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HcmV?d00001
diff --git a/lab2/common.h b/lab2/common.h
index 94b55bd..53e8c5c 100644
--- a/lab2/common.h
+++ b/lab2/common.h
@@ -6,8 +6,8 @@
/* DELIM | DATE | DELIM */
struct __attribute__((packed)) Frame {
char frame_delim_start[2]; /* DLE STX */
-
- /* TODO 2: Add source and destination */
+ int source;
+ int dest;
char payload[30]; /* Datele pe care vrem sa le transmitem */
char frame_delim_end[2]; /* DLE ETX */
};
diff --git a/lab2/recv.c b/lab2/recv.c
index 3e6d72d..041fb58 100644
--- a/lab2/recv.c
+++ b/lab2/recv.c
@@ -16,68 +16,83 @@
#define PORT 10001
#include "common.h"
+#define BUFFER_SIZE 32
/* Our unique layer 2 ID */
static int ID = 123131;
+int recv_bytes(char *buffer, int length) {
+ int i = 0;
+ while (i < length) {
+ char c = recv_byte();
+ if (c == DLE) {
+ char next = recv_byte();
+ if (next == DLE) {
+ buffer[i++] = DLE;
+ } else {
+ return -1;
+ }
+ } else {
+ buffer[i++] = c;
+ }
+ }
+ return i;
+}
+
/* 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 */
+ char frame;
+ char frame2;
+
+ fprintf(stderr, "1\n");
+ frame = recv_byte();
+ fprintf(stderr, "2\n");
+ frame2 = recv_byte();
+ fprintf(stderr, "3\n");
+
+ while( ((frame != DLE) && (frame2 != STX)) || (frame == DLE && frame2 != STX)
+ || (frame != DLE && frame2 == STX)) {
+ frame = frame2;
+ frame2 = recv_byte();
+ }
- /* If everything went well return the number of bytes received */
- return 0;
+ int source;
+ int dest;
+ (void) source;
+ recv_bytes((char *)&source, sizeof(int));
+ recv_bytes((char *)&dest, sizeof(int));
+ if (dest != ID) {
+ fprintf(stderr, "skipping\n");
+ return -1;
+ }
+
+ int i;
+ for (i = 0; i < size; i++) {
+ char byte = recv_byte();
+ if (byte == DLE) {
+ char next = recv_byte();
+ if (next == ETX) {
+ buf[i] = '\0';
+ break;
+ } else if (next == DLE) {
+ buf[i] = DLE;
+ } else {
+ return -1;
+ }
+ } else {
+ buf[i] = byte;
+ }
+ }
+ return i;
}
int main(int argc,char** argv){
- /* Don't modify this */
init(HOST,PORT);
- // TODO remove these recives, whih are hardcoded to receive a "Hello"
- // message, and replace them with code that can receive any message.
- char c;
-
- /* Wait for the start of a frame */
- char c1,c2;
- c1 = recv_byte();
- c2 = recv_byte();
-
- /* Cat timp nu am primit DLE STX citim bytes */
- while((c1 != DLE) && (c2 != STX)) {
- c1 = c2;
- c2 = recv_byte();
- }
-
-
- printf("%d ## %d\n",c1, c2);
- c = recv_byte();
- printf("%c\n", c);
-
- c = recv_byte();
- printf("%c\n", c);
-
- c = recv_byte();
- printf("%c\n", c);
-
- c = recv_byte();
- printf("%c\n", c);
-
- c = recv_byte();
- printf("%c\n", c);
-
- c = recv_byte();
- printf("%c\n", c);
-
- /* TODO 1.0: Allocate a buffer and call recv_frame */
-
+ char buffer[BUFFER_SIZE];
+ recv_frame(buffer, BUFFER_SIZE);
+ printf("%s\n", buffer);
/* TODO 3: Measure latency in a while loop for any frame that contains
* a timestamp we receive, print frame_size and latency */
diff --git a/lab2/send.c b/lab2/send.c
index 7e70a31..e817e30 100644
--- a/lab2/send.c
+++ b/lab2/send.c
@@ -22,21 +22,38 @@
/* Our unqiue layer 2 ID */
static int ID = 123131;
+#define BUFFER_SIZE 32
/* 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. */
-
+ struct Frame *new_frame = (struct Frame *)malloc(sizeof(struct Frame));
+ new_frame->frame_delim_start[0] = DLE;
+ new_frame->frame_delim_start[1] = STX;
/* 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 */
+ if (size > sizeof(new_frame->payload)) {
+ fprintf(stderr, "buffer size exceeds payload size\n");
+ free(new_frame);
+ return -1;
+ }
+ memcpy(new_frame->payload, buf, size);
+ new_frame->frame_delim_end[0] = DLE;
+ new_frame->frame_delim_end[1] = ETX;
+
+ new_frame->source = ID;
+ new_frame->dest = ID;
+
+ char *frame = (char *)new_frame;
+ int size_of_frame = sizeof(struct Frame);
+ for (int i = 0; i < size_of_frame; i++) {
+ if (frame[i] == DLE) {
+ send_byte(DLE);
+ }
+ send_byte(frame[i]);
+ }
+ free(new_frame);
return 0;
}
@@ -44,22 +61,10 @@ int main(int argc,char** argv){
// Don't touch this
init(HOST,PORT);
- // TODO remove these sends, whih are hardcoded to send a "Hello"
- // message, and replace them with code that can send any message.
- /* Send Hello */
- send_byte(DLE);
- send_byte(STX);
- send_byte('H');
- send_byte('e');
- send_byte('l');
- 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 */
-
+ char buffer[BUFFER_SIZE];
+ fgets(buffer, BUFFER_SIZE, stdin);
+ int length = strlen(buffer);
+ send_frame(buffer, length - 1);
/* TODO 3.1: Get a timestamp of the current time copy it in the the payload */
/* TODO 3.0: Update the maximum size of the payload in Frame to 100 (in common.h), send the frame */
diff --git a/lab3/common.c b/lab3/common.c
index 6ace0f1..81fe35c 100644
--- a/lab3/common.c
+++ b/lab3/common.c
@@ -1,26 +1,33 @@
#include "common.h"
+#include <arpa/inet.h>
uint8_t simple_csum(uint8_t *buf, size_t len) {
/* TODO 1.1: Implement the simple checksum algorithm */
uint8_t sum = 0;
-
- for (int i = 0; i < len; i++) {
+
+ for (size_t i = 0; i < len; i++) {
sum += buf[i];
}
-
return sum;
}
uint32_t crc32(uint8_t *buf, size_t len)
{
/* TODO 2.1: Implement the CRC 32 algorithm */
+ uint32_t crc = ~0;
+ const uint32_t POLY = 0xEDB88320;
- /* Iterate through each byte of buff */
-
- /* Iterate through each bit */
- /* If the bit is 1, compute the new reminder */
-
- /* By convention, we negate the crc */
- return 0;
+ for (size_t i = 0; i < len; i++) {
+ crc = crc ^ buf[i];
+ for (size_t j = 0; j < 8; j++) {
+ if (crc & 1) {
+ crc = (crc >> 1) ^ POLY;
+ } else {
+ crc = (crc >> 1);
+ }
+ }
+ }
+ crc = ~crc;
+ return crc;
}
diff --git a/lab3/link_emulator.err b/lab3/link_emulator.err
new file mode 100644
index 0000000..e69de29
diff --git a/lab3/link_emulator.out b/lab3/link_emulator.out
new file mode 100644
index 0000000..e69de29
diff --git a/lab3/recv.c b/lab3/recv.c
index 84f3e99..7be817a 100644
--- a/lab3/recv.c
+++ b/lab3/recv.c
@@ -7,6 +7,7 @@
#include "common.h"
#include "link_emulator/lib.h"
#include "include/utils.h"
+#include <inttypes.h>
/**
* You can change these to communicate with another colleague.
@@ -27,21 +28,41 @@ int main(int argc,char** argv) {
/* Receive the frame from the link */
int len = link_recv(&t, sizeof(struct l3_msg));
DIE(len < 0, "Receive message");
-
/* We have to convert it to host order */
+ uint32_t temp = t.hdr.sum;
uint32_t recv_sum = ntohl(t.hdr.sum);
- t.hdr.sum = 0;
- int sum_ok = (simple_csum((void *) &t, sizeof(struct l3_msg)) == recv_sum);
+ //int sum_ok = (simple_csum((void *) &t, sizeof(struct l3_msg)) == recv_sum);
/* TODO 2: Change to crc32 */
-
+ t.hdr.sum = 0;
+ int ok_sum = (crc32((uint8_t *) &t, sizeof(struct l3_msg)) == recv_sum);
/* Since we are sending messages with a payload of 1500 - sizeof(header), most of the times the bytes from
* 30 - 1500 will be corrupted and thus when we are printing or string message "Hello world" we see no probems.
* This will be visible when we will be sending a file */
- printf("[RECV] len=%d; sum(%s)=0x%04hx; payload=\"%s\";\n", t.hdr.len, sum_ok ? "GOOD" : "BAD", recv_sum, t.payload);
+ printf("[RECV] len=%d; sum(%s)=0x%04x; payload=\"%s\";\n", t.hdr.len, ok_sum ? "GOOD" : "BAD", recv_sum, t.payload);
/* TODO 3.1: In a loop, recv a frame and check if the CRC is good */
+ while (true) {
+ link_recv(&t, sizeof(struct l3_msg));
+ uint32_t recieved_sum = ntohl(t.hdr.sum);
+ t.hdr.sum = 0;
+ int sum_good = (crc32((uint8_t *) &t, sizeof(struct l3_msg)) == recieved_sum);
+ if (!sum_good) {
+ struct l3_msg nack_msg;
+ memset(&nack_msg, 0, sizeof(struct l3_msg));
+ strcpy(nack_msg.payload, "NACK");
+ nack_msg.hdr.len = strlen(nack_msg.payload);
+ nack_msg.hdr.sum = htonl(crc32((uint8_t *)&nack_msg, sizeof(struct l3_msg)));
+ link_send(&nack_msg, sizeof(struct l3_msg));
+ } else {
+ printf("[RECV] len=%d; sum(%s)=0x%04hx; payload=\"%s\";\n", t.hdr.len, sum_good ? "GOOD" : "BAD", recieved_sum, t.payload);
+ FILE *file = fopen("recv.data", "a");
+ DIE(file == NULL, "Failed to open recv.data");
+ fwrite(t.payload, 1, t.hdr.len, file);
+ fclose(file);
+ }
+ }
/* TODO 3.2: If the crc is bad, send a NACK frame */
/* TODO 3.2: Otherwise, write the frame payload to a file recv.data */
diff --git a/lab3/send.c b/lab3/send.c
index c9f4e5b..dd7c8d7 100644
--- a/lab3/send.c
+++ b/lab3/send.c
@@ -30,17 +30,40 @@ int main(int argc,char** argv) {
t.hdr.sum = 0;
/* Since sum is on 32 bits, we have to convert it to network order */
- t.hdr.sum = htonl(simple_csum((void *) &t, sizeof(struct l3_msg)));
-
+ //t.hdr.sum = htonl(simple_csum((void *) &t, sizeof(struct l3_msg)));
+ uint32_t temp = crc32((uint8_t *) &t, sizeof(struct l3_msg));
+ printf("[SEND] len=%d; sum=0x%04x; payload=\"%s\";\n", t.hdr.len, temp, t.payload);
/* TODO 2.0: Call crc32 function */
-
+ t.hdr.sum = htonl(temp);
+
/* Send the message */
link_send(&t, sizeof(struct l3_msg));
/* TODO 3.1: Receive the confirmation */
-
/* TODO 3.2: If we received a NACK, retransmit the previous frame */
+ struct l3_msg recv;
+ link_recv(&recv, sizeof(struct l3_msg));
+ while (strcmp(recv.payload, "NACK") == 0) {
+ link_send(&t, sizeof(struct l3_msg));
+ link_recv(&recv, sizeof(struct l3_msg));
+ }
+
+ FILE *f;
+ f = fopen("input.txt", "rb");
+ size_t bytes_read;
+ while ((bytes_read = fread(t.payload, 1, 1500, f)) > 0) {
+ t.hdr.len = bytes_read;
+ t.hdr.sum = 0;
+ t.hdr.sum = htonl(crc32((uint8_t *) &t, sizeof(struct l3_msg)));
+ link_send(&t, sizeof(struct l3_msg));
+ link_recv(&recv, sizeof(struct l3_msg));
+ while (strcmp(recv.payload, "NACK") == 0) {
+ link_send(&t, sizeof(struct l3_msg));
+ link_recv(&recv, sizeof(struct l3_msg));
+ }
+ }
+ fclose(f);
/* TODO 3.3: Update this to read the content of a file and send it as
* chunks of that file given a MTU of 1500 bytes */
--
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