This repo shows the code for an assignment for the course Networks at the university of Leiden's Bachelor of Computer Science.
The goal was to first design a streaming protocol. This protocol is documented in protocol.txt. Then the protocol was to be implemented using C.
The repo contains a client and server implementation. Further explaination of the code and functionality can be viewed in the pdf file networks2.pdf.
Compile using make
Clean binary files using make clean
This code was writen on linux and compiled using gcc
Client Arguments:
./client -b [Size of buffer]
-b [Size of buffer] // This is the size of the buffer to fill before we can start playing the audio
// Not required has a default of 65536
Server Arguments:
./server -f [Filename]
-f [Filename] // This is filename of the .wav audiofile to play
// Required
The repo contains tubthumping.wav. This can be used to test the server: -f tubthumping.wav
Data is sent using this packet layout:
// 0 7 8 15 16 23 24 31
// +--------+--------+--------+--------+
// | Number of |
// | total samples |
// +--------+--------+--------+--------+
// | Current sample |
// | number |
// +--------+--------+--------+--------+
// | Number of | Compr. | Samples|
// | data bytes | level | in data|
// +--------+--------+--------+--------+
// | Checksum | Padding |
// | | |
// +--------+--------+--------+--------+
// |
// | Data bytes ...
// +--------+-------- ...
Number of total samples: The number of total samples in the entire audio file
Current sample number: The sample number of the first sample of the data bytes
Number of data bytes: Number of bytes in the data bytes field
Compr. level: The current compression level
Samples in data: How many samples are in the data bytes field
Checksum: The Internet checksum of the entire packet with checksum=0
Padding: Necessary to pad to 32 bytes increments
Data bytes: The actual data bytes
The struct to store this packet layout in:
struct s_packet {
uint32_t num_samples; // Number of total samples
uint32_t sample_number; // Current sample number
uint16_t data_bytes; // Number of data bytes
uint8_t compression_level; // Compr. level
uint8_t samples_in_data; // Samples in data
uint16_t checksum; // Checksum
uint8_t data[]; // Data bytes
};
Example of how the client en server connect and start streaming
Client Server
| |
Start Start waiting
trying to for start command
send start |
command |
| ----Start--> |
| R
| Start command recieved
| |
| Start sending data packets
| <--Data---- |
R |
First data |
packet recieved |
Start recieve loop |
| |
| |
| <--Data---- |
R |
...
| |
| <--Data---- |
R |
| |
Check connection |
quality |
| |
Send compression_level
request |
| |
|--Compr_level--> |
| R
| update compression level
| continue sending data packets
...
Client connection steps:
1. Start sending start to server
Repeat until recieve
2. Start main loop
3. Recieve packet
4. Handle packet
5. if only 1 byte recieved == 1, sending finished, exit loop
6, If i % ERROR_DETECTION_WAIT_BLOCK do error-detection and compression level update
Server connection steps
1. Wait for client start packet
2. Start main send loop
3. Check if can recieve
4. Recieve compression level update -> update compression level
4. Send data packets
5. If last data packet sent, exit loop
6. Send 1 byte which equals 1 to tell the client it is done sending
DEFINE DIRECTIVES
--------------------------------------------------------------------------------
dataclient.c:
#define OPTSTR "b:"
Don't change - it tells the argument parser to parse -b
#define SAMPLE_SIZE 4
Don't change - the number of bytes in a single non-compressed sample
#define LOCALPORT 1235
#define SERVERPORT 1234
The local/client port and the server port
Can be changed, but need to be the same on the server side
#define SERVER_IP "127.0.0.2"
#define CLIENT_IP "127.0.0.1"
The client and server ip, can be changed if the programs are not on the same linux system
#define NUM_CHANNELS 2
#define SAMPLE_RATE 44100
Don't change - The number of channels and the sample rate of the WAV file
#define MAX_PACKET_SIZE 16 + (SAMPLE_SIZE * 256) // Hardcoded max packet size
This is the maximum size a packet can get - 16 bytes for the header + 256 samples * number of bytes in 1 sample
#define COMPRESSION_UPDATING_ENABLED 1
If this is 1 the client will send compression level requests to the server according to the avg packet droprate.
#define ERROR_DETECTION_WAIT_BLOCK 32896
How many samples should the error detection algorithm wait between checks
#define ROLLING_AVERAGE_LENGTH 4
Don't change - Hardcoded rolling average length
--------------------------------------------------------------------------------
slowserver.c
#define SERVERPORT 1234
#define LOCALPORT 1235
The local/client port and the server port
Can be changed, but need to be the same on the client side
#define SERVER_IP "127.0.0.2"
#define CLIENT_IP "127.0.0.1"
The client and server ip, can be changed if the programs are not on the same linux system
#define OPTSTR "f:"
Don't change - it tells the argument parser to parse -f
#define SAMPLE_SIZE 4
Don't change - the number of bytes in a single non-compressed sample
#define SAMPLES_PER_PACKET 64
The number of samples per packet - Default: 64 Max: 252 --- Must be multiple of 4 (uint8_t max 255)
#define STARTING_COMPRESSION 0
The compression level the server will start at when sending data
// worst -- perfect
// 1 -- 5
#define CONNECTION_QUALITY 5
The connection quality, worst means more delay and drops. Perfect means no delay or drops
#define PACKET_DELAY_LENGTH 200000 // microseconds
The delay in microsecond for the server to wait when delaying a packet
--------------------------------------------------------------------------------
Both main functions are very long, this is because many variables are created and necessary in many parts of main To now put parts of main into a function would give the function way to many parameters and would make main even less readable Sadly this is a design mistake at the start and I should have taken more time to design a system that does not rely on this many variables
I would have liked to have the audio player show a progressbar. But this progressbar would have interfered with the streaming progressbar. And would have created a lot of difficulty with the multithreading so I decided it was beter to not implement this. Maybe it would have been possible using ncurses. But that is out of the scope of this project
The code inside progressbar/progressbar.c is not mine but created by github user amullins83 https://gist.github.com/amullins83/24b5ef48657c08c4005a8fab837b7499
The internet checksum implementation is taken from https://www.csee.usf.edu/~kchriste/tools/checksum.c