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server.c
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server.c
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#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netdb.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <math.h>
#include <time.h>
#define ANSI_COLOR_RED "\x1b[31m"
#define ANSI_COLOR_GREEN "\x1b[32m"
#define ANSI_COLOR_BLUE "\x1b[34m"
#define ANSI_COLOR_RESET "\x1b[0m"
#define MAXLEN 512
/* welcome message */
const char WELCOME[] = "OK START Welcome, I compute mean and variance!\n";
/* error messages */
const char ERR_SYNTAX[] = "ERR SYNTAX ";
const char ERR_STATS[] = "ERR STATS ";
const char ERR_DATA[] = "ERR DATA ";
/* OK messages */
const char OK_STATS[] = "OK STATS ";
const char OK_DATA[] = "OK DATA ";
char data[MAXLEN];
double mean(int *values) {
int sum = 0;
double mean;
int i;
for(i = 0; values[i] != 0; i++) {
sum += values[i];
}
return sum/i;
}
double variance(int *values, double mean) {
int sum = 0;
int i;
for(i = 0; values[i] != 0; i++) {
sum += pow((values[i]-mean), 2);
}
return sum/(i-1);
}
void calculate(int childSocket) {
int values[MAXLEN];
double m, v;
int counter = 0;
char message[MAXLEN] = "";
char buffer[MAXLEN] = "";
memset(values, '\0', MAXLEN);
for(int i = 0; i < strlen(data); i++) {
if(data[i] == ' ') {
counter++;
}
}
if(counter < 1) {
strcpy(message, ERR_STATS);
strcat(message, "Not enough data to compute mean or variance.\n");
write(childSocket, message, sizeof message);
}
else {
fprintf(stdout, ANSI_COLOR_BLUE "Calculating mean and variance...\n" ANSI_COLOR_RESET);
char *token = strtok(data, " ");
int i = 0;
while(token) {
values[i] = atof(token);
token = strtok(NULL, " ");
i++;
}
for(int i = 0; values[i] != '\0'; i++) {
printf("%d", values[i]);
}
printf("\n");
m = mean(values);
v = variance(values, m);
sprintf(buffer, "%d %f %f\n", counter, m, v);
strcpy(message, OK_STATS);
strcat(message, buffer);
write(childSocket, message, sizeof message);
fprintf(stdout, "Message sent.\n");
memset(values, '\0', MAXLEN);
memset(data, '\0', MAXLEN);
}
}
int evaluateData(int childSocket) {
int counter = 0;
int dataReceived;
char buffer[MAXLEN] = "";
char receiveBuffer[MAXLEN] = "";
char message[MAXLEN] = "";
read(childSocket, receiveBuffer, sizeof receiveBuffer);
fprintf(stdout, ANSI_COLOR_BLUE "Received:%s" ANSI_COLOR_RESET, receiveBuffer);
/* check if data has correct syntax */
if(receiveBuffer[0] == ' ') {
strcpy(message, ERR_SYNTAX);
strcat(message, "Leading whitespace.\n");
write(childSocket, message, sizeof message);
return -1;
}
if(receiveBuffer[strlen(receiveBuffer)-1] != '\n') {
strcpy(message, ERR_SYNTAX);
strcat(message, "Terminator character absent.\n");
write(childSocket, message, sizeof message);
return -1;
}
for(int i = 0; i < strlen(receiveBuffer)-2; i++) {
if(isalpha(receiveBuffer[i]) || ispunct(receiveBuffer[i]) || iscntrl(receiveBuffer[i])) {
sprintf(buffer, "Invalid character: %c\n", receiveBuffer[i]);
strcpy(message, ERR_SYNTAX);
strcat(message, buffer);
write(childSocket, message, sizeof message);
return -1;
}
}
/* if data has been sent, check if it's congruent and then store it */
if(receiveBuffer[0] != '0') {
for(int i = 0; i < strlen(receiveBuffer); i++) {
if(receiveBuffer[i] == ' ') {
counter++;
}
}
char *token = strtok(receiveBuffer, " ");
if(atoi(token) == counter) {
strcpy(message, OK_DATA);
sprintf(buffer, "%d\n", counter);
strcat(message, buffer);
write(childSocket, message, sizeof message);
}
else {
strcpy(message, ERR_DATA);
strcat(message, "Incorrect number of samples sent.\n");
write(childSocket, message, sizeof message);
return 0;
}
token = strtok(NULL, "\n");
if(data[0] != '\0') {
strcat(data, " ");
}
strcat(data, token);
}
/* received 0, process data */
else if (receiveBuffer[0] == '0'){
calculate(childSocket);
}
return 0;
}
int main(int argc, char **argv) {
if(argc != 2) {
fprintf(stderr, "Usage: %s <port>", argv[0]);
exit(1);
}
int serverSocket, serverPort, returnStatus;
struct sockaddr_in server;
serverSocket = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if(serverSocket < 0) {
perror(ANSI_COLOR_RED "Socket error");
fprintf(stdout, ANSI_COLOR_RESET);
exit(1);
}
fprintf(stdout, ANSI_COLOR_BLUE "Socket created.\n" ANSI_COLOR_RESET);
serverPort = atoi(argv[1]);
memset(&server, '\0', sizeof server);
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_port = htons(serverPort);
if(bind(serverSocket, (struct sockaddr*)&server, sizeof server) < 0) {
perror(ANSI_COLOR_RED "Bind error");
fprintf(stdout, ANSI_COLOR_RESET);
close(serverSocket);
exit(1);
}
fprintf(stdout, ANSI_COLOR_BLUE "Bind completed.\n" ANSI_COLOR_RESET);
returnStatus = listen(serverSocket, 5);
if (returnStatus == -1) {
perror(ANSI_COLOR_RED "Listen error");
fprintf(stdout, ANSI_COLOR_RESET);
close(serverSocket);
exit(1);
}
while(1) {
struct sockaddr_in clientName = {0};
int childSocket;
int clientNameLength = sizeof clientName;
int connected = 0;
int status = 0;
childSocket = accept(serverSocket, (struct sockaddr*)&clientName, &clientNameLength);
if(childSocket < 0) {
perror(ANSI_COLOR_RED "Accept error");
fprintf(stdout, ANSI_COLOR_RESET);
close(serverSocket);
exit(1);
}
fprintf(stdout, ANSI_COLOR_GREEN "Client connected, address %s\n" ANSI_COLOR_RESET, inet_ntoa(clientName.sin_addr));
fprintf(stdout, ANSI_COLOR_BLUE "Sending welcome message...\n" ANSI_COLOR_RESET);
write(childSocket, WELCOME, sizeof WELCOME);
connected = 1;
while(connected) {
fprintf(stdout, ANSI_COLOR_BLUE "Waiting for input...\n" ANSI_COLOR_RESET);
if(evaluateData(childSocket) < 0) {
connected = 0;
fprintf(stdout, ANSI_COLOR_RED "Closing connection.\n" ANSI_COLOR_RESET);
}
}
/* close socket */
close(childSocket);
/* clear data buffer to avoid sending data to other connecting clients */
memset(data, '\0', sizeof data);
}
close(serverSocket);
return 0;
}