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socketUDPPingServer.c

Aug 5, 2023LeifMessinger
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socketUDPServer.c

Aug 5, 2023LeifMessinger

0 likes • 3 views

// Server side implementation of UDP client-server model
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define PORT 8008
#define RECIEVE_BUFFER_SIZE 1024
const char* responseMessage = "Hello from server";
// Driver code
int main() {
//Create a UDP socket
//int socket(int domain, int type, int protocol);
//Domain is the place where the data goes. AF_BLUETOOTH, AF_INET6, AF_UNIX is local communication between different programs
//Type is the type of connection, so connection based (TCP), connectionless (UDP) or somewhere in between or beyond
//Protocol is an enum or flags that give some more options specific to that type. For SOCK_STREAM, you can force it to use SCTP instead of TCP. For SOCK_RAW, it can give you control over the ip frame, and even the ethernet frame.
//So this function makes a file descriptor to an IPV4 UDP 'connection' with no options.
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
// Creating socket file descriptor
if ( sockfd < 0) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
struct sockaddr_in serverAddress;
memset(&serverAddress, 0, sizeof(serverAddress));
// Filling server information
serverAddress.sin_family = AF_INET; // IPv4
serverAddress.sin_addr.s_addr = INADDR_ANY;
serverAddress.sin_port = htons(PORT);
// Bind the socket with the server address
if(bind(sockfd, (const struct sockaddr*)&serverAddress, sizeof(serverAddress))){ //Bind returns 0 if succeeded, or -1 if failed. -1 is still true.
perror("bind failed");
exit(EXIT_FAILURE);
}
struct sockaddr_in clientAddress; unsigned int clientAddressSize = sizeof(clientAddress);
memset(&clientAddress, 0, clientAddressSize);
char buffer[RECIEVE_BUFFER_SIZE];
int bytesRecieved = recvfrom(sockfd, (char*)buffer, RECIEVE_BUFFER_SIZE, MSG_WAITALL, (struct sockaddr*) &clientAddress, &clientAddressSize); //sets clientAddress to the client's address and the new size
buffer[bytesRecieved] = '\0';
printf("Client : %s\n", buffer);
sendto(sockfd, (const char*)responseMessage, strlen(responseMessage), MSG_CONFIRM, (const struct sockaddr*) &clientAddress, clientAddressSize);
printf("Hello message sent.\n");
return 0;
}

fork() example

Nov 19, 2022CodeCatch

0 likes • 2 views

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main() {
pid_t pid; /* could be int */
int i;
pid = fork();
printf("PID=%d\n", pid);
if (pid > 0) {
/* parent */
for (i = 0; i < 10; i++)
printf("\t\t\tPARENT %d\n", i);
} else {
/* child */
for (i = 0; i < 10; i++)
printf("CHILD %d\n", i);
}
return 0;
}

execlp() example

Nov 19, 2022CodeCatch

0 likes • 0 views

#include <stdio.h>
#include <unistd.h>
int main() {
char * cmd[] = {
"who",
"ls",
"date"
};
int i;
printf("0=who 1=ls 2=date : ");
scanf("%d", & i);
execlp(cmd[i], cmd[i], (char * ) 0);
printf("execlp failed\n");
return 0;
}

socketUDPPingClient.c

Aug 5, 2023LeifMessinger

0 likes • 3 views

// Client side implementation of UDP client-server model
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define PORT 8008
#define MAXLINE 1024
// Driver code
int main() {
char buffer[MAXLINE];
struct sockaddr_in servaddr;
// Creating socket file descriptor
int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if ( sockfd < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
struct timeval timeout;
timeout.tv_sec = 1; //Wait 1 second
timeout.tv_usec = 0;
if (setsockopt (sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");
if (setsockopt (sockfd, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof timeout) < 0) perror("setsockopt failed\n");
memset(&servaddr, 0, sizeof(servaddr));
// Filling server information
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
servaddr.sin_addr.s_addr = inet_addr("192.168.4.65");
for(int i = 0; i < 10; ++i){
char* message = "PING";
int sendStatus = sendto(sockfd, (const char *)message, strlen(message), MSG_CONFIRM, (const struct sockaddr *) &servaddr, sizeof(servaddr));
if(sendStatus >= 0){
printf("Sent PING\n");
}else{
printf("Send failed\n");
continue;
}
int len = sizeof(struct sockaddr_in);
int bytesRecieved = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, (struct sockaddr *) &servaddr, &len); //We can reuse servaddr because the port the server sends messages from is the same one we send to
if(bytesRecieved >= 0){
buffer[bytesRecieved] = '\0';
printf("Recieved %s\n", buffer);
}else{
printf("Recieved nothing: Packet Dropped\n", buffer);
}
}
close(sockfd);
return 0;
}

socketTCPServer.c

Aug 5, 2023LeifMessinger

0 likes • 0 views

// compile: gcc socketTCPServer.c -o socketTCPServer.out
// usage : ./socketTCPServer.out port
// Server
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
int main(int argc, char *argv[]){
int listenfd = 0, connfd = 0, cli_size, portno;
struct sockaddr_in serv_addr, cli_addr;
char sendBuff[1025];
if((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1){
printf("socket error\n");
exit(EXIT_FAILURE);
}
memset(&serv_addr, '0', sizeof(serv_addr));
memset(sendBuff, '0', sizeof(sendBuff));
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
portno = atoi(argv[1]);
serv_addr.sin_port = htons(portno);
const int on = 1;
setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
if(bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1){
printf("bind error\n");
exit(EXIT_FAILURE);
}
if(listen(listenfd, 5) == -1){
printf("listen error\n");
exit(EXIT_FAILURE);
}
while(1){
cli_size = sizeof(cli_addr);
if((connfd = accept(listenfd, (struct sockaddr*)&cli_addr, &cli_size)) == -1){
printf("accept error\n");
exit(EXIT_FAILURE);
}
strcpy(sendBuff, "Server Message: SUCCESS\n");
write(connfd, sendBuff, strlen(sendBuff));
close(connfd);
sleep(1);
}
return 0;
}

socketUDPClient.c

Aug 5, 2023LeifMessinger

0 likes • 1 view

// Server side implementation of UDP client-server model
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#define PORT 8008
#define MAXLINE 1024
// Driver code
int main(){
int sockfd;
char buffer[MAXLINE];
char *hello = "Hello from server";
struct sockaddr_in servaddr, cliaddr;
// Creating socket file descriptor
if ( (sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0 ) {
perror("socket creation failed");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
memset(&cliaddr, 0, sizeof(cliaddr));
// Filling server information
servaddr.sin_family = AF_INET; // IPv4
servaddr.sin_addr.s_addr = INADDR_ANY;
servaddr.sin_port = htons(PORT);
// Bind the socket with the server address
if ( bind(sockfd, (const struct sockaddr *)&servaddr, sizeof(servaddr)) < 0 ){
perror("bind failed");
exit(EXIT_FAILURE);
}
int len, n;
len = sizeof(cliaddr); //len is value/result
n = recvfrom(sockfd, (char *)buffer, MAXLINE, MSG_WAITALL, ( struct sockaddr *) &cliaddr, &len);
buffer[n] = '\0';
printf("Client : %s\n", buffer);
sendto(sockfd, (const char *)hello, strlen(hello), MSG_CONFIRM, (const struct sockaddr *) &cliaddr, len);
printf("Hello message sent.\n");
return 0;
}