Unix Network Programming Tutorial77

Unix network programming is a powerful tool that allows you to create applications that can communicate over a network. This tutorial will teach you the basics of Unix network programming, including how to create sockets, connect to servers, and send and receive data.

Creating Sockets

The first step to network programming is to create a socket. A socket is a software endpoint that allows two processes to communicate over a network. To create a socket, you use the socket() function. The socket() function takes three arguments: the domain, the type, and the protocol.
The domain specifies the network family that the socket will be used for. The most common domain is AF_INET, which specifies the IPv4 address family.
The type specifies the type of socket that you want to create. The most common types are SOCK_STREAM, which specifies a stream socket, and SOCK_DGRAM, which specifies a datagram socket.
The protocol specifies the protocol that you want to use. The most common protocol is IPPROTO_TCP, which specifies the TCP protocol.

The following code shows how to create a socket:```c
#include
int main() {
int sockfd;
sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sockfd == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
// ...
}
```

Connecting to Servers

Once you have created a socket, you can connect to a server. To connect to a server, you use the connect() function. The connect() function takes three arguments: the socket descriptor, the address of the server, and the length of the address.

The following code shows how to connect to a server:```c
#include
int main() {
int sockfd;
struct sockaddr_in servaddr;
sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sockfd == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(8080);
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1) {
perror("connect");
exit(EXIT_FAILURE);
}
// ...
}
```

Sending and Receiving Data

Once you have connected to a server, you can send and receive data. To send data, you use the send() function. The send() function takes three arguments: the socket descriptor, the data to send, and the length of the data.

To receive data, you use the recv() function. The recv() function takes three arguments: the socket descriptor, the buffer to receive the data, and the length of the buffer.

The following code shows how to send and receive data:```c
#include
int main() {
int sockfd;
struct sockaddr_in servaddr;
char buf[1024];
sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
if (sockfd == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(8080);
servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
if (connect(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) == -1) {
perror("connect");
exit(EXIT_FAILURE);
}
// Send data
if (send(sockfd, "Hello world!", 12, 0) == -1) {
perror("send");
exit(EXIT_FAILURE);
}
// Receive data
if (recv(sockfd, buf, sizeof(buf), 0) == -1) {
perror("recv");
exit(EXIT_FAILURE);
}
// Print the data
printf("%s", buf);
// ...
}
```

Conclusion

This tutorial has taught you the basics of Unix network programming. You now know how to create sockets, connect to servers, and send and receive data. This knowledge will allow you to create powerful applications that can communicate over a network.

2024-12-10

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