snipplets.dev/code/C/unixsocket/server.c

123 lines
2.6 KiB
C

// https://systemprogrammingatntu.github.io/mp2/unix_socket.html
#define SOCKET_NAME "/tmp/resol.sock"
#define BUFFER_SIZE 12
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
int main(int argc, char *argv[]) {
struct sockaddr_un addr;
int down_flag = 0;
int ret;
int listen_socket;
int data_socket;
int result;
char buffer[BUFFER_SIZE];
/*
* In case the program exited inadvertently on the last run,
* remove the socket.
*/
unlink(SOCKET_NAME);
/* Create local socket. */
listen_socket = socket(AF_UNIX, SOCK_STREAM, 0);
if (listen_socket == -1) {
perror("socket");
exit(EXIT_FAILURE);
}
/*
* For portability clear the whole structure, since some
* implementations have additional (nonstandard) fields in
* the structure.
*/
memset(&addr, 0, sizeof(struct sockaddr_un));
/* Bind socket to socket name. */
addr.sun_family = AF_UNIX;
strncpy(addr.sun_path, SOCKET_NAME, sizeof(addr.sun_path) - 1);
ret = bind(listen_socket, (const struct sockaddr *)&addr, sizeof(struct sockaddr_un));
if (ret == -1) {
perror("bind");
exit(EXIT_FAILURE);
}
/*
* Prepare for accepting connections. The backlog size is set
* to 20. So while one request is being processed other requests
* can be waiting.
*/
ret = listen(listen_socket, 20);
if (ret == -1) {
perror("listen");
exit(EXIT_FAILURE);
}
/* This is the main loop for handling connections. */
for (;;) {
/* Wait for incoming connection. */
data_socket = accept(listen_socket, NULL, NULL);
if (data_socket == -1) {
perror("accept");
exit(EXIT_FAILURE);
}
result = 0;
for (;;) {
/* Wait for next data packet. */
ret = read(data_socket, buffer, BUFFER_SIZE);
if (ret == -1) {
perror("read");
exit(EXIT_FAILURE);
}
/* Ensure buffer is 0-terminated. */
buffer[BUFFER_SIZE - 1] = 0;
/* Handle commands. */
if (!strncmp(buffer, "DOWN", BUFFER_SIZE)) {
down_flag = 1;
break;
}
if (!strncmp(buffer, "END", BUFFER_SIZE)) {
break;
}
/* Add received summand. */
result += atoi(buffer);
}
/* Send result. */
sprintf(buffer, "%d", result);
ret = write(data_socket, buffer, BUFFER_SIZE);
if (ret == -1) {
perror("write");
exit(EXIT_FAILURE);
}
/* Close socket. */
close(data_socket);
/* Quit on DOWN command. */
if (down_flag) {
break;
}
}
close(listen_socket);
/* Unlink the socket. */
unlink(SOCKET_NAME);
exit(EXIT_SUCCESS);
}