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