From 0c12d9c3fd09f4881eb80d8f2b632ab3310f6010 Mon Sep 17 00:00:00 2001
From: scratko <m@scratko.xyz>
Date: Fri, 13 Sep 2024 16:14:33 +0300
Subject: Initial commit

---
 server.c | 137 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 server.c

(limited to 'server.c')

diff --git a/server.c b/server.c
new file mode 100644
index 0000000..57300eb
--- /dev/null
+++ b/server.c
@@ -0,0 +1,137 @@
+#include <stdio.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <unistd.h>
+#include <string.h>
+
+#ifndef INBUFSIZE
+#define INBUFSIZE 1024
+#endif
+
+#ifndef LISTEN_QLEN
+#define LISTEN_QLEN 32
+#endif
+
+struct thread_data {
+    int counter;
+    pthread_mutex_t mutex;
+    sem_t semaphore;
+    int fd;
+};
+
+static void change_counter(char *buffer, pthread_mutex_t *mutex, int *counter,
+                           int fd)
+{
+    int tmp_counter = 0;
+    char counter_buffer[13];
+
+    if(!strcmp(buffer, "up")) {
+        pthread_mutex_lock(mutex);
+        ++*counter;
+        pthread_mutex_unlock(mutex);
+        write(fd, "Ok\n", strlen("Ok\n"));
+    } else if(!strcmp(buffer, "down")) {
+        pthread_mutex_lock(mutex);
+        --*counter;
+        pthread_mutex_unlock(mutex);
+        write(fd, "Ok\n", strlen("Ok\n"));
+    } else if(!strcmp(buffer, "show")) {
+        pthread_mutex_lock(mutex);
+        tmp_counter = *counter;
+        pthread_mutex_unlock(mutex);
+        sprintf(counter_buffer, "%d\n", tmp_counter);
+        write(fd, counter_buffer, strlen(counter_buffer));
+    } else
+        write(fd, "unknown command\n", strlen("unknown command\n"));
+}
+
+static void *worker_thread(void *data)
+{
+    int data_left, i;
+    char buffer[INBUFSIZE];
+    struct thread_data *local_data = data;
+    pthread_mutex_t *mutex = &local_data->mutex;
+    sem_t *semaphore = &local_data->semaphore;
+    int *counter = &local_data->counter;
+    int fd = local_data->fd;
+    char tmp_symbol;
+
+    sem_post(semaphore);
+    pthread_detach(pthread_self());
+
+    for(;;) {
+        data_left = read(fd, buffer, INBUFSIZE);
+        if(data_left <= 0)
+            break;
+        for(i = 0; i < data_left; ++i) {
+            if(buffer[i] == '\r' || buffer[i] == '\n') {
+                tmp_symbol = buffer[i];
+                buffer[i] = '\0';
+                change_counter(buffer, mutex, counter, fd);
+                if(tmp_symbol == '\r')
+                    ++i;
+                if(i + 1 != data_left) {
+                    data_left -= i + 1;
+                    memmove(buffer, buffer+i+1, data_left);
+                    i = -1;
+                } else
+                    break;
+            }
+        }
+    }
+    close(fd);
+    return 0;
+}
+
+static void init_data(struct thread_data *data)
+{
+    data->counter = 0;
+    pthread_mutex_init(&data->mutex, NULL);
+    sem_init(&data->semaphore, 0, 0);
+}
+
+int main(int argc, char **argv)
+{
+    int server_socket, opt;
+    unsigned short port;
+    struct sockaddr_in addr;
+    struct thread_data data;
+    pthread_t thr;
+    socklen_t len;
+
+    if(argc != 2) {
+        fprintf(stderr, "usage: ./program <server port> \n");
+        return 1;
+    }
+    port = strtol(argv[1], NULL, 10);
+    server_socket = socket(AF_INET, SOCK_STREAM, 0);
+    if(server_socket == -1) {
+        perror("socket");
+        return 0;
+    }
+    opt = 1;
+    setsockopt(server_socket, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
+
+    addr.sin_family = AF_INET;
+    addr.sin_addr.s_addr = htonl(INADDR_ANY);
+    addr.sin_port = htons(port);
+
+    if(bind(server_socket, (struct sockaddr*) &addr, sizeof(addr)) == -1) {
+        perror("bind");
+        return 1;
+    }
+
+    listen(server_socket, LISTEN_QLEN);
+    len = sizeof(addr);
+    init_data(&data);
+
+    for(;;) {
+        data.fd = accept(server_socket, (struct sockaddr*) &addr, &len);
+        pthread_create(&thr, NULL, worker_thread, &data);
+        sem_wait(&data.semaphore);
+    }
+    return 0;
+}
-- 
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