os_labs/lab8/server.c

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C
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2020-06-18 11:37:04 +10:00
#include "config.h"
#include <arpa/inet.h>
#include <ctype.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
#include <unistd.h>
#define MAX(a,b) ((a)>(b)?(a):(b))
#define STR_EQ(a, b) (!strcmp((a),(b)))
#define WARNING(fmt, ...) fprintf(stderr,fmt,##__VA_ARGS__)
#define FATAL(fmt, ...) do {\
WARNING(fmt,##__VA_ARGS__);\
exit(1);\
} while (0)
char *handle_cmd(char *buff) {
char *ret = NULL;
if (!*buff) {
ret = strdup("Empty request\n");
}
else if (isalpha(buff[0])) {
if (STR_EQ(buff, "time")) {
// Respond with current time
time_t t = time(NULL);
ret = strdup(ctime(&t));
} else {
ret = strdup("Unknown command\n");
}
} else {
// Get files
int fd = open(buff, O_RDONLY);
if (fd == -1) {
perror("open()");
WARNING("Can't open file %s\n", buff);
return strdup("ERROR: server failed to obtain file.\n");
}
struct stat f_stat;
if(fstat(fd, &f_stat) == -1) {
perror("fstat()");
WARNING("Can't stat file %s\n", buff);
return strdup("ERROR: server failed to obtain file.\n");
}
ret = malloc(f_stat.st_size);
read(fd, ret, f_stat.st_size);
close(fd);
}
return ret;
}
void sig_hnd(int signum) {
switch (signum) {
case SIGUSR1:
WARNING("SIGUSR1 handled\n");
break;
case SIGUSR2:
WARNING("SIGUSR2 handled\n");
break;
}
}
int main() {
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd == -1) {
perror("socket()");
FATAL("Error while creating socket\n");
}
fcntl(sockfd, F_SETFL, O_NONBLOCK);
struct sockaddr_in srv_addr = {.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY),
.sin_port = htons(PORT)},
clt_addr;
int err = bind(sockfd, (const struct sockaddr *) &srv_addr, sizeof(srv_addr));
if (err == -1) {
perror("bind()");
FATAL("Error binding socket to address\n");
}
err = listen(sockfd, PENDING_CONNS_MAX);
if (err == -1) {
perror("listen()");
FATAL("Error putting socket to passive mode\n");
}
printf("Listening on port %d...\n", PORT);
signal(SIGUSR1, sig_hnd);
signal(SIGUSR2, sig_hnd);
char buff[4096] = {0};
fd_set readset, allset;
FD_ZERO(&allset);
FD_SET(sockfd, &allset);
struct timeval timeout = {.tv_sec = TIMEOUT_SECS, .tv_usec = 0};
socklen_t socklen = sizeof(clt_addr);
for (;;) {
readset = allset;
if (select(FD_SETSIZE, &readset, NULL, NULL, &timeout) == -1) {
perror("select()");
FATAL("Server error\n");
}
for (int i = 0; i < FD_SETSIZE; ++i) {
if (FD_ISSET(i, &readset)) {
if (i == sockfd) {
int sock = accept(sockfd, (struct sockaddr *) &clt_addr, &socklen);
if (sock == -1) {
perror("accept()");
FATAL("Acception failed.\n");
}
printf("Client accepted...\n");
fcntl(sock, F_SETFL, O_NONBLOCK);
FD_SET(sock, &allset);
} else {
int bytes_read = recv(i, buff, sizeof(buff), 0);
if (bytes_read <= 0) {
close(i);
FD_CLR(i, &allset);
printf("Client disconnected...\n");
continue;
}
char *read_buff = handle_cmd(buff);
if (send(i, read_buff, strlen(read_buff), 0) == -1) {
perror("send()");
FATAL("Error sending data.\n");
}
free(read_buff);
memset(buff, 0, 4096);
}
}
}
}
return 0;
}