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main.c
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#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <signal.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/errno.h>
#include <netinet/in.h>
#include <arpa/inet.h>
/* Settings ---------------------------------------------------------- */
#define DEFAULT_PORT 8080
#define DEFAULT_ROOT "/var/www"
#define BUF_SIZE 1024
#define USE_SYSLOG 0
/* ------------------------------------------------------------------- */
#define BACKLOG 5
extern char *__progname;
static uint16_t port = DEFAULT_PORT;
static const char* document_root = DEFAULT_ROOT;
static const char* response =
"HTTP/1.0 200 OK\r\n"
"Content-Type: text/html\r\n"
"\r\n"
"<!DOCTYPE html>\r\n"
"<html>"
"<head>\r\n"
"<title>it works</title>\r\n"
"</head>\r\n"
"<body>\r\n"
"<p>it works</p>\r\n"
"</body>\r\n"
"</html>\r\n";
#if USE_SYSLOG
#define SYSLOG(...) syslog(__VA_ARGS__)
#else
#define SYSLOG(...)
#endif
void sigchld (int n);
int main(int argc, char *argv[])
{
int c;
int sockfd;
int optval = 1;
struct sockaddr_in sa_in;
int connection_fd;
struct sockaddr client_addr;
pid_t pid;
/* オプション解析 */
while ((c = getopt(argc, argv, "p:d:")) != -1) {
switch (c) {
case 'p':
port = (uint16_t)atoi(optarg);
break;
case 'd':
document_root = optarg;
break;
default:
exit(EXIT_FAILURE);
}
}
if ((argc - optind) != 0) {
/* オプション解析エラー */
exit(EXIT_FAILURE);
}
/* Syslog */
#if USE_SYSLOG
openlog(__progname, LOG_PID, LOG_DAEMON);
#endif
/* ソケットを開く */
sockfd = socket(PF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
SYSLOG(LOG_ERR, "socket: %m");
perror("socket");
exit(EXIT_FAILURE);
}
/*-
* https://www.jpcert.or.jp/sc-rules/c-fio22-c.html
* FD_CLOEXEC
*/
if (fcntl(sockfd, F_SETFD, FD_CLOEXEC) < 0) {
SYSLOG(LOG_ERR, "fcntl: %m");
perror("fcntl");
exit(EXIT_FAILURE);
}
/* TIME_WAITでも使えるように */
if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (void *)&optval, sizeof(optval)) < 0) {
SYSLOG(LOG_ERR, "setsockopt: %m");
perror("setsockopt");
exit(EXIT_FAILURE);
}
/* バインド（IPv4） */
memset(&sa_in, 0, sizeof(struct sockaddr_in));
sa_in.sin_family = AF_INET;
sa_in.sin_addr.s_addr = htonl(INADDR_ANY);
sa_in.sin_port = htons(port);
if (bind(sockfd, (struct sockaddr*)&sa_in, sizeof(struct sockaddr)) < 0) {
SYSLOG(LOG_ERR, "bind: %m");
perror("bind");
exit(EXIT_FAILURE);
}
/* リッスンを始める */
if (listen(sockfd, BACKLOG) < 0) {
SYSLOG(LOG_ERR, "listen: %m");
perror("listen");
exit(EXIT_FAILURE);
}
/* Accept Filter */
#ifdef SO_ACCEPTFILTER
{
struct accept_filter_arg afa;
bzero(&afa, sizeof(afa));
strcpy(afa.af_name, "httpready");
setsockopt(sockfd, SOL_SOCKET, SO_ACCEPTFILTER, &afa, sizeof(afa));
}
#elif TCP_DEFER_ACCEPT
{
int optval = 1;
setsockopt(sockfd, IPPROTO_TCP, TCP_DEFER_ACCEPT, &optval, sizeof(optval));
}
#endif
/* TODO: Daemonize */
setsid();
/*-
* シグナルの設定
* https://www.jpcert.or.jp/sc-rules/c-sig01-c.html
*/
{
struct sigaction act;
memset(&act, 0, sizeof(act));
act.sa_handler = sigchld;
if (sigemptyset(&act.sa_mask) < 0) {
SYSLOG(LOG_ERR, "sigemptyset: %m");
perror("sigemptyset");
exit(EXIT_FAILURE);
}
act.sa_flags = SA_NOCLDSTOP | SA_RESTART;
if (sigaction(SIGCHLD, &act, NULL) < 0) {
SYSLOG(LOG_ERR, "sigaction: %m");
perror("sigaction");
exit(EXIT_FAILURE);
}
}
for (;;) {
socklen_t client_addr_size = sizeof(client_addr);
connection_fd = accept(sockfd, &client_addr, &client_addr_size);
if (connection_fd < 0) {
if (errno == EINTR || errno == EAGAIN || errno == ECONNABORTED)
continue;
// EPROTO continue
SYSLOG(LOG_ERR, "accept: %m");
perror("accept");
exit(EXIT_FAILURE);
}
pid = fork();
if (pid < 0) {
SYSLOG(LOG_ERR, "fork: %m");
perror("fork");
exit(EXIT_FAILURE);
}
/* 子プロセスの処理 */
if (pid == 0) {
close(sockfd);
/* Request */
{
char inet_addrstr[INET_ADDRSTRLEN];
char buf[BUF_SIZE];
if (inet_ntop(AF_INET, &((struct sockaddr_in *)&client_addr)->sin_addr, inet_addrstr, sizeof(inet_addrstr)) < 0) {
SYSLOG(LOG_WARNING, "inet_ntop: %m");
perror("inet_ntop");
puts("accessed from UNKNOWN HOST");
} else {
printf("accessed from %s\n", inet_addrstr);
}
read(connection_fd, buf, sizeof(buf));
write(connection_fd, response, strlen(response));
}
if (close(connection_fd) < 0) {
SYSLOG(LOG_ERR, "close: %m");
perror("close");
exit(EXIT_FAILURE);
}
/* 子プロセスの終了 */
exit(EXIT_SUCCESS);
}
close(connection_fd);
}
return 0;
}
/* SIGCHLDシグナルハンドラ */
void sigchld (int n)
{
pid_t pid;
int status;
do {
pid = waitpid((pid_t)-1, &status, WNOHANG);
if (pid < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
if (errno != ECHILD) {
SYSLOG(LOG_ERR, "waitpid: %m");
perror("waitpid");
}
break;
}
} while (pid > 0);
}