#include "config.h"
#include "run-command.h"
#include "strbuf.h"
#include "string-list.h"
#include "trace2.h"
#include "version.h"
#include "dir.h"
#include "date.h"

#define TR2_CAT "test-http-server"

static const char *pid_file;
static int verbose;
static int reuseaddr;

static const char test_http_auth_usage[] =
"http-server [--verbose]\n"
"           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
"           [--reuseaddr] [--pid-file=<file>]\n"
"           [--listen=<host_or_ipaddr>]* [--port=<n>]\n"
;

/* Timeout, and initial timeout */
static unsigned int timeout;
static unsigned int init_timeout;

static void logreport(const char *label, const char *err, va_list params)
{
	struct strbuf msg = STRBUF_INIT;

	strbuf_addf(&msg, "[%"PRIuMAX"] %s: ", (uintmax_t)getpid(), label);
	strbuf_vaddf(&msg, err, params);
	strbuf_addch(&msg, '\n');

	fwrite(msg.buf, sizeof(char), msg.len, stderr);
	fflush(stderr);

	strbuf_release(&msg);
}

__attribute__((format (printf, 1, 2)))
static void logerror(const char *err, ...)
{
	va_list params;
	va_start(params, err);
	logreport("error", err, params);
	va_end(params);
}

__attribute__((format (printf, 1, 2)))
static void loginfo(const char *err, ...)
{
	va_list params;
	if (!verbose)
		return;
	va_start(params, err);
	logreport("info", err, params);
	va_end(params);
}

static void set_keep_alive(int sockfd)
{
	int ka = 1;

	if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
		if (errno != ENOTSOCK)
			logerror("unable to set SO_KEEPALIVE on socket: %s",
				strerror(errno));
	}
}

/*
 * The code in this section is used by "worker" instances to service
 * a single connection from a client.  The worker talks to the client
 * on 0 and 1.
 */

enum worker_result {
	/*
	 * Operation successful.
	 * Caller *might* keep the socket open and allow keep-alive.
	 */
	WR_OK       = 0,

	/*
	 * Various errors while processing the request and/or the response.
	 * Close the socket and clean up.
	 * Exit child-process with non-zero status.
	 */
	WR_IO_ERROR = 1<<0,

	/*
	 * Close the socket and clean up.  Does not imply an error.
	 */
	WR_HANGUP   = 1<<1,

	WR_STOP_THE_MUSIC = (WR_IO_ERROR | WR_HANGUP),
};

static enum worker_result worker(void)
{
	const char *response = "HTTP/1.1 501 Not Implemented\r\n";
	char *client_addr = getenv("REMOTE_ADDR");
	char *client_port = getenv("REMOTE_PORT");
	enum worker_result wr = WR_OK;

	if (client_addr)
		loginfo("Connection from %s:%s", client_addr, client_port);

	set_keep_alive(0);

	while (1) {
		if (write_in_full(1, response, strlen(response)) < 0) {
			logerror("unable to write response");
			wr = WR_IO_ERROR;
		}

		if (wr & WR_STOP_THE_MUSIC)
			break;
	}

	close(0);
	close(1);

	return !!(wr & WR_IO_ERROR);
}

/*
 * This section contains the listener and child-process management
 * code used by the primary instance to accept incoming connections
 * and dispatch them to async child process "worker" instances.
 */

static int addrcmp(const struct sockaddr_storage *s1,
		   const struct sockaddr_storage *s2)
{
	const struct sockaddr *sa1 = (const struct sockaddr*) s1;
	const struct sockaddr *sa2 = (const struct sockaddr*) s2;

	if (sa1->sa_family != sa2->sa_family)
		return sa1->sa_family - sa2->sa_family;
	if (sa1->sa_family == AF_INET)
		return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
		    &((struct sockaddr_in *)s2)->sin_addr,
		    sizeof(struct in_addr));
#ifndef NO_IPV6
	if (sa1->sa_family == AF_INET6)
		return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
		    &((struct sockaddr_in6 *)s2)->sin6_addr,
		    sizeof(struct in6_addr));
#endif
	return 0;
}

static int max_connections = 32;

static unsigned int live_children;

static struct child {
	struct child *next;
	struct child_process cld;
	struct sockaddr_storage address;
} *firstborn;

static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
{
	struct child *newborn, **cradle;

	newborn = xcalloc(1, sizeof(*newborn));
	live_children++;
	memcpy(&newborn->cld, cld, sizeof(*cld));
	memcpy(&newborn->address, addr, addrlen);
	for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
		if (!addrcmp(&(*cradle)->address, &newborn->address))
			break;
	newborn->next = *cradle;
	*cradle = newborn;
}

/*
 * This gets called if the number of connections grows
 * past "max_connections".
 *
 * We kill the newest connection from a duplicate IP.
 */
static void kill_some_child(void)
{
	const struct child *blanket, *next;

	if (!(blanket = firstborn))
		return;

	for (; (next = blanket->next); blanket = next)
		if (!addrcmp(&blanket->address, &next->address)) {
			kill(blanket->cld.pid, SIGTERM);
			break;
		}
}

static void check_dead_children(void)
{
	int status;
	pid_t pid;

	struct child **cradle, *blanket;
	for (cradle = &firstborn; (blanket = *cradle);)
		if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
			const char *dead = "";
			if (status)
				dead = " (with error)";
			loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);

			/* remove the child */
			*cradle = blanket->next;
			live_children--;
			child_process_clear(&blanket->cld);
			free(blanket);
		} else
			cradle = &blanket->next;
}

static struct strvec cld_argv = STRVEC_INIT;
static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
{
	struct child_process cld = CHILD_PROCESS_INIT;

	if (max_connections && live_children >= max_connections) {
		kill_some_child();
		sleep(1);  /* give it some time to die */
		check_dead_children();
		if (live_children >= max_connections) {
			close(incoming);
			logerror("Too many children, dropping connection");
			return;
		}
	}

	if (addr->sa_family == AF_INET) {
		char buf[128] = "";
		struct sockaddr_in *sin_addr = (void *) addr;
		inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
		strvec_pushf(&cld.env, "REMOTE_ADDR=%s", buf);
		strvec_pushf(&cld.env, "REMOTE_PORT=%d",
				 ntohs(sin_addr->sin_port));
#ifndef NO_IPV6
	} else if (addr->sa_family == AF_INET6) {
		char buf[128] = "";
		struct sockaddr_in6 *sin6_addr = (void *) addr;
		inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
		strvec_pushf(&cld.env, "REMOTE_ADDR=[%s]", buf);
		strvec_pushf(&cld.env, "REMOTE_PORT=%d",
				 ntohs(sin6_addr->sin6_port));
#endif
	}

	strvec_pushv(&cld.args, cld_argv.v);
	cld.in = incoming;
	cld.out = dup(incoming);

	if (cld.out < 0)
		logerror("could not dup() `incoming`");
	else if (start_command(&cld))
		logerror("unable to fork");
	else
		add_child(&cld, addr, addrlen);
}

static void child_handler(int signo)
{
	/*
	 * Otherwise empty handler because systemcalls will get interrupted
	 * upon signal receipt
	 * SysV needs the handler to be rearmed
	 */
	signal(SIGCHLD, child_handler);
}

static int set_reuse_addr(int sockfd)
{
	int on = 1;

	if (!reuseaddr)
		return 0;
	return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
			  &on, sizeof(on));
}

struct socketlist {
	int *list;
	size_t nr;
	size_t alloc;
};

static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
{
#ifdef NO_IPV6
	static char ip[INET_ADDRSTRLEN];
#else
	static char ip[INET6_ADDRSTRLEN];
#endif

	switch (family) {
#ifndef NO_IPV6
	case AF_INET6:
		inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
		break;
#endif
	case AF_INET:
		inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
		break;
	default:
		xsnprintf(ip, sizeof(ip), "<unknown>");
	}
	return ip;
}

#ifndef NO_IPV6

static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
{
	int socknum = 0;
	char pbuf[NI_MAXSERV];
	struct addrinfo hints, *ai0, *ai;
	int gai;
	long flags;

	xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
	memset(&hints, 0, sizeof(hints));
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_protocol = IPPROTO_TCP;
	hints.ai_flags = AI_PASSIVE;

	gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
	if (gai) {
		logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
		return 0;
	}

	for (ai = ai0; ai; ai = ai->ai_next) {
		int sockfd;

		sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
		if (sockfd < 0)
			continue;
		if (sockfd >= FD_SETSIZE) {
			logerror("Socket descriptor too large");
			close(sockfd);
			continue;
		}

#ifdef IPV6_V6ONLY
		if (ai->ai_family == AF_INET6) {
			int on = 1;
			setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
				   &on, sizeof(on));
			/* Note: error is not fatal */
		}
#endif

		if (set_reuse_addr(sockfd)) {
			logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
			close(sockfd);
			continue;
		}

		set_keep_alive(sockfd);

		if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
			logerror("Could not bind to %s: %s",
				 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
				 strerror(errno));
			close(sockfd);
			continue;	/* not fatal */
		}
		if (listen(sockfd, 5) < 0) {
			logerror("Could not listen to %s: %s",
				 ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
				 strerror(errno));
			close(sockfd);
			continue;	/* not fatal */
		}

		flags = fcntl(sockfd, F_GETFD, 0);
		if (flags >= 0)
			fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);

		ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
		socklist->list[socklist->nr++] = sockfd;
		socknum++;
	}

	freeaddrinfo(ai0);

	return socknum;
}

#else /* NO_IPV6 */

static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
{
	struct sockaddr_in sin;
	int sockfd;
	long flags;

	memset(&sin, 0, sizeof sin);
	sin.sin_family = AF_INET;
	sin.sin_port = htons(listen_port);

	if (listen_addr) {
		/* Well, host better be an IP address here. */
		if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
			return 0;
	} else {
		sin.sin_addr.s_addr = htonl(INADDR_ANY);
	}

	sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0)
		return 0;

	if (set_reuse_addr(sockfd)) {
		logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
		close(sockfd);
		return 0;
	}

	set_keep_alive(sockfd);

	if (bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0) {
		logerror("Could not bind to %s: %s",
			 ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
			 strerror(errno));
		close(sockfd);
		return 0;
	}

	if (listen(sockfd, 5) < 0) {
		logerror("Could not listen to %s: %s",
			 ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
			 strerror(errno));
		close(sockfd);
		return 0;
	}

	flags = fcntl(sockfd, F_GETFD, 0);
	if (flags >= 0)
		fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);

	ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
	socklist->list[socklist->nr++] = sockfd;
	return 1;
}

#endif

static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
{
	if (!listen_addr->nr)
		setup_named_sock("127.0.0.1", listen_port, socklist);
	else {
		int i, socknum;
		for (i = 0; i < listen_addr->nr; i++) {
			socknum = setup_named_sock(listen_addr->items[i].string,
						   listen_port, socklist);

			if (socknum == 0)
				logerror("unable to allocate any listen sockets for host %s on port %u",
					 listen_addr->items[i].string, listen_port);
		}
	}
}

static int service_loop(struct socketlist *socklist)
{
	struct pollfd *pfd;
	int i;

	CALLOC_ARRAY(pfd, socklist->nr);

	for (i = 0; i < socklist->nr; i++) {
		pfd[i].fd = socklist->list[i];
		pfd[i].events = POLLIN;
	}

	signal(SIGCHLD, child_handler);

	for (;;) {
		int i;
		int nr_ready;
		int timeout = (pid_file ? 100 : -1);

		check_dead_children();

		nr_ready = poll(pfd, socklist->nr, timeout);
		if (nr_ready < 0) {
			if (errno != EINTR) {
				logerror("Poll failed, resuming: %s",
				      strerror(errno));
				sleep(1);
			}
			continue;
		}
		else if (nr_ready == 0) {
			/*
			 * If we have a pid_file, then we watch it.
			 * If someone deletes it, we shutdown the service.
			 * The shell scripts in the test suite will use this.
			 */
			if (!pid_file || file_exists(pid_file))
				continue;
			goto shutdown;
		}

		for (i = 0; i < socklist->nr; i++) {
			if (pfd[i].revents & POLLIN) {
				union {
					struct sockaddr sa;
					struct sockaddr_in sai;
#ifndef NO_IPV6
					struct sockaddr_in6 sai6;
#endif
				} ss;
				socklen_t sslen = sizeof(ss);
				int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
				if (incoming < 0) {
					switch (errno) {
					case EAGAIN:
					case EINTR:
					case ECONNABORTED:
						continue;
					default:
						die_errno("accept returned");
					}
				}
				handle(incoming, &ss.sa, sslen);
			}
		}
	}

shutdown:
	loginfo("Starting graceful shutdown (pid-file gone)");
	for (i = 0; i < socklist->nr; i++)
		close(socklist->list[i]);

	return 0;
}

static int serve(struct string_list *listen_addr, int listen_port)
{
	struct socketlist socklist = { NULL, 0, 0 };

	socksetup(listen_addr, listen_port, &socklist);
	if (socklist.nr == 0)
		die("unable to allocate any listen sockets on port %u",
		    listen_port);

	loginfo("Ready to rumble");

	/*
	 * Wait to create the pid-file until we've setup the sockets
	 * and are open for business.
	 */
	if (pid_file)
		write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());

	return service_loop(&socklist);
}

/*
 * This section is executed by both the primary instance and all
 * worker instances.  So, yes, each child-process re-parses the
 * command line argument and re-discovers how it should behave.
 */

int cmd_main(int argc, const char **argv)
{
	int listen_port = 0;
	struct string_list listen_addr = STRING_LIST_INIT_NODUP;
	int worker_mode = 0;
	int i;

	trace2_cmd_name("test-http-server");
	setup_git_directory_gently(NULL);

	for (i = 1; i < argc; i++) {
		const char *arg = argv[i];
		const char *v;

		if (skip_prefix(arg, "--listen=", &v)) {
			string_list_append(&listen_addr, xstrdup_tolower(v));
			continue;
		}
		if (skip_prefix(arg, "--port=", &v)) {
			char *end;
			unsigned long n;
			n = strtoul(v, &end, 0);
			if (*v && !*end) {
				listen_port = n;
				continue;
			}
		}
		if (!strcmp(arg, "--worker")) {
			worker_mode = 1;
			trace2_cmd_mode("worker");
			continue;
		}
		if (!strcmp(arg, "--verbose")) {
			verbose = 1;
			continue;
		}
		if (skip_prefix(arg, "--timeout=", &v)) {
			timeout = atoi(v);
			continue;
		}
		if (skip_prefix(arg, "--init-timeout=", &v)) {
			init_timeout = atoi(v);
			continue;
		}
		if (skip_prefix(arg, "--max-connections=", &v)) {
			max_connections = atoi(v);
			if (max_connections < 0)
				max_connections = 0; /* unlimited */
			continue;
		}
		if (!strcmp(arg, "--reuseaddr")) {
			reuseaddr = 1;
			continue;
		}
		if (skip_prefix(arg, "--pid-file=", &v)) {
			pid_file = v;
			continue;
		}

		fprintf(stderr, "error: unknown argument '%s'\n", arg);
		usage(test_http_auth_usage);
	}

	/* avoid splitting a message in the middle */
	setvbuf(stderr, NULL, _IOFBF, 4096);

	if (listen_port == 0)
		listen_port = DEFAULT_GIT_PORT;

	/*
	 * If no --listen=<addr> args are given, the setup_named_sock()
	 * code will use receive a NULL address and set INADDR_ANY.
	 * This exposes both internal and external interfaces on the
	 * port.
	 *
	 * Disallow that and default to the internal-use-only loopback
	 * address.
	 */
	if (!listen_addr.nr)
		string_list_append(&listen_addr, "127.0.0.1");

	/*
	 * worker_mode is set in our own child process instances
	 * (that are bound to a connected socket from a client).
	 */
	if (worker_mode)
		return worker();

	/*
	 * `cld_argv` is a bit of a clever hack. The top-level instance
	 * of test-http-server does the normal bind/listen/accept stuff.
	 * For each incoming socket, the top-level process spawns
	 * a child instance of test-http-server *WITH* the additional
	 * `--worker` argument. This causes the child to set `worker_mode`
	 * and immediately call `worker()` using the connected socket (and
	 * without the usual need for fork() or threads).
	 *
	 * The magic here is made possible because `cld_argv` is static
	 * and handle() (called by service_loop()) knows about it.
	 */
	strvec_push(&cld_argv, argv[0]);
	strvec_push(&cld_argv, "--worker");
	for (i = 1; i < argc; ++i)
		strvec_push(&cld_argv, argv[i]);

	/*
	 * Setup primary instance to listen for connections.
	 */
	return serve(&listen_addr, listen_port);
}