// #define DEBUG_CTX_DECLARED (1)  // All others define this as extern

#include "common.h"
#include "utils.h"
#include "console.h"

extern char **environ;

/*
 * Add list of argv's from GSOCKET_ARGS to argv[]
 * result: argv[0] + GSOCKET_ARGS + argv[1..n]
 */
static void
add_env_argv(int *argcptr, char **argvptr[])
{
	char *str_orig = GS_getenv("GSOCKET_ARGS");
	if (str_orig == NULL)
		str_orig = GS_getenv("GS_ARGS");
	char *str = NULL;
	char *next;
	char **newargv = NULL;
	int newargc;

	if (str_orig == NULL)
		return;

	str = strdup(str_orig);
	next = str;

	newargv = malloc(1 * sizeof *argvptr);
	memcpy(&newargv[0], argvptr[0], 1 * sizeof *argvptr);
	newargc = 1; 

	while (next != NULL)
	{
		while (*str == ' ')
			str++;

		next = strchr(str, ' ');
		if (next != NULL)
		{
			*next = 0;
			next++;
		}
		// catch if last character is ' '
		if (strlen(str) > 0)
		{
			/* *next == '\0'; str points to argument (0-terminated) */
			newargc++;
			// DEBUGF("%d. arg = '%s'\n", newargc, str);
			newargv = realloc(newargv, newargc * sizeof newargv);
			newargv[newargc - 1] = str;
		}

		str = next;
		if (str == NULL)
			break;
	}

	// Copy original argv[1..n]
	newargv = realloc(newargv, (newargc + *argcptr) * sizeof newargv);
	memcpy(newargv + newargc, *argvptr + 1, (*argcptr - 1) * sizeof *argvptr);

	newargc += (*argcptr - 1);
	newargv[newargc] = NULL;

	*argcptr = newargc;
	*argvptr = newargv;
	// DEBUGF("Total argv[] == %d\n", newargc);
	// int i;
	// for (i = 0; i < newargc; i++)
	// 	DEBUGF("argv[%d] = %s\n", i, newargv[i]);
}

void
init_defaults(int *argcptr, char **argvptr[])
{
#ifdef DEBUG
	gopt.is_built_debug = 1;
#endif
	gopt.log_fp = stderr;
	gopt.err_fp = stderr;
	signal(SIGPIPE, SIG_IGN);
	signal(SIGCHLD, SIG_IGN);	// no defunct childs please
	gopt.prg_name = NULL;
	if (argvptr != NULL)
	{
		gopt.prg_name = *argvptr[0];

		if ((gopt.prg_name != NULL) && (gopt.prg_name[0] == '/'))
		{
			char *ptr;
			ptr = strrchr(gopt.prg_name, '/');
			if (ptr != NULL)
				gopt.prg_name = ptr + 1;
		}
		if (gopt.prg_name != NULL)
			gopt.prg_name = strdup(gopt.prg_name);
	}

	/* MacOS process limit is 256 which makes Socks-Proxie yield...*/
	struct rlimit rlim;
	memset(&rlim, 0, sizeof rlim);
	int ret;
	ret = getrlimit(RLIMIT_NOFILE, &rlim);
	if (ret == 0)
	{
		rlim.rlim_cur = MIN(rlim.rlim_max, FD_SETSIZE);
		ret = setrlimit(RLIMIT_NOFILE, &rlim);
		getrlimit(RLIMIT_NOFILE, &rlim);
		// DEBUGF_C("Max File Des: %llu (max = %llu)\n", rlim.rlim_cur, rlim.rlim_max);
	}

	// If started directly from a +s shell (ps. tcsh's startup script fail hard
	// if euid != uid)
	uid_t e = geteuid();
	if (e != getuid())
		ret = setreuid(e, e);
	e = getegid();
	if (e != getgid())
		ret = setregid(e, e);

	add_env_argv(argcptr, argvptr);

	gopt.app_keepalive_sec = GS_APP_KEEPALIVE;
}

GS *
gs_create(void)
{
	GS *gs = GS_new(&gopt.gs_ctx, &gopt.gs_addr);
	XASSERT(gs != NULL, "%s\n", GS_CTX_strerror(&gopt.gs_ctx));
	
	if (gopt.token_str != NULL)
		GS_set_token(gs, gopt.token_str, strlen(gopt.token_str));

	return gs;
}

static void
cb_sigterm(int sig)
{
	exit(EX_SIGTERM);	// will call cb_atexit()
}

void
get_winsize(void)
{
	int ret;

	memcpy(&gopt.winsize_prev, &gopt.winsize, sizeof gopt.winsize_prev);
	
	ret = ioctl(STDOUT_FILENO, TIOCGWINSZ, &gopt.winsize);
	if ((ret == 0) && (gopt.winsize.ws_col != 0))
	{
		/* SUCCESS */
		DEBUGF_M("Columns: %d, Rows: %d\n", gopt.winsize.ws_col, gopt.winsize.ws_row);
	} else {
		gopt.winsize.ws_col = 80;
		gopt.winsize.ws_row = 24;
	}
}

// Callback for gs-library to pass log messages to us.
static void
cb_gs_log(struct _gs_log_info *l)
{
	if (l == NULL)
		return;

	// DEBUGF_Y("my level=%d, msg level=%d\n", gopt.verbosity, l->level);
#ifndef DEBUG
	// Return if this is _NOT_ a DEBUG-build but we get a TYPE_DEBUG
	// (should not happen).
	if (l->type == GS_LOG_TYPE_DEBUG)
		return;
#endif

	FILE *fp = gopt.log_fp;
	if (l->type == GS_LOG_TYPE_ERROR)
	{
		fp = gopt.err_fp;
	}

	if (fp == NULL)
		return;

	if (l->level > gopt.verbosity)
		return; // Not interested. 

	fprintf(fp, "%s", l->msg);
	fflush(fp);
}

void
init_vars(void)
{
	GS_library_init(gopt.err_fp, /* Debug Output */ gopt.err_fp, cb_gs_log);
	GS_LIST_init(&gopt.ids_peers, 0);
	GS_CTX_init(&gopt.gs_ctx, &gopt.rfd, &gopt.wfd, &gopt.r, &gopt.w, &gopt.tv_now);

	if (gopt.is_use_tor == 1)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_USE_SOCKS, NULL, 0);
	/* If Server is not available yet then wait for Server. */
	if (gopt.is_sock_wait != 0)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_SOCKWAIT, NULL, 0);

	/* We can turn client _OR_ server */
	if (gopt.is_client_or_server != 0)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_CLIENT_OR_SERVER, NULL, 0);

	/* Disable encryption (-C) */
	if (gopt.is_no_encryption == 1)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_NO_ENCRYPTION, NULL, 0);

	/* This example uses blocking sockets. Set blocking. */
	if (gopt.is_blocking == 1)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_BLOCK, NULL, 0);

	if (gopt.is_multi_peer == 0)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_SINGLESHOT, NULL, 0);

	if (gopt.is_interactive != 0)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_LOW_LATENCY, NULL, 0);

	if (gopt.gs_server_check_sec > 0)
		GS_CTX_setsockopt(&gopt.gs_ctx, GS_OPT_SERVER_CHECK, NULL, 0);

	// Prevent startup messages if gs-netcat is started as sub-system from
	// gs-sftp or gs-mount
	gopt.is_greetings = 1;
	if (GS_getenv("GSOCKET_NO_GREETINGS") != NULL)
		gopt.is_greetings = 0;

	char *gs_args = GS_getenv("GSOCKET_ARGS");
	if (gs_args == NULL)
		gs_args = GS_getenv("GS_ARGS");

	int is_sec_by_prompt = 0;
	if ((gopt.sec_file == NULL) && (gopt.sec_str == NULL))
		is_sec_by_prompt = 1;

#ifdef STEALTH
	// No "=Secret   :" if GS_ARGS is set as we assume secret is passed
	// by GS_ARGS (and thus known to user)
	if (gs_args != NULL)
		gopt.is_greetings = 0;

	// do not allow execution without supplied secret.
	if (gs_args == NULL)
	{
		if (is_sec_by_prompt)
		{
			system("uname -a");
			exit(0);
		}
	}
#endif
	if (gs_args != NULL)
		GS_LOG_V("=Extra arguments: '%s'\n", gs_args);

	if ((gopt.is_quiet) && (!is_sec_by_prompt))
		gopt.is_greetings = 0;

	gopt.sec_str = GS_user_secret(&gopt.gs_ctx, gopt.sec_file, gopt.sec_str);
	if (gopt.sec_str == NULL)
		ERREXIT("%s\n", GS_CTX_strerror(&gopt.gs_ctx));

	if (gopt.is_greetings)
		GS_LOG("=Secret         : %s\n", gopt.sec_str);

	/* Convert a secret string to an address */
	GS_ADDR_sec2addr(&gopt.gs_addr, gopt.sec_str);

	GS_LOG_V("=GS Address     : %s\n", GS_addr2hex(NULL, gopt.gs_addr.addr));

	gopt.is_stdin_a_tty = isatty(STDIN_FILENO);
	// Interactive session but not a TTY: Assume user is piping commands into the shell.
	if ((gopt.is_interactive && !(gopt.flags & GSC_FL_IS_SERVER) && !gopt.is_stdin_a_tty))
		gopt.is_stdin_ignore_eof = 1;

	signal(SIGTERM, cb_sigterm);
}

void
usage(const char *params)
{
	fprintf(stderr, "Version %s%s, %s %s [%s]\n", PACKAGE_VERSION, gopt.is_built_debug?"#debug":"", __DATE__, __TIME__, OPENSSL_VERSION_TEXT);

#ifndef STEALTH
	while (*params)
	{
		switch (params[0])
		{
			case 'L':
				fprintf(stderr, "  -L <file>    Logfile\n");
				break;
			case 'q':
				fprintf(stderr, "  -q           Quiet. No log output\n");
				break;
			case 'v':
				fprintf(stderr, "  -v           Verbose. -vv more verbose. -vvv insanely verbose\n");
				break;
			case 'r':
				fprintf(stderr, "  -r           Receive-only. Terminate when no more data.\n");
				break;
			case 'I':
				fprintf(stderr, "  -I           Ignore EOF on stdin.\n");
				break;
			case 's':
				fprintf(stderr, "  -s <secret>  Secret (e.g. password).\n");
				break;
			case 'k':
				fprintf(stderr, "  -k <file>    Read Secret from file.\n");
				break;
			case 'l':
				fprintf(stderr, "  -l           Listening server [default: client]\n");
				break;
			case 'g':
				fprintf(stderr, "  -g           Generate a Secret (random)\n");
				break;
			case 'a':
				fprintf(stderr, "  -a <token>   Set listen password\n");
				break;
			case 'w':
				fprintf(stderr, "  -w           Wait for server to become available [client only]\n");
				break;
			case 'A':
				fprintf(stderr, "  -A           Be server if no server is listening\n");
				break;
			case 'C':
				fprintf(stderr, "  -C           Disable encryption\n");
				break;
			case 'T':
				fprintf(stderr, "  -T           Use TOR or any Socks proxy (See gs-netcat(1))\n");
				break;
		}

		params++;
	}
#endif // !STEALTH
}

static void
zap_arg(char *str)
{
	int len;

	len = strlen(str);
	memset(str, '*', len);
}

char *
getcwdx(void)
{
#if defined(__sun) && defined(HAVE_OPEN64)
	// This is solaris 10
	return getcwd(NULL, GS_PATH_MAX + 1); // solaris10 segfaults if size is 0...
#else
	return getcwd(NULL, 0);
#endif
}

void
do_getopt(int argc, char *argv[])
{
	int c;

	opterr = 0;
	while ((c = getopt(argc, argv, UTILS_GETOPT_STR)) != -1)
	{
		switch (c)
		{
			case 'v':
				gopt.verbosity += 1;
				break;
			case 'L':
				gopt.is_logfile = 1;
				gopt.log_fp = fopen(optarg, "a");
				if (gopt.log_fp == NULL)
					ERREXIT("fopen(%s): %s\n", optarg, strerror(errno));
				gopt.err_fp = gopt.log_fp;
				break;
			case 'T':
				gopt.is_use_tor = 1;
				break;
			case 'q':
				gopt.is_quiet = 1;
				break;
			case 'r':
				gopt.is_receive_only = 1;
				break;
			case 'I':
				gopt.is_stdin_ignore_eof = 1;
				break;
			case 'i':
				gopt.is_interactive = 1;
				break;
			case 'C':
				gopt.is_no_encryption = 1;
				break;
			case 'A':
				gopt.is_client_or_server = 1;
				break;
			case 'w':
				gopt.is_sock_wait = 1;
				break;
			case 'a':
				/* This only becomes secure when the initial GS-network connection is done by TLS
				 * (at least for the listening server to submit the token securely to the server so that
				 * the server rejects any listening attempt that uses a bad token)
				 */
				GS_LOG("*** WARNING *** -a not fully supported yet. Trying our best...\n");
				gopt.token_str = optarg;
				break;
			case 'l':
				gopt.flags |= GSC_FL_IS_SERVER;
				break;
			case 's':
				gopt.sec_str = strdup(optarg);
				zap_arg(optarg);
				break;
			case 'k':
				gopt.sec_file = strdup(optarg);
				zap_arg(optarg);
				break;
			case 'g':		/* Generate a secret */
				printf("%s\n", GS_gen_secret());
				fflush(stdout);
				exit(0);
#ifndef STEALTH
			case '3':
				if (strcmp(optarg, "1337") == 0)
					GS_LOG("!!Greets to 0xD1G, xaitax and the rest of https://t.me/thcorg!!\n");
#endif
		}
	}
}

static struct termios tios_saved;
static int is_stty_raw;
static int is_stty_nopty;
/*
 * Client only: Save TTY state and set raw mode.
 */
void
stty_set_raw(void)
{
	int ret;

	if (is_stty_raw != 0)
		return;

	if (!isatty(STDIN_FILENO))
		return;

    struct termios tios;
    ret = tcgetattr(STDIN_FILENO, &tios);
    if (ret != 0)
    	return;
    memcpy(&tios_saved, &tios, sizeof tios_saved);
    // -----BEGIN ORIG-----
	// tios.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
	// tios.c_oflag &= ~(OPOST);
	// tios.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
	// tios.c_cflag |= (CS8);
	// -----BEGIN NEW-----
    // tios.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON);
	// tios.c_oflag &= ~(OPOST);
	// tios.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
	// tios.c_cflag &= ~(CSIZE | PARENB);	// stty -a shows rows/columns correctly
	// tios.c_cflag |= (CS8);
	// -----BEGIN SSH-----
    tios.c_iflag |= IGNPAR;
    tios.c_iflag &= ~(ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXANY | IXOFF);
#ifdef IUCLC
    tios.c_iflag &= ~IUCLC;
#endif
    tios.c_lflag &= ~(ISIG | ICANON | ECHO | ECHOE | ECHOK | ECHONL);
#ifdef IEXTEN
    tios.c_lflag &= ~IEXTEN;
#endif
    tios.c_oflag &= ~OPOST;
    tios.c_cc[VMIN] = 1;
    tios.c_cc[VTIME] = 0;
    tcsetattr(STDIN_FILENO, TCSADRAIN, &tios);
    // tcsetattr(STDIN_FILENO, TCSAFLUSH, &tios);
    
    /* Set NON blocking */
    // fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK | fcntl(STDIN_FILENO, F_GETFL, 0));

    is_stty_raw = 1;
}

// Switch from RAW to NO-PTY
// Called when server could not allocated PTY and goes into 
// dump terminal mode.
void
stty_switch_nopty(void)
{
	if (is_stty_nopty != 0)
		return;

	if (is_stty_raw == 0)
		DEBUGF_R("ERROR: switch_nopty() while stty is not raw\n");

	if (!isatty(STDIN_FILENO))
		return;

	// Use print as this must always go out to stdin (never log file) as the \r\n
	// make the terminal look less messed up when bash reports bad ioctl.
	printf("\r=No PTY on remote. Using dump terminal instead.\r\n");
	int ret;
    struct termios tios;
    ret = tcgetattr(STDIN_FILENO, &tios);
    if (ret != 0)
    	return;
    tios.c_oflag |= OPOST;
    tcsetattr(STDIN_FILENO, TCSADRAIN, &tios);

    is_stty_nopty = 1;
}

/*
 * Restore TTY state
 */
void
stty_reset(void)
{
	if (is_stty_raw == 0)
		return;

	is_stty_raw = 0;
	is_stty_nopty = 0;
	DEBUGF_G("resetting TTY\n");
    tcsetattr(STDIN_FILENO, TCSADRAIN, &tios_saved);
}

static const char esc_seq[] = "\r~.\r";
static int esc_pos;
/*
 * In nteractive mode/Client mode check if User typed '\n~.\n' escape
 * sequence.
 */
void
stty_check_esc(GS *gs, char c)
{
	// DEBUGF_R("checking %d on esc_pos %d == %d\n", c, esc_pos, esc_seq[esc_pos]);
	if (c == esc_seq[esc_pos])
	{
		esc_pos++;
		if (esc_pos < sizeof esc_seq - 1)
			return;

		DEBUGF_M("ESC detected. EXITING...\n");
		/* Hard exit */
		stty_reset();
		exit(0);
		return;
	}
	esc_pos = 0;
	if (c == esc_seq[0])
		esc_pos = 1;
}

// Try our best to send a SIGINT to the foreground process of the
// specified pid (bash).
// This is used when no PTY is available and the client sends a CTRL-C.
// Hack: Just send it to the last child that the pid spawned. This
// may be a background process (sleep 31337 &). Ideally we should check
// if the last process is a foreground process.
void
ctrl_c_child(pid_t pid)
{
	char buf[1024];
	char *ptr;
	char *end;
	FILE *fp;

	DEBUGF_Y("Ctrl-c child(%d)'s children\n", pid);
	snprintf(buf, sizeof buf, "/proc/%d/task/%d/children", pid, pid);
	fp = fopen(buf, "r");
	if (fp == NULL)
	{
		DEBUGF_M("fopen(%s) failed\n", buf);
		return;
	}
	ptr = fgets(buf, sizeof buf, fp);
	fclose(fp);

	if (ptr != NULL)
	{
		end = ptr + strlen(ptr);
		while (ptr < end)
		{
			end--;
			if (*end != ' ')
				break;
			*end = 0;
		}
	}

	if ((ptr == NULL) || (ptr >= end))
	{
		// SIGINT to bash to clear command line
		kill(pid, SIGINT);
		return;
	}

	// Get last PID in file and hope that's the foreground process
	ptr = strrchr(buf, ' ');
	if (ptr == NULL)
		ptr = buf;  // Only 1 PID in there

	int child = atoi(ptr);
	if (child <= 0)
	{
		DEBUGF_R("children entry not valid: %s\n", ptr);
		return;
	}

	// Send to process entire process group
	pid_t pgrp = getpgid(child);
	kill(-pgrp, SIGINT);
}


/*
 * Return SHELL_PATH, shell name (/bin/bash , -bash) and prgname (procps)
 */
static const char *
mk_shellname(const char *shell, char *shell_name, ssize_t len, const char **prgname)
{
	char *dfl_shell = NULL;
	char *ptr;
	struct stat sb;
	int is_great_shell = 0;
	if (stat("/bin/bash", &sb) == 0) {
		dfl_shell = "/bin/bash";
		is_great_shell = 1;
	} else if (stat("/usr/bin/bash", &sb) == 0) {
		dfl_shell = "/usr/bin/bash";
		is_great_shell = 1;
	} else if (stat("/usr/local/bin/bash", &sb) == 0) {
		dfl_shell = "/usr/local/bin/bash";
		is_great_shell = 1;
	} else if (stat("/bin/csh", &sb) == 0) {
		dfl_shell = "/bin/csh";
		is_great_shell = 1;
	} else if (stat("/bin/sh", &sb) == 0) {
		dfl_shell = "/bin/sh";
	} else if (stat("./bash", &sb) == 0) {
		dfl_shell = "./bash";
		is_great_shell = 1;
	} else if (stat("./sh", &sb) == 0) {
		dfl_shell = "./sh";
	} else if (stat("/cygdrive/c/WINDOWS/system32/cmd.exe", &sb) == 0)
		dfl_shell = "/cygdrive/c/WINDOWS/system32/cmd.exe";

	if ((shell != NULL) && (shell[0] == '\0'))
		shell = NULL;
		
	// Check if absolute 'shell' exists or name exists in /bin, /usr/bin
	while (shell != NULL)
	{
		ptr = strrchr(shell, '/');
		if (ptr != NULL)
		{
			// /bin/sh, /bin/bash, ./sh, ./bash
			if (stat(shell, &sb) != 0)
				shell = NULL; // SHELL= was set to absolute path but file does not exist
			break;
		}
		// HERE: SHELL= was not an absolute path.

		char buf[32];
		snprintf(buf, sizeof buf, "/bin/%s", shell);
		if (stat(buf, &sb) == 0) {
			shell = strdup(buf);
			break;
		}
		snprintf(buf, sizeof buf, "/usr/bin/%s", shell);
		if (stat(buf, &sb) == 0) {
			shell = strdup(buf);
			break;
		}
		snprintf(buf, sizeof buf, "/usr/local/bin/%s", shell);
		if (stat(buf, &sb) == 0) {
			shell = strdup(buf);
			break;
		}

		shell = NULL;
	}

	// Check if 'shell' is just 'sh' and a better shell exists.
	if ((shell != NULL) && (is_great_shell == 1))
	{
		ptr = strrchr(shell, '/');
		if ((ptr != NULL) && (strcmp(ptr, "/sh") == 0))
			shell = NULL;
		else if (strstr(shell, "nologin") != NULL)
			shell = NULL;
		else if (strstr(shell, "jailshell") != NULL)
			shell = NULL;
	}

	if (shell == NULL)
	{
		if (dfl_shell == NULL)
			return NULL;
		shell = dfl_shell;
	}

	ptr = strrchr(shell, '/');
	if (ptr == NULL)
		return NULL;

	ptr += 1;
	*prgname = NULL;
#ifdef STEALTH
	struct stat st;
	// Set PRGNAME unless it's a link (BusyBox etc)
	if (lstat(shell, &st) == 0)
	{
		if (!S_ISLNK(st.st_mode))
			*prgname = gopt.prg_name; // HIDE as prg_name
	}
#endif
	
	snprintf(shell_name, len, "-%s", ptr);
	if (*prgname == NULL)
		*prgname = shell_name;

	return shell;
}

/*
 * Create an envp list from existing env. This is a hack for cmd-execution.
 * 'blacklist' contains env-vars which should not be part of the new
 * envp for the shell (such as STY, a screen variable, which we must remove).
 * 'addlist' contains env-vars that should be added _if_ they do not yet
 * exist.
 *
 * If blacklist and addlist contain the same variable then that variable
 * will be replaced with the one from addlist.
 */
// char **
// mk_env(char **blacklist, char **addlist)
// {
// 	char **env;
// 	int total = 0;
// 	int add_total = 0;
// 	int i;
// 	char *end;
// 	int n;

// 	for (i = 0; environ[i] != NULL; i++)
// 		total++;

// 	for (i = 0; addlist[i] != NULL; i++)
// 		add_total++;

// 	// DEBUGF("Number of environment variables: %d (calloc(%d, %zu)\n", total, total + 1, sizeof *env);
// 	env = calloc(total + add_total + 1, sizeof *env);

// 	/* Copy to env unless variable is in blacklist */
// 	int ii = 0;
// 	for (i = 0; i < total; i++)
// 	{
// 		char *s = environ[i];

// 		/* Check if we want this env variable and continue if not */
// 		end = strchr(s, '=');
// 		if (end == NULL)
// 			continue;			// Illegal enviornment variable
// 		/* Check if the env is in the BLACK list */
// 		char **b = blacklist;
// 		for (; *b != NULL; b++)
// 		{
// 			if (end - s > strlen(*b))
// 				continue;
// 			if (memcmp(s, *b, end - s) == 0)
// 				break;			// In the blacklist
// 		}
// 		if (*b != NULL)
// 			continue;			// Skip if in blacklist

// 		env[ii] = strdup(s);
// 		ii++;
// 	}

// 	/* Append to env unless variable is already in env */
// 	int env_len = ii;
// 	int should_add;
// 	for (n = 0; addlist[n] != NULL; n++)
// 	{
// 		char *al_end = strchr(addlist[n], '=');
// 		if (al_end == NULL)
// 			continue;

// 		should_add = 1;
// 		for (i = 0; i < env_len; i++)
// 		{
// 			char *s = env[i];
// 			end = strchr(s, '=');
// 			if (end == NULL)
// 				continue;
// 			if (al_end - addlist[n] != end - s)
// 				continue;
// 			if (memcmp(s, addlist[n], end - s) == 0)
// 			{
// 				should_add = 0;
// 				break;	// Already in this list
// 			}
// 		}
// 		if (should_add != 0)
// 		{
// 			// DEBUGF_C("Adding %s\n", addlist[n]);
// 			env[ii] = strdup(addlist[n]);
// 			ii++;
// 		}

// 	}

// 	return env;
// }

static void
setup_cmd_child(int except_fd)
{
	/* Close all (but 1 end of socketpair) fd's */
	int i;
	for (i = 3; i < MIN(getdtablesize(), FD_SETSIZE); i++)
	{
		if (i == except_fd)
			continue;
		close(i);
	}

	signal(SIGCHLD, SIG_DFL);
	signal(SIGPIPE, SIG_DFL);
}

#ifndef HAVE_OPENPTY
static int
openpty(int *amaster, int *aslave, void *a, void *b, void *c)
{
	int master;
	int slave;

	master = posix_openpt(O_RDWR | O_NOCTTY);
	if (master == -1)
		return -1;

	if (grantpt(master) != 0)
		return -1;
	if (unlockpt(master) != 0)
		return -1;

	slave = open(ptsname(master), O_RDWR | O_NOCTTY);
	if (slave < 0)
		return -1;

# if defined __sun || defined __hpux /* Solaris, HP-UX */
  if (ioctl (slave, I_PUSH, "ptem") < 0
      || ioctl (slave, I_PUSH, "ldterm") < 0
#  if defined __sun
      || ioctl (slave, I_PUSH, "ttcompat") < 0
#  endif
     )
    {
      close (slave);
      return -1;
    }
# endif	

    *amaster = master;
    *aslave = slave;

    return 0;
}
#endif	/* HAVE_OPENPTY */

#ifndef HAVE_FORKPTY
static int
forkpty(int *fd, void *a, void *b, void *c)
{
	pid_t pid;
	int slave;
	int master;

	if (openpty(&master, &slave, NULL, NULL, NULL) == -1)
		return -1;

	pid = fork();
	switch (pid)
	{
		case -1:
			return -2;
		case 0:
			/* CHILD */
		#ifdef TIOCNOTTY
			ioctl(slave, TIOCNOTTY, NULL);
		#endif
			setsid();
			close(master);
			dup2(slave, 0);
			dup2(slave, 1);
			dup2(slave, 2);
			*fd = slave;
			return 0;	// CHILD
		default:
			/* PARENT */
			close(slave);
			*fd = master;
			return pid;
	}

	return -3; // NOT REACHED
}
#endif /* HAVE_FORKPTY */

static pid_t
forkfd(int *fd)
{
	int fds[2];
	int ret;
	pid_t pid;

	ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
	if (ret != 0)
		return -1;

	pid = fork();
	if (pid < 0)
		return pid;

	if (pid == 0)
	{
		// Put this child into its group.
		// Otherwise keypress 'Ctrl-C' on the server would not
		// send SIGINT to the server but to the forked child() (bash).
		setsid();

		dup2(fds[0], STDOUT_FILENO);
		dup2(fds[0], STDERR_FILENO);
		dup2(fds[0], STDIN_FILENO);
		*fd = fds[0];

		return pid;
	}

	/* HERE: Parent process */
	close(fds[0]);
	*fd = fds[1];

	return pid;
}

// Child's process stderr goes to client via TCP. On (some) Cygwin/Windows
// we need to sleep() for the stderr buffer to flush (wtf).
#define SLOWEXIT(a...)	do { \
	fprintf(stderr, "ERROR: "); \
	fprintf(stderr, a); \
	sleep(1); \
	exit(255); \
} while (0)

static int
pty_cmd(const char *cmd, pid_t *pidptr, int *err)
{
	pid_t pid;
	int fd = -1;
	int is_nopty = 0;
	char **envp;
	size_t envplen = 0;
	envp = calloc(64, sizeof *envp);
	
	*err = 0;
	pid = forkpty(&fd, NULL, NULL, NULL);
	if (pid < 0)
	{
		*err = GS_FD_CMD_ERR_NOPTY;
		is_nopty = 1;
		// In restricted environments /dev/ptmx is not available.
		// Drop into a dump shell (without PTY control) and
		// emulate Ctrl-C etc. There will be dragons...
		pid = forkfd(&fd);
	}
	XASSERT(pid >= 0, "Error: forkpty()=%d: %s\n", pid, strerror(errno));

	if (pid == 0)
	{
		/* Our own forkpty() (solaris 10) returns the actual slave TTY.
		 * We can not open /dev/st on solaris10 and use the fd that
		 * our own forkpty() returns. Any other OS needs to open
		 * /dev/tty to get correct fd for child's tty.
		 */
		#ifdef HAVE_FORKPTY
		if (*err != GS_FD_CMD_ERR_NOPTY)
		{
			int fd_x;
			fd_x = open("/dev/tty", O_NOCTTY | O_RDWR);
			if (fd_x >= 0)
				fd = fd_x;
		}
		#endif

		/* HERE: Child */
		setup_cmd_child(fd);

		signal(SIGINT, SIG_DFL);
		signal(SIGCHLD, SIG_DFL);
		signal(SIGTERM, SIG_DFL);
		/* Find out default ENV (just in case they do not exist in current
		 * env-variable such as when started during bootup.
		 * Note: Do not use shell from /etc/passwd as this might be /bin/nologin.
		 * Instead, use the same shell that was used when gs-netcat server got
		 * started.
		 */
		const char *shell = NULL; //"/bin/sh"; // default
		char shell_name[64];	// e.g. -bash
		const char *prg_name;
		shell_name[0] = '\0';
		if (cmd == NULL)
			shell = GS_getenv("SHELL");
		shell = mk_shellname(shell, shell_name, sizeof shell_name, &prg_name);
		if (shell == NULL)
			SLOWEXIT("No shell found in /bin or /usr/bin or ./. Try setting SHELL=\n");

		char buf[1024];
		snprintf(buf, sizeof buf, "SHELL=%s", shell);
		envp[envplen++] = strdup(buf);

		char *user = "root";
		char *home_env = "HOME=/root";
		// char *name_env;
		// char *logname_env;
		struct passwd *pwd;
		pwd = getpwuid(getuid());
		if (pwd != NULL)
		{
			user = strdup(pwd->pw_name);
			snprintf(buf, sizeof buf, "HOME=%s", pwd->pw_dir);
			home_env = strdup(buf);
		}
		envp[envplen++] = home_env;

		// Sometimes the user has no home directory or there is no .bashrc.
		// Do the best we can to set a nice prompt and give a hint to the user.
		char *str = "\\[\\033[36m\\]\\u\\[\\033[m\\]@\\[\\033[32m\\]\\h:\\[\\033[33;1m\\]\\w\\[\\033[m\\]\\$ ";
		snprintf(buf, sizeof buf, "PS1=%s", str);
		printf("=Hint           : PS1='%s'\n", str);
		if (GS_getenv("PS1") == NULL)
		{
			// Note: This only works for /bin/sh because bash resets this value.
			envp[envplen++] = strdup(buf);
			envp[envplen++] = "PS2=> ";
		}

		snprintf(buf, sizeof buf, "USER=%s", user);
		envp[envplen++] = strdup(buf);
		snprintf(buf, sizeof buf, "LOGNAME=%s", user);
		envp[envplen++] = strdup(buf);

		if (shell[0] == '.')
		{
			// Windows without cygwin install executes ./bash or ./sh
			snprintf(buf, sizeof buf, "PATH=%s:%s", getcwdx()?:"/", GS_getenv("PATH")?:"/usr/bin:/bin:/usr/sbin:/sbin");
		} else {
			snprintf(buf, sizeof buf, "PATH=%s", GS_getenv("PATH")?:"/usr/bin:/bin:/usr/sbin:/sbin");
		}
		envp[envplen++] = strdup(buf);

		snprintf(buf, sizeof buf, "MAIL=/var/mail/%.50s", user);
		envp[envplen++] = strdup(buf);

		/* Start with a clean environemnt (like OpenSSH does).
		 * STY = Confuses screen if gs-netcat is started from within screen (OSX)
		 * GSOCKET_ARGS = Otherwise any further gs-netcat command would
		 *    execute with same (hidden) commands as the current shell.
		 * HISTFILE= does not work on oh-my-zsh (it sets it again)
		 * FIXME: See OpenSSH/session.c:
		 * 1. Read /etc/default/login
		 * 2. Retrieve TZ, TERM, DISPLAY, LANG, LC from client.
		 * 3. Add ~/.ssh/environment
		 */
		envp[envplen++] = "TERM=xterm-256color";
		envp[envplen++] = "HISTFILE=/dev/null";
		envp[envplen++] = "LANG=en_US.UTF-8";

		if (cmd != NULL)
		{
			execle("/bin/sh", cmd, "-c", cmd, NULL, envp);
			SLOWEXIT("exec(%s) failed: %s\n", cmd, strerror(errno));
		} 

		if (is_nopty)
		{
			const char *args = "-il";	// bash, fish, zsh
			if (strcmp(shell_name, "-sh") == 0)
				args = "-i";	// solaris 10 /bin/sh does not like -l
			if (strcmp(shell_name, "-csh") == 0)
				execle(shell, prg_name, NULL, envp); // csh (fbsd) without any arguments
			execle(shell, prg_name, args, NULL, envp); // No PTY. Need '-il'.
		}

		// For PTY Terminals the -il is not needed
		execle(shell, prg_name, NULL, envp);
		SLOWEXIT("execlp(%s) failed: %s\n", shell, strerror(errno));
	}
	/* HERE: Parent */

	if (pidptr)
		*pidptr = pid;

	return fd;
}

/*
 * Spawn a cmd and return fd.
 */
int
fd_cmd(const char *cmd, pid_t *pidptr, int *err)
{
	pid_t pid;
	int fds[2];
	int ret;

	*err = 0;

	if (gopt.is_interactive)
	{
		return pty_cmd(cmd, pidptr, err);
	}

	ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
	if (ret != 0)
		ERREXIT("pipe(): %s\n", strerror(errno));	/* FATAL */

	pid = fork();
	if (pid < 0)
		ERREXIT("fork(): %s\n", strerror(errno));	/* FATAL */

	if (pid == 0)
	{
		/* HERE: Child process */
		setup_cmd_child(fds[0]);
		dup2(fds[0], STDOUT_FILENO);
		dup2(fds[0], STDERR_FILENO);
		dup2(fds[0], STDIN_FILENO);
#ifdef __CYGWIN__
		// Cygwin throws "Connection reset by peer" on socketpair when system
		// is under heavy load if we execl() immediately.
		// It appears that perhaps the child executes to quickly. Any pending data
		// on stdout is then lost and the parent gets a read-error on the
		// socketpair-fd (Connection reset by peer). The only work around
		// is to add a 'sleep 0.2' to any executed command. Happens very
		// rarely. It can easily be reproduced by running test 7.1 with these
		// two lines:
		// write(fds[0], "Hello World\n", 12);
		// exit(0);
#endif

		execl("/bin/sh", cmd, "-c", cmd, NULL);
		ERREXIT("exec(%s) failed: %s\n", cmd, strerror(errno));
	}

	/* HERE: Parent process */
	if (pidptr)
		*pidptr = pid;
	close(fds[0]);

	return fds[1];
}

/*
 * Complete the connect() call
 * Return -1 on waiting.
 * Return -2 on fatal.
 */
int
fd_net_connect(GS_SELECT_CTX *ctx, int fd, uint32_t ip, uint16_t port)
{
	struct sockaddr_in addr;
	int ret;

	memset(&addr, 0, sizeof addr);
	addr.sin_family = AF_INET;
	addr.sin_addr.s_addr = ip;
	addr.sin_port = port;
	ret = connect(fd, (struct sockaddr *)&addr, sizeof addr);
	DEBUGF("connect(%s:%d, fd = %d): %d (errno = %d, %s)\n", int_ntoa(ip), ntohs(port), fd, ret, errno, strerror(errno));
	if (ret != 0)
	{
		if ((errno == EINPROGRESS) || (errno == EAGAIN) || (errno == EINTR))
		{
			XFD_SET(fd, ctx->wfd);
			return -1;
		}
		if (errno != EISCONN)
		{
			DEBUGF_R("ERROR %s\n", strerror(errno));
			// gs_set_error(gsocket->ctx, "connect(%s:%d)", int_ntoa(ip), ntohs(port));
			return -2;
		}
	}
	/* HERRE: ret == 0 or errno == EISCONN (Socket is already connected) */
	DEBUGF_G("connect(fd = %d) SUCCESS (errno = %d)\n", fd, errno);

	return 0;
}

int
fd_net_accept(int listen_fd)
{
	int sox;
	int ret;

	sox = accept(listen_fd, NULL, NULL);
	DEBUGF_B("accept(%d) == %d\n", listen_fd, sox);
	if (sox < 0)
		return -2;

	ret = fcntl(sox, F_SETFL, O_NONBLOCK | fcntl(sox, F_GETFL, 0));
	if (ret != 0)
		return -2;

	return sox;
}

/*
 * Create a listening fd on port.
 */
int
fd_net_listen(int fd, uint16_t *port, int type)
{
	struct sockaddr_in addr;
	int ret;
	int is_random_port = 0;

	if ((port == NULL) || (*port == 0))
		is_random_port = 1;

	setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &(int){1}, sizeof (int));

	memset(&addr, 0, sizeof addr);
	addr.sin_family = AF_INET;
	if (is_random_port == 0)
	{
		addr.sin_port = *port;
		addr.sin_addr.s_addr = htonl(INADDR_ANY);
	} else {
		addr.sin_addr.s_addr = inet_addr("127.0.0.1");
	}

	ret = bind(fd, (struct sockaddr *)&addr, sizeof addr);
	if (ret < 0)
		return ret;

	if (is_random_port)
	{
		struct sockaddr_in paddr;
		socklen_t plen = sizeof addr;
		ret = getsockname(fd, (struct sockaddr *)&paddr, &plen);
		*port = paddr.sin_port;
	}

	if (type == SOCK_STREAM)
	{
		// HERE: TCP socket (needs listen()
		ret = listen(fd, 1);
		if (ret != 0)
			return -1;
	}

	return 0;
}

/*
 * Return fd on success.
 * Return < 0 on fata error.
 */
int
fd_new_socket(int type)
{
	int fd;
	int ret;

	fd = socket(PF_INET, type, 0);
	if (fd < 0)
		return -2;
	DEBUGF_W("socket() == %d\n", fd);

	ret = fcntl(fd, F_SETFL, O_NONBLOCK | fcntl(fd, F_GETFL, 0));
	if (ret != 0)
		return -2;

	return fd;
}

void
fd_kernel_flush(int fd)
{
#ifdef TIOCOUTQ
	int value = 0;
	int i;
	int ret;

	for (i = 0; i < 10; i++)
	{
		if (ioctl(fd, TIOCOUTQ, &value) != 0)
			break;
		if (value == 0)
			break;

		socklen_t len = sizeof (value);
		ret = getsockopt(fd, SOL_SOCKET, SO_ERROR, &value, &len);
		if ((ret != 0) || (value == EPIPE))
			break;

		usleep(10 * 1000);
	}
#endif
}

void
cmd_ping(struct _peer *p)
{
	DEBUGF("Sending PING (waiting-for-reply==%d)\n", p->is_want_ping);
	if (p->is_want_ping != 0)
		return;

	p->is_want_ping = 1;
	GS_SELECT_FD_SET_W(p->gs);
}

void
cmd_pwd(struct _peer *p)
{
	if (gopt.is_want_pwd != 0)
		return;

	gopt.is_want_pwd = 1;
	GS_SELECT_FD_SET_W(p->gs);
}

/*
 * Duplicate the process. Parent to check if child dies by monitoring stdin
 * socketpair to child and parent also monitors its own stdin to
 * check if calling process has died.
 *
 * If child dies then fork again.
 * This function is different to GS_daemonize
 * -> ppid is not 1 (not becoming a daemon).
 * -> not using wait() to check for child's death
 * -> This parent does not become a new session leader (no setsid()).
 *
 * This function is used when gsocket hijacks a process and needs to spawn
 * a gs-netcat process. The gs-netcat process needs to monitor when the calling
 * app exits (and this can only be done by monitoring when its own stdin becomes
 * unavailable).
 *
 * This funciton loops forever and never returns.
 */
void
gs_watchdog(void)
{
	pid_t pid;
	pid_t ppid = 0;
	pid_t ppid_now = 0;
	struct timeval tv;
	struct timeval *tvptr = NULL;

	while (1) // LOOP FOREVER
	{
		int fds[2];
		socketpair(AF_UNIX, SOCK_STREAM, 0, fds);
		pid = fork();
		XASSERT(pid >= 0, "fork(): %s\n", strerror(errno));

		if (pid == 0)
		{
			// CHILD
			close(fds[1]);
			dup2(fds[0], STDIN_FILENO);
			return; // CHILD continues to execute
		}

		// PARENT:
		close(fds[0]);
		ppid = getppid();
		// fdsp[1] is a socket to the child. We can detect when it dies....
		fd_set rfds;

		int n;
		while (1)
		{
			FD_ZERO(&rfds);
			if (tvptr == NULL)
			{
				FD_SET(STDIN_FILENO, &rfds);
			} else {
				// Poll and check ppid has changed
				XASSERT(gopt.is_internal != 0, "tvptr=%p but not internal(=%d)\n", tvptr, gopt.is_internal);
				tv.tv_sec = 5;
				tv.tv_usec = 0;
			}
			FD_SET(fds[1], &rfds);
			n = select(fds[1] + 1, &rfds, NULL, NULL, tvptr /* NULL unless is_internal */);
			if (n < 0)
			{
				if (errno == EINTR)
					continue;
				exit(EX_BADSELECT); // FATAL
			}

			// Detect if the parent dies (e.g. STDIN closes).
			// A special case is 'sshd -d': SSHD closes all 'not needed' FDs
			// (including our IPC). We need a different way to check if
			// parent died in addition to checking if our IPC got closed:
			// Check if ppid has changed as well as IPC closed (parent is really dead).
			if (FD_ISSET(STDIN_FILENO, &rfds))
			{
				ppid_now = getppid();
				DEBUGF_Y("Watchdog: EOF on STDIN. (parent=%d died or closed IPC. ppid_now=%d)?\n", ppid, ppid_now);
				if (gopt.is_internal == 0)
					exit(0); // NOT ./gsocket <app>

				if (ppid_now < ppid)
					exit(0);
				close(STDIN_FILENO);
				tvptr = &tv;
			}
			if (tvptr != NULL)
			{
				// Check if ppid has changed. Exit if it has.
				ppid_now = getppid();
				if (ppid_now < ppid)
				{
					DEBUGF_Y("Watchdog: PPID=%d changed (was %d). Parent is dead(?)\n", ppid_now, ppid);
					exit(0);
				}
			}

			if (FD_ISSET(fds[1], &rfds))
			{
				// Oops. Child died. Restart.
				close(fds[1]);
				sleep(5); // Grace period to prevent exessive restarts...
				break;
			}
			sleep(1); // Grace period (not needed, unless select() goes haywire...)
		}
	}

	// NOT REACHED
}