// SPDX-License-Identifier: GPL-2.0-or-later

/* PESTO - Programmable Extensible Socket Translation Orchestrator
 *  front-end for passt(1) and pasta(1) forwarding configuration
 *
 * pesto.c - Main program (it's not actually extensible)
 *
 * Copyright (c) 2026 Red Hat GmbH
 * Author: Stefano Brivio <sbrivio@redhat.com>
 */

#include <arpa/inet.h>
#include <sys/prctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <errno.h>
#include <getopt.h>
#include <inttypes.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <unistd.h>

#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/filter.h>
#include <linux/seccomp.h>

#include "common.h"
#include "seccomp_pesto.h"
#include "serialise.h"
#include "ports.h"
#include "fwd_rule.h"
#include "pesto.h"
#include "log.h"
#include "pif.h"

int verbosity = 1;

/**
 * xmalloc() - Allocate memory, with fatal error on failure
 * @size:	Number of bytes to allocate
 */
static void *xmalloc(size_t size)
{
	void *p = malloc(size);

	if (!p)
		die("Memory allocation failure");
	return p;
}

/**
 * usage() - Print usage, exit with given status code
 * @name:	Executable name
 * @f:		Stream to print usage info to
 * @status:	Status code for exit(2)
 */
static void usage(const char *name, FILE *f, int status)
{
	FPRINTF(f, "Usage: %s [OPTION]... PATH\n", name);
	FPRINTF(f,
		"\n"
		"  -t, --tcp-ports SPEC	TCP inbound port forwarding\n"
		"    can be specified multiple times\n"
		"    SPEC can be:\n"
		"      'none': don't forward any ports\n"
		"      'auto': forward all ports currently bound in namespace\n"
		"      'all': forward all unbound, non-ephemeral ports\n"
		"      a comma-separated list, optionally ranged with '-'\n"
		"        and optional target ports after ':', with optional\n"
		"        address specification suffixed by '/' and optional\n"
		"        interface prefixed by '%%'. Examples:\n"
		"        -t 22	Forward local port 22 to port 22 in netns\n"
		"        -t 22:23	Forward local port 22 to port 23\n"
		"        -t 22,25	Forward ports 22, 25 to ports 22, 25\n"
		"        -t 22-80	Forward ports 22 to 80\n"
		"        -t 22-80:32-90	Forward ports 22 to 80 to\n"
		"			corresponding port numbers plus 10\n"
		"        -t 192.0.2.1/5	Bind port 5 of 192.0.2.1\n"
		"        -t 5-25,~10-20	Forward ports 5 to 9, and 21 to 25\n"
		"        -t ~25		Forward all bound ports except for 25\n"
		"    IPv6 bound ports are also forwarded for IPv4\n"
		"  -u, --udp-ports SPEC	UDP inbound port forwarding\n"
		"    SPEC is as described for TCP above\n"
		"    IPv6 bound ports are also forwarded for IPv4\n"
		"    unless specified, with '-t auto', UDP ports with numbers\n"
		"    corresponding to forwarded TCP port numbers are\n"
		"    forwarded too\n"
		"  -T, --tcp-ns SPEC	TCP port forwarding to init namespace\n"
		"    SPEC is as described above\n"
		"  -U, --udp-ns SPEC	UDP port forwarding to init namespace\n"
		"    SPEC is as described above\n"
		"  -v, --verbose		Be more verbose\n"
		"  -q, --quiet		Be less verbose\n"
		"  -h, --help		Display this help message and exit\n"
		"  --version		Show version and exit\n");
	exit(status);
}

/**
 * pesto_recv_str() - Receive a string from passt/pasta
 * @fd:		Control socket
 *
 * Return: pointer to malloc()ed string
 */
static const char *pesto_recv_str(int fd)
{
	uint32_t len;
	char *buf;

	if (seread_u32(fd, &len) < 0)
		die("Error reading from control socket");

	buf = xmalloc(len);
	if (seread_buf(fd, buf, len) < 0)
		die("Error reading from control socket");

	return buf;
}

struct pif_state {
	uint8_t pif;
	const char *name;
	uint32_t count;
	struct fwd_rule *rule;
};

struct conf_state {
	uint32_t npifs;
	struct pif_state pif[];
};

/**
 * pesto_read_pifs() - Read pif names and IDs from passt/pasta
 * @fd:		Control socket
 */
static struct conf_state *pesto_read_pifs(int fd)
{
	uint32_t num;
	struct conf_state *state;
	unsigned i;

	if (seread_u32(fd, &num) < 0)
		die("Error reading from control socket");

	debug("Receiving %"PRIu32" interface names", num);

	state = xmalloc(sizeof(*state) + num * sizeof(struct pif_state));
	state->npifs = num;

	for (i = 0; i < num; i++) {
		struct pif_state *ps = &state->pif[i];

		if (seread_u8(fd, &ps->pif) < 0)
			die("Error reading from control socket");
		ps->name = pesto_recv_str(fd);

		debug("%u: %s", ps->pif, ps->name);
	}

	return state;
}

/**
 * find_pif_state() - Find the pif state structure for a given pif id
 * @state:	Rule state information
 * @pif:	pif id
 *
 * Return: pointer to the pif_state for @pif, or NULL if not found
 */
static struct pif_state *find_pif_state(struct conf_state *state, uint8_t pif)
{
	unsigned i;

	for (i = 0; i < state->npifs; i++) {
		if (state->pif[i].pif == pif)
			return &state->pif[i];
	}

	return NULL;
}

/**
 * pesto_read_rules() - Read a set of rules for one pif
 * @fd:		Control socket
 * @state:	Rule state information to update
 *
 * Return: true if there may be more rules to read, false if finished
 */
static bool pesto_read_rules(int fd, struct conf_state *state)
{
	struct pif_state *ps;
	uint8_t pif;
	unsigned i;

	if (seread_u8(fd, &pif) < 0)
		die("Error reading from control socket");

	if (!pif)
		return false;

	ps = find_pif_state(state, pif);
	if (!ps)
		die("Received rules for an unknown pif");

	if (seread_u32(fd, &ps->count) < 0)
		die("Error reading from control socket");

	debug("Receiving rules %"PRIu32" rules for %s", ps->count, ps->name);

	ps->rule = xmalloc(sizeof(*ps->rule) * ps->count);

	for (i = 0; i < ps->count; i++) {
		if (fwd_rule_seread(fd, &ps->rule[i]) < 0)
			die("Error reading from control socket");
	}

	return true;
}

/**
 * show_state() - Show current rule state obtained from passt/pasta
 * @pifs:	PIF name information
 */
static void show_state(const struct conf_state *state)
{
	unsigned i, j;

	for (i = 0; i < state->npifs; i++) {
		const struct pif_state *ps = &state->pif[i];
		printf("Forwarding rules for %s interface\n", ps->name);
		for (j = 0; j < ps->count; j++) {
			const struct fwd_rule *rule = &ps->rule[j];
			char rulestr[FWD_RULE_STRLEN];

			printf("    %s\n", fwd_rule_ntop(rule, rulestr,
							 sizeof(rulestr)));
		}
	}
}

/**
 * main() - Entry point and whole program with loop
 * @argc:	Argument count
 * @argv:	Arguments: socket path, operation, port specifiers
 *
 * Return: 0 on success, won't return on failure
 *
 * #syscalls:pesto connect write close exit_group fstat brk getrandom openat
 * #syscalls:pesto socket s390x:socketcall i686:socketcall
 * #syscalls:pesto recvfrom recvmsg arm:recv ppc64le:recv
 * #syscalls:pesto sendto sendmsg arm:send ppc64le:send
 */
int main(int argc, char **argv)
{
	const struct option options[] = {
		{"quiet",	no_argument,		NULL,		'q' },
		{"verbose",	no_argument,		NULL,		'v' },
		{"help",	no_argument,		NULL,		'h' },
		{"version",	no_argument,		NULL,		1 },
		{"tcp-ports",	required_argument,	NULL,		't' },
		{"udp-ports",	required_argument,	NULL,		'u' },
		{"tcp-ns",	required_argument,	NULL,		'T' },
		{"udp-ns",	required_argument,	NULL,		'U' },
		{ 0 },
	};
	struct fwd_table fwd_in = { .count = 0 }, fwd_out = { .count = 0 };
	struct sockaddr_un a = { AF_UNIX, "" };
	const char *optstring = "vht:u:T:U:";
	enum fwd_mode fwd_default;
	struct pesto_hello hello;
	struct conf_state *state;
	struct sock_fprog prog;
	int optname, ret, s;
	uint32_t s_version;
	unsigned i;

	prog.len = (unsigned short)sizeof(filter_pesto) /
				   sizeof(filter_pesto[0]);
	prog.filter = filter_pesto;
	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) ||
	    prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog))
		die("Failed to apply seccomp filter");

	fwd_probe_ephemeral();

	do {
		optname = getopt_long(argc, argv, optstring, options, NULL);

		switch (optname) {
		case -1:
		case 0:
			break;
		case 'h':
			usage(argv[0], stdout, EXIT_SUCCESS);
			break;
		case 'q':
			verbosity--;
			break;
		case 'v':
			verbosity++;
			break;
		case 't':
		case 'u':
			fwd_default = FWD_MODE_UNSET;
			conf_ports(optname, optarg, &fwd_in, &fwd_default,
				   true, true, true);
			break;
		case 'T':
		case 'U':
			fwd_default = FWD_MODE_UNSET;
			conf_ports(optname, optarg, &fwd_out, &fwd_default,
				   true, true, true);
			break;
		case 1:
			FPRINTF(stdout, "pesto ");
			FPRINTF(stdout, VERSION_BLOB);
			exit(EXIT_SUCCESS);
		default:
			usage(argv[0], stderr, EXIT_FAILURE);
		}
	} while (optname != -1);

	if (argc - optind != 1)
		usage(argv[0], stderr, EXIT_FAILURE);

	if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
		die("Failed to create AF_UNIX socket: %s", strerror(errno));

	ret = snprintf(a.sun_path, sizeof(a.sun_path), "%s", argv[optind]);
	if (ret <= 0 || ret >= (int)sizeof(a.sun_path))
		die("Invalid socket path \"%s\"", argv[optind]);

	ret = connect(s, (struct sockaddr *)&a, sizeof(a));
	if (ret < 0) {
		die("Failed to connect to %s: %s",
		    a.sun_path, strerror(errno));
	}

	debug("Inbound rules from command line:");
	for (i = 0; i < fwd_in.count; i++) {
		const struct fwd_rule *rule = &fwd_in.rules[i].rule;
		char rulestr[FWD_RULE_STRLEN];

		debug("    %s", fwd_rule_ntop(rule, rulestr, sizeof(rulestr)));
	}

	debug("Outbound rules from command line:");
	for (i = 0; i < fwd_out.count; i++) {
		const struct fwd_rule *rule = &fwd_out.rules[i].rule;
		char rulestr[FWD_RULE_STRLEN];

		debug("    %s", fwd_rule_ntop(rule, rulestr, sizeof(rulestr)));
	}

	debug("Connected to passt/pasta control socket");
	
	ret = seread_var(s, &hello);
	if (ret < 0)
		die("Couldn't read server greeting: %s", strerror(errno));

	if (memcmp(hello.magic, PESTO_SERVER_MAGIC, sizeof(hello.magic)))
		die("Bad magic number from server");

	s_version = ntohl(hello.version);

	debug("Server protocol version: %"PRIu32, s_version);

	if (s_version > PESTO_PROTOCOL_VERSION) {
		die("Unknown server protocol version %"PRIu32" > %"PRIu32"\n",
		    s_version, PESTO_PROTOCOL_VERSION);
	}

	/* cppcheck-suppress knownConditionTrueFalse */
	if (!s_version) {
		if (PESTO_PROTOCOL_VERSION)
			die("Unsupported experimental server protocol");
		FPRINTF(stderr,
"Warning: Using experimental protocol version, client and server must match\n");
	}

	state = pesto_read_pifs(s);

	while (pesto_read_rules(s, state))
		;

	show_state(state);

	if (fwd_in.count) {
		sewrite_u8(s, PIF_HOST);
		sewrite_u32(s, fwd_in.count);
		for (i = 0; i < fwd_in.count; i++)
			fwd_rule_sewrite(s, &fwd_in.rules[i].rule);
	}

	if (fwd_out.count) {
		sewrite_u8(s, PIF_SPLICE);
		sewrite_u32(s, fwd_out.count);
		for (i = 0; i < fwd_out.count; i++)
			fwd_rule_sewrite(s, &fwd_out.rules[i].rule);
	}

	sewrite_u8(s, PIF_NONE);

	exit(0);
}