/*	$OpenBSD: parser.c,v 1.77 2022/09/03 21:24:02 job Exp $ */
/*
 * Copyright (c) 2019 Claudio Jeker <claudio@openbsd.org>
 * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/queue.h>
#include <sys/tree.h>
#include <sys/types.h>

#include <assert.h>
#include <err.h>
#include <fcntl.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <unistd.h>
#include <imsg.h>

#include <openssl/asn1.h>
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>

#include "extern.h"

static X509_STORE_CTX	*ctx;
static struct auth_tree	 auths = RB_INITIALIZER(&auths);
static struct crl_tree	 crlt = RB_INITIALIZER(&crlt);

struct parse_repo {
	RB_ENTRY(parse_repo)	 entry;
	char			*path;
	char			*validpath;
	unsigned int		 id;
};

static RB_HEAD(repo_tree, parse_repo)	repos = RB_INITIALIZER(&repos);

static inline int
repocmp(struct parse_repo *a, struct parse_repo *b)
{
	return a->id - b->id;
}

RB_GENERATE_STATIC(repo_tree, parse_repo, entry, repocmp);

static struct parse_repo *
repo_get(unsigned int id)
{
	struct parse_repo needle = { .id = id };

	return RB_FIND(repo_tree, &repos, &needle);
}

static void
repo_add(unsigned int id, char *path, char *validpath)
{
	struct parse_repo *rp;

	if ((rp = calloc(1, sizeof(*rp))) == NULL)
		err(1, NULL);
	rp->id = id;
	if (path != NULL)
		if ((rp->path = strdup(path)) == NULL)
			err(1, NULL);
	if (validpath != NULL)
		if ((rp->validpath = strdup(validpath)) == NULL)
			err(1, NULL);

	if (RB_INSERT(repo_tree, &repos, rp) != NULL)
		errx(1, "repository already added: id %d, %s", id, path);
}

/*
 * Build access path to file based on repoid, path, location and file values.
 */
static char *
parse_filepath(unsigned int repoid, const char *path, const char *file,
    enum location loc)
{
	struct parse_repo	*rp;
	char			*fn, *repopath;

	/* build file path based on repoid, entity path and filename */
	rp = repo_get(repoid);
	if (rp == NULL)
		errx(1, "build file path: repository %u missing", repoid);

	if (loc == DIR_VALID)
		repopath = rp->validpath;
	else
		repopath = rp->path;

	if (repopath == NULL)
		return NULL;

	if (path == NULL) {
		if (asprintf(&fn, "%s/%s", repopath, file) == -1)
			err(1, NULL);
	} else {
		if (asprintf(&fn, "%s/%s/%s", repopath, path, file) == -1)
			err(1, NULL);
	}
	return fn;
}

/*
 * Parse and validate a ROA.
 * This is standard stuff.
 * Returns the roa on success, NULL on failure.
 */
static struct roa *
proc_parser_roa(char *file, const unsigned char *der, size_t len)
{
	struct roa		*roa;
	struct auth		*a;
	struct crl		*crl;
	X509			*x509;

	if ((roa = roa_parse(&x509, file, der, len)) == NULL)
		return NULL;

	a = valid_ski_aki(file, &auths, roa->ski, roa->aki);
	crl = crl_get(&crlt, a);

	if (!valid_x509(file, ctx, x509, a, crl, 0)) {
		X509_free(x509);
		roa_free(roa);
		return NULL;
	}
	X509_free(x509);

	roa->talid = a->cert->talid;

	/*
	 * Check CRL to figure out the soonest transitive expiry moment
	 */
	if (crl != NULL && roa->expires > crl->expires)
		roa->expires = crl->expires;

	/*
	 * Scan the cert tree to figure out the soonest transitive
	 * expiry moment
	 */
	for (; a != NULL; a = a->parent) {
		if (roa->expires > a->cert->expires)
			roa->expires = a->cert->expires;
	}

	return roa;
}

/*
 * Check all files and their hashes in a MFT structure.
 * Return zero on failure, non-zero on success.
 */
static int
proc_parser_mft_check(const char *fn, struct mft *p)
{
	const enum location loc[2] = { DIR_TEMP, DIR_VALID };
	size_t	 i;
	int	 rc = 1;
	char	*path;

	for (i = 0; i < p->filesz; i++) {
		struct mftfile *m = &p->files[i];
		int try, fd = -1, noent = 0, valid = 0;
		for (try = 0; try < 2 && !valid; try++) {
			if ((path = parse_filepath(p->repoid, p->path, m->file,
			    loc[try])) == NULL)
				continue;
			fd = open(path, O_RDONLY);
			if (fd == -1 && errno == ENOENT)
				noent++;
			free(path);

			/* remember which path was checked */
			m->location = loc[try];
			valid = valid_filehash(fd, m->hash, sizeof(m->hash));
		}

		if (!valid) {
			/* silently skip not-existing unknown files */
			if (m->type == RTYPE_INVALID && noent == 2)
				continue;
			warnx("%s: bad message digest for %s", fn, m->file);
			rc = 0;
			continue;
		}
	}

	return rc;
}

/*
 * Load the correct CRL using the info from the MFT.
 */
static struct crl *
parse_load_crl_from_mft(struct entity *entp, struct mft *mft, enum location loc)
{
	struct crl	*crl = NULL;
	unsigned char	*f = NULL;
	char		*fn = NULL;
	size_t		 flen;

	while (1) {
		fn = parse_filepath(entp->repoid, entp->path, mft->crl, loc);
		if (fn == NULL)
			goto next;

		f = load_file(fn, &flen);
		if (f == NULL && errno != ENOENT)
			warn("parse file %s", fn);
		if (f == NULL)
			goto next;
		if (!valid_hash(f, flen, mft->crlhash, sizeof(mft->crlhash)))
			goto next;
		crl = crl_parse(fn, f, flen);
next:
		free(f);
		free(fn);
		f = NULL;
		fn = NULL;

		if (crl != NULL)
			return crl;
		if (loc == DIR_TEMP)
			loc = DIR_VALID;
		else
			return NULL;
	}
}

/*
 * Parse and validate a manifest file. Skip checking the fileandhash
 * this is done in the post check. After this step we know the mft is
 * valid and can be compared.
 * Return the mft on success or NULL on failure.
 */
static struct mft *
proc_parser_mft_pre(char *file, const unsigned char *der, size_t len,
    struct entity *entp, enum location loc, struct crl **crl)
{
	struct mft	*mft;
	X509		*x509;
	struct auth	*a;

	*crl = NULL;
	if ((mft = mft_parse(&x509, file, der, len)) == NULL)
		return NULL;
	*crl = parse_load_crl_from_mft(entp, mft, loc);

	a = valid_ski_aki(file, &auths, mft->ski, mft->aki);
	if (!valid_x509(file, ctx, x509, a, *crl, 1)) {
		X509_free(x509);
		mft_free(mft);
		crl_free(*crl);
		*crl = NULL;
		return NULL;
	}
	X509_free(x509);

	mft->repoid = entp->repoid;
	return mft;
}

/*
 * Do the end of manifest validation.
 * Return the mft on success or NULL on failure.
 */
static struct mft *
proc_parser_mft_post(char *file, struct mft *mft, const char *path)
{
	/* check that now is not before from */
	time_t now = time(NULL);

	if (mft == NULL) {
		warnx("%s: no valid mft available", file);
		return NULL;
	}

	/* check that now is not before from */
	if (now < mft->valid_since) {
		warnx("%s: mft not yet valid %s", file,
		    time2str(mft->valid_since));
		mft->stale = 1;
	}
	/* check that now is not after until */
	if (now > mft->valid_until) {
		warnx("%s: mft expired on %s", file,
		    time2str(mft->valid_until));
		mft->stale = 1;
	}

	if (path != NULL)
		if ((mft->path = strdup(path)) == NULL)
			err(1, NULL);

	if (!mft->stale)
		if (!proc_parser_mft_check(file, mft)) {
			mft_free(mft);
			return NULL;
		}

	return mft;
}

/*
 * Load the most recent MFT by opening both options and comparing the two.
 */
static char *
proc_parser_mft(struct entity *entp, struct mft **mp)
{
	struct mft	*mft1 = NULL, *mft2 = NULL;
	struct crl	*crl, *crl1 = NULL, *crl2 = NULL;
	char		*f, *file, *file1, *file2;
	size_t		 flen;

	*mp = NULL;
	file1 = parse_filepath(entp->repoid, entp->path, entp->file, DIR_VALID);
	file2 = parse_filepath(entp->repoid, entp->path, entp->file, DIR_TEMP);

	if (file1 != NULL) {
		f = load_file(file1, &flen);
		if (f == NULL && errno != ENOENT)
			warn("parse file %s", file1);
		mft1 = proc_parser_mft_pre(file1, f, flen, entp, DIR_VALID,
		    &crl1);
		free(f);
	}
	if (file2 != NULL) {
		f = load_file(file2, &flen);
		if (f == NULL && errno != ENOENT)
			warn("parse file %s", file2);
		mft2 = proc_parser_mft_pre(file2, f, flen, entp, DIR_TEMP,
		    &crl2);
		free(f);
	}

	if (mft_compare(mft1, mft2) == 1) {
		mft_free(mft2);
		crl_free(crl2);
		free(file2);
		*mp = proc_parser_mft_post(file1, mft1, entp->path);
		crl = crl1;
		file = file1;
	} else {
		mft_free(mft1);
		crl_free(crl1);
		free(file1);
		*mp = proc_parser_mft_post(file2, mft2, entp->path);
		crl = crl2;
		file = file2;
	}

	if (*mp != NULL) {
		if (!crl_insert(&crlt, crl)) {
			warnx("%s: duplicate AKI %s", file, crl->aki);
			crl_free(crl);
		}
	} else {
		crl_free(crl);
	}
	return file;
}

/*
 * Certificates are from manifests (has a digest and is signed with
 * another certificate) Parse the certificate, make sure its
 * signatures are valid (with CRLs), then validate the RPKI content.
 * This returns a certificate (which must not be freed) or NULL on
 * parse failure.
 */
static struct cert *
proc_parser_cert(char *file, const unsigned char *der, size_t len)
{
	struct cert	*cert;
	struct crl	*crl;
	struct auth	*a;

	/* Extract certificate data. */

	cert = cert_parse_pre(file, der, len);
	cert = cert_parse(file, cert);
	if (cert == NULL)
		return NULL;

	a = valid_ski_aki(file, &auths, cert->ski, cert->aki);
	crl = crl_get(&crlt, a);

	if (!valid_x509(file, ctx, cert->x509, a, crl, 0) ||
	    !valid_cert(file, a, cert)) {
		cert_free(cert);
		return NULL;
	}

	cert->talid = a->cert->talid;

	/*
	 * Add validated CA certs to the RPKI auth tree.
	 */
	if (cert->purpose == CERT_PURPOSE_CA)
		auth_insert(&auths, cert, a);

	return cert;
}

/*
 * Root certificates come from TALs (has a pkey and is self-signed).
 * Parse the certificate, ensure that its public key matches the
 * known public key from the TAL, and then validate the RPKI
 * content.
 *
 * This returns a certificate (which must not be freed) or NULL on
 * parse failure.
 */
static struct cert *
proc_parser_root_cert(char *file, const unsigned char *der, size_t len,
    unsigned char *pkey, size_t pkeysz, int talid)
{
	struct cert		*cert;

	/* Extract certificate data. */

	cert = cert_parse_pre(file, der, len);
	cert = ta_parse(file, cert, pkey, pkeysz);
	if (cert == NULL)
		return NULL;

	if (!valid_ta(file, &auths, cert)) {
		warnx("%s: certificate not a valid ta", file);
		cert_free(cert);
		return NULL;
	}

	cert->talid = talid;

	/*
	 * Add valid roots to the RPKI auth tree.
	 */
	auth_insert(&auths, cert, NULL);

	return cert;
}

/*
 * Parse a ghostbuster record
 */
static void
proc_parser_gbr(char *file, const unsigned char *der, size_t len)
{
	struct gbr		*gbr;
	X509			*x509;
	struct crl		*crl;
	struct auth		*a;

	if ((gbr = gbr_parse(&x509, file, der, len)) == NULL)
		return;

	a = valid_ski_aki(file, &auths, gbr->ski, gbr->aki);
	crl = crl_get(&crlt, a);

	/* return value can be ignored since nothing happens here */
	valid_x509(file, ctx, x509, a, crl, 0);

	X509_free(x509);
	gbr_free(gbr);
}

/*
 * Parse an ASPA object
 */
static struct aspa *
proc_parser_aspa(char *file, const unsigned char *der, size_t len)
{
	struct aspa		*aspa;
	struct auth		*a;
	struct crl		*crl;
	X509			*x509;

	if ((aspa = aspa_parse(&x509, file, der, len)) == NULL)
		return NULL;

	a = valid_ski_aki(file, &auths, aspa->ski, aspa->aki);
	crl = crl_get(&crlt, a);

	if (!valid_x509(file, ctx, x509, a, crl, 0)) {
		X509_free(x509);
		aspa_free(aspa);
		return NULL;
	}
	X509_free(x509);

	aspa->talid = a->cert->talid;

	if (crl != NULL && aspa->expires > crl->expires)
		aspa->expires = crl->expires;

	for (; a != NULL; a = a->parent) {
		if (aspa->expires > a->cert->expires)
			aspa->expires = a->cert->expires;
	}

	return aspa;
}

/*
 * Load the file specified by the entity information.
 */
static char *
parse_load_file(struct entity *entp, unsigned char **f, size_t *flen)
{
	char *file;

	file = parse_filepath(entp->repoid, entp->path, entp->file,
	    entp->location);
	if (file == NULL)
		errx(1, "no path to file");

	*f = load_file(file, flen);
	if (*f == NULL)
		warn("parse file %s", file);

	return file;
}

/*
 * Process an entity and responing to parent process.
 */
static void
parse_entity(struct entityq *q, struct msgbuf *msgq)
{
	struct entity	*entp;
	struct tal	*tal;
	struct cert	*cert;
	struct mft	*mft;
	struct roa	*roa;
	struct aspa	*aspa;
	struct ibuf	*b;
	unsigned char	*f;
	size_t		 flen;
	char		*file;
	int		 c;

	while ((entp = TAILQ_FIRST(q)) != NULL) {
		TAILQ_REMOVE(q, entp, entries);

		/* handle RTYPE_REPO first */
		if (entp->type == RTYPE_REPO) {
			repo_add(entp->repoid, entp->path, entp->file);
			entity_free(entp);
			continue;
		}

		/* pass back at least type, repoid and filename */
		b = io_new_buffer();
		io_simple_buffer(b, &entp->type, sizeof(entp->type));

		file = NULL;
		f = NULL;
		switch (entp->type) {
		case RTYPE_TAL:
			io_str_buffer(b, entp->file);
			if ((tal = tal_parse(entp->file, entp->data,
			    entp->datasz)) == NULL)
				errx(1, "%s: could not parse tal file",
				    entp->file);
			tal->id = entp->talid;
			tal_buffer(b, tal);
			tal_free(tal);
			break;
		case RTYPE_CER:
			file = parse_load_file(entp, &f, &flen);
			io_str_buffer(b, file);
			if (entp->data != NULL)
				cert = proc_parser_root_cert(file,
				    f, flen, entp->data, entp->datasz,
				    entp->talid);
			else
				cert = proc_parser_cert(file, f, flen);
			c = (cert != NULL);
			io_simple_buffer(b, &c, sizeof(int));
			if (cert != NULL) {
				cert->repoid = entp->repoid;
				cert_buffer(b, cert);
			}
			/*
			 * The parsed certificate data "cert" is now
			 * managed in the "auths" table, so don't free
			 * it here.
			 */
			break;
		case RTYPE_CRL:
			/*
			 * CRLs are already loaded with the MFT so nothing
			 * really needs to be done here.
			 */
			file = parse_filepath(entp->repoid, entp->path,
			    entp->file, entp->location);
			io_str_buffer(b, file);
			break;
		case RTYPE_MFT:
			file = proc_parser_mft(entp, &mft);
			io_str_buffer(b, file);
			c = (mft != NULL);
			io_simple_buffer(b, &c, sizeof(int));
			if (mft != NULL)
				mft_buffer(b, mft);
			mft_free(mft);
			break;
		case RTYPE_ROA:
			file = parse_load_file(entp, &f, &flen);
			io_str_buffer(b, file);
			roa = proc_parser_roa(file, f, flen);
			c = (roa != NULL);
			io_simple_buffer(b, &c, sizeof(int));
			if (roa != NULL)
				roa_buffer(b, roa);
			roa_free(roa);
			break;
		case RTYPE_GBR:
			file = parse_load_file(entp, &f, &flen);
			io_str_buffer(b, file);
			proc_parser_gbr(file, f, flen);
			break;
		case RTYPE_ASPA:
			file = parse_load_file(entp, &f, &flen);
			io_str_buffer(b, file);
			aspa = proc_parser_aspa(file, f, flen);
			c = (aspa != NULL);
			io_simple_buffer(b, &c, sizeof(int));
			if (aspa != NULL)
				aspa_buffer(b, aspa);
			aspa_free(aspa);
			break;
		default:
			errx(1, "unhandled entity type %d", entp->type);
		}

		free(f);
		free(file);
		io_close_buffer(msgq, b);
		entity_free(entp);
	}
}

/*
 * Process responsible for parsing and validating content.
 * All this process does is wait to be told about a file to parse, then
 * it parses it and makes sure that the data being returned is fully
 * validated and verified.
 * The process will exit cleanly only when fd is closed.
 */
void
proc_parser(int fd)
{
	struct entityq	 q;
	struct msgbuf	 msgq;
	struct pollfd	 pfd;
	struct entity	*entp;
	struct ibuf	*b, *inbuf = NULL;

	/* Only allow access to the cache directory. */
	if (unveil(".", "r") == -1)
		err(1, "unveil cachedir");
	if (pledge("stdio rpath", NULL) == -1)
		err(1, "pledge");

	ERR_load_crypto_strings();
	OpenSSL_add_all_ciphers();
	OpenSSL_add_all_digests();
	x509_init_oid();

	if ((ctx = X509_STORE_CTX_new()) == NULL)
		cryptoerrx("X509_STORE_CTX_new");

	TAILQ_INIT(&q);

	msgbuf_init(&msgq);
	msgq.fd = fd;

	pfd.fd = fd;

	for (;;) {
		pfd.events = POLLIN;
		if (msgq.queued)
			pfd.events |= POLLOUT;

		if (poll(&pfd, 1, INFTIM) == -1) {
			if (errno == EINTR)
				continue;
			err(1, "poll");
		}
		if ((pfd.revents & (POLLERR|POLLNVAL)))
			errx(1, "poll: bad descriptor");

		/* If the parent closes, return immediately. */

		if ((pfd.revents & POLLHUP))
			break;

		if ((pfd.revents & POLLIN)) {
			b = io_buf_read(fd, &inbuf);
			if (b != NULL) {
				entp = calloc(1, sizeof(struct entity));
				if (entp == NULL)
					err(1, NULL);
				entity_read_req(b, entp);
				TAILQ_INSERT_TAIL(&q, entp, entries);
				ibuf_free(b);
			}
		}

		if (pfd.revents & POLLOUT) {
			switch (msgbuf_write(&msgq)) {
			case 0:
				errx(1, "write: connection closed");
			case -1:
				err(1, "write");
			}
		}

		parse_entity(&q, &msgq);
	}

	while ((entp = TAILQ_FIRST(&q)) != NULL) {
		TAILQ_REMOVE(&q, entp, entries);
		entity_free(entp);
	}

	auth_tree_free(&auths);
	crl_tree_free(&crlt);

	X509_STORE_CTX_free(ctx);
	msgbuf_clear(&msgq);

	ibuf_free(inbuf);

	exit(0);
}