diff options
Diffstat (limited to 'src/libknot/cookies.c')
| -rw-r--r-- | src/libknot/cookies.c | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/src/libknot/cookies.c b/src/libknot/cookies.c new file mode 100644 index 0000000..e7b3354 --- /dev/null +++ b/src/libknot/cookies.c @@ -0,0 +1,170 @@ +/* Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz> + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. + */ + +#include <assert.h> +#include <stdbool.h> + +#include "libknot/attribute.h" +#include "libknot/cookies.h" +#include "libknot/endian.h" +#include "libknot/errcode.h" +#include "contrib/string.h" +#include "contrib/sockaddr.h" +#include "contrib/openbsd/siphash.h" + +_public_ +int knot_edns_cookie_client_generate(knot_edns_cookie_t *out, + const knot_edns_cookie_params_t *params) +{ + if (out == NULL || params == NULL || params->server_addr == NULL) { + return KNOT_EINVAL; + } + + SIPHASH_CTX ctx; + assert(sizeof(params->secret) == sizeof(SIPHASH_KEY)); + SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret); + + size_t addr_len = 0; + void *addr = sockaddr_raw(params->server_addr, &addr_len); + assert(addr); + SipHash24_Update(&ctx, addr, addr_len); + + uint64_t hash = SipHash24_End(&ctx); + memcpy(out->data, &hash, sizeof(hash)); + out->len = sizeof(hash); + + return KNOT_EOK; +} + +_public_ +int knot_edns_cookie_client_check(const knot_edns_cookie_t *cc, + const knot_edns_cookie_params_t *params) +{ + if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE) { + return KNOT_EINVAL; + } + + knot_edns_cookie_t ref; + int ret = knot_edns_cookie_client_generate(&ref, params); + if (ret != KNOT_EOK) { + return ret; + } + assert(ref.len == KNOT_EDNS_COOKIE_CLNT_SIZE); + + ret = const_time_memcmp(cc->data, ref.data, KNOT_EDNS_COOKIE_CLNT_SIZE); + if (ret != 0) { + return KNOT_EINVAL; + } + + return KNOT_EOK; +} + +static int cookie_server_generate(knot_edns_cookie_t *out, + const knot_edns_cookie_t *cc, + const knot_edns_cookie_params_t *params) +{ + assert(out && params); + + if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE || + params->client_addr == NULL) { + return KNOT_EINVAL; + } else if (out->data[0] != KNOT_EDNS_COOKIE_VERSION) { + return KNOT_ENOTSUP; + } + + SIPHASH_CTX ctx; + assert(sizeof(params->secret) == sizeof(SIPHASH_KEY)); + SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret); + + SipHash24_Update(&ctx, cc->data, cc->len); + SipHash24_Update(&ctx, out->data, out->len); + + size_t addr_len = 0; + void *addr = sockaddr_raw(params->client_addr, &addr_len); + assert(addr); + SipHash24_Update(&ctx, addr, addr_len); + + uint64_t hash = SipHash24_End(&ctx); + memcpy(out->data + out->len, &hash, sizeof(hash)); + out->len += sizeof(hash); + + return KNOT_EOK; + +} + +_public_ +int knot_edns_cookie_server_generate(knot_edns_cookie_t *out, + const knot_edns_cookie_t *cc, + const knot_edns_cookie_params_t *params) +{ + if (out == NULL || params == NULL) { + return KNOT_EINVAL; + } + + out->data[0] = params->version; + out->data[1] = 0; /* reserved */ + out->data[2] = 0; /* reserved */ + out->data[3] = 0; /* reserved */ + out->len = 4; + + uint32_t now = htobe32(params->timestamp); + memcpy(&out->data[out->len], &now, sizeof(now)); + out->len += sizeof(now); + + return cookie_server_generate(out, cc, params); +} + +_public_ +int knot_edns_cookie_server_check(const knot_edns_cookie_t *sc, + const knot_edns_cookie_t *cc, + const knot_edns_cookie_params_t *params) +{ + if (sc == NULL || sc->len < KNOT_EDNS_COOKIE_SRVR_MIN_SIZE || params == NULL) { + return KNOT_EINVAL; + } + + uint32_t cookie_time; + memcpy(&cookie_time, &sc->data[4], sizeof(cookie_time)); + cookie_time = be32toh(cookie_time); + + uint32_t min_time = params->timestamp - params->lifetime_before; + uint32_t max_time = params->timestamp + params->lifetime_after; + if (cookie_time < min_time || cookie_time > max_time) { + return KNOT_ERANGE; + } + + const int fixed_len = 8; + knot_edns_cookie_t ref; + memcpy(ref.data, sc->data, fixed_len); + ref.len = fixed_len; + + int ret = cookie_server_generate(&ref, cc, params); + if (ret != KNOT_EOK) { + return ret; + } + + if (sc->len != ref.len) { + return KNOT_EINVAL; + } + + ret = const_time_memcmp(sc->data + fixed_len, ref.data + fixed_len, + sc->len - fixed_len); + if (ret != 0) { + return KNOT_EINVAL; + } + + return KNOT_EOK; +} |