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-rw-r--r--src/libknot/xdp/tcp_iobuf.c266
1 files changed, 266 insertions, 0 deletions
diff --git a/src/libknot/xdp/tcp_iobuf.c b/src/libknot/xdp/tcp_iobuf.c
new file mode 100644
index 0000000..88ebcc3
--- /dev/null
+++ b/src/libknot/xdp/tcp_iobuf.c
@@ -0,0 +1,266 @@
+/* Copyright (C) 2022 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 <stdlib.h>
+#include <string.h>
+
+#include "libknot/xdp/tcp_iobuf.h"
+
+#include "contrib/macros.h"
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/error.h"
+
+static void iov_clear(struct iovec *iov)
+{
+ free(iov->iov_base);
+ memset(iov, 0, sizeof(*iov));
+}
+
+static void iov_inc(struct iovec *iov, size_t shift)
+{
+ assert(shift <= iov->iov_len);
+ iov->iov_base += shift;
+ iov->iov_len -= shift;
+}
+
+/*! \brief Strip 2-byte length prefix from a payload. */
+static void iov_inc2(struct iovec *iov)
+{
+ iov_inc(iov, sizeof(uint16_t));
+}
+
+static size_t tcp_payload_len(const struct iovec *payload)
+{
+ assert(payload->iov_len >= 2);
+ uint16_t val;
+ memcpy(&val, payload->iov_base, sizeof(val));
+ return be16toh(val) + sizeof(val);
+}
+
+static bool iov_inc_pf(struct iovec *iov)
+{
+ size_t shift = tcp_payload_len(iov);
+ if (iov->iov_len >= shift) {
+ iov_inc(iov, shift);
+ return true;
+ } else {
+ return false;
+ }
+}
+
+static size_t iov_count(const struct iovec *iov)
+{
+ size_t res = 0;
+ struct iovec tmp = *iov;
+ while (tmp.iov_len >= sizeof(uint16_t) && iov_inc_pf(&tmp)) {
+ res++;
+ }
+ return res;
+}
+
+static void iov_append(struct iovec *what, const struct iovec *with)
+{
+ // NOTE: what->iov_base must be pre-allocated large enough
+ memcpy(what->iov_base + what->iov_len, with->iov_base, with->iov_len);
+ what->iov_len += with->iov_len;
+}
+
+_public_
+int knot_tcp_inbuf_update(struct iovec *buffer, struct iovec data,
+ struct iovec **inbufs, size_t *inbufs_count,
+ size_t *buffers_total)
+{
+ size_t res_count = 0;
+ struct iovec *res = NULL, *cur = NULL;
+
+ *inbufs = NULL;
+ *inbufs_count = 0;
+
+ if (data.iov_len < 1) {
+ return KNOT_EOK;
+ }
+ if (buffer->iov_len == 1) {
+ ((uint8_t *)buffer->iov_base)[1] = ((uint8_t *)data.iov_base)[0];
+ buffer->iov_len++;
+ iov_inc(&data, 1);
+ if (data.iov_len < 1) {
+ return KNOT_EOK;
+ }
+ }
+ if (buffer->iov_len > 0) {
+ size_t buffer_req = tcp_payload_len(buffer);
+ assert(buffer_req > buffer->iov_len);
+ struct iovec data_use = { data.iov_base, buffer_req - buffer->iov_len };
+ if (data_use.iov_len <= data.iov_len) { // usable payload combined from buffer and data ---> res[0] allocated tohether with res
+ iov_inc(&data, data_use.iov_len);
+
+ res_count = 1 + iov_count(&data);
+ res = malloc(res_count * sizeof(*res) + buffer_req);
+ if (res == NULL) {
+ return KNOT_ENOMEM;
+ }
+ res[0].iov_base = (void *)(res + res_count);
+ res[0].iov_len = 0;
+ iov_append(&res[0], buffer);
+ iov_append(&res[0], &data_use);
+ assert(res[0].iov_len == buffer_req);
+ iov_inc2(&res[0]);
+
+ cur = &res[1];
+ *buffers_total -= buffer->iov_len;
+ iov_clear(buffer);
+ } else { // just extend the buffer with data
+ void *bufnew = realloc(buffer->iov_base, buffer->iov_len + data.iov_len);
+ if (bufnew == NULL) {
+ return KNOT_ENOMEM;
+ }
+ buffer->iov_base = bufnew;
+ iov_append(buffer, &data);
+ *buffers_total += data.iov_len;
+ return KNOT_EOK;
+ }
+ } else { // just allocate res
+ res_count = iov_count(&data);
+ if (res_count > 0) {
+ res = malloc(res_count * sizeof(*res));
+ if (res == NULL) {
+ return KNOT_ENOMEM;
+ }
+ cur = &res[0];
+ }
+ }
+
+ void *last;
+ while (data.iov_len > 1) {
+ last = data.iov_base;
+ if (!iov_inc_pf(&data)) {
+ break;
+ }
+ assert(cur);
+ cur->iov_base = last;
+ cur->iov_len = data.iov_base - last;
+ iov_inc2(cur);
+ cur++;
+ }
+ assert(cur == ((res_count) ? res + res_count : res));
+
+ // store the final incomplete payload to buffer
+ if (data.iov_len > 0) {
+ assert(buffer->iov_base == NULL);
+ buffer->iov_base = malloc(MAX(data.iov_len, 2));
+ if (buffer->iov_base == NULL) {
+ free(res);
+ return KNOT_ENOMEM;
+ }
+ *buffers_total += MAX(data.iov_len, 2);
+ buffer->iov_len = 0;
+ iov_append(buffer, &data);
+ }
+
+ *inbufs = res;
+ *inbufs_count = res_count;
+
+ return KNOT_EOK;
+}
+
+_public_
+int knot_tcp_outbufs_add(knot_tcp_outbuf_t **bufs, uint8_t *data, size_t len,
+ bool ignore_lastbyte, uint32_t mss, size_t *outbufs_total)
+{
+ if (len > UINT16_MAX) {
+ return KNOT_ELIMIT;
+ }
+ knot_tcp_outbuf_t **end = bufs;
+ while (*end != NULL) { // NOTE: this can be optimized by adding "end" pointer for the price of larger knot_tcp_conn_t struct
+ end = &(*end)->next;
+ }
+ uint16_t prefix = htobe16(len), prefix_len = sizeof(prefix);
+ while (len > 0) {
+ uint16_t newlen = MIN(len + prefix_len, mss);
+ knot_tcp_outbuf_t *newob = calloc(1, sizeof(*newob) + newlen);
+ if (newob == NULL) {
+ return KNOT_ENOMEM;
+ }
+ *outbufs_total += sizeof(*newob) + newlen;
+ newob->len = newlen;
+ if (ignore_lastbyte) {
+ newob->len--;
+ }
+ memcpy(newob->bytes, &prefix, prefix_len);
+ memcpy(newob->bytes + prefix_len, data, newlen - prefix_len);
+
+ *end = newob;
+ end = &newob->next;
+
+ data += newlen - prefix_len;
+ len -= newlen - prefix_len;
+
+ prefix_len = 0;
+ }
+ return KNOT_EOK;
+}
+
+static bool seqno_lower(uint32_t seqno, uint32_t ackno, uint32_t ackno_min)
+{
+ if (ackno_min <= ackno) {
+ return (seqno >= ackno_min && seqno <= ackno);
+ } else {
+ return (seqno >= ackno_min || seqno <= ackno);
+ }
+}
+
+_public_
+void knot_tcp_outbufs_ack(knot_tcp_outbuf_t **bufs, uint32_t ackno, size_t *outbufs_total)
+{
+ uint32_t ackno_min = ackno - (UINT32_MAX / 2); // FIXME better?
+ while (*bufs != NULL && (*bufs)->sent && seqno_lower((*bufs)->seqno + (*bufs)->len, ackno, ackno_min)) {
+ knot_tcp_outbuf_t *tofree = *bufs;
+ *bufs = tofree->next;
+ *outbufs_total -= tofree->len + sizeof(*tofree);
+ free(tofree);
+ }
+}
+
+_public_
+void knot_tcp_outbufs_can_send(knot_tcp_outbuf_t *bufs, ssize_t window_size, bool resend,
+ knot_tcp_outbuf_t **send_start, size_t *send_count)
+{
+ *send_count = 0;
+ *send_start = bufs;
+ while (*send_start != NULL && (*send_start)->sent && !resend) {
+ window_size -= (*send_start)->len;
+ *send_start = (*send_start)->next;
+ }
+
+ knot_tcp_outbuf_t *can_send = *send_start;
+ while (can_send != NULL && window_size >= can_send->len) {
+ (*send_count)++;
+ window_size -= can_send->len;
+ can_send = can_send->next;
+ }
+}
+
+_public_
+size_t knot_tcp_outbufs_usage(knot_tcp_outbuf_t *bufs)
+{
+ size_t res = 0;
+ for (knot_tcp_outbuf_t *i = bufs; i != NULL; i = i->next) {
+ res += i->len + sizeof(*i);
+ }
+ return res;
+}
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