diff --git a/contrib/opentracing/src/event.c b/contrib/opentracing/src/event.c
new file mode 100644
index 0000000..90b5828
--- /dev/null
+++ b/contrib/opentracing/src/event.c
@@ -0,0 +1,332 @@
+/***
+ * Copyright 2020 HAProxy Technologies
+ *
+ * This file is part of the HAProxy OpenTracing filter.
+ *
+ * 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 2
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#include "include.h"
+
+
+#define FLT_OT_EVENT_DEF(a,b,c,d,e,f)   { AN_##b##_##a, SMP_OPT_DIR_##b, SMP_VAL_FE_##c, SMP_VAL_BE_##d, e, f },
+const struct flt_ot_event_data flt_ot_event_data[FLT_OT_EVENT_MAX] = { FLT_OT_EVENT_DEFINES };
+#undef FLT_OT_EVENT_DEF
+
+
+/***
+ * NAME
+ *   flt_ot_scope_run_span -
+ *
+ * ARGUMENTS
+ *   s         -
+ *   f         -
+ *   chn       -
+ *   dir       -
+ *   span      -
+ *   data      -
+ *   conf_span -
+ *   ts        -
+ *   err       -
+ *
+ * DESCRIPTION
+ *   -
+ *
+ * RETURN VALUE
+ *   Returns a negative value if an error occurs, 0 if it needs to wait,
+ *   any other value otherwise.
+ */
+static int flt_ot_scope_run_span(struct stream *s, struct filter *f, struct channel *chn, uint dir, struct flt_ot_scope_span *span, struct flt_ot_scope_data *data, const struct flt_ot_conf_span *conf_span, const struct timespec *ts, char **err)
+{
+	struct flt_ot_conf *conf = FLT_OT_CONF(f);
+	int                 retval = FLT_OT_RET_OK;
+
+	FLT_OT_FUNC("%p, %p, %p, %u, %p, %p, %p, %p, %p:%p", s, f, chn, dir, span, data, conf_span, ts, FLT_OT_DPTR_ARGS(err));
+
+	if (span == NULL)
+		FLT_OT_RETURN(retval);
+
+	if (span->span == NULL) {
+		span->span = ot_span_init(conf->tracer->tracer, span->id, ts, NULL, span->ref_type, FLT_OT_DEREF(span->ref_ctx, idx, -1), span->ref_span, data->tags, data->num_tags, err);
+		if (span->span == NULL)
+			retval = FLT_OT_RET_ERROR;
+	}
+	else if (data->num_tags > 0)
+		if (ot_span_tag(span->span, data->tags, data->num_tags) == -1)
+			retval = FLT_OT_RET_ERROR;
+
+	if ((span->span != NULL) && (data->baggage != NULL))
+		if (ot_span_set_baggage(span->span, data->baggage) == -1)
+			retval = FLT_OT_RET_ERROR;
+
+	if ((span->span != NULL) && (data->num_log_fields > 0))
+		if (ot_span_log(span->span, data->log_fields, data->num_log_fields) == -1)
+			retval = FLT_OT_RET_ERROR;
+
+	if ((span->span != NULL) && (conf_span->ctx_id != NULL)) {
+		struct otc_http_headers_writer  writer;
+		struct otc_text_map            *text_map = NULL;
+		struct otc_span_context        *span_ctx;
+
+		span_ctx = ot_inject_http_headers(conf->tracer->tracer, span->span, &writer, err);
+		if (span_ctx != NULL) {
+			int i = 0;
+
+			if (conf_span->ctx_flags & (FLT_OT_CTX_USE_VARS | FLT_OT_CTX_USE_HEADERS)) {
+				for (text_map = &(writer.text_map); i < text_map->count; i++) {
+					if (!(conf_span->ctx_flags & FLT_OT_CTX_USE_VARS))
+						/* Do nothing. */;
+					else if (flt_ot_var_register(FLT_OT_VARS_SCOPE, conf_span->ctx_id, text_map->key[i], err) == -1)
+						retval = FLT_OT_RET_ERROR;
+					else if (flt_ot_var_set(s, FLT_OT_VARS_SCOPE, conf_span->ctx_id, text_map->key[i], text_map->value[i], dir, err) == -1)
+						retval = FLT_OT_RET_ERROR;
+
+					if (!(conf_span->ctx_flags & FLT_OT_CTX_USE_HEADERS))
+						/* Do nothing. */;
+					else if (flt_ot_http_header_set(chn, conf_span->ctx_id, text_map->key[i], text_map->value[i], err) == -1)
+						retval = FLT_OT_RET_ERROR;
+				}
+			}
+
+			span_ctx->destroy(&span_ctx);
+			otc_text_map_destroy(&text_map, OTC_TEXT_MAP_FREE_KEY | OTC_TEXT_MAP_FREE_VALUE);
+		}
+	}
+
+	FLT_OT_RETURN(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_ot_scope_run -
+ *
+ * ARGUMENTS
+ *   s          -
+ *   f          -
+ *   chn        -
+ *   conf_scope -
+ *   ts         -
+ *   dir        -
+ *   err        -
+ *
+ * DESCRIPTION
+ *   -
+ *
+ * RETURN VALUE
+ *   Returns a negative value if an error occurs, 0 if it needs to wait,
+ *   any other value otherwise.
+ */
+int flt_ot_scope_run(struct stream *s, struct filter *f, struct channel *chn, struct flt_ot_conf_scope *conf_scope, const struct timespec *ts, uint dir, char **err)
+{
+	struct flt_ot_conf         *conf = FLT_OT_CONF(f);
+	struct flt_ot_conf_context *conf_ctx;
+	struct flt_ot_conf_span    *conf_span;
+	struct flt_ot_conf_str     *finish;
+	struct timespec             ts_now;
+	int                         retval = FLT_OT_RET_OK;
+
+	FLT_OT_FUNC("%p, %p, %p, %p, %p, %u, %p:%p", s, f, chn, conf_scope, ts, dir, FLT_OT_DPTR_ARGS(err));
+
+	FLT_OT_DBG(3, "channel: %s, mode: %s (%s)", flt_ot_chn_label(chn), flt_ot_pr_mode(s), flt_ot_stream_pos(s));
+	FLT_OT_DBG(3, "run scope '%s' %d", conf_scope->id, conf_scope->event);
+	FLT_OT_DBG_CONF_SCOPE("run scope ", conf_scope);
+
+	if (ts == NULL) {
+		(void)clock_gettime(CLOCK_MONOTONIC, &ts_now);
+
+		ts = &ts_now;
+	}
+
+	if (conf_scope->cond != NULL) {
+		enum acl_test_res res;
+		int               rc;
+
+		res = acl_exec_cond(conf_scope->cond, s->be, s->sess, s, dir | SMP_OPT_FINAL);
+		rc  = acl_pass(res);
+		if (conf_scope->cond->pol == ACL_COND_UNLESS)
+			rc = !rc;
+
+		FLT_OT_DBG(3, "the ACL rule %s", rc ? "matches" : "does not match");
+
+		/*
+		 * If the rule does not match, the current scope is skipped.
+		 *
+		 * If it is a root span, further processing of the session is
+		 * disabled.  As soon as the first span is encountered which
+		 * is marked as root, further search is interrupted.
+		 */
+		if (!rc) {
+			list_for_each_entry(conf_span, &(conf_scope->spans), list)
+				if (conf_span->flag_root) {
+					FLT_OT_DBG(0, "session disabled");
+
+					FLT_OT_RT_CTX(f->ctx)->flag_disabled = 1;
+
+					_HA_ATOMIC_ADD(conf->cnt.disabled + 0, 1);
+
+					break;
+				}
+
+			FLT_OT_RETURN(retval);
+		}
+	}
+
+	list_for_each_entry(conf_ctx, &(conf_scope->contexts), list) {
+		struct otc_text_map *text_map;
+
+		FLT_OT_DBG(3, "run context '%s' -> '%s'", conf_scope->id, conf_ctx->id);
+		FLT_OT_DBG_CONF_CONTEXT("run context ", conf_ctx);
+
+		/*
+		 * The OpenTracing context is read from the HTTP header
+		 * or from HAProxy variables.
+		 */
+		if (conf_ctx->flags & FLT_OT_CTX_USE_HEADERS)
+			text_map = flt_ot_http_headers_get(chn, conf_ctx->id, conf_ctx->id_len, err);
+		else
+			text_map = flt_ot_vars_get(s, FLT_OT_VARS_SCOPE, conf_ctx->id, dir, err);
+
+		if (text_map != NULL) {
+			if (flt_ot_scope_context_init(f->ctx, conf->tracer->tracer, conf_ctx->id, conf_ctx->id_len, text_map, dir, err) == NULL)
+				retval = FLT_OT_RET_ERROR;
+
+			otc_text_map_destroy(&text_map, OTC_TEXT_MAP_FREE_KEY | OTC_TEXT_MAP_FREE_VALUE);
+		} else {
+			retval = FLT_OT_RET_ERROR;
+		}
+	}
+
+	list_for_each_entry(conf_span, &(conf_scope->spans), list) {
+		struct flt_ot_scope_data   data;
+		struct flt_ot_scope_span  *span;
+		struct flt_ot_conf_sample *sample;
+
+		FLT_OT_DBG(3, "run span '%s' -> '%s'", conf_scope->id, conf_span->id);
+		FLT_OT_DBG_CONF_SPAN("run span ", conf_span);
+
+		(void)memset(&data, 0, sizeof(data));
+
+		span = flt_ot_scope_span_init(f->ctx, conf_span->id, conf_span->id_len, conf_span->ref_type, conf_span->ref_id, conf_span->ref_id_len, dir, err);
+		if (span == NULL)
+			retval = FLT_OT_RET_ERROR;
+
+		list_for_each_entry(sample, &(conf_span->tags), list) {
+			FLT_OT_DBG(3, "adding tag '%s' -> '%s'", sample->key, sample->value);
+
+			if (flt_ot_sample_add(s, dir, sample, &data, FLT_OT_EVENT_SAMPLE_TAG, err) == FLT_OT_RET_ERROR)
+				retval = FLT_OT_RET_ERROR;
+		}
+
+		list_for_each_entry(sample, &(conf_span->logs), list) {
+			FLT_OT_DBG(3, "adding log '%s' -> '%s'", sample->key, sample->value);
+
+			if (flt_ot_sample_add(s, dir, sample, &data, FLT_OT_EVENT_SAMPLE_LOG, err) == FLT_OT_RET_ERROR)
+				retval = FLT_OT_RET_ERROR;
+		}
+
+		list_for_each_entry(sample, &(conf_span->baggages), list) {
+			FLT_OT_DBG(3, "adding baggage '%s' -> '%s'", sample->key, sample->value);
+
+			if (flt_ot_sample_add(s, dir, sample, &data, FLT_OT_EVENT_SAMPLE_BAGGAGE, err) == FLT_OT_RET_ERROR)
+				retval = FLT_OT_RET_ERROR;
+		}
+
+		if (retval != FLT_OT_RET_ERROR)
+			if (flt_ot_scope_run_span(s, f, chn, dir, span, &data, conf_span, ts, err) == FLT_OT_RET_ERROR)
+				retval = FLT_OT_RET_ERROR;
+
+		flt_ot_scope_data_free(&data);
+	}
+
+	list_for_each_entry(finish, &(conf_scope->finish), list)
+		if (flt_ot_scope_finish_mark(f->ctx, finish->str, finish->str_len) == -1)
+			retval = FLT_OT_RET_ERROR;
+
+	flt_ot_scope_finish_marked(f->ctx, ts);
+	flt_ot_scope_free_unused(f->ctx, chn);
+
+	FLT_OT_RETURN(retval);
+}
+
+
+/***
+ * NAME
+ *   flt_ot_event_run -
+ *
+ * ARGUMENTS
+ *   s     -
+ *   f     -
+ *   chn   -
+ *   event -
+ *   err   -
+ *
+ * DESCRIPTION
+ *   -
+ *
+ * RETURN VALUE
+ *   Returns a negative value if an error occurs, 0 if it needs to wait,
+ *   any other value otherwise.
+ */
+int flt_ot_event_run(struct stream *s, struct filter *f, struct channel *chn, int event, char **err)
+{
+	struct flt_ot_conf       *conf = FLT_OT_CONF(f);
+	struct flt_ot_conf_scope *conf_scope;
+	struct timespec           ts;
+	int                       retval = FLT_OT_RET_OK;
+
+	FLT_OT_FUNC("%p, %p, %p, %d, %p:%p", s, f, chn, event, FLT_OT_DPTR_ARGS(err));
+
+	FLT_OT_DBG(3, "channel: %s, mode: %s (%s)", flt_ot_chn_label(chn), flt_ot_pr_mode(s), flt_ot_stream_pos(s));
+	FLT_OT_DBG(3, "run event '%s' %d", flt_ot_event_data[event].name, event);
+
+#ifdef DEBUG_OT
+	_HA_ATOMIC_ADD(conf->cnt.event[event].htx + (htx_is_empty(htxbuf(&(chn->buf))) ? 1 : 0), 1);
+#endif
+
+	FLT_OT_RT_CTX(f->ctx)->analyzers |= flt_ot_event_data[event].an_bit;
+
+	/* All spans should be created/completed at the same time. */
+	(void)clock_gettime(CLOCK_MONOTONIC, &ts);
+
+	/*
+	 * It is possible that there are defined multiple scopes that use the
+	 * same event.  Therefore, there must not be a 'break' here, ie an
+	 * exit from the 'for' loop.
+	 */
+	list_for_each_entry(conf_scope, &(conf->scopes), list) {
+		if (conf_scope->event != event)
+			/* Do nothing. */;
+		else if (!conf_scope->flag_used)
+			FLT_OT_DBG(3, "scope '%s' %d not used", conf_scope->id, conf_scope->event);
+		else if (flt_ot_scope_run(s, f, chn, conf_scope, &ts, flt_ot_event_data[event].smp_opt_dir, err) == FLT_OT_RET_ERROR)
+			retval = FLT_OT_RET_ERROR;
+	}
+
+	flt_ot_vars_dump(s);
+	flt_ot_http_headers_dump(chn);
+
+	FLT_OT_DBG(3, "event = %d, chn = %p, s->req = %p, s->res = %p", event, chn, &(s->req), &(s->res));
+
+	FLT_OT_RETURN(retval);
+}
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */