Squashed 'third_party/rawrtc/rawrtc/' content from commit aa3ae4b24

Change-Id: I38a655a4259b62f591334e90a1315bd4e7e4d8ec
git-subtree-dir: third_party/rawrtc/rawrtc
git-subtree-split: aa3ae4b247275cc6e69c30613b3a4ba7fdc82d1b
diff --git a/tools/helper/common.c b/tools/helper/common.c
new file mode 100644
index 0000000..e4be7a2
--- /dev/null
+++ b/tools/helper/common.c
@@ -0,0 +1,225 @@
+#include "common.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+#include <stdlib.h>  // exit
+#include <string.h>  // strerror
+
+#define DEBUG_MODULE "helper-common"
+#define DEBUG_LEVEL 7
+#include <re_dbg.h>
+
+/*
+ * Ignore success code list.
+ */
+enum rawrtc_code const ignore_success[] = {RAWRTC_CODE_SUCCESS};
+size_t const ignore_success_length = ARRAY_SIZE(ignore_success);
+
+/*
+ * Function to be called before exiting.
+ */
+void before_exit(void) {
+    // Close
+    rawrtc_close(true);
+
+    // Check memory leaks
+    tmr_debug();
+    mem_debug();
+}
+
+/*
+ * Exit on error code.
+ */
+void exit_on_error(
+    enum rawrtc_code const code,
+    enum rawrtc_code const ignore[],
+    size_t const n_ignore,
+    char const* const file,
+    uint32_t const line) {
+    size_t i;
+
+    // Ignore?
+    for (i = 0; i < n_ignore; ++i) {
+        if (code == ignore[i]) {
+            return;
+        }
+    }
+
+    // Handle
+    switch (code) {
+        case RAWRTC_CODE_SUCCESS:
+            return;
+        case RAWRTC_CODE_NOT_IMPLEMENTED:
+            DEBUG_WARNING("Not implemented in %s %" PRIu32 "\n", file, line);
+            return;
+        default:
+            DEBUG_WARNING(
+                "Error in %s %" PRIu32 " (%d): %s\n", file, line, code, rawrtc_code_to_str(code));
+            before_exit();
+            exit((int) code);
+    }
+}
+
+/*
+ * Exit on POSIX error code.
+ */
+void exit_on_posix_error(int code, char const* const file, uint32_t line) {
+    if (code != 0) {
+        DEBUG_WARNING("Error in %s %" PRIu32 " (%d): %s\n", file, line, code, strerror(code));
+        before_exit();
+        exit(code);
+    }
+}
+
+/*
+ * Exit with a custom error message.
+ */
+void exit_with_error(char const* const file, uint32_t line, char const* const formatter, ...) {
+    char* message;
+
+    // Format message
+    va_list ap;
+    va_start(ap, formatter);
+    re_vsdprintf(&message, formatter, ap);
+    va_end(ap);
+
+    // Print message
+    DEBUG_WARNING("%s %" PRIu32 ": %s\n", file, line, message);
+
+    // Un-reference & bye
+    mem_deref(message);
+    before_exit();
+    exit(1);
+}
+
+/*
+ * Check if the ICE candidate type is enabled.
+ */
+bool ice_candidate_type_enabled(
+    struct client* const client, enum rawrtc_ice_candidate_type const type) {
+    char const* const type_str = rawrtc_ice_candidate_type_to_str(type);
+    size_t i;
+
+    // All enabled?
+    if (client->n_ice_candidate_types == 0) {
+        return true;
+    }
+
+    // Specifically enabled?
+    for (i = 0; i < client->n_ice_candidate_types; ++i) {
+        if (str_cmp(client->ice_candidate_types[i], type_str) == 0) {
+            return true;
+        }
+    }
+
+    // Nope
+    return false;
+}
+
+/*
+ * Print ICE candidate information.
+ */
+void print_ice_candidate(
+    struct rawrtc_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    struct rawrtc_peer_connection_ice_candidate* const pc_candidate,  // nullable
+    struct client* const client) {
+    if (candidate) {
+        enum rawrtc_code const ignore[] = {RAWRTC_CODE_NO_VALUE};
+        enum rawrtc_code error;
+        char* foundation;
+        enum rawrtc_ice_protocol protocol;
+        uint32_t priority;
+        char* ip;
+        uint16_t port;
+        enum rawrtc_ice_candidate_type type;
+        enum rawrtc_ice_tcp_candidate_type tcp_type;
+        char const* tcp_type_str = "n/a";
+        char* related_address = NULL;
+        uint16_t related_port = 0;
+        char* mid = NULL;
+        uint8_t media_line_index = UINT8_MAX;
+        char* media_line_index_str = NULL;
+        char* username_fragment = NULL;
+        bool is_enabled;
+        int level;
+
+        // Get candidate information
+        EOE(rawrtc_ice_candidate_get_foundation(&foundation, candidate));
+        EOE(rawrtc_ice_candidate_get_protocol(&protocol, candidate));
+        EOE(rawrtc_ice_candidate_get_priority(&priority, candidate));
+        EOE(rawrtc_ice_candidate_get_ip(&ip, candidate));
+        EOE(rawrtc_ice_candidate_get_port(&port, candidate));
+        EOE(rawrtc_ice_candidate_get_type(&type, candidate));
+        error = rawrtc_ice_candidate_get_tcp_type(&tcp_type, candidate);
+        switch (error) {
+            case RAWRTC_CODE_SUCCESS:
+                tcp_type_str = rawrtc_ice_tcp_candidate_type_to_str(tcp_type);
+                break;
+            case RAWRTC_CODE_NO_VALUE:
+                break;
+            default:
+                EOE(error);
+                break;
+        }
+        EOEIGN(rawrtc_ice_candidate_get_related_address(&related_address, candidate), ignore);
+        EOEIGN(rawrtc_ice_candidate_get_related_port(&related_port, candidate), ignore);
+        if (pc_candidate) {
+            EOEIGN(rawrtc_peer_connection_ice_candidate_get_sdp_mid(&mid, pc_candidate), ignore);
+            error = rawrtc_peer_connection_ice_candidate_get_sdp_media_line_index(
+                &media_line_index, pc_candidate);
+            switch (error) {
+                case RAWRTC_CODE_SUCCESS:
+                    EOE(rawrtc_sdprintf(&media_line_index_str, "%" PRIu8, media_line_index));
+                    break;
+                case RAWRTC_CODE_NO_VALUE:
+                    break;
+                default:
+                    EOE(error);
+                    break;
+            }
+            EOEIGN(
+                rawrtc_peer_connection_ice_candidate_get_username_fragment(
+                    &username_fragment, pc_candidate),
+                ignore);
+        }
+        is_enabled = ice_candidate_type_enabled(client, type);
+
+        // Print candidate (meh, lot's of repeated code... feel free to suggest an alternative)
+        level = is_enabled ? DBG_INFO : DBG_DEBUG;
+        if (!pc_candidate) {
+            dbg_printf(
+                level,
+                "(%s) ICE candidate: foundation=%s, protocol=%s"
+                ", priority=%" PRIu32 ", ip=%s, port=%" PRIu16 ", type=%s, tcp-type=%s"
+                ", related-address=%s, related-port=%" PRIu16 "; URL: %s; %s\n",
+                client->name, foundation, rawrtc_ice_protocol_to_str(protocol), priority, ip, port,
+                rawrtc_ice_candidate_type_to_str(type), tcp_type_str,
+                related_address ? related_address : "n/a", related_port, url ? url : "n/a",
+                is_enabled ? "enabled" : "disabled");
+        } else {
+            dbg_printf(
+                level,
+                "(%s) ICE candidate: foundation=%s, protocol=%s"
+                ", priority=%" PRIu32 ", ip=%s, port=%" PRIu16 ", type=%s, tcp-type=%s"
+                ", related-address=%s, related-port=%" PRIu16 "; URL: %s"
+                "; mid=%s, media_line_index=%s, username_fragment=%s; %s\n",
+                client->name, foundation, rawrtc_ice_protocol_to_str(protocol), priority, ip, port,
+                rawrtc_ice_candidate_type_to_str(type), tcp_type_str,
+                related_address ? related_address : "n/a", related_port, url ? url : "n/a",
+                mid ? mid : "n/a", media_line_index_str ? media_line_index_str : "n/a",
+                username_fragment ? username_fragment : "n/a", is_enabled ? "enabled" : "disabled");
+        }
+
+        // Unreference
+        mem_deref(username_fragment);
+        mem_deref(media_line_index_str);
+        mem_deref(mid);
+        mem_deref(related_address);
+        mem_deref(ip);
+        mem_deref(foundation);
+    } else {
+        DEBUG_INFO("(%s) ICE gatherer last local candidate\n", client->name);
+    }
+}
diff --git a/tools/helper/common.h b/tools/helper/common.h
new file mode 100644
index 0000000..e2a34ad
--- /dev/null
+++ b/tools/helper/common.h
@@ -0,0 +1,95 @@
+#pragma once
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+
+enum {
+    PARAMETERS_MAX_LENGTH = 8192,
+};
+
+/*
+ * SCTP parameters that need to be negotiated.
+ */
+struct sctp_parameters {
+    struct rawrtc_sctp_capabilities* capabilities;
+    uint16_t port;
+};
+
+/*
+ * Client structure. Can be extended.
+ */
+struct client {
+    char* name;
+    char** ice_candidate_types;
+    size_t n_ice_candidate_types;
+};
+
+/*
+ * Data channel helper structure. Can be extended.
+ */
+struct data_channel_helper {
+    struct le le;
+    struct rawrtc_data_channel* channel;
+    char* label;
+    struct client* client;
+    void* arg;
+};
+
+/*
+ * Ignore success code list.
+ */
+extern enum rawrtc_code const ignore_success[];
+extern size_t const ignore_success_length;
+
+/*
+ * Helper macros for exiting with error messages.
+ */
+#define EOE(code) exit_on_error(code, ignore_success, ignore_success_length, __FILE__, __LINE__)
+#define EOEIGN(code, ignore) exit_on_error(code, ignore, ARRAY_SIZE(ignore), __FILE__, __LINE__)
+#define EOR(code) exit_on_posix_error(code, __FILE__, __LINE__)
+#if (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) || (__GNUC__ >= 3)
+#    define EWE(...) exit_with_error(__FILE__, __LINE__, __VA_ARGS__)
+#elif defined(__GNUC__)
+#    define EWE(args...) exit_with_error(__FILE__, __LINE__, args)
+#endif
+
+/*
+ * Function to be called before exiting.
+ */
+void before_exit(void);
+
+/*
+ * Exit on error code.
+ */
+void exit_on_error(
+    enum rawrtc_code const code,
+    enum rawrtc_code const ignore[],
+    size_t const n_ignore,
+    char const* const file,
+    uint32_t const line);
+
+/*
+ * Exit on POSIX error code.
+ */
+void exit_on_posix_error(int code, char const* const file, uint32_t line);
+
+/*
+ * Exit with a custom error message.
+ */
+void exit_with_error(char const* const file, uint32_t line, char const* const formatter, ...);
+
+/*
+ * Check if the ICE candidate type is enabled.
+ */
+bool ice_candidate_type_enabled(
+    struct client* const client, enum rawrtc_ice_candidate_type const type);
+
+/*
+ * Print ICE candidate information.
+ */
+void print_ice_candidate(
+    struct rawrtc_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    struct rawrtc_peer_connection_ice_candidate* const pc_candidate,  // nullable
+    struct client* const client);
diff --git a/tools/helper/handler.c b/tools/helper/handler.c
new file mode 100644
index 0000000..f6d8d1a
--- /dev/null
+++ b/tools/helper/handler.c
@@ -0,0 +1,337 @@
+#include "handler.h"
+#include "common.h"
+#include "utils.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+#include <string.h>  // strlen
+
+#define DEBUG_MODULE "helper-handler"
+#define DEBUG_LEVEL 7
+#include <re_dbg.h>
+
+/*
+ * Print the ICE gatherer's state.
+ */
+void default_ice_gatherer_state_change_handler(
+    enum rawrtc_ice_gatherer_state const state,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_ice_gatherer_state_to_name(state);
+    (void) arg;
+    DEBUG_PRINTF("(%s) ICE gatherer state: %s\n", client->name, state_name);
+}
+
+/*
+ * Print the ICE gatherer's error event.
+ */
+void default_ice_gatherer_error_handler(
+    struct rawrtc_ice_candidate* const candidate,  // read-only, nullable
+    char const* const url,  // read-only
+    uint16_t const error_code,  // read-only
+    char const* const error_text,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    (void) candidate;
+    (void) error_code;
+    (void) arg;
+    DEBUG_NOTICE("(%s) ICE gatherer error, URL: %s, reason: %s\n", client->name, url, error_text);
+}
+
+/*
+ * Print the newly gathered local candidate.
+ */
+void default_ice_gatherer_local_candidate_handler(
+    struct rawrtc_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    (void) arg;
+    print_ice_candidate(candidate, url, NULL, client);
+}
+
+/*
+ * Print the ICE transport's state.
+ */
+void default_ice_transport_state_change_handler(
+    enum rawrtc_ice_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_ice_transport_state_to_name(state);
+    (void) arg;
+    DEBUG_PRINTF("(%s) ICE transport state: %s\n", client->name, state_name);
+}
+
+/*
+ * Print the ICE candidate pair change event.
+ */
+void default_ice_transport_candidate_pair_change_handler(
+    struct rawrtc_ice_candidate* const local,  // read-only
+    struct rawrtc_ice_candidate* const remote,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    (void) local;
+    (void) remote;
+    DEBUG_PRINTF("(%s) ICE transport candidate pair change\n", client->name);
+}
+
+/*
+ * Print the DTLS transport's state.
+ */
+void default_dtls_transport_state_change_handler(
+    enum rawrtc_dtls_transport_state const state,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_dtls_transport_state_to_name(state);
+    DEBUG_PRINTF("(%s) DTLS transport state change: %s\n", client->name, state_name);
+}
+
+/*
+ * Print the DTLS transport's error event.
+ */
+void default_dtls_transport_error_handler(
+    // TODO: error.message (probably from OpenSSL)
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    // TODO: Print error message
+    DEBUG_WARNING("(%s) DTLS transport error: %s\n", client->name, "???");
+}
+
+#if RAWRTC_HAVE_SCTP_REDIRECT_TRANSPORT
+/*
+ * Print the SCTP redirect transport's state.
+ */
+void default_sctp_redirect_transport_state_change_handler(
+    enum rawrtc_sctp_redirect_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_sctp_redirect_transport_state_to_name(state);
+    DEBUG_PRINTF("(%s) SCTP redirect transport state change: %s\n", client->name, state_name);
+}
+#endif
+
+/*
+ * Print the SCTP transport's state.
+ */
+void default_sctp_transport_state_change_handler(
+    enum rawrtc_sctp_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_sctp_transport_state_to_name(state);
+    DEBUG_PRINTF("(%s) SCTP transport state change: %s\n", client->name, state_name);
+}
+
+/*
+ * Print the newly created data channel's parameter.
+ */
+void default_data_channel_handler(
+    struct rawrtc_data_channel* const channel,  // read-only, MUST be referenced when used
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    struct rawrtc_data_channel_parameters* parameters;
+    enum rawrtc_code const ignore[] = {RAWRTC_CODE_NO_VALUE};
+    char* label = NULL;
+
+    // Get data channel label and protocol
+    EOE(rawrtc_data_channel_get_parameters(&parameters, channel));
+    EOEIGN(rawrtc_data_channel_parameters_get_label(&label, parameters), ignore);
+    DEBUG_INFO("(%s) New data channel instance: %s\n", client->name, label ? label : "n/a");
+    mem_deref(label);
+    mem_deref(parameters);
+}
+
+/*
+ * Print the data channel open event.
+ */
+void default_data_channel_open_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+) {
+    struct data_channel_helper* const channel = arg;
+    struct client* const client = channel->client;
+    DEBUG_PRINTF("(%s) Data channel open: %s\n", client->name, channel->label);
+}
+
+/*
+ * Print the data channel buffered amount low event.
+ */
+void default_data_channel_buffered_amount_low_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+) {
+    struct data_channel_helper* const channel = arg;
+    struct client* const client = channel->client;
+    DEBUG_PRINTF("(%s) Data channel buffered amount low: %s\n", client->name, channel->label);
+}
+
+/*
+ * Print the data channel error event.
+ */
+void default_data_channel_error_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+) {
+    struct data_channel_helper* const channel = arg;
+    struct client* const client = channel->client;
+    DEBUG_WARNING("(%s) Data channel error: %s\n", client->name, channel->label);
+}
+
+/*
+ * Print the data channel close event.
+ */
+void default_data_channel_close_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+) {
+    struct data_channel_helper* const channel = arg;
+    struct client* const client = channel->client;
+    DEBUG_PRINTF("(%s) Data channel closed: %s\n", client->name, channel->label);
+}
+
+char const* const separator = ", ";
+
+static int debug_data_channel_message_flags(
+    struct re_printf* const pf, enum rawrtc_data_channel_message_flag const flags) {
+    int err = 0;
+    char const* prefix = "";
+
+    if (flags & RAWRTC_DATA_CHANNEL_MESSAGE_FLAG_IS_ABORTED) {
+        err |= re_hprintf(pf, "%saborted", prefix);
+        prefix = separator;
+    }
+    if (flags & RAWRTC_DATA_CHANNEL_MESSAGE_FLAG_IS_COMPLETE) {
+        err |= re_hprintf(pf, "%scomplete", prefix);
+        prefix = separator;
+    }
+    if (flags & RAWRTC_DATA_CHANNEL_MESSAGE_FLAG_IS_STRING) {
+        err |= re_hprintf(pf, "%sstring", prefix);
+        prefix = separator;
+    }
+    if (flags & RAWRTC_DATA_CHANNEL_MESSAGE_FLAG_IS_BINARY) {
+        err |= re_hprintf(pf, "%sbinary", prefix);
+    }
+
+    return err;
+}
+
+/*
+ * Print the data channel's received message's size.
+ */
+void default_data_channel_message_handler(
+    struct mbuf* const buffer,
+    enum rawrtc_data_channel_message_flag const flags,
+    void* const arg  // will be casted to `struct data_channel_helper*`
+) {
+    struct data_channel_helper* const channel = arg;
+    struct client* const client = channel->client;
+    DEBUG_PRINTF(
+        "(%s) Incoming message for data channel %s: %zu bytes; flags=(%H)\n", client->name,
+        channel->label, mbuf_get_left(buffer), debug_data_channel_message_flags, flags);
+}
+
+/*
+ * Print negotiation needed (duh!)
+ */
+void default_negotiation_needed_handler(void* const arg) {
+    struct client* const client = arg;
+    DEBUG_PRINTF("(%s) Negotiation needed\n", client->name);
+}
+
+/*
+ * Print the peer connection's state.
+ */
+void default_peer_connection_state_change_handler(
+    enum rawrtc_peer_connection_state const state,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_peer_connection_state_to_name(state);
+    DEBUG_PRINTF("(%s) Peer connection state change: %s\n", client->name, state_name);
+}
+
+/*
+ * Print the newly gathered local candidate (peer connection variant).
+ */
+void default_peer_connection_local_candidate_handler(
+    struct rawrtc_peer_connection_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    void* const arg) {
+    struct client* const client = arg;
+    struct rawrtc_ice_candidate* ortc_candidate = NULL;
+
+    // Get underlying ORTC ICE candidate (if any)
+    if (candidate) {
+        EOE(rawrtc_peer_connection_ice_candidate_get_ortc_candidate(&ortc_candidate, candidate));
+    }
+
+    // Print local candidate
+    print_ice_candidate(ortc_candidate, url, candidate, client);
+    mem_deref(ortc_candidate);
+}
+
+/*
+ * Print the peer connections local candidate error event.
+ */
+void default_peer_connection_local_candidate_error_handler(
+    struct rawrtc_peer_connection_ice_candidate* const candidate,  // read-only, nullable
+    char const* const url,  // read-only
+    uint16_t const error_code,  // read-only
+    char const* const error_text,  // read-only
+    void* const arg  // will be casted to `struct client*`
+) {
+    struct client* const client = arg;
+    (void) candidate;
+    (void) error_code;
+    (void) arg;
+    DEBUG_NOTICE("(%s) ICE candidate error, URL: %s, reason: %s\n", client->name, url, error_text);
+}
+
+/*
+ * Print the signaling state.
+ */
+void default_signaling_state_change_handler(
+    enum rawrtc_signaling_state const state,  // read-only
+    void* const arg) {
+    struct client* const client = arg;
+    char const* const state_name = rawrtc_signaling_state_to_name(state);
+    DEBUG_PRINTF("(%s) Signaling state change: %s\n", client->name, state_name);
+}
+
+/*
+ * Stop the main loop.
+ */
+void default_signal_handler(int sig) {
+    DEBUG_INFO("Got signal: %d, terminating...\n", sig);
+    re_cancel();
+}
+
+/*
+ * FD-listener that stops the main loop in case the input buffer
+ * contains a line feed or a carriage return.
+ */
+void stop_on_return_handler(int flags, void* arg) {
+    char buffer[128];
+    size_t length;
+    (void) flags;
+    (void) arg;
+
+    // Get message from stdin
+    if (!fgets((char*) buffer, 128, stdin)) {
+        EOR(errno);
+    }
+    length = strlen(buffer);
+
+    // Exit?
+    if (length > 0 && length < 3 && (buffer[0] == '\n' || buffer[0] == '\r')) {
+        // Stop main loop
+        DEBUG_INFO("Exiting\n");
+        re_cancel();
+    }
+}
diff --git a/tools/helper/handler.h b/tools/helper/handler.h
new file mode 100644
index 0000000..56d4211
--- /dev/null
+++ b/tools/helper/handler.h
@@ -0,0 +1,181 @@
+#pragma once
+#include "common.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+
+/*
+ * Print the ICE gatherer's state.
+ */
+void default_ice_gatherer_state_change_handler(
+    enum rawrtc_ice_gatherer_state const state,  // read-only
+    void* const arg);
+
+/*
+ * Print the ICE gatherer's error event.
+ */
+void default_ice_gatherer_error_handler(
+    struct rawrtc_ice_candidate* const host_candidate,  // read-only, nullable
+    char const* const url,  // read-only
+    uint16_t const error_code,  // read-only
+    char const* const error_text,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the newly gatherered local candidate.
+ * Will print local parameters on stdout in case the client is not
+ * used in loopback mode.
+ */
+void default_ice_gatherer_local_candidate_handler(
+    struct rawrtc_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the ICE transport's state.
+ */
+void default_ice_transport_state_change_handler(
+    enum rawrtc_ice_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the ICE candidate pair change event.
+ */
+void default_ice_transport_candidate_pair_change_handler(
+    struct rawrtc_ice_candidate* const local,  // read-only
+    struct rawrtc_ice_candidate* const remote,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the DTLS transport's state.
+ */
+void default_dtls_transport_state_change_handler(
+    enum rawrtc_dtls_transport_state const state,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the DTLS transport's error event.
+ */
+void default_dtls_transport_error_handler(
+    // TODO: error.message (probably from OpenSSL)
+    void* const arg  // will be casted to `struct client*`
+);
+
+#if RAWRTC_HAVE_SCTP_REDIRECT_TRANSPORT
+/*
+ * Print the SCTP redirect transport's state.
+ */
+void default_sctp_redirect_transport_state_change_handler(
+    enum rawrtc_sctp_redirect_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+);
+#endif
+
+/*
+ * Print the SCTP transport's state.
+ */
+void default_sctp_transport_state_change_handler(
+    enum rawrtc_sctp_transport_state const state,
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the newly created data channel's parameter.
+ */
+void default_data_channel_handler(
+    struct rawrtc_data_channel* const data_channel,  // read-only, MUST be referenced when used
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print the data channel open event.
+ */
+void default_data_channel_open_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print the data channel buffered amount low event.
+ */
+void default_data_channel_buffered_amount_low_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print the data channel error event.
+ */
+void default_data_channel_error_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print the data channel close event.
+ */
+void default_data_channel_close_handler(
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print the data channel's received message's size.
+ */
+void default_data_channel_message_handler(
+    struct mbuf* const buffer,
+    enum rawrtc_data_channel_message_flag const flags,
+    void* const arg  // will be casted to `struct data_channel_helper*`
+);
+
+/*
+ * Print negotiation needed (duh!)
+ */
+void default_negotiation_needed_handler(void* const arg);
+
+/*
+ * Print the peer connection's state.
+ */
+void default_peer_connection_state_change_handler(
+    enum rawrtc_peer_connection_state const state,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the newly gathered local candidate (peer connection variant).
+ */
+void default_peer_connection_local_candidate_handler(
+    struct rawrtc_peer_connection_ice_candidate* const candidate,
+    char const* const url,  // read-only
+    void* const arg);
+
+/*
+ * Print the peer connections local candidate error event.
+ */
+void default_peer_connection_local_candidate_error_handler(
+    struct rawrtc_peer_connection_ice_candidate* const candidate,  // read-only, nullable
+    char const* const url,  // read-only
+    uint16_t const error_code,  // read-only
+    char const* const error_text,  // read-only
+    void* const arg  // will be casted to `struct client*`
+);
+
+/*
+ * Print the signaling state.
+ */
+void default_signaling_state_change_handler(
+    enum rawrtc_signaling_state const state,  // read-only
+    void* const arg);
+
+/*
+ * Stop the main loop.
+ */
+void default_signal_handler(int sig);
+
+/*
+ * FD-listener that stops the main loop in case the input buffer is
+ * empty.
+ */
+void stop_on_return_handler(int flags, void* arg);
diff --git a/tools/helper/meson.build b/tools/helper/meson.build
new file mode 100644
index 0000000..b9ef950
--- /dev/null
+++ b/tools/helper/meson.build
@@ -0,0 +1,6 @@
+helper_sources = files([
+    'common.c',
+    'handler.c',
+    'parameters.c',
+    'utils.c',
+])
diff --git a/tools/helper/parameters.c b/tools/helper/parameters.c
new file mode 100644
index 0000000..46ae22b
--- /dev/null
+++ b/tools/helper/parameters.c
@@ -0,0 +1,448 @@
+#include "parameters.h"
+#include "common.h"
+#include "utils.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+
+#define DEBUG_MODULE "helper-parameters"
+#define DEBUG_LEVEL 7
+#include <re_dbg.h>
+
+/*
+ * Set ICE parameters in dictionary.
+ */
+void set_ice_parameters(struct rawrtc_ice_parameters* const parameters, struct odict* const dict) {
+    char* username_fragment;
+    char* password;
+    bool ice_lite;
+
+    // Get values
+    EOE(rawrtc_ice_parameters_get_username_fragment(&username_fragment, parameters));
+    EOE(rawrtc_ice_parameters_get_password(&password, parameters));
+    EOE(rawrtc_ice_parameters_get_ice_lite(&ice_lite, parameters));
+
+    // Set ICE parameters
+    EOR(odict_entry_add(dict, "usernameFragment", ODICT_STRING, username_fragment));
+    EOR(odict_entry_add(dict, "password", ODICT_STRING, password));
+    EOR(odict_entry_add(dict, "iceLite", ODICT_BOOL, ice_lite));
+
+    // Un-reference values
+    mem_deref(password);
+    mem_deref(username_fragment);
+}
+
+/*
+ * Set ICE candidates in dictionary.
+ */
+void set_ice_candidates(struct rawrtc_ice_candidates* const parameters, struct odict* const array) {
+    size_t i;
+    struct odict* node;
+
+    // Set ICE candidates
+    for (i = 0; i < parameters->n_candidates; ++i) {
+        enum rawrtc_code error;
+        struct rawrtc_ice_candidate* const candidate = parameters->candidates[i];
+        char* foundation;
+        uint32_t priority;
+        char* ip;
+        enum rawrtc_ice_protocol protocol;
+        uint16_t port;
+        enum rawrtc_ice_candidate_type type;
+        enum rawrtc_ice_tcp_candidate_type tcp_type = RAWRTC_ICE_TCP_CANDIDATE_TYPE_ACTIVE;
+        char* related_address = NULL;
+        uint16_t related_port = 0;
+        char* key;
+
+        // Create object
+        EOR(odict_alloc(&node, 16));
+
+        // Get values
+        EOE(rawrtc_ice_candidate_get_foundation(&foundation, candidate));
+        EOE(rawrtc_ice_candidate_get_priority(&priority, candidate));
+        EOE(rawrtc_ice_candidate_get_ip(&ip, candidate));
+        EOE(rawrtc_ice_candidate_get_protocol(&protocol, candidate));
+        EOE(rawrtc_ice_candidate_get_port(&port, candidate));
+        EOE(rawrtc_ice_candidate_get_type(&type, candidate));
+        error = rawrtc_ice_candidate_get_tcp_type(&tcp_type, candidate);
+        EOE(error == RAWRTC_CODE_NO_VALUE ? RAWRTC_CODE_SUCCESS : error);
+        error = rawrtc_ice_candidate_get_related_address(&related_address, candidate);
+        EOE(error == RAWRTC_CODE_NO_VALUE ? RAWRTC_CODE_SUCCESS : error);
+        error = rawrtc_ice_candidate_get_related_port(&related_port, candidate);
+        EOE(error == RAWRTC_CODE_NO_VALUE ? RAWRTC_CODE_SUCCESS : error);
+
+        // Set ICE candidate values
+        EOR(odict_entry_add(node, "foundation", ODICT_STRING, foundation));
+        EOR(odict_entry_add(node, "priority", ODICT_INT, (int64_t) priority));
+        EOR(odict_entry_add(node, "ip", ODICT_STRING, ip));
+        EOR(odict_entry_add(node, "protocol", ODICT_STRING, rawrtc_ice_protocol_to_str(protocol)));
+        EOR(odict_entry_add(node, "port", ODICT_INT, (int64_t) port));
+        EOR(odict_entry_add(node, "type", ODICT_STRING, rawrtc_ice_candidate_type_to_str(type)));
+        if (protocol == RAWRTC_ICE_PROTOCOL_TCP) {
+            EOR(odict_entry_add(
+                node, "tcpType", ODICT_STRING, rawrtc_ice_tcp_candidate_type_to_str(tcp_type)));
+        }
+        if (related_address) {
+            EOR(odict_entry_add(node, "relatedAddress", ODICT_STRING, related_address));
+        }
+        if (related_port > 0) {
+            EOR(odict_entry_add(node, "relatedPort", (int64_t) ODICT_INT, related_port));
+        }
+
+        // Add to array
+        EOE(rawrtc_sdprintf(&key, "%zu", i));
+        EOR(odict_entry_add(array, key, ODICT_OBJECT, node));
+
+        // Un-reference values
+        mem_deref(key);
+        mem_deref(related_address);
+        mem_deref(ip);
+        mem_deref(foundation);
+        mem_deref(node);
+    }
+}
+
+/*
+ * Set DTLS parameters in dictionary.
+ */
+void set_dtls_parameters(
+    struct rawrtc_dtls_parameters* const parameters, struct odict* const dict) {
+    enum rawrtc_dtls_role role;
+    struct odict* array;
+    struct odict* node;
+    struct rawrtc_dtls_fingerprints* fingerprints;
+    size_t i;
+
+    // Get and set DTLS role
+    EOE(rawrtc_dtls_parameters_get_role(&role, parameters));
+    EOR(odict_entry_add(dict, "role", ODICT_STRING, rawrtc_dtls_role_to_str(role)));
+
+    // Create array
+    EOR(odict_alloc(&array, 16));
+
+    // Get and set fingerprints
+    EOE(rawrtc_dtls_parameters_get_fingerprints(&fingerprints, parameters));
+    for (i = 0; i < fingerprints->n_fingerprints; ++i) {
+        struct rawrtc_dtls_fingerprint* const fingerprint = fingerprints->fingerprints[i];
+        enum rawrtc_certificate_sign_algorithm sign_algorithm;
+        char* value;
+        char* key;
+
+        // Create object
+        EOR(odict_alloc(&node, 16));
+
+        // Get values
+        EOE(rawrtc_dtls_fingerprint_get_sign_algorithm(&sign_algorithm, fingerprint));
+        EOE(rawrtc_dtls_fingerprint_get_value(&value, fingerprint));
+
+        // Set fingerprint values
+        EOR(odict_entry_add(
+            node, "algorithm", ODICT_STRING,
+            rawrtc_certificate_sign_algorithm_to_str(sign_algorithm)));
+        EOR(odict_entry_add(node, "value", ODICT_STRING, value));
+
+        // Add to array
+        EOE(rawrtc_sdprintf(&key, "%zu", i));
+        EOR(odict_entry_add(array, key, ODICT_OBJECT, node));
+
+        // Un-reference values
+        mem_deref(key);
+        mem_deref(value);
+        mem_deref(node);
+    }
+
+    // Un-reference fingerprints
+    mem_deref(fingerprints);
+
+    // Add array to object
+    EOR(odict_entry_add(dict, "fingerprints", ODICT_ARRAY, array));
+    mem_deref(array);
+}
+
+/*
+ * Set SCTP parameters in dictionary.
+ */
+void set_sctp_parameters(
+    struct rawrtc_sctp_transport* const transport,
+    struct sctp_parameters* const parameters,
+    struct odict* const dict) {
+    uint64_t max_message_size;
+    uint16_t port;
+
+    // Get values
+    EOE(rawrtc_sctp_capabilities_get_max_message_size(&max_message_size, parameters->capabilities));
+    EOE(rawrtc_sctp_transport_get_port(&port, transport));
+
+    // Ensure maximum message size fits into int64
+    if (max_message_size > INT64_MAX) {
+        EOE(RAWRTC_CODE_INSUFFICIENT_SPACE);
+    }
+
+    // Set ICE parameters
+    EOR(odict_entry_add(dict, "maxMessageSize", ODICT_INT, (int64_t) max_message_size));
+    EOR(odict_entry_add(dict, "port", ODICT_INT, (int64_t) port));
+}
+
+#if RAWRTC_HAVE_SCTP_REDIRECT_TRANSPORT
+/*
+ * Set SCTP redirect parameters in dictionary.
+ */
+void set_sctp_redirect_parameters(
+    struct rawrtc_sctp_redirect_transport* const transport,
+    struct sctp_parameters* const parameters,
+    struct odict* const dict) {
+    uint64_t max_message_size;
+    uint16_t port;
+
+    // Get values
+    EOE(rawrtc_sctp_capabilities_get_max_message_size(&max_message_size, parameters->capabilities));
+    EOE(rawrtc_sctp_redirect_transport_get_port(&port, transport));
+
+    // Ensure maximum message size fits into int64
+    if (max_message_size > INT64_MAX) {
+        EOE(RAWRTC_CODE_INSUFFICIENT_SPACE);
+    }
+
+    // Set ICE parameters
+    EOR(odict_entry_add(dict, "maxMessageSize", ODICT_INT, (int64_t) max_message_size));
+    EOR(odict_entry_add(dict, "port", ODICT_INT, (int64_t) port));
+}
+#endif
+
+/*
+ * Get ICE parameters from dictionary.
+ */
+enum rawrtc_code get_ice_parameters(
+    struct rawrtc_ice_parameters** const parametersp, struct odict* const dict) {
+    enum rawrtc_code error = RAWRTC_CODE_SUCCESS;
+    char* username_fragment;
+    char* password;
+    bool ice_lite;
+
+    // Get ICE parameters
+    error |= dict_get_entry(&username_fragment, dict, "usernameFragment", ODICT_STRING, true);
+    error |= dict_get_entry(&password, dict, "password", ODICT_STRING, true);
+    error |= dict_get_entry(&ice_lite, dict, "iceLite", ODICT_BOOL, true);
+    if (error) {
+        return error;
+    }
+
+    // Create ICE parameters instance
+    return rawrtc_ice_parameters_create(parametersp, username_fragment, password, ice_lite);
+}
+
+static void ice_candidates_destroy(void* arg) {
+    struct rawrtc_ice_candidates* const candidates = arg;
+    size_t i;
+
+    // Un-reference each item
+    for (i = 0; i < candidates->n_candidates; ++i) {
+        mem_deref(candidates->candidates[i]);
+    }
+}
+
+/*
+ * Get ICE candidates from dictionary.
+ * Filter by enabled ICE candidate types if `client` argument is set to
+ * non-NULL.
+ */
+enum rawrtc_code get_ice_candidates(
+    struct rawrtc_ice_candidates** const candidatesp,
+    struct odict* const dict,
+    struct client* const client) {
+    size_t n;
+    struct rawrtc_ice_candidates* candidates;
+    enum rawrtc_code error = RAWRTC_CODE_SUCCESS;
+    struct le* le;
+
+    // Get length
+    n = list_count(&dict->lst) + 1;
+
+    // Allocate & set length immediately
+    // Note: We allocate more than we need in case ICE candidate types are being filtered but... meh
+    candidates = mem_zalloc(
+        sizeof(*candidates) + (sizeof(struct rawrtc_ice_candidate*) * n), ice_candidates_destroy);
+    if (!candidates) {
+        EWE("No memory to allocate ICE candidates array");
+    }
+    candidates->n_candidates = 0;
+
+    // Get ICE candidates
+    for (le = list_head(&dict->lst); le != NULL; le = le->next) {
+        struct odict* const node = ((struct odict_entry*) le->data)->u.odict;
+        char const* type_str = NULL;
+        enum rawrtc_ice_candidate_type type;
+        char* foundation;
+        uint32_t priority;
+        char* ip;
+        char const* protocol_str = NULL;
+        enum rawrtc_ice_protocol protocol;
+        uint16_t port;
+        char const* tcp_type_str = NULL;
+        enum rawrtc_ice_tcp_candidate_type tcp_type = RAWRTC_ICE_TCP_CANDIDATE_TYPE_ACTIVE;
+        char* related_address = NULL;
+        uint16_t related_port = 0;
+        struct rawrtc_ice_candidate* candidate;
+
+        // Get ICE candidate
+        error |= dict_get_entry(&type_str, node, "type", ODICT_STRING, true);
+        error |= rawrtc_str_to_ice_candidate_type(&type, type_str);
+        error |= dict_get_entry(&foundation, node, "foundation", ODICT_STRING, true);
+        error |= dict_get_uint32(&priority, node, "priority", true);
+        error |= dict_get_entry(&ip, node, "ip", ODICT_STRING, true);
+        error |= dict_get_entry(&protocol_str, node, "protocol", ODICT_STRING, true);
+        error |= rawrtc_str_to_ice_protocol(&protocol, protocol_str);
+        error |= dict_get_uint16(&port, node, "port", true);
+        if (protocol == RAWRTC_ICE_PROTOCOL_TCP) {
+            error |= dict_get_entry(&tcp_type_str, node, "tcpType", ODICT_STRING, true);
+            error |= rawrtc_str_to_ice_tcp_candidate_type(&tcp_type, tcp_type_str);
+        }
+        dict_get_entry(&related_address, node, "relatedAddress", ODICT_STRING, false);
+        dict_get_uint16(&related_port, node, "relatedPort", false);
+        if (error) {
+            goto out;
+        }
+
+        // Create and add ICE candidate
+        error = rawrtc_ice_candidate_create(
+            &candidate, foundation, priority, ip, protocol, port, type, tcp_type, related_address,
+            related_port);
+        if (error) {
+            goto out;
+        }
+
+        // Print ICE candidate
+        print_ice_candidate(candidate, NULL, NULL, client);
+
+        // Store if ICE candidate type enabled
+        if (ice_candidate_type_enabled(client, type)) {
+            candidates->candidates[candidates->n_candidates++] = candidate;
+        } else {
+            mem_deref(candidate);
+        }
+    }
+
+    // End-of-candidates
+    candidates->candidates[candidates->n_candidates++] = NULL;
+
+out:
+    if (error) {
+        mem_deref(candidates);
+    } else {
+        // Set pointer
+        *candidatesp = candidates;
+    }
+    return error;
+}
+
+static void dtls_fingerprints_destroy(void* arg) {
+    struct rawrtc_dtls_fingerprints* const fingerprints = arg;
+    size_t i;
+
+    // Un-reference each item
+    for (i = 0; i < fingerprints->n_fingerprints; ++i) {
+        mem_deref(fingerprints->fingerprints[i]);
+    }
+}
+
+/*
+ * Get DTLS parameters from dictionary.
+ */
+enum rawrtc_code get_dtls_parameters(
+    struct rawrtc_dtls_parameters** const parametersp, struct odict* const dict) {
+    size_t n;
+    struct rawrtc_dtls_parameters* parameters = NULL;
+    struct rawrtc_dtls_fingerprints* fingerprints;
+    enum rawrtc_code error;
+    char const* role_str = NULL;
+    enum rawrtc_dtls_role role;
+    struct odict* node;
+    struct le* le;
+    size_t i;
+
+    // Get fingerprints array and length
+    error = dict_get_entry(&node, dict, "fingerprints", ODICT_ARRAY, true);
+    if (error) {
+        return error;
+    }
+    n = list_count(&node->lst);
+
+    // Allocate & set length immediately
+    fingerprints = mem_zalloc(
+        sizeof(*fingerprints) + (sizeof(struct rawrtc_dtls_fingerprints*) * n),
+        dtls_fingerprints_destroy);
+    if (!fingerprints) {
+        EWE("No memory to allocate DTLS fingerprint array");
+    }
+    fingerprints->n_fingerprints = n;
+
+    // Get role
+    error |= dict_get_entry(&role_str, dict, "role", ODICT_STRING, true);
+    error |= rawrtc_str_to_dtls_role(&role, role_str);
+    if (error) {
+        role = RAWRTC_DTLS_ROLE_AUTO;
+    }
+
+    // Get fingerprints
+    for (le = list_head(&node->lst), i = 0; le != NULL; le = le->next, ++i) {
+        char* algorithm_str = NULL;
+        enum rawrtc_certificate_sign_algorithm algorithm;
+        char* value;
+        node = ((struct odict_entry*) le->data)->u.odict;
+
+        // Get fingerprint
+        error |= dict_get_entry(&algorithm_str, node, "algorithm", ODICT_STRING, true);
+        error |= rawrtc_str_to_certificate_sign_algorithm(&algorithm, algorithm_str);
+        error |= dict_get_entry(&value, node, "value", ODICT_STRING, true);
+        if (error) {
+            goto out;
+        }
+
+        // Create and add fingerprint
+        error = rawrtc_dtls_fingerprint_create(&fingerprints->fingerprints[i], algorithm, value);
+        if (error) {
+            goto out;
+        }
+    }
+
+    // Create DTLS parameters
+    error = rawrtc_dtls_parameters_create(
+        &parameters, role, fingerprints->fingerprints, fingerprints->n_fingerprints);
+
+out:
+    mem_deref(fingerprints);
+
+    if (error) {
+        mem_deref(parameters);
+    } else {
+        // Set pointer
+        *parametersp = parameters;
+    }
+    return error;
+}
+
+/*
+ * Get SCTP parameters from dictionary.
+ */
+enum rawrtc_code get_sctp_parameters(
+    struct sctp_parameters* const parameters, struct odict* const dict) {
+    enum rawrtc_code error;
+    uint64_t max_message_size;
+
+    // Get maximum message size
+    error = dict_get_entry(&max_message_size, dict, "maxMessageSize", ODICT_INT, true);
+    if (error) {
+        return error;
+    }
+
+    // Get port
+    error = dict_get_uint16(&parameters->port, dict, "port", false);
+    if (error && error != RAWRTC_CODE_NO_VALUE) {
+        // Note: Nothing to do in NO VALUE case as port has been set to 0 by default
+        return error;
+    }
+
+    // Create SCTP capabilities instance
+    return rawrtc_sctp_capabilities_create(&parameters->capabilities, max_message_size);
+}
diff --git a/tools/helper/parameters.h b/tools/helper/parameters.h
new file mode 100644
index 0000000..bc6a5aa
--- /dev/null
+++ b/tools/helper/parameters.h
@@ -0,0 +1,67 @@
+#pragma once
+#include "common.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+
+/*
+ * Set ICE parameters in dictionary.
+ */
+void set_ice_parameters(struct rawrtc_ice_parameters* const parameters, struct odict* const dict);
+
+/*
+ * Set ICE candidates in dictionary.
+ */
+void set_ice_candidates(struct rawrtc_ice_candidates* const parameters, struct odict* const array);
+
+/*
+ * Set DTLS parameters in dictionary.
+ */
+void set_dtls_parameters(struct rawrtc_dtls_parameters* const parameters, struct odict* const dict);
+
+/*
+ * Set SCTP parameters in dictionary.
+ */
+void set_sctp_parameters(
+    struct rawrtc_sctp_transport* const transport,
+    struct sctp_parameters* const parameters,
+    struct odict* const dict);
+
+#if RAWRTC_HAVE_SCTP_REDIRECT_TRANSPORT
+/*
+ * Set SCTP redirect parameters in dictionary.
+ */
+void set_sctp_redirect_parameters(
+    struct rawrtc_sctp_redirect_transport* const transport,
+    struct sctp_parameters* const parameters,
+    struct odict* const dict);
+#endif
+
+/*
+ * Get ICE parameters from dictionary.
+ */
+enum rawrtc_code get_ice_parameters(
+    struct rawrtc_ice_parameters** const parametersp, struct odict* const dict);
+
+/*
+ * Get ICE candidates from dictionary.
+ * Filter by enabled ICE candidate types if `client` argument is set to
+ * non-NULL.
+ */
+enum rawrtc_code get_ice_candidates(
+    struct rawrtc_ice_candidates** const candidatesp,
+    struct odict* const dict,
+    struct client* const client);
+
+/*
+ * Get DTLS parameters from dictionary.
+ */
+enum rawrtc_code get_dtls_parameters(
+    struct rawrtc_dtls_parameters** const parametersp, struct odict* const dict);
+
+/*
+ * Get SCTP parameters from dictionary.
+ */
+enum rawrtc_code get_sctp_parameters(
+    struct sctp_parameters* const parameters, struct odict* const dict);
diff --git a/tools/helper/utils.c b/tools/helper/utils.c
new file mode 100644
index 0000000..2c15b00
--- /dev/null
+++ b/tools/helper/utils.c
@@ -0,0 +1,380 @@
+#include "utils.h"
+#include "common.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+#include <limits.h>  // ULONG_MAX
+#include <stdlib.h>  // strto*
+#include <string.h>  // strlen
+
+#define DEBUG_MODULE "helper-utils"
+#define DEBUG_LEVEL 7
+#include <re_dbg.h>
+
+/*
+ * Convert string to uint16.
+ */
+bool str_to_uint16(uint16_t* const numberp, char* const str) {
+    char* end;
+    unsigned long number = strtoul(str, &end, 10);
+
+    // Check result (this function is insane, srsly...)
+    if (*end != '\0' || (number == ULONG_MAX && errno == ERANGE)) {
+        return false;
+    }
+
+    // Check bounds
+#if (ULONG_MAX > UINT16_MAX)
+    if (number > UINT16_MAX) {
+        return false;
+    }
+#endif
+
+    // Done
+    *numberp = (uint16_t) number;
+    return true;
+}
+
+/*
+ * Convert string to uint64.
+ */
+bool str_to_uint64(uint64_t* const numberp, char* const str) {
+    char* end;
+    unsigned long long number = strtoull(str, &end, 10);
+
+    // Check result (this function is insane, srsly...)
+    if (*end != '\0' || (number == ULONG_MAX && errno == ERANGE)) {
+        return false;
+    }
+
+    // Check bounds
+#if (ULONG_MAX > UINT64_MAX)
+    if (number > UINT64_MAX) {
+        return false;
+    }
+#endif
+
+    // Done
+    *numberp = (uint64_t) number;
+    return true;
+}
+
+/*
+ * Convert string to uint32.
+ */
+bool str_to_uint32(uint32_t* const numberp, char* const str) {
+    uint64_t number;
+    bool success = str_to_uint64(&number, str);
+
+    // Validate
+    if (!success || number > UINT32_MAX) {
+        return false;
+    }
+
+    // Done
+    *numberp = (uint32_t) number;
+    return true;
+}
+
+/*
+ * Get a dictionary entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_entry(
+    void* const valuep,
+    struct odict* const parent,
+    char* const key,
+    enum odict_type const type,
+    bool required) {
+    struct odict_entry const* entry;
+
+    // Check arguments
+    if (!valuep || !parent || !key) {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Do lookup
+    entry = odict_lookup(parent, key);
+
+    // Check for entry
+    if (!entry) {
+        if (required) {
+            DEBUG_WARNING("'%s' missing\n", key);
+            return RAWRTC_CODE_INVALID_ARGUMENT;
+        } else {
+            return RAWRTC_CODE_NO_VALUE;
+        }
+    }
+
+    // Check for type
+    if (entry->type != type) {
+        DEBUG_WARNING("'%s' is of different type than expected\n", key);
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Set value according to type
+    switch (type) {
+        case ODICT_OBJECT:
+        case ODICT_ARRAY:
+            *((struct odict * * const) valuep) = entry->u.odict;
+            break;
+        case ODICT_STRING:
+            *((char** const) valuep) = entry->u.str;
+            break;
+        case ODICT_INT:
+            *((int64_t* const) valuep) = entry->u.integer;
+            break;
+        case ODICT_DOUBLE:
+            *((double* const) valuep) = entry->u.dbl;
+            break;
+        case ODICT_BOOL:
+            *((bool* const) valuep) = entry->u.boolean;
+            break;
+        case ODICT_NULL:
+            *((char** const) valuep) = NULL;  // meh!
+            break;
+        default:
+            return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Done
+    return RAWRTC_CODE_SUCCESS;
+}
+
+/*
+ * Get a uint32 entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_uint32(
+    uint32_t* const valuep, struct odict* const parent, char* const key, bool required) {
+    enum rawrtc_code error;
+    int64_t value;
+
+    // Check arguments
+    if (!valuep || !parent || !key) {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Get int64_t
+    error = dict_get_entry(&value, parent, key, ODICT_INT, required);
+    if (error) {
+        return error;
+    }
+
+    // Check bounds
+    if (value < 0 || value > UINT32_MAX) {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Set value & done
+    *valuep = (uint32_t) value;
+    return RAWRTC_CODE_SUCCESS;
+}
+
+/*
+ * Get a uint16 entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_uint16(
+    uint16_t* const valuep, struct odict* const parent, char* const key, bool required) {
+    enum rawrtc_code error;
+    int64_t value;
+
+    // Check arguments
+    if (!valuep || !parent || !key) {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Get int64_t
+    error = dict_get_entry(&value, parent, key, ODICT_INT, required);
+    if (error) {
+        return error;
+    }
+
+    // Check bounds
+    if (value < 0 || value > UINT16_MAX) {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+
+    // Set value & done
+    *valuep = (uint16_t) value;
+    return RAWRTC_CODE_SUCCESS;
+}
+
+/*
+ * Get JSON from stdin and parse it to a dictionary.
+ */
+enum rawrtc_code get_json_stdin(struct odict** const dictp  // de-referenced
+) {
+    char buffer[PARAMETERS_MAX_LENGTH];
+    size_t length;
+
+    // Get message from stdin
+    if (!fgets((char*) buffer, PARAMETERS_MAX_LENGTH, stdin)) {
+        EWE("Error polling stdin");
+    }
+    length = strlen(buffer);
+
+    // Exit?
+    if (length == 1 && buffer[0] == '\n') {
+        return RAWRTC_CODE_NO_VALUE;
+    }
+
+    // Decode JSON
+    EOR(json_decode_odict(dictp, 16, buffer, length, 3));
+    return RAWRTC_CODE_SUCCESS;
+}
+
+/*
+ * Get the ICE role from a string.
+ */
+enum rawrtc_code get_ice_role(
+    enum rawrtc_ice_role* const rolep,  // de-referenced
+    char const* const str) {
+    // Get ICE role
+    switch (str[0]) {
+        case '0':
+            *rolep = RAWRTC_ICE_ROLE_CONTROLLED;
+            return RAWRTC_CODE_SUCCESS;
+        case '1':
+            *rolep = RAWRTC_ICE_ROLE_CONTROLLING;
+            return RAWRTC_CODE_SUCCESS;
+        default:
+            return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+}
+
+/*
+ * Get the congestion control algorithm from a string.
+ */
+enum rawrtc_code get_congestion_control_algorithm(
+    enum rawrtc_sctp_transport_congestion_ctrl* const algorithmp,  // de-referenced
+    char const* const str) {
+    if (str_casecmp(str, "RFC2581") == 0) {
+        *algorithmp = RAWRTC_SCTP_TRANSPORT_CONGESTION_CTRL_RFC2581;
+        return RAWRTC_CODE_SUCCESS;
+    } else if (str_casecmp(str, "HSTCP") == 0) {
+        *algorithmp = RAWRTC_SCTP_TRANSPORT_CONGESTION_CTRL_HSTCP;
+        return RAWRTC_CODE_SUCCESS;
+    } else if (str_casecmp(str, "HTCP") == 0) {
+        *algorithmp = RAWRTC_SCTP_TRANSPORT_CONGESTION_CTRL_HTCP;
+        return RAWRTC_CODE_SUCCESS;
+    } else if (str_casecmp(str, "RTCC") == 0) {
+        *algorithmp = RAWRTC_SCTP_TRANSPORT_CONGESTION_CTRL_RTCC;
+        return RAWRTC_CODE_SUCCESS;
+    } else {
+        return RAWRTC_CODE_INVALID_ARGUMENT;
+    }
+}
+
+static void data_channel_helper_destroy(void* arg) {
+    struct data_channel_helper* const channel = arg;
+
+    // Unset handler argument & handlers of the channel
+    if (channel->channel) {
+        EOE(rawrtc_data_channel_unset_handlers(channel->channel));
+    }
+
+    // Remove from list
+    list_unlink(&channel->le);
+
+    // Un-reference
+    mem_deref(channel->arg);
+    mem_deref(channel->label);
+    mem_deref(channel->channel);
+}
+
+/*
+ * Create a data channel helper instance.
+ */
+void data_channel_helper_create(
+    struct data_channel_helper** const channel_helperp,  // de-referenced
+    struct client* const client,
+    char* const label) {
+    // Allocate
+    struct data_channel_helper* const channel =
+        mem_zalloc(sizeof(*channel), data_channel_helper_destroy);
+    if (!channel) {
+        EOE(RAWRTC_CODE_NO_MEMORY);
+        return;
+    }
+
+    // Set fields
+    channel->client = client;
+    EOE(rawrtc_strdup(&channel->label, label));
+
+    // Set pointer & done
+    *channel_helperp = channel;
+}
+
+/*
+ * Create a data channel helper instance from parameters.
+ */
+void data_channel_helper_create_from_channel(
+    struct data_channel_helper** const channel_helperp,  // de-referenced
+    struct rawrtc_data_channel* channel,
+    struct client* const client,
+    void* const arg  // nullable
+) {
+    enum rawrtc_code error;
+    struct rawrtc_data_channel_parameters* parameters;
+    char* label;
+
+    // Allocate
+    struct data_channel_helper* const channel_helper =
+        mem_zalloc(sizeof(*channel_helper), data_channel_helper_destroy);
+    if (!channel_helper) {
+        EOE(RAWRTC_CODE_NO_MEMORY);
+        return;
+    }
+
+    // Get parameters
+    EOE(rawrtc_data_channel_get_parameters(&parameters, channel));
+
+    // Get & set label
+    error = rawrtc_data_channel_parameters_get_label(&label, parameters);
+    switch (error) {
+        case RAWRTC_CODE_SUCCESS:
+            EOE(rawrtc_strdup(&channel_helper->label, label));
+            mem_deref(label);
+            break;
+        case RAWRTC_CODE_NO_VALUE:
+            EOE(rawrtc_strdup(&channel_helper->label, "n/a"));
+            break;
+        default:
+            EOE(error);
+    }
+
+    // Set fields
+    channel_helper->client = client;
+    channel_helper->channel = channel;
+    channel_helper->arg = mem_ref(arg);
+
+    // Set pointer
+    *channel_helperp = channel_helper;
+
+    // Un-reference & done
+    mem_deref(parameters);
+}
+
+/*
+ * Add the ICE candidate to the remote ICE transport if the ICE
+ * candidate type is enabled.
+ */
+void add_to_other_if_ice_candidate_type_enabled(
+    struct client* const client,
+    struct rawrtc_ice_candidate* const candidate,
+    struct rawrtc_ice_transport* const transport) {
+    if (candidate) {
+        enum rawrtc_ice_candidate_type type;
+
+        // Get ICE candidate type
+        EOE(rawrtc_ice_candidate_get_type(&type, candidate));
+
+        // Add to other client as remote candidate (if type enabled)
+        if (ice_candidate_type_enabled(client, type)) {
+            EOE(rawrtc_ice_transport_add_remote_candidate(transport, candidate));
+        }
+    } else {
+        // Last candidate is always being added
+        EOE(rawrtc_ice_transport_add_remote_candidate(transport, candidate));
+    }
+}
diff --git a/tools/helper/utils.h b/tools/helper/utils.h
new file mode 100644
index 0000000..d521b80
--- /dev/null
+++ b/tools/helper/utils.h
@@ -0,0 +1,90 @@
+#pragma once
+#include "common.h"
+#include <rawrtc.h>
+#include <rawrtcc.h>
+#include <rawrtcdc.h>
+#include <re.h>
+
+/*
+ * Convert string to uint16.
+ */
+bool str_to_uint16(uint16_t* const numberp, char* const str);
+
+/*
+ * Convert string to uint64.
+ */
+bool str_to_uint64(uint64_t* const numberp, char* const str);
+
+/*
+ * Convert string to uint32.
+ */
+bool str_to_uint32(uint32_t* const numberp, char* const str);
+
+/*
+ * Get a dictionary entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_entry(
+    void* const valuep,
+    struct odict* const parent,
+    char* const key,
+    enum odict_type const type,
+    bool required);
+
+/*
+ * Get a uint32 entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_uint32(
+    uint32_t* const valuep, struct odict* const parent, char* const key, bool required);
+
+/*
+ * Get a uint16 entry and store it in `*valuep`.
+ */
+enum rawrtc_code dict_get_uint16(
+    uint16_t* const valuep, struct odict* const parent, char* const key, bool required);
+
+/*
+ * Get JSON from stdin and parse it to a dictionary.
+ */
+enum rawrtc_code get_json_stdin(struct odict** const dictp  // de-referenced
+);
+
+/*
+ * Get the ICE role from a string.
+ */
+enum rawrtc_code get_ice_role(
+    enum rawrtc_ice_role* const rolep,  // de-referenced
+    char const* const str);
+
+/*
+ * Get the congestion control algorithm from a string.
+ */
+enum rawrtc_code get_congestion_control_algorithm(
+    enum rawrtc_sctp_transport_congestion_ctrl* const algorithmp,  // de-referenced
+    char const* const str);
+
+/*
+ * Create a data channel helper instance.
+ */
+void data_channel_helper_create(
+    struct data_channel_helper** const channel_helperp,  // de-referenced
+    struct client* const client,
+    char* const label);
+
+/*
+ * Create a data channel helper instance from parameters.
+ */
+void data_channel_helper_create_from_channel(
+    struct data_channel_helper** const channel_helperp,  // de-referenced
+    struct rawrtc_data_channel* channel,
+    struct client* const client,
+    void* const arg  // nullable
+);
+
+/*
+ * Add the ICE candidate to the remote ICE transport if the ICE
+ * candidate type is enabled.
+ */
+void add_to_other_if_ice_candidate_type_enabled(
+    struct client* const client,
+    struct rawrtc_ice_candidate* const candidate,
+    struct rawrtc_ice_transport* const transport);