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Proxy: Update documentation, streamline the code
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Tidy up naming to reduce confusion between supported proxy types.

Provides simpler proxy examples.

Fixes issue with COAP_PROXY_REVERSE_STRIP.

Support upstream server using AF_UNIX.
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@mrdeep1
mrdeep1 committed Feb 20, 2025
1 parent 4289cb0 commit c4d933a
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Showing 10 changed files with 416 additions and 232 deletions.
26 changes: 15 additions & 11 deletions examples/coap-server.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -627,7 +627,7 @@ static ssize_t user_length = -1;

static size_t proxy_host_name_count = 0;
static const char **proxy_host_name_list = NULL;
static coap_proxy_server_list_t forward_proxy = { NULL, 0, 0, COAP_PROXY_FORWARD, 0, 300};
static coap_proxy_server_list_t forward_proxy = { NULL, 0, 0, COAP_PROXY_FORWARD_STATIC, 0, 300};
static coap_proxy_server_list_t reverse_proxy = { NULL, 0, 0, COAP_PROXY_REVERSE_STRIP, 0, 10};

static coap_dtls_cpsk_t *
Expand All @@ -646,12 +646,12 @@ setup_cpsk(char *client_sni) {

static void
hnd_forward_proxy_uri(coap_resource_t *resource,
coap_session_t *session,
coap_session_t *req_session,
const coap_pdu_t *request,
const coap_string_t *query COAP_UNUSED,
coap_pdu_t *response) {

if (!coap_proxy_forward_request(session, request, response, resource,
if (!coap_proxy_forward_request(req_session, request, response, resource,
NULL, &forward_proxy)) {
coap_log_debug("hnd_forward_proxy_uri: Failed to forward PDU\n");
/* Non ACK response code set on error detection */
Expand All @@ -662,12 +662,12 @@ hnd_forward_proxy_uri(coap_resource_t *resource,

static void
hnd_reverse_proxy_uri(coap_resource_t *resource,
coap_session_t *session,
coap_session_t *rsp_session,
const coap_pdu_t *request,
const coap_string_t *query COAP_UNUSED,
coap_pdu_t *response) {

if (!coap_proxy_forward_request(session, request, response, resource,
if (!coap_proxy_forward_request(rsp_session, request, response, resource,
NULL, &reverse_proxy)) {
coap_log_debug("hnd_reverse_proxy_uri: Failed to forward PDU\n");
/* Non ACK response code set on error detection */
Expand Down Expand Up @@ -1085,11 +1085,11 @@ proxy_event_handler(coap_session_t *session COAP_UNUSED,
}

static coap_response_t
reverse_response_handler(coap_session_t *session,
reverse_response_handler(coap_session_t *rsp_session,
const coap_pdu_t *sent COAP_UNUSED,
const coap_pdu_t *received,
const coap_mid_t id COAP_UNUSED) {
return coap_proxy_forward_response(session, received, NULL);
return coap_proxy_forward_response(rsp_session, received, NULL);
}

static void
Expand Down Expand Up @@ -1517,7 +1517,9 @@ proxy_dtls_setup(coap_context_t *ctx, coap_proxy_server_list_t *proxy_info) {
for (i = 0; i < proxy_info->entry_count; i++) {
coap_proxy_server_t *proxy_server = &proxy_info->entry[i];

if (proxy_info->type == COAP_PROXY_DIRECT || proxy_info->type == COAP_PROXY_DIRECT_STRIP) {
if (proxy_info->type == COAP_PROXY_FORWARD_DYNAMIC ||
proxy_info->type == COAP_PROXY_FORWARD_DYNAMIC_STRIP) {
/* This will get filled in by the libcoap proxy logic */
memset(client_sni, 0, sizeof(client_sni));
} else {
snprintf(client_sni, sizeof(client_sni), "%*.*s", (int)proxy_server->uri.host.length,
Expand Down Expand Up @@ -1581,7 +1583,7 @@ usage(const char *program, const char *version) {
"\t \t\tuntil one of the dynamic resources has been deleted\n"
"\t-e \t\tEcho back the data sent with a PUT\n"
"\t-f scheme://address[:port]\n"
"\t \t\tAct as a reverse proxy where scheme, address, optional\n"
"\t \t\tAct as a reverse proxy where scheme, address and optional\n"
"\t \t\tport define how to connect to the internal server.\n"
"\t \t\tScheme is one of coap, coaps, coap+tcp, coaps+tcp,\n"
"\t \t\tcoap+ws, and coaps+ws. http(s) is not currently supported.\n"
Expand Down Expand Up @@ -1826,10 +1828,12 @@ cmdline_proxy(char *arg) {
coap_log_err("Unsupported CoAP Proxy protocol\n");
return 0;
}
forward_proxy.type = COAP_PROXY_FORWARD;
forward_proxy.type = COAP_PROXY_FORWARD_STATIC;
forward_proxy.idle_timeout_secs = 300;
} else {
memset(&uri, 0, sizeof(uri));
forward_proxy.type = COAP_PROXY_DIRECT_STRIP;
forward_proxy.type = COAP_PROXY_FORWARD_DYNAMIC_STRIP;
forward_proxy.idle_timeout_secs = 10;
}

new_entry = realloc(forward_proxy.entry,
Expand Down
42 changes: 27 additions & 15 deletions include/coap3/coap_proxy.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -25,12 +25,23 @@
*/

typedef enum {
COAP_PROXY_REVERSE, /**< Act as a reverse proxy */
COAP_PROXY_REVERSE_STRIP, /**< Act as a reverse proxy, strip out proxy options */
COAP_PROXY_FORWARD, /**< Act as a forward proxy */
COAP_PROXY_FORWARD_STRIP, /**< Act as a forward proxy, strip out proxy options */
COAP_PROXY_DIRECT, /**< Act as a direct proxy */
COAP_PROXY_DIRECT_STRIP, /**< Act as a direct proxy, strip out proxy options */
COAP_PROXY_REVERSE, /**< Act as a reverse proxy */
COAP_PROXY_REVERSE_STRIP, /**< Act as a reverse proxy,
strip out proxy options */
COAP_PROXY_FORWARD_STATIC, /**< Act as a forward-static proxy */
COAP_PROXY_FORWARD_STATIC_STRIP, /**< Act as a forward-static proxy,
strip out proxy options */
COAP_PROXY_FORWARD_DYNAMIC, /**< Act as a forward-dynamic proxy
using the request's Proxy-Uri or
Proxy-Scheme options to determine
server */
COAP_PROXY_FORWARD_DYNAMIC_STRIP, /**< Act as a forward-dynamic proxy,
strip out proxy options */
/* For backward compatability */
COAP_PROXY_FORWARD = COAP_PROXY_FORWARD_STATIC,
COAP_PROXY_FORWARD_STRIP = COAP_PROXY_FORWARD_STATIC_STRIP,
COAP_PROXY_DIRECT = COAP_PROXY_FORWARD_DYNAMIC,
COAP_PROXY_DIRECT_STRIP = COAP_PROXY_FORWARD_DYNAMIC_STRIP,
} coap_proxy_t;

typedef struct coap_proxy_server_t {
Expand All @@ -42,13 +53,14 @@ typedef struct coap_proxy_server_t {

typedef struct coap_proxy_server_list_t {
coap_proxy_server_t *entry; /**< Set of servers to connect to */
size_t entry_count; /**< The number of servers */
size_t entry_count; /**< The number of servers in entry list */
size_t next_entry; /**< Next server to use (% entry_count) */
coap_proxy_t type; /**< The proxy type */
int track_client_session; /**< If 1, track individual connections to upstream
server, else 0 for all clients to share the same
ongoing session */
unsigned int idle_timeout_secs; /**< Proxy session idle timeout (0 is no timeout) */
unsigned int idle_timeout_secs; /**< Proxy upstream session idle timeout
(0 is no timeout) */
} coap_proxy_server_list_t;

/**
Expand All @@ -64,16 +76,16 @@ int coap_verify_proxy_scheme_supported(coap_uri_scheme_t scheme);
* Forward incoming request upstream to the next proxy/server.
*
* Possible scenarios:
* Acting as a reverse proxy - connect to internal server
* Acting as a reverse proxy - connect to defined internal server
* (possibly round robin load balancing over multiple servers).
* Acting as a forward proxy - connect to host defined in Proxy-Uri
* Acting as a forward-dynamic proxy - connect to host defined in Proxy-Uri
* or Proxy-Scheme with Uri-Host (and maybe Uri-Port).
* Acting as a relay proxy - connect to defined upstream server
* Acting as a forward-static proxy - connect to defined upstream server
* (possibly round robin load balancing over multiple servers).
*
* A request that should go direct to this server is not supported here.
*
* @param session The client session.
* @param req_session The client session.
* @param request The client's request PDU.
* @param response The response PDU that will get sent back to the client.
* @param resource The resource associated with this request.
Expand All @@ -83,7 +95,7 @@ int coap_verify_proxy_scheme_supported(coap_uri_scheme_t scheme);
* @return @c 1 if success, or @c 0 if failure (@p response code set to
* appropriate value).
*/
int COAP_API coap_proxy_forward_request(coap_session_t *session,
int COAP_API coap_proxy_forward_request(coap_session_t *req_session,
const coap_pdu_t *request,
coap_pdu_t *response,
coap_resource_t *resource,
Expand All @@ -93,7 +105,7 @@ int COAP_API coap_proxy_forward_request(coap_session_t *session,
/**
* Forward the returning response back to the appropriate client.
*
* @param session The session handling the response.
* @param rsp_session The upstream session receiving the response.
* @param received The received PDU.
* @param cache_key Updated with the cache key pointer provided to
* coap_proxy_forward_request(). The caller should
Expand All @@ -102,7 +114,7 @@ int COAP_API coap_proxy_forward_request(coap_session_t *session,
*
* @return One of COAP_RESPONSE_FAIL or COAP_RESPONSE_OK.
*/
coap_response_t COAP_API coap_proxy_forward_response(coap_session_t *session,
coap_response_t COAP_API coap_proxy_forward_response(coap_session_t *rsp_session,
const coap_pdu_t *received,
coap_cache_key_t **cache_key);

Expand Down
2 changes: 1 addition & 1 deletion include/coap3/coap_proxy_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ void coap_proxy_remove_association(coap_session_t *session, int send_failure);
* Forward incoming request upstream to the next proxy/server.
*
* Possible scenarios:
* Acting as a reverse proxy - connect to internal server
* Acting as a reverse proxy - connect to defined internal server
* (possibly round robin load balancing over multiple servers).
* Acting as a forward proxy - connect to host defined in Proxy-Uri
* or Proxy-Scheme with Uri-Host (and maybe Uri-Port).
Expand Down
1 change: 1 addition & 0 deletions include/coap3/coap_resource_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@ struct coap_resource_t {
unsigned int cacheable:1; /**< can be cached */
unsigned int is_unknown:1; /**< resource created for unknown handler */
unsigned int is_proxy_uri:1; /**< resource created for proxy URI handler */
unsigned int is_reverse_proxy:1; /**< resource created for reverse proxy URI handler */

/**
* Used to store handlers for the seven coap methods @c GET, @c POST, @c PUT,
Expand Down
2 changes: 1 addition & 1 deletion man/coap-server.txt.in
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,7 @@ OPTIONS - General
Echo back the data sent with a PUT.

*-f* scheme://address[:port]::
Act as a reverse proxy where scheme, address, optional
Act as a reverse proxy where scheme, address and optional
port define how to connect to the internal server.
Scheme is one of coap, coaps, coap+tcp, coaps+tcp,
coap+ws, and coaps+ws. http(s) is not currently supported.
Expand Down
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