Proxy: Update Proxy support for Proxy-Uri: CoAP option

Add code to better support the Proxy-Uri: and Proxy-Scheme: CoAP Options.

examples/client.c:

Make sure that the Proxy-Uri: option is added (if set) when clearing down an
observation (fixes obgm#112).
Check that Proxy-Uri: option has a maximum data length of 1034 bytes.
Handle user defined Proxy-Scheme: option correctly.
Update -P option to include scheme to be used when connecting to the proxy.

examples/coap-server.c:

Add in hnd_proxy_uri() handler function. This has support for a direct or ongoing
proxy connection for the coap* protocols. The ongoing connection is set up as a
different CoAP session and is assocated with the incoming session for relaying
requests / responses.

Internal functions taken from client.c are used where appropriate.

Proxy support code has a SERVER_CAN_PROXY wrapper, so footprint can easily be
reduced if required.

New -P and -u options added to support ongoing connections.

include/coap2/net.h:

Add in tracking the proxy uri handler into coap_context_t.

include/coap2/resource.h:

Track whether a resource definition is for Proxy-Uri:/Proxy-Scheme:.
Define the coap_resource_proxy_uri_init() function for handling the Proxy-Uri:
option or Proxy-Scheme: option in an incoming request.

include/coap2/uri.h:

Add in COAP_URI_SCHEME_HTTP and COAP_URI_SCHEME_HTTPS as valid Proxy-Uri:
schemes.
Define the coap_split_proxy_uri() function (similar to coap_split_uri() but
supports the proxy extras.  Both now use a common sub function internally.

libcoap-2.map:
libcoap-2.sym:

Expose the new coap_resource_proxy_uri_init() and coap_split_proxy_uri()
functions.

man/Makefile.am:

Handle coap_resource_get_userdata(3) now being over the 10 definition limit
in man/coap_resource.txt.in.

man/coap-client.txt.in:

Update documentation for the -P option.

man/coap-server.txt.in:

Document the new -P proxy option.
Document the new -u user option.

man/coap_resource.txt.in:

Include documentation for coap_resource_proxy_uri_init().

src/coap_debug.c:

Output the Proxy-Scheme: Option as text.

src/net.c:

Sanity check and handle COAP_OPTION_PROXY_URI and COAP_OPTION_PROXY_SCHEME
in handle_request().

src/resource.c:

Add in coap_resource_proxy_uri_init() function.
Handle the addition of a proxy uri handler in coap_add_resource().

src/uri.c:

Rename coap_split_uri() to coap_split_uri_sub() and add in extra proxy
handling support based on input parameters.

Create new coap_split_uri() and coap_split_proxy_uri() which call
coap_split_uri_sub() appropriately.

TODO:

Remove reference to Proxy support required

TODO

@@ -11,8 +11,6 @@ Classification of issues:
 =================
 * CRITICAL ISSUES
 =================
--> Proxy functionality
- -> A coap-server should be able to act as proxy server
 
 ================
 * SERIOUS ISSUES

examples/client.c

@@ -58,6 +58,9 @@ static coap_optlist_t *optlist = NULL;
 static coap_uri_t uri;
 static coap_string_t proxy = { 0, NULL };
 static uint16_t proxy_port = COAP_DEFAULT_PORT;
+static coap_uri_scheme_t proxy_scheme = COAP_URI_SCHEME_COAP;
+static int proxy_scheme_option = 0;
+static int uri_host_option = 0;
 static unsigned int ping_seconds = 0;
 
 /* reading is done when this flag is set */
@@ -197,7 +200,7 @@ coap_new_request(coap_context_t *ctx,
     else {
       unsigned char buf[4];
       coap_add_option(pdu,
-                      COAP_OPTION_SIZE1,
+                      COAP_OPTION_SIZE1,  /* 60 */
                       coap_encode_var_safe8(buf, sizeof(buf), length),
                       buf);
 
@@ -232,17 +235,21 @@ clear_obs(coap_context_t *ctx, coap_session_t *session) {
   }
 
   for (option = optlist; option; option = option->next ) {
-    if (option->number == COAP_OPTION_URI_HOST) {
+    switch (option->number) {
+    case COAP_OPTION_URI_HOST : /*  3 */
       if (!coap_add_option(pdu, option->number, option->length,
                            option->data)) {
         goto error;
       }
       break;
+    default:
+      ;
     }
   }
 
+  /* Observe option comes after Uri-Host, but before the others */
   if (!coap_add_option(pdu,
-      COAP_OPTION_OBSERVE,
+      COAP_OPTION_OBSERVE,  /* 6 */
       coap_encode_var_safe(buf, sizeof(buf), COAP_OBSERVE_CANCEL),
       buf)) {
     coap_log(LOG_CRIT, "cannot add option Observe: %u\n", COAP_OBSERVE_CANCEL);
@@ -269,10 +276,23 @@ clear_obs(coap_context_t *ctx, coap_session_t *session) {
     block.num = 0;
     block.m = 0;
     coap_add_option(pdu,
-      COAP_OPTION_BLOCK2,
+      COAP_OPTION_BLOCK2,  /* 23 */
       coap_encode_var_safe(buf, sizeof(buf), (block.num << 4 | block.m << 3 | block.szx)),
       buf);
   }
+  for (option = optlist; option; option = option->next ) {
+    switch (option->number) {
+    case COAP_OPTION_PROXY_URI :    /* 35 */
+    case COAP_OPTION_PROXY_SCHEME : /* 39 */
+      if (!coap_add_option(pdu, option->number, option->length,
+                           option->data)) {
+        goto error;
+      }
+      break;
+    default:
+      ;
+    }
+  }
 
   if (coap_get_log_level() < LOG_DEBUG)
     coap_show_pdu(LOG_INFO, pdu);
@@ -377,7 +397,7 @@ nack_handler(coap_context_t *context UNUSED_PARAM,
     break;
   case COAP_NACK_ICMP_ISSUE:
   default:
-    break;
+    ;
   }
   return;
 }
@@ -475,11 +495,22 @@ message_handler(struct coap_context_t *ctx,
           coap_log(LOG_DEBUG, "query block %d\n",
                    (coap_opt_block_num(block_opt) + 1));
           coap_add_option(pdu,
-                          blktype,
+                          blktype,     /* 23 or 27 */
                           coap_encode_var_safe(buf, sizeof(buf),
                                  ((coap_opt_block_num(block_opt) + 1) << 4) |
                                   COAP_OPT_BLOCK_SZX(block_opt)), buf);
 
+          for (option = optlist; option; option = option->next ) {
+            switch (option->number) {
+              case COAP_OPTION_PROXY_URI :    /* 35 */
+              case COAP_OPTION_PROXY_SCHEME : /* 39 */
+                coap_add_option(pdu, option->number, option->length,
+                                option->data);
+                break;
+              default:
+                ;     /* skip other options */
+            }
+          }
           tid = coap_send(session, pdu);
 
           if (tid == COAP_INVALID_TID) {
@@ -562,7 +593,7 @@ message_handler(struct coap_context_t *ctx,
                                 option->data);
                 break;
               default:
-              ;     /* skip other options */
+                ;     /* skip other options */
             }
           }
 
@@ -573,12 +604,24 @@ message_handler(struct coap_context_t *ctx,
 
           coap_log(LOG_DEBUG, "send block %d\n", block.num);
           coap_add_option(pdu,
-                          COAP_OPTION_BLOCK1,
+                          COAP_OPTION_BLOCK1,  /* 27 */
                           coap_encode_var_safe(buf, sizeof(buf),
                           (block.num << 4) | (block.m << 3) | block.szx), buf);
 
+          for (option = optlist; option; option = option->next ) {
+            switch (option->number) {
+              case COAP_OPTION_PROXY_URI :    /* 35 */
+              case COAP_OPTION_PROXY_SCHEME : /* 39 */
+                coap_add_option(pdu, option->number, option->length,
+                                option->data);
+                break;
+              default:
+                ;     /* skip other options */
+            }
+          }
+
           coap_add_option(pdu,
-                          COAP_OPTION_SIZE1,
+                          COAP_OPTION_SIZE1,  /* 60 */
                           coap_encode_var_safe8(buf, sizeof(buf), payload.length),
                           buf);
 
@@ -645,7 +688,7 @@ usage( const char *program, const char *version) {
      "Usage: %s [-a addr] [-b [num,]size] [-e text] [-f file] [-l loss]\n"
      "\t\t[-m method] [-o file] [-p port] [-r] [-s duration] [-t type]\n"
      "\t\t[-v num] [-A type] [-B seconds] [-H hoplimit] [-K interval] [-N]\n"
-     "\t\t[-O num,text] [-P addr[:port]] [-T token] [-U]\n"
+     "\t\t[-O num,text] [-P scheme://address[:port]] [-T token] [-U]\n"
      "\t\t[[-h match_hint_file] [-k key] [-u user]]\n"
      "\t\t[[-c certfile] [-j keyfile] [-C cafile] [-J pkcs11_pin]\n"
      "\t\t[-R root_cafile] [-S match_pki_sni_file]] URI\n"
@@ -680,13 +723,15 @@ usage( const char *program, const char *version) {
      "\t-H hoplimit\tSet the Hop Limit count to hoplimit for proxies. Must\n"
      "\t       \t\thave a value between 1 and 255 inclusive.\n"
      "\t       \t\tDefault is '16'\n"
-     "\t-K interval\tsend a ping after interval seconds of inactivity\n"
+     "\t-K interval\tSend a ping after interval seconds of inactivity\n"
      "\t-N     \t\tSend NON-confirmable message\n"
      "\t-O num,text\tAdd option num with contents text to request. If the\n"
      "\t       \t\ttext begins with 0x, then the hex text is converted to\n"
      "\t       \t\tbinary data\n"
-     "\t-P addr[:port]\tUse proxy (automatically adds Proxy-Uri option to\n"
-     "\t       \t\trequest)\n"
+     "\t-P scheme://address[:port]\tScheme, address and optional port to\n"
+     "\t       \t\tdefine how to connect to a CoAP proxy (automatically adds\n"
+     "\t       \t\tProxy-Uri option to request) to forward the request to.\n"
+     "\t       \t\tScheme is one of coap, coaps, coap+tcp and coaps+tcp\n"
      "\t-T token\tInclude specified token\n"
      "\t-U     \t\tNever include Uri-Host or Uri-Port options\n"
      ,program, version, coap_string_tls_version(buffer, sizeof(buffer))
@@ -836,16 +881,11 @@ cmdline_uri(char *arg, int create_uri_opts) {
   size_t buflen;
   int res;
 
-  if (proxy.length) {   /* create Proxy-Uri from argument */
+  if (!proxy_scheme_option && proxy.length) {   /* create Proxy-Uri from argument */
     size_t len = strlen(arg);
-    while (len > 270) {
-      coap_insert_optlist(&optlist,
-                  coap_new_optlist(COAP_OPTION_PROXY_URI,
-                  270,
-                  (unsigned char *)arg));
-
-      len -= 270;
-      arg += 270;
+    if (len > 1034) {
+      coap_log(LOG_ERR, "Absolute URI length must be <= 1034 bytes for a proxy\n");
+      return -1;
     }
 
     coap_insert_optlist(&optlist,
@@ -978,7 +1018,35 @@ cmdline_subscribe(char *arg) {
 
 static int
 cmdline_proxy(char *arg) {
-  char *proxy_port_str = strrchr((const char *)arg, ':'); /* explicit port ? */
+  char *proxy_port_str;
+
+  if (strncmp(arg, "coap", 4) == 0) {
+    if (strncmp(arg, "coaps+tcp://", 12) == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAPS_TCP;
+      proxy_port = COAPS_DEFAULT_PORT;
+      arg += 12;
+    }
+    else if (strncmp(arg, "coap+tcp://", 11) == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAP_TCP;
+      proxy_port = COAP_DEFAULT_PORT;
+      arg += 11;
+    }
+    else if (strncmp(arg, "coaps://", 8) == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAPS;
+      proxy_port = COAPS_DEFAULT_PORT;
+      arg += 8;
+    }
+    else if (strncmp(arg, "coap://", 7) == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAP;
+      proxy_port = COAP_DEFAULT_PORT;
+      arg += 7;
+    }
+    else {
+      coap_log(LOG_WARNING, "Invalid proxy protocol prefix '%s'\n", arg);
+      return 0;
+    }
+  }
+  proxy_port_str = strrchr((const char *)arg, ':'); /* explicit port ? */
   if (proxy_port_str) {
     char *ipv6_delimiter = strrchr((const char *)arg, ']');
     if (!ipv6_delimiter) {
@@ -1084,6 +1152,31 @@ cmdline_option(char *arg) {
     coap_insert_optlist(&optlist,
                         coap_new_optlist(num, strlen(arg), (unsigned char *)arg));
   }
+  if (num == COAP_OPTION_PROXY_SCHEME) {
+    proxy_scheme_option = 1;
+    if (strcmp(arg, "coaps+tcp") == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAPS_TCP;
+      proxy_port = COAPS_DEFAULT_PORT;
+    }
+    else if (strcmp(arg, "coap+tcp") == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAP_TCP;
+      proxy_port = COAP_DEFAULT_PORT;
+    }
+    else if (strcmp(arg, "coaps") == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAPS;
+      proxy_port = COAPS_DEFAULT_PORT;
+    }
+    else if (strcmp(arg, "coap") == 0) {
+      proxy_scheme = COAP_URI_SCHEME_COAP;
+      proxy_port = COAP_DEFAULT_PORT;
+    }
+    else {
+      coap_log(LOG_WARNING, "%s is not a supported CoAP Proxy-Scheme\n", arg);
+    }
+  }
+  if (num == COAP_OPTION_URI_HOST) {
+    uri_host_option = 1;
+  }
 }
 
 /**
@@ -1559,6 +1652,7 @@ main(int argc, char **argv) {
   ssize_t user_length = -1, key_length = 0;
   int create_uri_opts = 1;
   size_t i;
+  coap_uri_scheme_t scheme;
 #ifndef _WIN32
   struct sigaction sa;
 #endif
@@ -1705,9 +1799,11 @@ main(int argc, char **argv) {
     server.length = proxy.length;
     server.s = proxy.s;
     port = proxy_port;
+    scheme = proxy_scheme;
   } else {
     server = uri.host;
-    port = uri.port;
+    port = proxy_scheme_option ? proxy_port : uri.port;
+    scheme = proxy_scheme_option ? proxy_scheme : uri.scheme;
   }
 
   /* resolve destination address where server should be sent */
@@ -1732,11 +1828,11 @@ main(int argc, char **argv) {
   session = get_session(
     ctx,
     node_str[0] ? node_str : NULL, port_str,
-    uri.scheme==COAP_URI_SCHEME_COAP_TCP ? COAP_PROTO_TCP :
-    uri.scheme==COAP_URI_SCHEME_COAPS_TCP ? COAP_PROTO_TLS :
+    scheme==COAP_URI_SCHEME_COAP_TCP ? COAP_PROTO_TCP :
+    scheme==COAP_URI_SCHEME_COAPS_TCP ? COAP_PROTO_TLS :
     (reliable ?
-        uri.scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_TLS : COAP_PROTO_TCP
-      : uri.scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_DTLS : COAP_PROTO_UDP),
+        scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_TLS : COAP_PROTO_TCP
+      : scheme==COAP_URI_SCHEME_COAPS ? COAP_PROTO_DTLS : COAP_PROTO_UDP),
     &dst,
     user_length >= 0 ? user : NULL,
     user_length >= 0 ? user_length : 0,
@@ -1770,11 +1866,11 @@ main(int argc, char **argv) {
 
   /* construct CoAP message */
 
-  if (!proxy.length && addrptr
+  if (!uri_host_option && (!proxy.length && addrptr
       && (inet_ntop(dst.addr.sa.sa_family, addrptr, addr, sizeof(addr)) != 0)
       && (strlen(addr) != uri.host.length
       || memcmp(addr, uri.host.s, uri.host.length) != 0)
-      && create_uri_opts) {
+      && create_uri_opts)) {
         /* add Uri-Host */
 
         coap_insert_optlist(&optlist,
@@ -1857,6 +1953,8 @@ main(int argc, char **argv) {
   }
   if (valid_ihs.count)
     free(valid_ihs.ih_list);
+  if (proxy.s)
+    coap_free(proxy.s);
   coap_delete_optlist(optlist);
   if (payload.s) coap_free(payload.s);
   coap_session_release( session );