feat: add zlib compression support

Makefile.am

@@ -141,7 +141,8 @@ jrpcd_LDADD = libdaemon.la \
               -lcap
 if ENABLE_OPENSSL
 jrpcd_LDADD += $(CRYPTO_LIBS) \
-               $(SSL_LIBS)
+               $(SSL_LIBS) \
+               $(Z_LIBS)
 endif
 endif
 
@@ -163,6 +164,7 @@ sysagentd_LDADD = libdaemon.la \
                   libminkplugin.la \
                   libminkdb.la \
                   ${NCURSES_LIBS} \
+                  ${Z_LIBS} \
                   -lcap
 endif     
 

configure.ac

@@ -237,6 +237,12 @@ AC_CHECK_LIB([ncurses],
              [AC_SUBST([NCURSES_LIBS], ["-lncurses"])],
              [AC_MSG_ERROR([ncurses library not found!])])
 
+# zlib
+AC_CHECK_LIB([z], 
+             [inflateEnd],
+             [AC_SUBST([Z_LIBS], ["-lz"])],
+             [AC_MSG_ERROR([libz not found!])])
+
 # pthread
 AC_CHECK_LIB([pthread], [pthread_create], , AC_MSG_ERROR([pthread library not found!]))
 # sctp
@@ -281,6 +287,7 @@ AC_CHECK_HEADERS([      arpa/inet.h \
                         boost/algorithm/string/trim.hpp \
                         boost/range/as_array.hpp \
                         boost/tokenizer.hpp \
+                        zlib.h \
                         unistd.h], , AC_MSG_ERROR([Header file missing!]))
 
 # Checks for typedefs, structures, and compiler characteristics.

src/services/json_rpc/events.cpp

@@ -13,6 +13,7 @@
 #include <daemon.h>
 #include <atomic.h>
 #include <gdt.pb.enums_only.h>
+#include <zlib.h>
 
 using data_vec_t = std::vector<uint8_t>;
 namespace beast = boost::beast;
@@ -108,6 +109,52 @@ static void handle_error(const mink_utils::VariantParam *vp_err,
 
 }
 
+static std::string sparam_zlib_decmpress(const uint8_t *data, 
+                                         const std::size_t sz,
+                                         char *out_buff, 
+                                         const std::size_t out_buf_sz){
+    // output string
+    std::string s;
+    // decompress
+    z_stream zs;
+    zs.zalloc = Z_NULL;
+    zs.zfree = Z_NULL;
+    zs.opaque = Z_NULL;
+    // input size
+    zs.avail_in = sz;
+    // input data
+    zs.next_in = (Bytef *)data;
+    zs.avail_out = out_buf_sz;
+    zs.next_out = (Bytef *)out_buff;
+    // init decompress struct
+    int z_res = inflateInit(&zs);
+    if(z_res != Z_OK){
+        // cleanup
+        delete data;
+    }
+    // decompress
+    do {
+        // inflate and flush to buffer
+        z_res = inflate(&zs, Z_SYNC_FLUSH);
+        // error
+        if (z_res < 0 && z_res != Z_BUF_ERROR)
+            break;
+
+        //  append uncompressed data
+        s.append(out_buff, out_buf_sz - zs.avail_out);
+        // update zlib struct
+        if (zs.avail_out == 0) {
+            zs.avail_out = out_buf_sz;
+            zs.next_out = (Bytef *)out_buff;
+        }
+    } while (z_res != Z_STREAM_END);
+
+    // zlib cleanup
+    inflateEnd(&zs);
+    // res
+    return s;
+}
+
 void EVSrvcMsgRecv::run(gdt::GDTCallbackArgs *args){
     gdt::ServiceMessage* smsg = args->get<gdt::ServiceMessage>(gdt::GDT_CB_INPUT_ARGS, 
                                                                gdt::GDT_CB_ARGS_SRVC_MSG);
@@ -196,6 +243,10 @@ void EVSrvcMsgRecv::run(gdt::GDTCallbackArgs *args){
 
     // loop GDT params
     mink_utils::PooledVPMap<uint32_t>::it_t it = smsg->vpmap.get_begin();
+
+    // zlib out buffer
+    char z_out_buff[65535];
+
     // loop param map
     for(; it != smsg->vpmap.get_end(); it++){
         // param name from ID
@@ -208,8 +259,15 @@ void EVSrvcMsgRecv::run(gdt::GDTCallbackArgs *args){
         if(pt == mink_utils::DPT_POINTER){
             auto data = static_cast<data_vec_t *>((void *)it->second);
             try {
-                std::string s(reinterpret_cast<char *>(data->data()),
-                              data->size());
+                // output string
+                std::string s = sparam_zlib_decmpress(data->data(),
+                                                      data->size(),
+                                                      z_out_buff,
+                                                      sizeof(z_out_buff));
+                // compressed/uncompressed
+                if (s.empty()) {
+                    s.assign(reinterpret_cast<char *>(data->data()), data->size());
+                }
                 // new json object
                 auto o = json::object();
                 o[pname] = s;
@@ -235,23 +293,20 @@ void EVSrvcMsgRecv::run(gdt::GDTCallbackArgs *args){
 
         // STRING as OCTETES (check if printable)
         } else if (pt == mink_utils::DPT_OCTETS) {
+            // sparam data
             unsigned char *od = static_cast<unsigned char *>(it->second);
-            /*
-            bool is_p = true;
-            for (int i = 0; i < it->second.get_size(); i++) {
-                if (!std::isprint(od[i])) {
-                    is_p = false;
-                    break;
-                }
+            // output string
+            val = sparam_zlib_decmpress(od,
+                                        it->second.get_size(),
+                                        z_out_buff,
+                                        sizeof(z_out_buff));
+
+            // compressed/uncompressed
+            if (val.empty()) {
+                val.assign(reinterpret_cast<char *>(od), it->second.get_size());
             }
-            if (!is_p) continue;
-            val = std::move(std::string(reinterpret_cast<char *>(od),
-                                        it->second.get_size()));
-            */
-            val = std::move(std::string(reinterpret_cast<char *>(od),
-                                        it->second.get_size()));
-
-            // ignore other types
+
+        // ignore other types
         } else continue;
 
         // setup json object

src/services/sysagent/plugins/openwrt/Makefile.am

@@ -2,4 +2,4 @@ pkglib_LTLIBRARIES += plg_sysagent_openwrt.la
 plg_sysagent_openwrt_la_SOURCES = src/services/sysagent/plugins/openwrt/plg_sysagent_openwrt.cpp
 plg_sysagent_openwrt_la_CPPFLAGS = ${COMMON_INCLUDES} ${GRPC_CFLAGS} -Isrc/proto
 plg_sysagent_openwrt_la_LDFLAGS = -version-info 1:0:0 -shared -module -export-dynamic
-plg_sysagent_openwrt_la_LIBADD = ${UBUS_LIBS} ${UBOX_LIBS} ${BLOBMSG_JSON_LIBS} ${JSONC_LIBS}
+plg_sysagent_openwrt_la_LIBADD = ${UBUS_LIBS} ${UBOX_LIBS} ${BLOBMSG_JSON_LIBS} ${JSONC_LIBS} ${Z_LIBS}

src/services/sysagent/plugins/openwrt/plg_sysagent_openwrt.cpp

@@ -27,6 +27,7 @@ extern "C" {
     #include <libubox/blobmsg_json.h>
 }
 #include <boost/beast/core/detail/base64.hpp>
+#include <zlib.h>
 
 /*********/
 /* types */
@@ -367,7 +368,52 @@ static void ubus_event_cb(ubus_request *req, int type, blob_attr *msg){
                                 ->get_param_factory()
                                 ->new_param(gdt::SPT_OCTETS);
     if(sp){
-        sp->set_data(ic->ev_usr_cb->buff, strlen(ic->ev_usr_cb->buff));
+        // compress
+        z_stream zs;
+        zs.zalloc = Z_NULL;
+        zs.zfree = Z_NULL;
+        zs.opaque = Z_NULL;
+        // input size
+        zs.avail_in = strlen(ic->ev_usr_cb->buff);
+        // input data
+        zs.next_in = (Bytef *)ic->ev_usr_cb->buff;
+        //output buffer size
+        char z_out_buff[zs.avail_in * 2];
+        zs.avail_out = sizeof(z_out_buff);
+        zs.next_out = (Bytef *)z_out_buff;
+        // init struct
+        if(deflateInit(&zs, Z_BEST_COMPRESSION) != Z_OK){
+            set_ubus_error(ic->smsg, mink::error::EC_UNKNOWN);
+            // cleanup
+            blob_buf_free(&ic->msg);
+            delete ic->ev_usr_cb;
+            delete ic;
+            return;
+        }
+        // compress data
+        int zres = deflate(&zs, Z_FINISH);
+        if(zres != Z_STREAM_END){
+            set_ubus_error(ic->smsg, mink::error::EC_UNKNOWN);
+            // cleanup
+            blob_buf_free(&ic->msg);
+            delete ic->ev_usr_cb;
+            delete ic;
+            return;
+
+        }
+        // finish
+        if(deflateEnd(&zs) != Z_OK){
+            set_ubus_error(ic->smsg, mink::error::EC_UNKNOWN);
+            // cleanup
+            blob_buf_free(&ic->msg);
+            delete ic->ev_usr_cb;
+            delete ic;
+            return;
+        }
+
+        // switch buffers 
+        memcpy(ic->ev_usr_cb->buff, z_out_buff, zs.total_out);
+        sp->set_data(ic->ev_usr_cb->buff, zs.total_out);
         sp->set_id(PT_OWRT_UBUS_RESULT);
         sp->set_extra_type(0);
         pmap->push_back(sp);
@@ -402,8 +448,6 @@ static void impl_firmware_update(gdt::ServiceMessage *smsg){
         auto res = base64::decode(arr.data(), data.data(), data.size());
         if (fwrite(arr.data(), res.first, 1, f) != 1)
             throw std::invalid_argument("size mismatch while writing file");
-
-        fflush(f);
         fclose(f);
 
     } catch (std::exception &e) {