Implement MOTD feature in keydb-cli

Former-commit-id: a6c56416fc1bf09f1ecbae45195290209aa93c89

src/Makefile

@@ -264,7 +264,7 @@ $(REDIS_CHECK_AOF_NAME): $(REDIS_SERVER_NAME)
 
 # keydb-cli
 $(REDIS_CLI_NAME): $(REDIS_CLI_OBJ)
-	$(REDIS_LD) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/linenoise/linenoise.o $(FINAL_LIBS)
+	$(REDIS_LD) -o $@ $^ ../deps/hiredis/libhiredis.a ../deps/linenoise/linenoise.o $(FINAL_LIBS) -lcurl
 
 # keydb-benchmark
 $(REDIS_BENCHMARK_NAME): $(REDIS_BENCHMARK_OBJ)

src/redis-cli.c

@@ -45,6 +45,8 @@
 #include <fcntl.h>
 #include <limits.h>
 #include <math.h>
+#include <sys/types.h>
+#include <pwd.h>
 
 #include <hiredis.h>
 #include <sds.h> /* use sds.h from hiredis, so that only one set of sds functions will be present in the binary */
@@ -6532,6 +6534,116 @@ static void intrinsicLatencyMode(void) {
     }
 }
 
+/*------------------------------------------------------------------------------
+ * Message of the day
+ *--------------------------------------------------------------------------- */
+#ifndef NO_MOTD
+#include <curl/curl.h> 
+
+static const char *szMotdCachePath()
+{
+    static sds sdsMotdCachePath = NULL;
+    if (sdsMotdCachePath != NULL)
+        return sdsMotdCachePath;
+
+    struct passwd *pw = getpwuid(getuid());
+    if (pw == NULL)
+        return "";
+    const char *homedir = pw->pw_dir;
+    sdsMotdCachePath = sdsnew(homedir);
+    sdsMotdCachePath = sdscat(sdsMotdCachePath, "/.keydb-cli-motd");
+    return sdsMotdCachePath;
+}
+static size_t motd_write_callback(void *ptr, size_t size, size_t nmemb, sds *str)
+{
+    *str = sdscatlen(*str, ptr, size*nmemb);
+    return (size*nmemb);
+}
+
+static char *fetchMOTDFromCache()
+{
+    struct stat attrib;
+    if (stat(szMotdCachePath(), &attrib) != 0)
+        return NULL;
+    time_t t = attrib.st_mtim.tv_sec;
+    time_t now = time(NULL);
+    if ((now - t) < 14400)
+    {
+        // If our cache was updated no more than 4 hours ago use it instead of fetching the MOTD
+        FILE *pf = fopen(szMotdCachePath(), "rb");
+        if (pf == NULL)
+            return NULL;
+        fseek(pf, 0L, SEEK_END);
+        long cb = ftell(pf);
+        fseek(pf, 0L, SEEK_SET);    // rewind
+        sds str = sdsnewlen(NULL, cb);
+        size_t cbRead = fread(str, 1, cb, pf);
+        fclose(pf);
+        if ((long)cbRead != cb)
+        {
+            sdsfree(str);
+            return NULL;
+        }
+        return str;
+    }
+    return NULL;
+}
+
+static void setMOTDCache(const char *sz)
+{
+    FILE *pf = fopen(szMotdCachePath(), "wb");
+    size_t celem = fwrite(sz, strlen(sz), 1, pf);
+    (void)celem;    // best effort
+    fclose(pf);
+}
+
+static char *fetchMOTD()
+{
+    sds str;
+    CURL *curl;
+    CURLcode res;
+
+    /* First try and get the string from the cache */
+    str = fetchMOTDFromCache();
+    if (str != NULL)
+        return str;
+
+    str = sdsnew("");
+    curl = curl_easy_init();
+    if(curl) {
+        curl_easy_setopt(curl, CURLOPT_URL, "http://api.keydb.dev/motd/motd.txt");
+        curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L); // follow redirects
+        curl_easy_setopt(curl, CURLOPT_TIMEOUT, 2); // take no more than two seconds
+        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, motd_write_callback);
+        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &str);
+
+        /* Perform the request, res will get the return code */ 
+        res = curl_easy_perform(curl);
+        /* Check for errors */ 
+        if(res != CURLE_OK)
+        {
+            sdsfree(str);
+            str = NULL;
+        }
+
+        /* always cleanup */ 
+        curl_easy_cleanup(curl);
+
+        if (str != NULL)
+            setMOTDCache(str);
+    }
+    return str;
+}
+
+#else
+
+static char *fetchMOTD()
+{
+    return NULL;
+}
+
+#endif
+
 /*------------------------------------------------------------------------------
  * Program main()
  *--------------------------------------------------------------------------- */
@@ -6700,6 +6812,15 @@ int main(int argc, char **argv) {
 
     /* Start interactive mode when no command is provided */
     if (argc == 0 && !config.eval) {
+        /* Show the message of the day if we are interactive */
+        if (config.output == OUTPUT_STANDARD) {
+            char *szMotd = fetchMOTD();
+            if (szMotd != NULL) {
+                printf("Message of the day:\n  %s\n", szMotd);
+                sdsfree(szMotd);
+            }
+        }
+
         /* Ignore SIGPIPE in interactive mode to force a reconnect */
         signal(SIGPIPE, SIG_IGN);
 
@@ -6711,6 +6832,7 @@ int main(int argc, char **argv) {
 
     /* Otherwise, we have some arguments to execute */
     if (cliConnect(0) != REDIS_OK) exit(1);
+
     if (config.eval) {
         return evalMode(argc,argv);
     } else {