in_syslog: Add support for RFC 6587 octet-counting

plugins/in_syslog/syslog.c

@@ -244,7 +244,11 @@ static struct flb_config_map config_map[] = {
      0, FLB_TRUE, offsetof(struct flb_syslog, source_address_key),
      "Key where the source address will be injected"
     },
-
+    {
+     FLB_CONFIG_MAP_STR, "frame", (char *) NULL,
+     0, FLB_TRUE, offsetof(struct flb_syslog, frame_str),
+     "TCP framing: newline (default) or octet_counting (RFC 6587)"
+    },
 
     /* EOF */
     {0}

plugins/in_syslog/syslog.h

@@ -33,6 +33,10 @@
 /* 32KB chunk size */
 #define FLB_SYSLOG_CHUNK   "32768"
 
+/* TCP framing */
+#define FLB_SYSLOG_FRAME_NEWLINE        0
+#define FLB_SYSLOG_FRAME_OCTET_COUNTING 1
+
 struct syslog_conn;
 
 /* Context / Config*/
@@ -67,6 +71,10 @@ struct flb_syslog {
     flb_sds_t raw_message_key;
     flb_sds_t source_address_key;
 
+    /* TCP framing */
+    flb_sds_t frame_str;
+    int frame_type;
+
     int dgram_mode_flag;
     int collector_id;
     struct mk_event *collector_event;

plugins/in_syslog/syslog_conf.c

@@ -107,6 +107,19 @@ struct flb_syslog *syslog_conf_create(struct flb_input_instance *ins,
         ctx->mode = FLB_SYSLOG_UNIX_UDP;
     }
 
+    /* TCP Frame type (only applies to stream modes; default newline) */
+    ctx->frame_type = FLB_SYSLOG_FRAME_NEWLINE;
+    if (ctx->frame_str != NULL) {
+        if (strcasecmp(ctx->frame_str, "octet_counting") == 0 ||
+            strcasecmp(ctx->frame_str, "octet") == 0) {
+            ctx->frame_type = FLB_SYSLOG_FRAME_OCTET_COUNTING;
+        }
+        else if (strcasecmp(ctx->frame_str, "newline") != 0) {
+            flb_plg_warn(ins, "[in_syslog] unknown frame '%s', using 'newline'",
+                         ctx->frame_str);
+        }
+    }
+
     /* Check if TCP mode was requested */
     if (ctx->mode == FLB_SYSLOG_TCP || ctx->mode == FLB_SYSLOG_UDP) {
         /* Listen interface (if not set, defaults to 0.0.0.0:5140) */

plugins/in_syslog/syslog_conn.c

@@ -178,6 +178,8 @@ struct syslog_conn *syslog_conn_add(struct flb_connection *connection,
     conn->ins     = ctx->ins;
     conn->buf_len = 0;
     conn->buf_parsed = 0;
+    conn->frame_expected_len = 0;
+    conn->frame_have_len = 0;
 
     /* Allocate read buffer */
     conn->buf_data = flb_malloc(ctx->buffer_chunk_size);

plugins/in_syslog/syslog_conn.h

@@ -35,6 +35,9 @@ struct syslog_conn {
     size_t buf_size;                 /* Buffer size                       */
     size_t buf_len;                  /* Buffer length                     */
     size_t buf_parsed;               /* Parsed buffer (offset)            */
+    /* Octet-counting framing state */
+    size_t frame_expected_len;       /* remaining message bytes needed    */
+    int    frame_have_len;           /* 0 = need length, 1 = have length  */
     struct flb_input_instance *ins;  /* Parent plugin instance            */
     struct flb_syslog *ctx;          /* Plugin configuration context      */
     struct flb_connection *connection;

plugins/in_syslog/syslog_prot.c

@@ -218,21 +218,55 @@ int syslog_prot_process(struct syslog_conn *conn)
 
     flb_log_event_encoder_reset(ctx->log_encoder);
 
-    /* Always parse while some remaining bytes exists */
+    /* Always parse while some remaining bytes exist */
     while (eof < end) {
-        /* Lookup the ending byte */
-        eof = p = conn->buf_data + conn->buf_parsed;
-        while (*eof != '\n' && *eof != '\0' && eof < end) {
-            eof++;
+        if (ctx->frame_type == FLB_SYSLOG_FRAME_NEWLINE) {
+            /* newline framing (current behavior) */
+            eof = p = conn->buf_data + conn->buf_parsed;
+            while (*eof != '\n' && *eof != '\0' && eof < end) {
+                eof++;
+            }
+            /* Incomplete message */
+            if (eof == end || (*eof != '\n' && *eof != '\0')) {
+                break;
+            }
+            len = (eof - p);
         }
-
-        /* Incomplete message */
-        if (eof == end || (*eof != '\n' && *eof != '\0')) {
-            break;
+        else {
+            /* RFC 6587 octet-counting framing: <len> SP <msg> */
+            p = conn->buf_data + conn->buf_parsed;
+
+            if (!conn->frame_have_len) {
+                char *sp = p;
+                size_t n = 0;
+                while (sp < end && *sp >= '0' && *sp <= '9') {
+                    if (n > SIZE_MAX / 10) {
+                        n = SIZE_MAX;
+                        break;
+                    }
+                    n = n * 10 + (size_t)(*sp - '0');
+                    sp++;
+                }
+                if (sp == end) {
+                    break;
+                }
+                if (*sp != ' ') {
+                    flb_plg_warn(ctx->ins, "invalid octet-counting length");
+                    return -1;
+                }
+                conn->buf_parsed += (sp - p) + 1;
+                conn->frame_expected_len = n;
+                conn->frame_have_len = 1;
+                p = conn->buf_data + conn->buf_parsed;
+                end = conn->buf_data + conn->buf_len;
+            }
+            if ((size_t)(end - p) < conn->frame_expected_len) {
+                break;
+            }
+            len = (int)conn->frame_expected_len;
         }
 
         /* No data ? */
-        len = (eof - p);
         if (len == 0) {
             consume_bytes(conn->buf_data, 1, conn->buf_len);
             conn->buf_len--;
@@ -266,7 +300,18 @@ int syslog_prot_process(struct syslog_conn *conn)
             flb_plg_debug(ctx->ins, "unparsed log message: %.*s", len, p);
         }
 
-        conn->buf_parsed += len + 1;
+        if (ctx->frame_type == FLB_SYSLOG_FRAME_NEWLINE) {
+            conn->buf_parsed += len + 1;
+        }
+        else {
+            conn->buf_parsed += len;
+            conn->frame_expected_len = 0;
+            conn->frame_have_len = 0;
+            if (conn->buf_parsed < conn->buf_len &&
+                conn->buf_data[conn->buf_parsed] == '\n') {
+                conn->buf_parsed += 1;
+            }
+        }
         end = conn->buf_data + conn->buf_len;
         eof = conn->buf_data + conn->buf_parsed;
     }

plugins/in_syslog/syslog_prot.h

@@ -22,6 +22,8 @@
 
 #include <fluent-bit/flb_info.h>
 
+#include <stdint.h>
+
 #include "syslog.h"
 
 #define FLB_MAP_EXPAND_SUCCESS   0