Changeset 7e6b54d

Timestamp:

09/03/15 15:21:45 (6 years ago)

Author:

Shane Alcock <salcock@…>

Branches:

4.0.1-hotfixes, cachetimestamps, develop, dpdk-ndag, etsilive, libtrace4, master, ndag_format, pfring, rc-4.0.1, rc-4.0.2, rc-4.0.3, rc-4.0.4, ringdecrementfix, ringperformance, ringtimestampfixes

Children:

0a368ae

Parents:

87cba74

Message:

Re-work the RT protocol to be usable cross-platform

• All structures are packed to avoid padding mismatches.
• All fields are in network byte order.
• Added 'version' and 'magic' fields to the header so we can identify version mismatches or invalid packets more easily.
• Acknowledgements are now sent for 1/10 received packets and are treated as cumulative acknowledgements. Reordering shouldn't happen at this layer, since we are using TCP for transport.
• Replace enum types in headers with uint32_t, so we can be sure of what size these fields will be.

Location:

lib

Files:

• format_rt.c (modified) (10 diffs)
• rt_protocol.h (modified) (7 diffs)

lib/format_rt.c

@@ -98 +98 @@
         /* Header for the packet currently being received */
         rt_header_t rt_hdr;
+
+        int unacked;
         
         /* Dummy traces that can be assigned to the received packets to ensure
@@ -155 +157 @@
         }
         
-        switch (connect_msg.type) {
+        if (connect_msg.magic != LIBTRACE_RT_MAGIC) {
+                trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
+                        "RT version mismatch: magic byte is incorrect");
+                return -1;
+        }
+
+        if (connect_msg.version != LIBTRACE_RT_VERSION) {
+                trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
+                        "RT version mismatch: version is incorrect (expected %d, got %d",
+                        LIBTRACE_RT_VERSION, connect_msg.version);
+                return -1;
+        }
+
+                
+        
+        switch (ntohl(connect_msg.type)) {
                 case TRACE_RT_DENY_CONN:
                         /* Connection was denied */
@@ -164 +181 @@
                                 reason = 0;
                         }       
-                        reason = deny_hdr.reason;
+                        reason = ntohl(deny_hdr.reason);
                         trace_set_err(libtrace, TRACE_ERR_INIT_FAILED,
                                 "Connection attempt is denied: %s",
@@ -179 +196 @@
                                 return -1;
                         }
-                        RT_INFO->reliable = hello_opts.reliable;
                         
+                        
+                        RT_INFO->reliable = hello_opts.reliable;
+                        RT_INFO->unacked = 0;
                         return 0;
                 default:
@@ -207 +226 @@
         RT_INFO->hostname = NULL;
         RT_INFO->port = 0;
+        RT_INFO->unacked = 0;
 }
 
@@ -245 +265 @@
         rt_header_t start_msg;
 
-        start_msg.type = TRACE_RT_START;
+        start_msg.type = htonl(TRACE_RT_START);
         start_msg.length = 0; 
 
@@ -265 +285 @@
         rt_header_t close_msg;
 
-        close_msg.type = TRACE_RT_CLOSE;
+        close_msg.type = htonl(TRACE_RT_CLOSE);
         close_msg.length = 0; 
         
@@ -502 +522 @@
         ack_hdr = (rt_ack_t *) (ack_buffer + sizeof(rt_header_t));
         
-        hdr->type = TRACE_RT_ACK;
-        hdr->length = sizeof(rt_ack_t);
-
-        ack_hdr->sequence = seqno;
-        
-        to_write = hdr->length + sizeof(rt_header_t);
+        hdr->type = htonl(TRACE_RT_ACK);
+        hdr->length = htons(sizeof(rt_ack_t));
+
+        ack_hdr->sequence = htonl(seqno);
+        
+        to_write = sizeof(rt_ack_t) + sizeof(rt_header_t);
         buf_ptr = ack_buffer;
 
@@ -575 +595 @@
         /* Send an ACK if required */
         if (RT_INFO->reliable > 0 && packet->type >= TRACE_RT_DATA_SIMPLE) {
-                if (rt_send_ack(libtrace, RT_INFO->rt_hdr.sequence) == -1)
+                RT_INFO->unacked ++;
+                if (RT_INFO->unacked >= RT_ACK_FREQUENCY) {
+                        if (rt_send_ack(libtrace, RT_INFO->rt_hdr.sequence) 
+                                        == -1)
                                 return -1;
+                        RT_INFO->unacked = 0;
+                }
         }
         
@@ -622 +647 @@
                 /* Need to store these in case the next rt_read overwrites 
                  * the buffer they came from! */
-                RT_INFO->rt_hdr.type = pkt_hdr->type;
-                RT_INFO->rt_hdr.length = pkt_hdr->length;
-                RT_INFO->rt_hdr.sequence = pkt_hdr->sequence;
+                RT_INFO->rt_hdr.type = ntohl(pkt_hdr->type);
+                RT_INFO->rt_hdr.length = ntohs(pkt_hdr->length);
+                RT_INFO->rt_hdr.sequence = ntohl(pkt_hdr->sequence);
         }
         packet->type = RT_INFO->rt_hdr.type;

lib/rt_protocol.h

@@ -50 +50 @@
 /** Maximum size for the RT header */
 #define RT_MAX_HDR_SIZE 256
-/** Maximum sequence number for the RT protocol */
-#define MAX_SEQUENCE 2147483647 
+
+#define RT_ACK_FREQUENCY (10)
+#define LIBTRACE_RT_VERSION (0x04)
+#define LIBTRACE_RT_MAGIC (0x5a)
 
 /* Procedure for adding new RT control types
@@ -84 +86 @@
         uint64_t length;        /**< The total length of the fifo */
         uint64_t used;          /**< The amount of fifo space in use */
-} fifo_info_t;
+} PACKED fifo_info_t;
 
 /** RT packet header */
 typedef struct rt_header {
         /** The type of RT packet */
-        libtrace_rt_types_t type;       
-        /** The length of the packet (not including the RT header */
+        uint32_t type;  
+        
+        uint8_t magic;
+
+        uint8_t version;
+
+        /** The length of the packet (not including the RT header */
         uint16_t length;                
         /** The sequence number of the packet */
         uint32_t sequence;
-} rt_header_t;
+} PACKED rt_header_t;
 
 /* TODO: Reorganise this struct once more hello info is added */
@@ -103 +110 @@
          *  i.e. expecting acknowledgements */
         uint8_t reliable;       
-} rt_hello_t;
+} PACKED rt_hello_t ;
 
 #if 0
@@ -115 +122 @@
         /** The sequence number of the last received RT packet */
         uint32_t sequence;
-} rt_ack_t;
+} PACKED rt_ack_t;
 
 /** RT Status sub-header */
@@ -121 +128 @@
         /** Statistics describing the current status of the sender fifo */
         fifo_info_t fifo_status;
-} rt_status_t;
+} PACKED rt_status_t;
 
 #if 0
@@ -154 +161 @@
 typedef struct rt_deny_conn {
         /** The reason that the connection was denied */
-        enum rt_conn_denied_t reason;
-} rt_deny_conn_t;
+        uint32_t reason;
+} PACKED rt_deny_conn_t;
 
 #if 0
@@ -187 +194 @@
         /** Length of the value string that follows the header */
         uint32_t value_len;
-} rt_metadata_t ;
+} PACKED rt_metadata_t;
 
 /** Specifications of duck structures - duck2_4 and duck2_5 match Endace's