- RawPckt: force FCS computation feature added

- IGMP transmission reworked
- IPv4: method for filling in checksum in rendered binary data added

packet.h

@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 
+#include <stdbool.h>
+
 /**
  * \struct RawPckt
  * \brief Raw packet received on wire
@@ -20,6 +22,9 @@
              uint32_t arg; ///> User-defined argument
          } tx;
      } ext; ///> Extensions
+     struct {
+        bool calculate_ethernet_CRC : 1; ///> Instruct the packet assembler to always computer FCS regardless of device capabilities
+     } opts;
  } RawPckt;
 
 struct PcktHeaderElement_;

pckt_assembler.c

@@ -28,7 +28,7 @@ int pckt_assemble(RawPckt *raw, Pckt *cooked, EthInterface *intf) {
         hdrIter = hdrIter->next;
     }
     frameSize = headerSize + cooked->payloadSize;// + 4; // header + payload
-    bool computeCRC = !(intf->capabilities & ETHINF_CAP_TX_CRC_OFFLOAD);
+    bool computeCRC = (!(intf->capabilities & ETHINF_CAP_TX_CRC_OFFLOAD)) || raw->opts.calculate_ethernet_CRC;
     if (computeCRC) { // + CRC32 checksum area if needed
         frameSize += 4;
     }
@@ -73,10 +73,10 @@ int pckt_assemble(RawPckt *raw, Pckt *cooked, EthInterface *intf) {
         }
     }
 
-    // insert CRC32 if interface is not capable of inserting CRC
+    // insert CRC32 if interface cannot handle CRC calculation or if explicitly requested
     if (computeCRC) {
         uint32_t crc = crc32(raw->payload, frameSize - 4);
-        memcpy(raw->payload + frameSize - 4, (const uint8_t *)&crc, 4);
+        memcpy(raw->payload + frameSize - 4, &crc, 4);
     }
 
     // turn off TX timestamping by default

prefab/conn_blocks/arp_connblock.c

@@ -80,6 +80,7 @@ void arp_send(const ConnBlock *connBlock, const ArpProps *props) {
 
     // send packet
     RawPckt rpckt;
+    memset(&rpckt, 0, sizeof(RawPckt));
     rpckt.size = txBufSize;
     rpckt.payload = txBuf;
     rpckt.ext.tx.txTsCb = NULL;

prefab/conn_blocks/custom_ethertype_connblock.c

@@ -73,6 +73,7 @@ int cet_send_arg(cbd d, const uint8_t *dest, const uint8_t *data, uint16_t size,
     cooked.time_ns = 0;
 
     RawPckt raw;
+    memset(&raw, 0, sizeof(RawPckt));
     pckt_assemble(&raw, &cooked, connBlock.sieve->intf);
     raw.ext.tx.arg = arg; // assign argument
     raw.ext.tx.txTsCb = connBlock.sieveLayer->txTsCb; // assign with TX timestamp callback

prefab/conn_blocks/icmp_connblock.c

@@ -81,6 +81,7 @@ static int icmp_recv_cb(const Pckt * pckt, PcktSieveLayerTag tag) {
 
             // assemble packet
             RawPckt raw;
+            memset(&raw, 0, sizeof(RawPckt));
             pckt_assemble(&raw, &reply, intf);
 
             // release headers

prefab/conn_blocks/igmp_connblock.c

@@ -7,6 +7,7 @@
 #include "../../dynmem.h"
 #include "../../pckt_assembler.h"
 #include "../../eth_interface.h"
+#include "etherlib/prefab/packet_parsers/ipv4_packet.h"
 #include "ipv4_connblock.h"
 #include "../packet_parsers/igmp_packet.h"
 
@@ -37,6 +38,9 @@ ConnBlock igmp_new_connblock(struct EthInterface_ *intf) {
 }
 
 static void igmp_send(ConnBlock * connBlock, ip4_addr ga, int mt) {
+    // fetch interface
+    EthInterface * intf = connBlock->sieve->intf;
+
     // allocate headers
     PcktHeaderElement * igmpHeader = ALLOC_HEADER_ELEMENT(IgmpProps);
     PcktHeaderElement * ipHeader = ALLOC_HEADER_ELEMENT(IPv4Props);
@@ -67,34 +71,49 @@ static void igmp_send(ConnBlock * connBlock, ip4_addr ga, int mt) {
 
     // IP
     layer = layer->parent;
-    ipv4_fill_props(ipProps, ETH_IGMP_HEADER_SIZE, ETH_IGMP_PACKET_CLASS, connBlock->sieve->intf->ip, ga);
+    ipv4_fill_props(ipProps, ETH_IGMP_HEADER_SIZE, ETH_IGMP_PACKET_CLASS, intf->ip, ga);
 
     // Ethernet
     ethmc_from_ipmc(ethProps->destAddr, ga);
-    memcpy(ethProps->sourceAddr, connBlock->sieve->intf->mac, ETH_HW_ADDR_LEN);
+    memcpy(ethProps->sourceAddr, intf->mac, ETH_HW_ADDR_LEN);
     ethProps->length_type = ETH_IPv4_PACKET_CLASS;
 
     // common fields for packet assembly
     ethProps->hdrInsFn = insert_ethernet_header;
     ethProps->headerSize = ETH_ETHERNET_HEADER_SIZE;
 
-    Pckt cooked;
+    // allocate transmit buffer
-    cooked.payload = NULL;
+    uint32_t txHeaderSize = ETH_ETHERNET_HEADER_SIZE + ETH_IPv4_HEADER_SIZE + ETH_IGMP_HEADER_SIZE;
-    cooked.payloadSize = 0;
+    uint32_t txBufSize = MAX(txHeaderSize + 4, ETH_FRAME_MIN_SIZE);
-    cooked.header = ethHeader;
+    uint8_t *txBuf = dynmem_alloc(txBufSize);
+    memset(txBuf, 0, txBufSize);
 
-    // NOT FILLED FIELDS
+    // insert Ethernet header
-    cooked.headerSize = 0;
+    insert_ethernet_header(txBuf, ethHeader, NULL);
-    cooked.time_s = 0;
-    cooked.time_ns = 0;
 
-    RawPckt raw;
+    // insert IPv4 header
-    pckt_assemble(&raw, &cooked, connBlock->sieve->intf);
+    insert_ipv4_header(txBuf + ETH_ETHERNET_HEADER_SIZE, ipHeader, intf);
+    ipv4_fill_in_chksum(txBuf + ETH_ETHERNET_HEADER_SIZE); // fill-in IPv4 checksum
 
-    ethinf_transmit(connBlock->sieve->intf, &raw);
+    // insert IGMP header
+    insert_igmp_header(txBuf + ETH_ETHERNET_HEADER_SIZE + ETH_IPv4_HEADER_SIZE, igmpHeader, intf);
 
-    // free headers
+    // release headers
-    pckthdr_chain_free(ethHeader);
+    dynmem_free(ethHeader);
+    dynmem_free(ipHeader);
+    dynmem_free(igmpHeader);
+
+    // calculate CRC
+    uint32_t crc = crc32(txBuf, txBufSize - 4);
+    memcpy(txBuf + txBufSize - 4, &crc, 4);
+
+    // send packet
+    RawPckt rpckt;
+    memset(&rpckt, 0, sizeof(RawPckt));
+    rpckt.size = txBufSize;
+    rpckt.payload = txBuf;
+    rpckt.ext.tx.txTsCb = NULL;
+    ethinf_transmit(intf, &rpckt);
 }
 
 void igmp_report_membership(ConnBlock * connBlock, ip4_addr ga) {

prefab/conn_blocks/tcp_connblock.c

@@ -694,6 +694,7 @@ int tcp_send_segment(const struct ConnBlock_ *connBlock, TcpFlag flags, TcpOptio
     cooked.time_ns = 0;
 
     RawPckt raw;
+    memset(&raw, 0, sizeof(RawPckt));
     pckt_assemble(&raw, &cooked, connBlock->sieve->intf);
 
     ethinf_transmit(connBlock->sieve->intf, &raw);

prefab/conn_blocks/udp_connblock.c

@@ -120,6 +120,7 @@ int udp_sendto_arg(cbd d, const uint8_t *data, uint32_t size, ip4_addr addr, uin
     cooked.time_ns = 0;
 
     RawPckt raw;
+    memset(&raw, 0, sizeof(RawPckt));
     pckt_assemble(&raw, &cooked, connBlock.sieve->intf);
     raw.ext.tx.arg = arg; // assign argument
     raw.ext.tx.txTsCb = connBlock.sieveLayer->txTsCb; // assign with TX timestamp callback

prefab/packet_parsers/ipv4_packet.c

@@ -145,3 +145,9 @@ void ipv4_fill_props(IPv4Props *ipProps,
     ipProps->headerSize = ETH_IPv4_HEADER_SIZE;
 
 }
+
+void ipv4_fill_in_chksum(uint8_t * hdr) {
+    uint8_t * ChkSumPtr = hdr + 10; // create a pointer to checksum position
+    uint16_t checksum = chksum(hdr, ETH_IPv4_HEADER_SIZE, false); // compute checksum
+    memcpy(ChkSumPtr, &checksum, 2); // copy checksum to the proper position
+}

prefab/packet_parsers/ipv4_packet.h

@@ -76,4 +76,10 @@ void ethmc_from_ipmc(uint8_t * hwa, ip4_addr ipa);
  */
 void ipv4_fill_props(IPv4Props *ipProps, uint32_t payloadSize, uint16_t protocol, ip4_addr srcIpA, ip4_addr dstIpA);
 
+/**
+ * Fill in IPv4 checksum, based on header data.
+ * @param hdr Pointer to the IPv4 header's beginning. Checksum field's position will be written.
+*/
+void ipv4_fill_in_chksum(uint8_t * hdr);
+
 #endif //ETHERLIB_IPV4_PACKET_H