[Bug Fix] speed_tester jumbo frames crash fix (#316)

Speed tester will no longer crash if you tell it to load a PCAP trace that contains jumbo frames without using the -j flag.

Commit log:

* [UPDATE] speed_tester jumbo frames crash fix

* [UPDTE] speed_tester jumbo frame usability improvement

Co-authored-by: aaron <aaron@localhost>

Author: aaronmhill01

examples/speed_tester/speed_tester.c

@@ -310,6 +310,7 @@ nf_setup(struct onvm_nf_local_ctx *nf_local_ctx) {
         const u_char *packet;
         struct pcap_pkthdr header;
         char errbuf[PCAP_ERRBUF_SIZE];
+        uint32_t max_elt_size;
 
         if (pcap_filename != NULL) {
                 printf("Replaying %s pcap file\n", pcap_filename);
@@ -326,10 +327,24 @@ nf_setup(struct onvm_nf_local_ctx *nf_local_ctx) {
 
                 i = 0;
 
+                /* 
+                 * max_elt_size is the maximum preallocated memory size permitted for each packet, 
+                 * adjusted for the memory offset of the rte_mbuf struct and header/tail lengths
+                 */
+                
+                max_elt_size = pktmbuf_pool->elt_size - sizeof(struct rte_mbuf) - pktmbuf_pool->header_size - pktmbuf_pool->trailer_size;
+
                 while (((packet = pcap_next(pcap, &header)) != NULL) && (i < packet_number)) {
                         struct onvm_pkt_meta *pmeta;
                         struct onvm_ft_ipv4_5tuple key;
 
+                        /* Length of the packet cannot exceed preallocated storage size */
+                        if (header.caplen > max_elt_size) {
+                                nf_local_ctx->nf->stats.tx_drop++;
+                                nf_local_ctx->nf->stats.act_drop++;
+                                continue;
+                        }
+
                         pkt = rte_pktmbuf_alloc(pktmbuf_pool);
                         if (pkt == NULL)
                                 break;
@@ -355,7 +370,7 @@ nf_setup(struct onvm_nf_local_ctx *nf_local_ctx) {
                 onvm_nflib_return_pkt_bulk(nf_local_ctx->nf, pkts, pkts_generated);
         } else {
 #endif
-                /*  use default number of initial packets if -c has not been used */
+                /* Use default number of initial packets if -c has not been used */
                 packet_number = (use_custom_pkt_count ? packet_number : DEFAULT_PKT_NUM);
                 struct rte_mbuf *pkts[packet_number];