Added ability to disable checksum generation and checking at compile-time

src/core/ipv4/ip.c

@@ -209,6 +209,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
   }
 
   /* verify checksum */
+#if CHECKSUM_CHECK_IP
   if (inet_chksum(iphdr, iphdrlen) != 0) {
 
     LWIP_DEBUGF(IP_DEBUG | 2, ("Checksum (0x%x) failed, IP packet dropped.\n", inet_chksum(iphdr, iphdrlen)));
@@ -219,6 +220,7 @@ ip_input(struct pbuf *p, struct netif *inp) {
     snmp_inc_ipindiscards();
     return ERR_OK;
   }
+#endif
 
   /* Trim pbuf. This should have been done at the netif layer,
      but we'll do it anyway just to be sure that its done. */
@@ -415,7 +417,9 @@ ip_output_if(struct pbuf *p, struct ip_addr *src, struct ip_addr *dest,
     }
 
     IPH_CHKSUM_SET(iphdr, 0);
+#if CHECKSUM_GEN_IP
     IPH_CHKSUM_SET(iphdr, inet_chksum(iphdr, IP_HLEN));
+#endif
   } else {
     iphdr = p->payload;
     dest = &(iphdr->dest);

src/core/tcp_in.c

@@ -136,6 +136,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
     return;
   }
 
+#if CHECKSUM_CHECK_TCP
   /* Verify TCP checksum. */
   if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
       (struct ip_addr *)&(iphdr->dest),
@@ -152,7 +153,7 @@ tcp_input(struct pbuf *p, struct netif *inp)
     pbuf_free(p);
     return;
   }
-
+#endif
 
   /* Move the payload pointer in the pbuf so that it points to the
      TCP data instead of the TCP header. */

src/core/tcp_out.c

@@ -400,9 +400,10 @@ tcp_output(struct tcp_pcb *pcb)
     TCPH_HDRLEN_SET(tcphdr, 5);
 
     tcphdr->chksum = 0;
+#if CHECKSUM_GEN_TCP
     tcphdr->chksum = inet_chksum_pseudo(p, &(pcb->local_ip), &(pcb->remote_ip),
           IP_PROTO_TCP, p->tot_len);
-
+#endif
 
     ip_output(p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
         IP_PROTO_TCP);
@@ -518,10 +519,12 @@ tcp_output_segment(struct tcp_seg *seg, struct tcp_pcb *pcb)
   seg->p->payload = seg->tcphdr;
 
   seg->tcphdr->chksum = 0;
+#if CHECKSUM_GEN_TCP
   seg->tcphdr->chksum = inet_chksum_pseudo(seg->p,
              &(pcb->local_ip),
              &(pcb->remote_ip),
              IP_PROTO_TCP, seg->p->tot_len);
+#endif
   TCP_STATS_INC(tcp.xmit);
 
   ip_output(seg->p, &(pcb->local_ip), &(pcb->remote_ip), pcb->ttl, pcb->tos,
@@ -552,9 +555,10 @@ tcp_rst(u32_t seqno, u32_t ackno,
   TCPH_HDRLEN_SET(tcphdr, 5);
 
   tcphdr->chksum = 0;
+#if CHECKSUM_GEN_TCP
   tcphdr->chksum = inet_chksum_pseudo(p, local_ip, remote_ip,
               IP_PROTO_TCP, p->tot_len);
-
+#endif
   TCP_STATS_INC(tcp.xmit);
    /* Send output with hardcoded TTL since we have no access to the pcb */
   ip_output(p, local_ip, remote_ip, TCP_TTL, 0, IP_PROTO_TCP);
@@ -621,8 +625,9 @@ tcp_keepalive(struct tcp_pcb *pcb)
    TCPH_HDRLEN_SET(tcphdr, 5);
    
    tcphdr->chksum = 0;
+#if CHECKSUM_GEN_TCP
    tcphdr->chksum = inet_chksum_pseudo(p, &pcb->local_ip, &pcb->remote_ip, IP_PROTO_TCP, p->tot_len);
-
+#endif
   TCP_STATS_INC(tcp.xmit);
 
    /* Send output to IP */

src/core/udp.c

@@ -246,6 +246,7 @@ udp_input(struct pbuf *p, struct netif *inp)
     if (IPH_PROTO(iphdr) == IP_PROTO_UDPLITE) {
 #endif /* IPv4 */
       /* Do the UDP Lite checksum */
+#if CHECKSUM_CHECK_UDP
       if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
          (struct ip_addr *)&(iphdr->dest),
          IP_PROTO_UDPLITE, ntohs(udphdr->len)) != 0) {
@@ -256,7 +257,9 @@ udp_input(struct pbuf *p, struct netif *inp)
   pbuf_free(p);
   goto end;
       }
+#endif
     } else {
+#if CHECKSUM_CHECK_UDP
       if (udphdr->chksum != 0) {
   if (inet_chksum_pseudo(p, (struct ip_addr *)&(iphdr->src),
        (struct ip_addr *)&(iphdr->dest),
@@ -270,6 +273,7 @@ udp_input(struct pbuf *p, struct netif *inp)
     goto end;
   }
       }
+#endif
     }
     pbuf_header(p, -UDP_HLEN);
     if (pcb != NULL) {
@@ -408,10 +412,14 @@ udp_send(struct udp_pcb *pcb, struct pbuf *p)
     /* set UDP message length in UDP header */
     udphdr->len = htons(pcb->chksum_len);
     /* calculate checksum */
+#if CHECKSUM_GEN_UDP
     udphdr->chksum = inet_chksum_pseudo(q, src_ip, &(pcb->remote_ip),
           IP_PROTO_UDP, pcb->chksum_len);
     /* chksum zero must become 0xffff, as zero means 'no checksum' */
     if (udphdr->chksum == 0x0000) udphdr->chksum = 0xffff;
+#else
+    udphdr->chksum = 0x0000;
+#endif
     /* output to IP */
     err = ip_output_if (q, src_ip, &pcb->remote_ip, pcb->ttl, pcb->tos, IP_PROTO_UDPLITE, netif);    
     snmp_inc_udpoutdatagrams();
@@ -419,11 +427,15 @@ udp_send(struct udp_pcb *pcb, struct pbuf *p)
     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP packet length %u\n", q->tot_len));
     udphdr->len = htons(q->tot_len);
     /* calculate checksum */
+#if CHECKSUM_GEN_UDP
     if ((pcb->flags & UDP_FLAGS_NOCHKSUM) == 0) {
       udphdr->chksum = inet_chksum_pseudo(q, src_ip, &pcb->remote_ip, IP_PROTO_UDP, q->tot_len);
       /* chksum zero must become 0xffff, as zero means 'no checksum' */
       if (udphdr->chksum == 0x0000) udphdr->chksum = 0xffff;
     }
+#else
+    udphdr->chksum = 0x0000;
+#endif
     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: UDP checksum 0x%04x\n", udphdr->chksum));
     snmp_inc_udpoutdatagrams();
     LWIP_DEBUGF(UDP_DEBUG, ("udp_send: ip_output_if (,,,,IP_PROTO_UDP,)\n"));

src/include/lwip/opt.h

@@ -495,6 +495,31 @@ a lot of data that needs to be copied, this should be set high. */
 
 #endif /* PPP_SUPPORT */
 
+/* checksum options - set to zero for hardware checksum support */
+
+#ifndef CHECKSUM_GEN_IP
+#define CHECKSUM_GEN_IP                 1
+#endif
+ 
+#ifndef CHECKSUM_GEN_UDP
+#define CHECKSUM_GEN_UDP                1
+#endif
+ 
+#ifndef CHECKSUM_GEN_TCP
+#define CHECKSUM_GEN_TCP                1
+#endif
+ 
+#ifndef CHECKSUM_CHECK_IP
+#define CHECKSUM_CHECK_IP               1
+#endif
+ 
+#ifndef CHECKSUM_CHECK_UDP
+#define CHECKSUM_CHECK_UDP              1
+#endif
+
+#ifndef CHECKSUM_CHECK_TCP
+#define CHECKSUM_CHECK_TCP              1
+#endif
 
 /* Debugging options all default to off */