From ff8b910222f92bbe1f50b5213fd90b78fde1a466 Mon Sep 17 00:00:00 2001
From: "Nicholas J. Kain" <nicholas@kain.us>
Date: Tue, 27 Oct 2020 14:45:15 -0400
Subject: [PATCH] Rename net_checksum161c to net_checksum16.

How many characters are summed at a time is an irrelevant
implementation detail.
---
 src/dhcp.c                                  | 18 +++++++++---------
 src/nk/{net_checksum.h => net_checksum16.h} | 14 +++++++-------
 2 files changed, 16 insertions(+), 16 deletions(-)
 rename src/nk/{net_checksum.h => net_checksum16.h} (77%)

diff --git a/src/dhcp.c b/src/dhcp.c
index c5e824c..5755ad6 100644
--- a/src/dhcp.c
+++ b/src/dhcp.c
@@ -40,7 +40,7 @@
 #include "nk/log.h"
 #include "nk/io.h"
 #include "nk/random.h"
-#include "nk/net_checksum.h"
+#include "nk/net_checksum16.h"
 
 #include "dhcp.h"
 #include "state.h"
@@ -133,7 +133,7 @@ static ssize_t send_dhcp_unicast(struct client_state_t cs[static 1],
 // Returns 1 if IP checksum is correct, otherwise 0.
 static int ip_checksum(struct ip_udp_dhcp_packet packet[static 1])
 {
-    return net_checksum161c(&packet->ip, sizeof packet->ip) == 0;
+    return net_checksum16(&packet->ip, sizeof packet->ip) == 0;
 }
 
 // Returns 1 if UDP checksum is correct, otherwise 0.
@@ -146,11 +146,11 @@ static int udp_checksum(struct ip_udp_dhcp_packet packet[static 1])
         .tot_len = packet->udp.len,
     };
     uint16_t udpcs =
-        net_checksum161c(&packet->udp,
+        net_checksum16(&packet->udp,
                          min_size_t(ntohs(packet->udp.len),
                                     sizeof *packet - sizeof(struct iphdr)));
-    uint16_t hdrcs = net_checksum161c(&ph, sizeof ph);
-    uint16_t cs = net_checksum161c_add(udpcs, hdrcs);
+    uint16_t hdrcs = net_checksum16(&ph, sizeof ph);
+    uint16_t cs = net_checksum16_add(udpcs, hdrcs);
     return cs == 0;
 }
 
@@ -285,10 +285,10 @@ static ssize_t send_dhcp_raw(struct dhcpmsg payload[static 1])
     iudmsg.udp.dest = htons(DHCP_SERVER_PORT);
     iudmsg.udp.len = htons(ud_len);
     iudmsg.udp.check = 0;
-    uint16_t udpcs = net_checksum161c(&iudmsg.udp, ud_len);
-    uint16_t phcs = net_checksum161c(&ph, sizeof ph);
-    iudmsg.udp.check = net_checksum161c_add(udpcs, phcs);
-    iudmsg.ip.check = net_checksum161c(&iudmsg.ip, sizeof iudmsg.ip);
+    uint16_t udpcs = net_checksum16(&iudmsg.udp, ud_len);
+    uint16_t phcs = net_checksum16(&ph, sizeof ph);
+    iudmsg.udp.check = net_checksum16_add(udpcs, phcs);
+    iudmsg.ip.check = net_checksum16(&iudmsg.ip, sizeof iudmsg.ip);
 
     struct sockaddr_ll da = {
         .sll_family = AF_PACKET,
diff --git a/src/nk/net_checksum.h b/src/nk/net_checksum16.h
similarity index 77%
rename from src/nk/net_checksum.h
rename to src/nk/net_checksum16.h
index e983ef6..bf94abe 100644
--- a/src/nk/net_checksum.h
+++ b/src/nk/net_checksum16.h
@@ -1,5 +1,5 @@
-#ifndef NCMLIB_NET_CHECKSUM_H
-#define NCMLIB_NET_CHECKSUM_H
+#ifndef NCMLIB_NET_CHECKSUM16_H
+#define NCMLIB_NET_CHECKSUM16_H
 
 // RFC 1071 is still a good reference.
 
@@ -9,7 +9,7 @@
 // representation, fold the carry bits that have spilled into the upper
 // 16-bits of the 32-bit unsigned value back into the 16-bit ones-complement
 // binary value.
-static inline uint16_t net_checksum161c_foldcarry(uint32_t v)
+static inline uint16_t net_checksum16_foldcarry(uint32_t v)
 {
     v = (v >> 16) + (v & 0xffff);
     v += v >> 16;
@@ -20,7 +20,7 @@ static inline uint16_t net_checksum161c_foldcarry(uint32_t v)
 // the binary value returned, when stored to memory, will match
 // the result on big endian; if the numeric value returned
 // must match big endian results, then call ntohs() on the result.
-static uint16_t net_checksum161c(const void *buf, size_t size)
+static uint16_t net_checksum16(const void *buf, size_t size)
 {
     const char *b = (const char *)buf;
     const char *bend = b + size;
@@ -37,17 +37,17 @@ static uint16_t net_checksum161c(const void *buf, size_t size)
         memcpy(&t, b, 2);
         sum += t;
     }
-    return ~net_checksum161c_foldcarry(sum + sumo);
+    return ~net_checksum16_foldcarry(sum + sumo);
 }
 
 // For two sequences of bytes A and B that return checksums CS(A) and CS(B),
 // this function will calculate the checksum CS(AB) of the concatenated value
 // AB given the checksums of the individual parts CS(A) and CS(B).
-static inline uint16_t net_checksum161c_add(uint16_t a, uint16_t b)
+static inline uint16_t net_checksum16_add(uint16_t a, uint16_t b)
 {
     const uint32_t A = a;
     const uint32_t B = b;
-    return ~net_checksum161c_foldcarry((~A & 0xffffu) + (~B & 0xffffu));
+    return ~net_checksum16_foldcarry((~A & 0xffffu) + (~B & 0xffffu));
 }
 
 #endif