net: spit out ip checksum routines into their own file

build.mk

@@ -45,6 +45,7 @@ clean:
 	rm seastar $(tests) *.o
 
 libnet = net/virtio.o net/net.o net/ip.o net/ethernet.o net/arp.o net/stack.o net/packet.o
+libnet += net/ip_checksum.o
 
 apps/seastar/seastar: apps/seastar/main.o core/reactor.o
 	$(link)
@@ -56,12 +57,16 @@ apps/httpd/httpd: apps/httpd/httpd.o core/reactor.o $(libnet)
 tests/fileiotest: tests/fileiotest.o core/reactor.o
 
 tests/virtiotest: tests/virtiotest.o net/virtio.o core/reactor.o net/net.o net/ip.o net/ethernet.o net/arp.o net/packet.o
+tests/virtiotest: net/ip_checksum.o
 
 tests/l3_test: tests/l3_test.o net/virtio.o core/reactor.o net/net.o net/ip.o net/ethernet.o net/arp.o net/packet.o
+tests/l3_test: net/ip_checksum.o
 
 tests/ip_test: tests/ip_test.o net/virtio.o core/reactor.o net/net.o net/ip.o net/arp.o net/ethernet.o net/packet.o
+tests/ip_test: net/ip_checksum.o
 
 tests/tcp_test: tests/tcp_test.o net/virtio.o core/reactor.o net/net.o net/ip.o net/arp.o net/ethernet.o net/packet.o
+tests/tcp_test: net/ip_checksum.o
 
 tests/timertest: tests/timertest.o core/reactor.o
 

net/ip.cc

@@ -17,35 +17,6 @@ std::ostream& operator<<(std::ostream& os, ipv4_address a) {
             (ip >> 0) & 0xff);
 }
 
-uint16_t ip_checksum(const void* data, size_t len) {
-    uint64_t csum = 0;
-    auto p64 = reinterpret_cast<const packed<uint64_t>*>(data);
-    while (len >= 8) {
-        auto old = csum;
-        csum += ntohq(*p64++);
-        csum += (csum < old);
-        len -= 8;
-    }
-    auto p16 = reinterpret_cast<const packed<uint16_t>*>(p64);
-    while (len >= 2) {
-        auto old = csum;
-        csum += ntohs(*p16++);
-        csum += (csum < old);
-        len -= 2;
-    }
-    auto p8 = reinterpret_cast<const uint8_t*>(p16);
-    if (len) {
-        auto old = csum;
-        csum += *p8++ << 8;
-        csum += (csum < old);
-        len -= 1;
-    }
-    csum = (csum & 0xffff) + ((csum >> 16) & 0xffff) + ((csum >> 32) & 0xffff) + (csum >> 48);
-    csum = (csum & 0xffff) + (csum >> 16);
-    csum = (csum & 0xffff) + (csum >> 16);
-    return htons(~csum);
-}
-
 ipv4::ipv4(interface* netif)
     : _netif(netif)
     , _global_arp(netif)
@@ -128,25 +99,4 @@ void ipv4::set_host_address(ipv4_address ip) {
     _arp.set_self_addr(ip);
 }
 
-void checksummer::sum(const char* data, size_t len) {
-    auto orig_len = len;
-    if (odd) {
-        partial += uint8_t(*data++);
-        --len;
-    }
-    partial += ip_checksum(data, len);
-    odd ^= orig_len & 1;
-}
-
-void checksummer::sum(const packet& p) {
-    for (auto&& f : p.fragments) {
-        sum(f.base, f.size);
-    }
-}
-
-uint16_t checksummer::get() const {
-    auto tmp = (partial & 0xffff) + (partial >> 16);
-    return tmp + (tmp >> 16);
-}
-
 }

net/ip.hh

@@ -18,8 +18,6 @@
 
 namespace net {
 
-uint16_t ip_checksum(const void* data, size_t len);
-
 class ipv4;
 template <uint8_t ProtoNum>
 class ipv4_l4;

net/ip_checksum.cc

@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2014 Cloudius Systems, Ltd.
+ */
+
+#include "ip_checksum.hh"
+#include "net.hh"
+#include <arpa/inet.h>
+
+namespace net {
+
+uint16_t ip_checksum(const void* data, size_t len) {
+    uint64_t csum = 0;
+    auto p64 = reinterpret_cast<const packed<uint64_t>*>(data);
+    while (len >= 8) {
+        auto old = csum;
+        csum += ntohq(*p64++);
+        csum += (csum < old);
+        len -= 8;
+    }
+    auto p16 = reinterpret_cast<const packed<uint16_t>*>(p64);
+    while (len >= 2) {
+        auto old = csum;
+        csum += ntohs(*p16++);
+        csum += (csum < old);
+        len -= 2;
+    }
+    auto p8 = reinterpret_cast<const uint8_t*>(p16);
+    if (len) {
+        auto old = csum;
+        csum += *p8++ << 8;
+        csum += (csum < old);
+        len -= 1;
+    }
+    csum = (csum & 0xffff) + ((csum >> 16) & 0xffff) + ((csum >> 32) & 0xffff) + (csum >> 48);
+    csum = (csum & 0xffff) + (csum >> 16);
+    csum = (csum & 0xffff) + (csum >> 16);
+    return htons(~csum);
+}
+
+void checksummer::sum(const char* data, size_t len) {
+    auto orig_len = len;
+    if (odd) {
+        partial += uint8_t(*data++);
+        --len;
+    }
+    partial += ip_checksum(data, len);
+    odd ^= orig_len & 1;
+}
+
+void checksummer::sum(const packet& p) {
+    for (auto&& f : p.fragments) {
+        sum(f.base, f.size);
+    }
+}
+
+uint16_t checksummer::get() const {
+    auto tmp = (partial & 0xffff) + (partial >> 16);
+    return tmp + (tmp >> 16);
+}
+
+}

net/ip_checksum.hh

@@ -5,8 +5,14 @@
 #ifndef IP_CHECKSUM_HH_
 #define IP_CHECKSUM_HH_
 
+#include "packet.hh"
+#include <cstdint>
+#include <cstddef>
+
 namespace net {
 
+uint16_t ip_checksum(const void* data, size_t len);
+
 struct checksummer {
     uint32_t partial = 0;
     bool odd = false;