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net/interfaces: use a uint32_t for ipv4 address

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The code was using a C "int", which is a signed 32-bit integer.
That means some valid IP addresses were negative numbers.
(In particular, the default router address handed out by AT&T
fiber: 192.168.1.254. No I don't know why they do that.)
A negative number is < 255, and so was treated by the Go code
as an error.

This fixes the unit test failure:

	$ go test -v -run=TestLikelyHomeRouterIPSyscallExec ./net/interfaces
	=== RUN   TestLikelyHomeRouterIPSyscallExec
	    interfaces_darwin_cgo_test.go:15: syscall() = invalid IP, false, netstat = 192.168.1.254, true
	--- FAIL: TestLikelyHomeRouterIPSyscallExec (0.00s)

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
This commit is contained in:
David Crawshaw 2021-02-02 10:03:26 -08:00 committed by David Crawshaw
parent 267531e4f8
commit d139fa9c92
1 changed files with 4 additions and 4 deletions
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8
net/interfaces/interfaces_darwin_cgo.go
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@ -15,7 +15,7 @@
// privateGatewayIPFromRoute returns the private gateway ip address from rtm, if it exists.
// Otherwise, it returns 0.
int privateGatewayIPFromRoute(struct rt_msghdr2 *rtm)
uint32_t privateGatewayIPFromRoute(struct rt_msghdr2 *rtm)
{
// sockaddrs are after the message header
struct sockaddr* dst_sa = (struct sockaddr *)(rtm + 1);
@ -38,7 +38,7 @@
return 0; // gateway not IPv4
struct sockaddr_in* gateway_si= (struct sockaddr_in *)gateway_sa;
int ip;
uint32_t ip;
ip = gateway_si->sin_addr.s_addr;
unsigned char a, b;
@ -62,7 +62,7 @@
// If no private gateway IP address was found, it returns 0.
// On an error, it returns an error code in (0, 255].
// Any private gateway IP address is > 255.
int privateGatewayIP()
uint32_t privateGatewayIP()
{
size_t needed;
int mib[6];
@ -90,7 +90,7 @@
struct rt_msghdr2 *rtm;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
rtm = (struct rt_msghdr2 *)next;
int ip;
uint32_t ip;
ip = privateGatewayIPFromRoute(rtm);
if (ip) {
free(buf);