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this fixes the net.IP from /proc/net/udp* being broken because they a… #336

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this fixes the net.IP from /proc/net/udp* being broken because they a… #336

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2 changes: 1 addition & 1 deletion fixtures.ttar
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Original file line number Diff line number Diff line change
Expand Up @@ -2189,7 +2189,7 @@ Mode: 644
Path: fixtures/proc/net/udp
Lines: 4
sl local_address rem_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
0: 0A000005:0016 00000000:0000 0A 00000000:00000001 00:00000000 00000000 0 0 2740 1 ffff88003d3af3c0 100 0 0 10 0
0: 0500000A:0016 00000000:0000 0A 00000000:00000001 00:00000000 00000000 0 0 2740 1 ffff88003d3af3c0 100 0 0 10 0
1: 00000000:0016 00000000:0000 0A 00000001:00000000 00:00000000 00000000 0 0 2740 1 ffff88003d3af3c0 100 0 0 10 0
2: 00000000:0016 00000000:0000 0A 00000001:00000001 00:00000000 00000000 0 0 2740 1 ffff88003d3af3c0 100 0 0 10 0
Mode: 644
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37 changes: 31 additions & 6 deletions net_udp.go
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,33 @@ func newNetUDPSummary(file string) (*NetUDPSummary, error) {
return netUDPSummary, nil
}

// NOTE: this function assumes the architecture is little endian, like x86 and amd64
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I'm not really comfortable assuming little endian here unless the kernel is consistent about the file format.

I have systems with big endian (mips64).

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This is what chatgpt recommends, seems reasonable: https://chat.openai.com/share/2586e0df-70b5-4b54-a55a-29a60e4b689d

func IsLittleEndian() bool {
    var testValue uint16 = 0xABCD
    testBytes := make([]byte, 2)
    binary.LittleEndian.PutUint16(testBytes, testValue)
    return testBytes[0] == 0xCD
}

// /proc/net/{t,u}dp{,6} files are network byte order for ipv4
// for ipv6 the address is four words consisting of four bytes each. In each of those four words the four bytes are written in reverse order.

func parseIP(hexIP string) (net.IP, error) {
var byteIP []byte
byteIP, err := hex.DecodeString(hexIP)
if err != nil {
return nil, fmt.Errorf(
"cannot parse address field in socket line: %s", hexIP)
}
switch len(byteIP) {
case 4:
return net.IP{byteIP[3], byteIP[2], byteIP[1], byteIP[0]}, nil
case 16:
i := net.IP{
byteIP[3], byteIP[2], byteIP[1], byteIP[0],
byteIP[7], byteIP[6], byteIP[5], byteIP[4],
byteIP[11], byteIP[10], byteIP[9], byteIP[8],
byteIP[15], byteIP[14], byteIP[13], byteIP[12],
}
return i, nil
default:
return nil, fmt.Errorf("Unable to parse IP %s", hexIP)
}
}

// parseNetUDPLine parses a single line, represented by a list of fields.
func parseNetUDPLine(fields []string) (*netUDPLine, error) {
line := &netUDPLine{}
Expand Down Expand Up @@ -174,9 +201,8 @@ func parseNetUDPLine(fields []string) (*netUDPLine, error) {
return nil, fmt.Errorf(
"cannot parse local_address field in udp socket line: %s", fields[1])
}
if line.LocalAddr, err = hex.DecodeString(l[0]); err != nil {
return nil, fmt.Errorf(
"cannot parse local_address value in udp socket line: %s", err)
if line.LocalAddr, err = parseIP(l[0]); err != nil {
return nil, err
}
if line.LocalPort, err = strconv.ParseUint(l[1], 16, 64); err != nil {
return nil, fmt.Errorf(
Expand All @@ -189,9 +215,8 @@ func parseNetUDPLine(fields []string) (*netUDPLine, error) {
return nil, fmt.Errorf(
"cannot parse rem_address field in udp socket line: %s", fields[1])
}
if line.RemAddr, err = hex.DecodeString(r[0]); err != nil {
return nil, fmt.Errorf(
"cannot parse rem_address value in udp socket line: %s", err)
if line.RemAddr, err = parseIP(r[0]); err != nil {
return nil, err
}
if line.RemPort, err = strconv.ParseUint(r[1], 16, 64); err != nil {
return nil, fmt.Errorf(
Expand Down
2 changes: 1 addition & 1 deletion net_udp_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -171,7 +171,7 @@ func Test_newNetUDP(t *testing.T) {
},
&netUDPLine{
Sl: 6073,
LocalAddr: net.IP{0, 0, 128, 254, 0, 0, 0, 0, 255, 173, 225, 86, 9, 102, 124, 254},
LocalAddr: net.IP{254, 128, 0, 0, 0, 0, 0, 0, 86, 225, 173, 255, 254, 124, 102, 9},
LocalPort: 51073,
RemAddr: net.IP{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
RemPort: 0,
Expand Down