unable to bind udp6 socket to a specific address

[nickdesaulniers]

var udp6 = dgram.createSocket('udp6');
udp6.bind(null, 'fe80::e46a:6cff:fe68:a76a');

throws Error: bind EADDRNOTAVAIL fe80::e46a:6cff:fe68:a76a but works for ipv4 addresses listed from os.networkInterfaces().

https://stackoverflow.com/questions/34259279/node-js-cant-bind-a-udp6-socket-to-a-specific-address

[mscdex]

What does strace show when you run that snippet?

[nickdesaulniers]

I'm on OSX. strace is not available.

[nickdesaulniers]

let me see if I can attach dtruss to the node process

[nickdesaulniers]

Running 'sudo dtruss -p pgrep -n node', this is the trace specifically on the execution of udp6.bind(null, 'fe80::2acf:e9ff:fe1f:3939'):

select(0x14, 0x102201F08, 0x102201F0C, 0x0, 0x0)         = 1 0
write(0x9, "\0", 0x1)        = 1 0
kevent(0x5, 0x7FFF5FBF71C0, 0x0)         = 1 0
read(0x8, "\0", 0x400)       = 1 0
read(0x11, "\r\0", 0x10000)      = 1 0
write(0xA, "\r\n\0", 0x2)        = 2 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
madvise(0x1015D9000, 0x21000, 0x9)       = 0 0
write(0xA, "Socket {\n  domain: \n   Domain {\n     domain: \033[1mnull\033[22m,\n     _events: { error: \033[36m[Function]\033[39m },\n     _eventsCount: \033[33m1\033[39m,\n     _maxListeners: \033[90mundefined\033[39m,\n     members: [] },\n  _events: {},\n  _eventsCount: \033[33m0\033[39m,\n  _maxListen", 0x273)        = 627 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
write(0xA, "\033[1G\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
write(0xA, "\033[0J\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
write(0xA, "> \0", 0x2)      = 2 0
read(0xD, "xx\0", 0x400)         = 2 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
write(0xA, "\033[3G\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
madvise(0x101783000, 0x41000, 0x9)       = 0 0
madvise(0x1015D9000, 0x21000, 0x9)       = 0 0
madvise(0x101783000, 0x41000, 0x9)       = 0 0
madvise(0x1015D9000, 0x21000, 0x9)       = 0 0
madvise(0x102300000, 0x83000, 0x9)       = 0 0
madvise(0x101783000, 0x41000, 0x9)       = 0 0
madvise(0x1015D9000, 0x21000, 0x9)       = 0 0
socket(0x1E, 0x2, 0x0)       = 21 0
ioctl(0x15, 0x8004667E, 0x7FFF5FBF5EE4)      = 0 0
ioctl(0x15, 0x20006601, 0x0)         = 0 0
setsockopt(0x15, 0xFFFF, 0x1022)         = 0 0
bind(0x15, 0x7FFF5FBF5F90, 0x1C)         = -1 Err#49
close(0x15)      = 0 0
write(0xA, "Error: bind EADDRNOTAVAIL fe80::2acf:e9ff:fe1f:3939\n    at Object.exports._errnoException (util.js:874:11)\n    at exports._exceptionWithHostPort (util.js:897:20)\n    at dgram.js:213:18\n    at doNTCallback3 (node.js:452:9)\n    at process._tickDomainCallback", 0x112)       = 274 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\0", 0x400)      = 1 0
write(0xA, "\033[1G\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\0", 0x400)      = 1 0
write(0xA, "\033[0J\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\0", 0x400)      = 1 0
write(0xA, "> \0", 0x2)      = 2 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
write(0xA, "\033[3G\0", 0x4)         = 4 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
read(0xD, "x\a\0", 0x400)        = 1 0
write(0xC, "x\0", 0x1)       = 1 0
select(0xE, 0x1022014D8, 0x1022014DC, 0x0, 0x0)      = 1 0
kevent(0x5, 0x7FFF5FBF71C0, 0x0)         = 0 0
read(0xD, "x\0", 0x400)      = 1 0
kevent(0x5, 0x7FFF5FBF71C0, 0x0)         = 0 0
mmap(0x2D80B15C4000, 0x200000, 0x0, 0x1042, 0xFF000000, 0x0)         = 0x2D80B15C4000 0
munmap(0x2D80B15C4000, 0x3C000)      = 0 0
munmap(0x2D80B1700000, 0xC4000)      = 0 0
mmap(0x2D80B1600000, 0x100000, 0x3, 0x1012, 0xFF000000, 0x0)         = 0x2D80B1600000 0
mmap(0x154FD3E00000, 0x200000, 0x0, 0x1052, 0xFF000000, 0x0)         = 0x154FD3E00000 0
psynch_cvsignal(0x100E19D00, 0xD0000001100, 0xD00)       = 256 0
psynch_cvwait(0x100E19D00, 0xA0000000E00, 0xA00)         = 0 0
kevent(0x5, 0x7FFF5FBF71C0, 0x0)         = 0 0
pwrite(0x14, "udp6.bind(null, 'fe80::2acf:e9ff:fe1f:3939')\nos.networkInterfaces()\nos = require('os')\nudp6 = dgram.createSocket('udp6')\nudp6.bind(null, 'fe80::2acf:e9ff:fe1f:3939')\ndgram = require('dgram')\nudp6.bind(null, 'fe80::2acf:e9ff:fe1f:3939')\nudp6 = dgram.createS", 0x1145, 0x0)         = 4421 0
write(0x9, "\0", 0x1)        = 1 0
kevent(0x5, 0x7FFF5FBF71C0, 0x0)         = 1 0
read(0x8, "\0", 0x400)       = 1 0

[nickdesaulniers]

I just tried this on my linux box. Rather than EADDRNOTAVAIL, I got an EINVAL.

man 2 bind says EINVAL means "EINVAL The socket is already bound to an address." What?! udp6._bindState is 0. How could it possibly be already bound?

ipv4 works on my linux box, but ipv6 does not.

[nickdesaulniers]

oh, so I just tried binding to a non fe80 ipv6 address, and it seemed to work...
ex '2620:101:80fc:224:2acf:e9ff:fe1f:3939'

[nickdesaulniers]

also, it seems to work if I bind to 'fe80::2acf:e9ff:fe1f:3939%en0' which is the string from ifconfig.

[nickdesaulniers]

it looks like for network peers to contact me on the fe80 address, they need to specify THEIR interface to contact me on, ex: nc6 -u fe80::2acf:e9ff:fe1f:3939%wlp3s0 65022

[nickdesaulniers]

ok, my linux buddies just gave me a refresher on link local addresses: https://en.wikipedia.org/wiki/Link-local_address

It seems that the sender will have to specify their networking interface and the receiver also has to specify their listening interface. There may not be any bugs here. Let me think about this over lunch, and when I get back, I'll probably end up closing this bug.

[nickdesaulniers]

I would mark this bug as invalid.