Cellular Network Infrastructure » OsmoGSMTester

Upgrading latest packages with apt-get (staying in debian8) + rebooting didn't help solving the issue.

I did a quick test by running the following program while the test was running and it never failed:

#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <ifaddrs.h>

int main(int argc, char** argv) {
        struct ifaddrs *ifaddr;

        if (getifaddrs(&ifaddr) == -1) {
                fpritnf(stderr, "fail\n");
                return 1;
        } else fprintf(stderr, "success\n");

return 0;
}

Closer look showed me that actually the check is "tun_ip_local_get(apn->tun.tun, &ipv6_tun_linklocal_ip, 1, IP_TYPE_IPv6_LINK) < 1" which means it checks not only for error, but asserts that the IP was found. Which means the getifaddrs is working fine but the address is not found. I run "ifconfig" and "ip l" while the test was running, and I only saw tun4 appearing. However, according to osmo-ggsn logs we see no error appearing.

After stracing osmo-ggsn, there seems to be something weird in the output of while setting ipv6 SIOCSIFADDR tun addr (tun_setaddr6):

write(2, "20171213202024691 DGGSN <0002> g"..., 6820171213202024691 DGGSN <0002> ggsn.c:201 APN(inet6): Starting
) = 68
write(2, "20171213202024693 DGGSN <0002> g"..., 8320171213202024693 DGGSN <0002> ggsn.c:204 APN(inet6): Opening TUN device tun6
) = 83
open("/dev/net/tun", O_RDWR)            = 6
ioctl(6, TUNSETIFF, 0x7ffe4d18a690)     = 0
ioctl(6, TUNSETNOCSUM, 0x1)             = 0
write(2, "20171213202024696 DGGSN <0002> g"..., 8220171213202024696 DGGSN <0002> ggsn.c:209 APN(inet6): Opened TUN device tun6
) = 82
fcntl(6, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK|O_LARGEFILE) = 0
fcntl(6, F_GETFD)                       = 0
fcntl(6, F_SETFD, FD_CLOEXEC)           = 0
write(2, "20171213202024697 DGGSN <0002> g"..., 10920171213202024697 DGGSN <0002> ggsn.c:232 APN(inet6): Setting tun IPv6 address fde4:8dba:82e1:2000::/56
) = 109
access("/proc/net", R_OK)               = 0
access("/proc/net/unix", R_OK)          = 0
socket(PF_LOCAL, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="tun6", ifr_index=42}) = 0
close(7)                                = 0
socket(PF_INET6, SOCK_DGRAM, IPPROTO_IP) = 7
ioctl(7, SIOCSIFADDR, {ifr_name="<FD>䍺<82><E1> ", ifr_addr={0x38 /* AF_??? */, "\0\0*\0\0\0\1\0\0\0\0\0\0\0"}}) = 0
close(7)                                = 0
socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 7
ioctl(7, SIOCSIFFLAGS, {ifr_name="tun6", ifr_flags=IFF_UP|IFF_RUNNING}) = 0
close(7)                                = 0
socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE) = 7
bind(7, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
getsockname(7, {sa_family=AF_NETLINK, pid=4567, groups=00000000}, [12]) = 0
sendto(7, "\24\0\0\0\22\0\1\3x}1Z\0\0\0\0\0\0\0\0", 20, 0, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"l\4\0\0\20\0\2\0x}1Z\327\21\0\0\0\0\4\3\1\0\0\0I\0\1\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 3412
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"t\4\0\0\20\0\2\0x}1Z\327\21\0\0\0\0\1\0\4\0\0\0\3\20\0\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 3412
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"t\4\0\0\20\0\2\0x}1Z\327\21\0\0\0\0\1\0\7\0\0\0\2\20\0\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 3412
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"p\4\0\0\20\0\2\0x}1Z\327\21\0\0\0\0\1\0\n\0\0\0\2\20\0\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 3392
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"\24\0\0\0\3\0\2\0x}1Z\327\21\0\0\0\0\0\0", 4096}], msg_controllen=0, msg_flags=0}, 0) = 20
sendto(7, "\24\0\0\0\26\0\1\3y}1Z\0\0\0\0\0\0\0\0", 20, 0, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 20
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"L\0\0\0\24\0\2\0y}1Z\327\21\0\0\2\10\200\376\1\0\0\0\10\0\1\0\177\0\0\1"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 1468
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"H\0\0\0\24\0\2\0y}1Z\327\21\0\0\n\200\200\376\1\0\0\0\24\0\1\0\0\0\0\0"..., 4096}], msg_controllen=0, msg_flags=0}, 0) = 288
recvmsg(7, {msg_name(12)={sa_family=AF_NETLINK, pid=0, groups=00000000}, msg_iov(1)=[{"\24\0\0\0\3\0\2\0y}1Z\327\21\0\0\0\0\0\0", 4096}], msg_controllen=0, msg_flags=0}, 0) = 20
close(7)                                = 0
write(2, "20171213202024703 DGGSN <0002> g"..., 11920171213202024703 DGGSN <0002> ggsn.c:252 APN(inet6): Cannot obtain IPv6 link-local address of interface: Success

However all return codes look fine (matches what we see in the logs).

I attach full strace.

EDIT: I forgot to say, the strace is taken as root, and I verified that indeed only tun4 was created, so it's not a permissions issue.

Here's the same output in R&D (which creates the tuns correctly):

write(2, "20171213204857407 DGGSN <0002> g"..., 6820171213204857407 DGGSN <0002> ggsn.c:201 APN(inet6): Starting
ESC[0;m) = 68
write(2, "20171213204857408 DGGSN <0002> g"..., 8320171213204857408 DGGSN <0002> ggsn.c:204 APN(inet6): Opening TUN device tun6
ESC[0;m) = 83
open("/dev/net/tun", O_RDWR)            = 6
ioctl(6, TUNSETIFF, 0x7fff7c1ba790)     = 0
ioctl(6, TUNSETNOCSUM, 0x1)             = 0
write(2, "20171213204857411 DGGSN <0002> g"..., 8220171213204857411 DGGSN <0002> ggsn.c:209 APN(inet6): Opened TUN device tun6
ESC[0;m) = 82
fcntl(6, F_GETFL)                       = 0x8002 (flags O_RDWR|O_LARGEFILE)
fcntl(6, F_SETFL, O_RDWR|O_NONBLOCK|O_LARGEFILE) = 0
fcntl(6, F_GETFD)                       = 0
fcntl(6, F_SETFD, FD_CLOEXEC)           = 0
write(2, "20171213204857412 DGGSN <0002> g"..., 10920171213204857412 DGGSN <0002> ggsn.c:232 APN(inet6): Setting tun IPv6 address fde4:8dba:82e1:2000::/56
ESC[0;m) = 109
access("/proc/net", R_OK)               = 0
access("/proc/net/unix", R_OK)          = 0
socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 7
ioctl(7, SIOCGIFINDEX, {ifr_name="tun6", }) = 0
close(7)                                = 0
socket(AF_INET6, SOCK_DGRAM, IPPROTO_IP) = 7
ioctl(7, SIOCSIFADDR, {ifr_name="\375\344\215\272\202\341 ", ifr_addr={sa_family=0x38 /* AF_??? */, sa_data="\0\0\272\1\0\0\1\0\0\0\0\0\0\0"}}) = 0
close(7)                                = 0
socket(AF_INET, SOCK_DGRAM, IPPROTO_IP) = 7
ioctl(7, SIOCSIFFLAGS, {ifr_name="tun6", ifr_flags=IFF_UP|IFF_RUNNING}) = 0
close(7)                                = 0
socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE) = 7
bind(7, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 0
getsockname(7, {sa_family=AF_NETLINK, nl_pid=25384, nl_groups=00000000}, [12]) = 0
sendto(7, {{len=20, type=0x12 /* NLMSG_??? */, flags=NLM_F_REQUEST|0x300, seq=1513194537, pid=0}, "\0\0\0\0"}, 20, 0, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 20
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=1232, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\4\3\1\0\0\0I\0\1\0\0\0\0\0\7\0\3\0lo\0\0\10\0\r\0\1\0\0\0"...}, {{len=1240, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0\2\0\0\0C\20\1\0\0\0\0\0\t\0\3\0eth0\0\0\0\0\10\0\r\0"...}, {{len=1240, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0\3\0\0\0C\20\1\0\0\0\0\0\t\0\3\0eth1\0\0\0\0\10\0\r\0"...}, {{len=3352834104, type=0x7fdd /* NLMSG_??? */, flags=0, seq=3374275523, pid=32733}, "\334\5\0\0\0\0\0\00080\330\307\335\177\0\0\260z?\311\335\177\0\0\310\244\33|\377\177\0\0"...}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 3712
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=1240, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0\4\0\0\0\3\20\0\0\0\0\0\0\t\0\3\0eth2\0\0\0\0\10\0\r\0"...}, {{len=1236, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0\5\0\0\0\2\20\0\0\0\0\0\0\n\0\3\0wlan0\0\0\0\10\0\r\0"...}, {{len=1244, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0Q\0\0\0\2\20\0\0\0\0\0\0\22\0\3\0wwp0s18f2u1u"...}, {{len=3374275523, type=0x7fdd /* NLMSG_??? */, flags=0, seq=1500, pid=0}, "80\330\307\335\177\0\0\260z?\311\335\177\0\0\310\244\33|\377\177\0\0\304\244\33|\377\177\0\0"...}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 3720
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=1248, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0R\0\0\0\2\20\0\0\0\0\0\0\24\0\3\0wwp0s18f2u1u"...}, {{len=1220, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\376\377S\0\0\0\220\20\0\0\0\0\0\0\24\0\3\0wwp0s18f2u1u"...}, {{len=1236, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0T\0\0\0\2\20\0\0\0\0\0\0\n\0\3\0wwan1\0\0\0\10\0\r\0"...}, {{len=0, type=0 /* NLMSG_??? */, flags=0, seq=524293, pid=0}}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 3704
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=1224, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\376\377U\0\0\0\220\20\0\0\0\0\0\0\24\0\3\0wwp0s18f2u1u"...}, {{len=1236, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\1\0V\0\0\0\2\20\0\0\0\0\0\0\n\0\3\0wwan2\0\0\0\10\0\r\0"...}, {{len=1228, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\376\377\271\1\0\0Q\0\1\0\0\0\0\0\t\0\3\0tun4\0\0\0\0\10\0\r\0"...}, {{len=0, type=0 /* NLMSG_??? */, flags=0, seq=524293, pid=0}}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 3688
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=1228, type=0x10 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\376\377\272\1\0\0Q\0\1\0\0\0\0\0\t\0\3\0tun6\0\0\0\0\10\0\r\0"...}, {{len=131088, type=0x8429 /* NLMSG_??? */, flags=NLM_F_REQUEST|NLM_F_DUMP_INTR|NLM_F_DUMP_FILTERED|0x5a00, seq=25384, pid=65536}, "V\0\0\0\2\20\0\0\0\0\0\0\n\0\3\0wwan2\0\0\0\10\0\r\0\350\3\0\0"...}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 1228
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=20, type=NLMSG_DONE, flags=NLM_F_MULTI, seq=1513194537, pid=25384}, "\0\0\0\0"}, {{len=442, type=0x51 /* NLMSG_??? */, flags=NLM_F_REQUEST, seq=0, pid=196617}, "tun6\0\0\0\0\10\0\r\0\364\1\0\0\5\0\20\0\0\0\0\0\5\0\21\0\0\0\0\0"...}, {{len=0, type=0 /* NLMSG_??? */, flags=0, seq=0, pid=0}}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
sendto(7, {{len=20, type=0x16 /* NLMSG_??? */, flags=NLM_F_REQUEST|0x300, seq=1513194538, pid=0}, "\0\0\0\0"}, 20, 0, {sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, 12) = 20
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=76, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\10\200\376\1\0\0\0\10\0\1\0\177\0\0\1\10\0\2\0\177\0\0\1\7\0\3\0lo\0\0"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\200\0\2\0\0\0\10\0\1\0\n\t\31e\10\0\2\0\n\t\31e\10\0\4\0\n\t\31\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\200\0\3\0\0\0\10\0\1\0\n**\1\10\0\2\0\n**\1\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\2\10\0\2\0\n**\2\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\3\10\0\2\0\n**\3\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\4\10\0\2\0\n**\4\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\5\10\0\2\0\n**\5\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\6\10\0\2\0\n**\6\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\7\10\0\2\0\n**\7\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\10\10\0\2\0\n**\10\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**\t\10\0\2\0\n**\t\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**2\10\0\2\0\n**2\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\201\0\3\0\0\0\10\0\1\0\n**3\10\0\2\0\n**3\10\0\4\0\n**\377"...}, {{len=88, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\200\0\4\0\0\0\10\0\1\0\n@\1\1\10\0\2\0\n@\1\1\10\0\4\0\n@\1\377"...}, {{len=80, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\200\0\4\0\0\0\10\0\1\0\300\250\1\310\10\0\2\0\300\250\1\310\t\0\3\0eth2"...}, {{len=80, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\2\30\200\0\271\1\0\0\10\0\1\0\260\20\336\1\10\0\2\0\260\20\336\1\t\0\3\0tun4"...}, {{len=0, type=0x24 /* NLMSG_??? */, flags=NLM_F_MULTI|NLM_F_ACK|NLM_F_ECHO, seq=0, pid=0}}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 1380
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n\200\200\376\1\0\0\0\24\0\1\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1\24\0\6\0"...}, {{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n@\200\375\2\0\0\0\24\0\1\0\376\200\0\0\0\0\0\0\2\r\271\377\3765:@\24\0\6\0"...}, {{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n@\200\375\3\0\0\0\24\0\1\0\376\200\0\0\0\0\0\0\2\r\271\377\3765:A\24\0\6\0"...}, {{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n@\200\375\271\1\0\0\24\0\1\0\376\200\0\0\0\0\0\0\216l\342-s>\364\265\24\0\6\0"...}, {{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n8\200\0\272\1\0\0\24\0\1\0\375\344\215\272\202\341 \0\0\0\0\0\0\0\0\0\24\0\6\0"...}, {{len=72, type=0x14 /* NLMSG_??? */, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\n@\200\375\272\1\0\0\24\0\1\0\376\200\0\0\0\0\0\0A@B1l\317\247\232\24\0\6\0"...}, {{len=131092, type=0x842a /* NLMSG_??? */, flags=NLM_F_REQUEST|NLM_F_DUMP_INTR|NLM_F_DUMP_FILTERED|0x5a00, seq=25384, pid=8460290}, "\3\0\0\0\10\0\1\0\n**\4\10\0\2\0\n**\4\10\0\4\0\n**\377\v\0\3\0"...}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 432
recvmsg(7, {msg_name={sa_family=AF_NETLINK, nl_pid=0, nl_groups=00000000}, msg_namelen=12, msg_iov=[{iov_base=[{{len=20, type=NLMSG_DONE, flags=NLM_F_MULTI, seq=1513194538, pid=25384}, "\0\0\0\0"}, {{len=1, type=0x14 /* NLMSG_??? */, flags=NLM_F_REQUEST, seq=0, pid=0}}], iov_len=4096}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, 0) = 20
close(7)                                = 0

I see no big differences. I attach the full strace log.

On the Prod machine, I checked how other tools set the IP (successfully).

I can create the tunnel with:

ip tuntap add dev tun6 mode tun user root group root

ip addr uses the entlink interface to set the ip.

ifconfig uses the same bits as us:

ioctl(5, SIOCGIFINDEX, {ifr_name="tun6", ifr_index=56}) = 0
ioctl(5, SIOCSIFADDR, {ifr_name="<FD>䍺<82><E1> ", ifr_addr={0x38 /* AF_??? */, "\0\0008\0\0\0\10\5\223\366\332\177\0\0"}}) = 0

I am probably not seeing the interface being created by osmo-ggsn because it is destroyed after trying to fetch the link-local ip, since apn_stop() is called which in turn calls tun_free().

Thinking more about it, that's what I think could be happening: IIRC, setting the IP is not immediate/synchronous, specially because some routing entries are added automatically. Which means we are probably setting up the tunnel correctly, but when we call getifaddrs() to get the list of IPs, the IP we just set is not yet there and we fail to get it. Then we destroy the iface.

We could try waiting a bit more or using the debugger to stop it for a while and see what happens (and if the iface is indeed correctly created and the IP is set).

With gdb I can see that the interface is created and that the IP is assigned. However, no link-local IP is assigned to the interface.

Prod:

62: tun46: <POINTOPOINT,UP,LOWER_UP> mtu 1500 qlen 500
    inet6 fde4:8dba:82e1:2000::/56 scope global
       valid_lft forever preferred_lft foreve

R&D:

447: tun46: <POINTOPOINT,UP,LOWER_UP> mtu 1500 state UNKNOWN qlen 500
    inet6 fde4:8dba:82e1:2000::/56 scope global
       valid_lft forever preferred_lft forever
    inet6 fe80::1d0:8ef4:21ff:fcc4/64 scope link flags 800
       valid_lft forever preferred_lft forever

I'm not sure how is that link-local IP assigned though.

I added code to osmo-ggsn to manually set up a link-local ip.

It can be used in osmo-gsm-tester as soon as it is merged + the trial is built: https://gerrit.osmocom.org/#/c/5349/

Then, we need to add the following line to osmo-ggsn.cfg in osmo-gsm-tester, for inet6:

ipv6 link-local fe80::1111:1111:1111:1111/64

and to inet64:

ipv6 link-local fe80::1111:1111:1111:1112/64

After this options are used, osmo-ggsn tester should start and configure ipv6 pools correctly, and we can enable ipv6 ctx tests again.

osmo-ggsn patches were merged. I pushed just now a commit for osmo-gsm-tester in gerrit to use the option. I already tried in a branch running in Prod setup that it works fine and that ipv6 context can be created successfully using ofono+osmo-ggsn.