https://bugzilla.kernel.org/show_bug.cgi?id=18132 Summary: ipv6(7) describes IP_PKTINFO, but should be IP_RECVPKTINFO instead Product: Documentation Version: unspecified Kernel Version: 2.6.32 Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: man-pages AssignedTo: documentation_man-pages@xxxxxxxxxxxxxxxxxxxx ReportedBy: cameron@xxxxxxxxxxxxxx Regression: No Created an attachment (id=29412) --> (https://bugzilla.kernel.org/attachment.cgi?id=29412) Small wrapper library around recvmsg According to the ipv6(7) manual page: IPV6_PKTINFO Set delivery of the IPV6_PKTINFO control message on incoming datagrams. Only allowed for SOCK_DGRAM or SOCK_RAW sockets. Argument is a pointer to a boolean value in an integer. COLOPHON This page is part of release 3.23 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/. (This is on Ubuntu 10.04, 32-bit) Thus, the following code should work, assuming an IPv6 UDP socket has been created: int on = 1 setsockopt(sock, IPPROTO_IPV6, IPV6_PKTINFO, &on, sizeof on) Yet, instead we see that the system call fails, with errno saying EINVAL. Here is strace output demonstrating this: socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP) = 3 bind(3, {sa_family=AF_INET6, sin6_port=htons(8421), inet_pton(AF_INET6, "::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0 setsockopt(3, SOL_IPV6, IPV6_PKTINFO, [1], 4) = -1 EINVAL (Invalid argument) According to Steven's Unix Network Programming, volume 1 (third ed.), in section 7.2, which lists a set of socket options, there is an IPV6_RECVPKTINFO, as well as things like IPV6_RECVHOPLIMIT and others, which are different to the ones without the RECV sub-prefix. From the description therein, it would appear that IPV6_PKTINFO is a "sticky" option (I haven't read much into that). cscope verifies that they are indeed different on this system: (in netinet/in.h) #define IPV6_RECVPKTINFO 49 #define IPV6_PKTINFO 50 #define IPV6_RECVHOPLIMIT 51 #define IPV6_HOPLIMIT 52 Using IPV6_RECVPKTINFO, we get the following strace socket(PF_INET6, SOCK_DGRAM, IPPROTO_UDP) = 3 bind(3, {sa_family=AF_INET6, sin6_port=htons(8421), inet_pton(AF_INET6, "::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = 0 setsockopt(3, SOL_IPV6, 0x31 /* IPV6_??? */, [1], 4) = 0 recvmsg(3, {msg_name(28)={sa_family=AF_INET6, sin6_port=htons(41202), inet_pton(AF_INET6, "::1", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, msg_iov(1)=[{"hi\n\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 128}], msg_controllen=32, {cmsg_len=32, cmsg_level=SOL_IPV6, cmsg_type=, ...}, msg_flags=0}, 0) = 3 recvfrom_detailed returned value 3 source family 10 address ::1 port 41202 destination family 10 address ::1 -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
