[Xquartz-dev] Re: xauth bus error

[Jeremy Huddleston]

Hi Greg,

Here's a stripped down app which reveals the problem.  Compile and run  
'./getaddrtest localhost' to see (up to endianness for the ipv4 addr):

entry 0:
	Family: AF_INET6
	sin6_port: 0
	sin6_flowinfo: 0
	sin6_scope_id: 0
	Address: 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.
entry 1:
	Family: AF_INET6
	sin6_port: 0
	sin6_flowinfo: 0
	sin6_scope_id: 0
	Address: 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.
entry 2:
	Family: AF_INET
	Address: 127.1.1.1

Note that the scope_id is the same... And I think that about covers  
all the items in sockaddr_in6 that we could match:

struct in6_addr {
         union {
                 __uint8_t   __u6_addr8[16];
                 __uint16_t  __u6_addr16[8];
                 __uint32_t  __u6_addr32[4];
         } __u6_addr;                    /* 128-bit IP6 address */
};

#define s6_addr   __u6_addr.__u6_addr8

struct sockaddr_in6 {
         __uint8_t       sin6_len;       /* length of this  
struct(sa_family_t)*/
         sa_family_t     sin6_family;    /* AF_INET6 (sa_family_t) */
         in_port_t       sin6_port;      /* Transport layer port #  
(in_port_t)*/
         __uint32_t      sin6_flowinfo;  /* IP6 flow information */
         struct in6_addr sin6_addr;      /* IP6 address */
         __uint32_t      sin6_scope_id;  /* scope zone index */
};


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On Jan 10, 2008, at 21:37, Greg Parker wrote:

> On Jan 10, 2008, at 8:55 PM, Jeremy Huddleston wrote:
>> So actually, I traced it back to duplicate entries appearing as a  
>> result of get_address_info()... and that seems to be coming from  
>> OSX's getaddrinfo() returning the duplicate entry:
>>
>> Is this a bug in getaddrinfo()?  Should it not be returning  
>> duplicates?  I don't see in the documentation anywhere that it  
>> guarantees uniqueness... so I'm going to try whipping together a  
>> patch to get_address_info() which prevents the duplicates from  
>> being passed on to the caller of get_address_info()... hopefully  
>> that will solve our problem.
>>
>> (gdb) n
>> 296	        if (getaddrinfo(host,NULL,&hints,&firstai) !=0) return  
>> NULL;
>> (gdb) n
>> 297		for (ai = firstai; ai != NULL; ai = ai->ai_next) {
>> (gdb) print *firstai
>> $1 = {
>> ai_flags = 0,
>> ai_family = 30,
>> ai_socktype = 1,
>> ai_protocol = 6,
>> ai_addrlen = 28,
>> ai_canonname = 0x0,
>> ai_addr = 0x3003e0,
>> ai_next = 0x300400
>> }
>> (gdb) print *firstai->ai_next
>> $2 = {
>> ai_flags = 0,
>> ai_family = 30,
>> ai_socktype = 1,
>> ai_protocol = 6,
>> ai_addrlen = 28,
>> ai_canonname = 0x0,
>> ai_addr = 0x300420,
>> ai_next = 0x300440
>> }
>
> These are both AF_INET6, IPPROTO_TCP, SOCK_STREAM.
>
>
>> (gdb) print *firstai->ai_addr
>> $4 = {
>> sa_len = 28 '\034',
>> sa_family = 30 '\036',
>> sa_data = '\0' <repeats 13 times>
>> }
>> (gdb) print *firstai->ai_next->ai_addr
>> $5 = {
>> sa_len = 28 '\034',
>> sa_family = 30 '\036',
>> sa_data = '\0' <repeats 13 times>
>> }
>
> What are the full contents of both of these? They're struct  
> sockaddr_in6, 28 bytes long. They may not be duplicates because this  
> only shows the first 16 bytes.
>
> My guess is that you're seeing IPv6 loopback on two different  
> interfaces (i.e. ::1%en0 for ethernet and ::1%en1 for wifi), or  
> perhaps an unscoped ::1 and a interface-specific ::1. In these  
> cases, sin6_addr will be all zeros with 0x01 at the end, and  
> sin6_scope_id (the last 4 of the 28 bytes) will differ.
>
>
> -- 
> Greg Parker     gparker at apple.com     Runtime Wrangler
>
>
> _______________________________________________
> Xquartz-dev mailing list
> Xquartz-dev at lists.macosforge.org
> http://lists.macosforge.org/mailman/listinfo/xquartz-dev

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