X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/0ff9ea389c749836c7c6f23f1e654bc9a5600ebf..055817455466c8eb60392f30bb7c689763962e17:/unix/uxnet.c diff --git a/unix/uxnet.c b/unix/uxnet.c index 0795d4d2..f1ef98b0 100644 --- a/unix/uxnet.c +++ b/unix/uxnet.c @@ -15,18 +15,23 @@ #include #include #include +#include #define DEFINE_PLUG_METHOD_MACROS #include "putty.h" #include "network.h" #include "tree234.h" +#ifndef X11_UNIX_PATH +# define X11_UNIX_PATH "/tmp/.X11-unix/X" +#endif + #define ipv4_is_loopback(addr) (inet_netof(addr) == IN_LOOPBACKNET) struct Socket_tag { struct socket_function_table *fn; /* the above variable absolutely *must* be the first in this structure */ - char *error; + const char *error; int s; Plug plug; void *private_ptr; @@ -56,7 +61,7 @@ struct Socket_tag { typedef struct Socket_tag *Actual_Socket; struct SockAddr_tag { - char *error; + const char *error; /* * Which address family this address belongs to. AF_INET for * IPv4; AF_INET6 for IPv6; AF_UNSPEC indicates that name @@ -64,9 +69,10 @@ struct SockAddr_tag { * in this SockAddr structure. */ int family; - unsigned long address; /* Address IPv4 style. */ -#ifdef IPV6 +#ifndef NO_IPV6 struct addrinfo *ai; /* Address IPv6 style. */ +#else + unsigned long address; /* Address IPv4 style. */ #endif char hostname[512]; /* Store an unresolved host name. */ }; @@ -89,7 +95,7 @@ static int cmpfortree(void *av, void *bv) static int cmpforsearch(void *av, void *bv) { Actual_Socket b = (Actual_Socket) bv; - int as = (int) av, bs = b->s; + int as = *(int *)av, bs = b->s; if (as < bs) return -1; if (as > bs) @@ -114,16 +120,21 @@ void sk_cleanup(void) } } -char *error_string(int error) +const char *error_string(int error) { return strerror(error); } -SockAddr sk_namelookup(const char *host, char **canonicalname) +SockAddr sk_namelookup(const char *host, char **canonicalname, int address_family) { SockAddr ret = snew(struct SockAddr_tag); +#ifndef NO_IPV6 + struct addrinfo hints; + int err; +#else unsigned long a; struct hostent *h = NULL; +#endif char realhost[8192]; /* Clear the structure and default to IPv4. */ @@ -132,61 +143,49 @@ SockAddr sk_namelookup(const char *host, char **canonicalname) *realhost = '\0'; ret->error = NULL; +#ifndef NO_IPV6 + hints.ai_flags = AI_CANONNAME; + hints.ai_family = address_family; + hints.ai_socktype = 0; + hints.ai_protocol = 0; + hints.ai_addrlen = 0; + hints.ai_addr = NULL; + hints.ai_canonname = NULL; + hints.ai_next = NULL; + err = getaddrinfo(host, NULL, NULL, &ret->ai); + if (err != 0) { + ret->error = gai_strerror(err); + return ret; + } + ret->family = ret->ai->ai_family; + *realhost = '\0'; + if (ret->ai->ai_canonname != NULL) + strncat(realhost, ret->ai->ai_canonname, sizeof(realhost) - 1); + else + strncat(realhost, host, sizeof(realhost) - 1); +#else if ((a = inet_addr(host)) == (unsigned long) INADDR_NONE) { -#ifdef IPV6 - if (getaddrinfo(host, NULL, NULL, &ret->ai) == 0) { - ret->family = ret->ai->ai_family; - } else -#endif - { - /* - * Otherwise use the IPv4-only gethostbyname... (NOTE: - * we don't use gethostbyname as a fallback!) - */ - if (ret->family == 0) { + /* + * Otherwise use the IPv4-only gethostbyname... (NOTE: + * we don't use gethostbyname as a fallback!) + */ + if (ret->family == 0) { /*debug(("Resolving \"%s\" with gethostbyname() (IPv4 only)...\n", host)); */ if ( (h = gethostbyname(host)) ) - ret->family = AF_INET; - } - if (ret->family == 0) { + ret->family = AF_INET; + } + if (ret->family == 0) { ret->error = (h_errno == HOST_NOT_FOUND || - h_errno == NO_DATA || - h_errno == NO_ADDRESS ? "Host does not exist" : - h_errno == TRY_AGAIN ? - "Temporary name service failure" : - "gethostbyname: unknown error"); + h_errno == NO_DATA || + h_errno == NO_ADDRESS ? "Host does not exist" : + h_errno == TRY_AGAIN ? + "Temporary name service failure" : + "gethostbyname: unknown error"); return ret; - } - } - -#ifdef IPV6 - /* If we got an address info use that... */ - if (ret->ai) { - - /* Are we in IPv4 fallback mode? */ - /* We put the IPv4 address into the a variable so we can further-on use the IPv4 code... */ - if (ret->family == AF_INET) - memcpy(&a, - (char *) &((struct sockaddr_in *) ret->ai-> - ai_addr)->sin_addr, sizeof(a)); - - /* Now let's find that canonicalname... */ - if (getnameinfo((struct sockaddr *) ret->ai->ai_addr, - ret->family == - AF_INET ? sizeof(struct sockaddr_in) : - sizeof(struct sockaddr_in6), realhost, - sizeof(realhost), NULL, 0, 0) != 0) { - strncpy(realhost, host, sizeof(realhost)); - } - } - /* We used the IPv4-only gethostbyname()... */ - else -#endif - { - memcpy(&a, h->h_addr, sizeof(a)); - /* This way we are always sure the h->h_name is valid :) */ - strncpy(realhost, h->h_name, sizeof(realhost)); } + memcpy(&a, h->h_addr, sizeof(a)); + /* This way we are always sure the h->h_name is valid :) */ + strncpy(realhost, h->h_name, sizeof(realhost)); } else { /* * This must be a numeric IPv4 address because it caused a @@ -196,6 +195,7 @@ SockAddr sk_namelookup(const char *host, char **canonicalname) strncpy(realhost, host, sizeof(realhost)); } ret->address = ntohl(a); +#endif realhost[lenof(realhost)-1] = '\0'; *canonicalname = snewn(1+strlen(realhost), char); strcpy(*canonicalname, realhost); @@ -214,20 +214,24 @@ SockAddr sk_nonamelookup(const char *host) void sk_getaddr(SockAddr addr, char *buf, int buflen) { -#ifdef IPV6 - if (addr->family == AF_INET6) { - FIXME; /* I don't know how to get a text form of an IPv6 address. */ - } else -#endif - if (addr->family == AF_INET) { + + if (addr->family == AF_UNSPEC) { + strncpy(buf, addr->hostname, buflen); + buf[buflen-1] = '\0'; + } else { +#ifndef NO_IPV6 + if (getnameinfo(addr->ai->ai_addr, addr->ai->ai_addrlen, buf, buflen, + NULL, 0, NI_NUMERICHOST) != 0) { + buf[0] = '\0'; + strncat(buf, "", buflen - 1); + } +#else struct in_addr a; + assert(addr->family == AF_INET); a.s_addr = htonl(addr->address); strncpy(buf, inet_ntoa(a), buflen); buf[buflen-1] = '\0'; - } else { - assert(addr->family == AF_UNSPEC); - strncpy(buf, addr->hostname, buflen); - buf[buflen-1] = '\0'; +#endif } } @@ -238,25 +242,32 @@ int sk_hostname_is_local(char *name) int sk_address_is_local(SockAddr addr) { -#ifdef IPV6 - if (addr->family == AF_INET6) { - FIXME; /* someone who can compile for IPV6 had better do this bit */ - } else -#endif - if (addr->family == AF_INET) { + + if (addr->family == AF_UNSPEC) + return 0; /* we don't know; assume not */ + else { +#ifndef NO_IPV6 + if (addr->family == AF_INET) + return ipv4_is_loopback( + ((struct sockaddr_in *)addr->ai->ai_addr)->sin_addr); + else if (addr->family == AF_INET6) + return IN6_IS_ADDR_LOOPBACK( + &((struct sockaddr_in6 *)addr->ai->ai_addr)->sin6_addr); + else + return 0; +#else struct in_addr a; + assert(addr->family == AF_INET); a.s_addr = htonl(addr->address); return ipv4_is_loopback(a); - } else { - assert(addr->family == AF_UNSPEC); - return 0; /* we don't know; assume not */ +#endif } } int sk_addrtype(SockAddr addr) { return (addr->family == AF_INET ? ADDRTYPE_IPV4 : -#ifdef IPV6 +#ifndef NO_IPV6 addr->family == AF_INET6 ? ADDRTYPE_IPV6 : #endif ADDRTYPE_NAME); @@ -264,21 +275,32 @@ int sk_addrtype(SockAddr addr) void sk_addrcopy(SockAddr addr, char *buf) { - assert(addr->family != AF_UNSPEC); -#ifdef IPV6 - if (addr->family == AF_INET6) { - memcpy(buf, (char*) addr->ai, 16); - } else + +#ifndef NO_IPV6 + if (addr->family == AF_INET) + memcpy(buf, &((struct sockaddr_in *)addr->ai->ai_addr)->sin_addr, + sizeof(struct in_addr)); + else if (addr->family == AF_INET6) + memcpy(buf, &((struct sockaddr_in6 *)addr->ai->ai_addr)->sin6_addr, + sizeof(struct in6_addr)); + else + assert(FALSE); +#else + struct in_addr a; + + assert(addr->family == AF_INET); + a.s_addr = htonl(addr->address); + memcpy(buf, (char*) &a.s_addr, 4); #endif - if (addr->family == AF_INET) { - struct in_addr a; - a.s_addr = htonl(addr->address); - memcpy(buf, (char*) &a.s_addr, 4); - } } void sk_addr_free(SockAddr addr) { + +#ifndef NO_IPV6 + if (addr->ai != NULL) + freeaddrinfo(addr->ai); +#endif sfree(addr); } @@ -305,7 +327,7 @@ static int sk_tcp_write_oob(Socket s, const char *data, int len); static void sk_tcp_set_private_ptr(Socket s, void *ptr); static void *sk_tcp_get_private_ptr(Socket s); static void sk_tcp_set_frozen(Socket s, int is_frozen); -static char *sk_tcp_socket_error(Socket s); +static const char *sk_tcp_socket_error(Socket s); static struct socket_function_table tcp_fn_table = { sk_tcp_plug, @@ -319,7 +341,7 @@ static struct socket_function_table tcp_fn_table = { sk_tcp_socket_error }; -Socket sk_register(void *sock, Plug plug) +Socket sk_register(OSSocket sockfd, Plug plug) { Actual_Socket ret; @@ -340,7 +362,7 @@ Socket sk_register(void *sock, Plug plug) ret->oobpending = FALSE; ret->listener = 0; - ret->s = (int)sock; + ret->s = sockfd; if (ret->s < 0) { ret->error = error_string(errno); @@ -356,16 +378,19 @@ Socket sk_register(void *sock, Plug plug) } Socket sk_new(SockAddr addr, int port, int privport, int oobinline, - int nodelay, Plug plug) + int nodelay, int keepalive, Plug plug) { int s; -#ifdef IPV6 +#ifndef NO_IPV6 struct sockaddr_in6 a6; #endif struct sockaddr_in a; + struct sockaddr_un au; + const struct sockaddr *sa; int err; Actual_Socket ret; short localport; + int fl, salen; /* * Create Socket structure. @@ -408,6 +433,11 @@ Socket sk_new(SockAddr addr, int port, int privport, int oobinline, setsockopt(s, IPPROTO_TCP, TCP_NODELAY, (void *) &b, sizeof(b)); } + if (keepalive) { + int b = TRUE; + setsockopt(s, SOL_SOCKET, SO_KEEPALIVE, (void *) &b, sizeof(b)); + } + /* * Bind to local address. */ @@ -416,85 +446,103 @@ Socket sk_new(SockAddr addr, int port, int privport, int oobinline, else localport = 0; /* just use port 0 (ie kernel picks) */ - /* Loop round trying to bind */ - while (1) { - int retcode; + /* BSD IP stacks need sockaddr_in zeroed before filling in */ + memset(&a,'\0',sizeof(struct sockaddr_in)); +#ifndef NO_IPV6 + memset(&a6,'\0',sizeof(struct sockaddr_in6)); +#endif -#ifdef IPV6 - if (addr->family == AF_INET6) { - memset(&a6, 0, sizeof(a6)); - a6.sin6_family = AF_INET6; -/*a6.sin6_addr = in6addr_any; *//* == 0 */ - a6.sin6_port = htons(localport); - } else + /* We don't try to bind to a local address for UNIX domain sockets. (Why + * do we bother doing the bind when localport == 0 anyway?) */ + if(addr->family != AF_UNIX) { + /* Loop round trying to bind */ + while (1) { + int retcode; + +#ifndef NO_IPV6 + if (addr->family == AF_INET6) { + /* XXX use getaddrinfo to get a local address? */ + a6.sin6_family = AF_INET6; + a6.sin6_addr = in6addr_any; + a6.sin6_port = htons(localport); + retcode = bind(s, (struct sockaddr *) &a6, sizeof(a6)); + } else #endif - { - a.sin_family = AF_INET; - a.sin_addr.s_addr = htonl(INADDR_ANY); - a.sin_port = htons(localport); + { + assert(addr->family == AF_INET); + a.sin_family = AF_INET; + a.sin_addr.s_addr = htonl(INADDR_ANY); + a.sin_port = htons(localport); + retcode = bind(s, (struct sockaddr *) &a, sizeof(a)); + } + if (retcode >= 0) { + err = 0; + break; /* done */ + } else { + err = errno; + if (err != EADDRINUSE) /* failed, for a bad reason */ + break; + } + + if (localport == 0) + break; /* we're only looping once */ + localport--; + if (localport == 0) + break; /* we might have got to the end */ } -#ifdef IPV6 - retcode = bind(s, (addr->family == AF_INET6 ? - (struct sockaddr *) &a6 : - (struct sockaddr *) &a), - (addr->family == - AF_INET6 ? sizeof(a6) : sizeof(a))); -#else - retcode = bind(s, (struct sockaddr *) &a, sizeof(a)); -#endif - if (retcode >= 0) { - err = 0; - break; /* done */ - } else { - err = errno; - if (err != EADDRINUSE) /* failed, for a bad reason */ - break; + + if (err) { + ret->error = error_string(err); + return (Socket) ret; } - - if (localport == 0) - break; /* we're only looping once */ - localport--; - if (localport == 0) - break; /* we might have got to the end */ - } - - if (err) { - ret->error = error_string(err); - return (Socket) ret; } /* * Connect to remote address. */ -#ifdef IPV6 - if (addr->family == AF_INET6) { - memset(&a, 0, sizeof(a)); - a6.sin6_family = AF_INET6; - a6.sin6_port = htons((short) port); - a6.sin6_addr = - ((struct sockaddr_in6 *) addr->ai->ai_addr)->sin6_addr; - } else -#endif - { + switch(addr->family) { +#ifndef NO_IPV6 + case AF_INET: + /* XXX would be better to have got getaddrinfo() to fill in the port. */ + ((struct sockaddr_in *)addr->ai->ai_addr)->sin_port = + htons(port); + sa = (const struct sockaddr *)addr->ai->ai_addr; + salen = addr->ai->ai_addrlen; + break; + case AF_INET6: + ((struct sockaddr_in *)addr->ai->ai_addr)->sin_port = + htons(port); + sa = (const struct sockaddr *)addr->ai->ai_addr; + salen = addr->ai->ai_addrlen; + break; +#else + case AF_INET: a.sin_family = AF_INET; a.sin_addr.s_addr = htonl(addr->address); a.sin_port = htons((short) port); - } + sa = (const struct sockaddr *)&a; + salen = sizeof a; + break; +#endif + case AF_UNIX: + assert(port == 0); /* to catch confused people */ + assert(strlen(addr->hostname) < sizeof au.sun_path); + memset(&au, 0, sizeof au); + au.sun_family = AF_UNIX; + strcpy(au.sun_path, addr->hostname); + sa = (const struct sockaddr *)&au; + salen = sizeof au; + break; - { - int i = 1; - ioctl(s, FIONBIO, &i); + default: + assert(0 && "unknown address family"); } - if (( -#ifdef IPV6 - connect(s, ((addr->family == AF_INET6) ? - (struct sockaddr *) &a6 : (struct sockaddr *) &a), - (addr->family == AF_INET6) ? sizeof(a6) : sizeof(a)) -#else - connect(s, (struct sockaddr *) &a, sizeof(a)) -#endif - ) < 0) { + fl = fcntl(s, F_GETFL); + if (fl != -1) + fcntl(s, F_SETFL, fl | O_NONBLOCK); + + if ((connect(s, sa, salen)) < 0) { if ( errno != EINPROGRESS ) { ret->error = error_string(errno); return (Socket) ret; @@ -511,14 +559,17 @@ Socket sk_new(SockAddr addr, int port, int privport, int oobinline, uxsel_tell(ret); add234(sktree, ret); + sk_addr_free(addr); + return (Socket) ret; } -Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only) +Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only, int address_family) { int s; -#ifdef IPV6 - struct sockaddr_in6 a6; +#ifndef NO_IPV6 + struct addrinfo hints, *ai; + char portstr[6]; #endif struct sockaddr_in a; int err; @@ -544,9 +595,31 @@ Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only) ret->listener = 1; /* + * Translate address_family from platform-independent constants + * into local reality. + */ + address_family = (address_family == ADDRTYPE_IPV4 ? AF_INET : + address_family == ADDRTYPE_IPV6 ? AF_INET6 : AF_UNSPEC); + +#ifndef NO_IPV6 + /* Let's default to IPv6. + * If the stack doesn't support IPv6, we will fall back to IPv4. */ + if (address_family == AF_UNSPEC) address_family = AF_INET6; +#else + /* No other choice, default to IPv4 */ + if (address_family == AF_UNSPEC) address_family = AF_INET; +#endif + + /* * Open socket. */ - s = socket(AF_INET, SOCK_STREAM, 0); + s = socket(address_family, SOCK_STREAM, 0); + + /* If the host doesn't support IPv6 try fallback to IPv4. */ + if (s < 0 && address_family == AF_INET6) { + address_family = AF_INET; + s = socket(address_family, SOCK_STREAM, 0); + } ret->s = s; if (s < 0) { @@ -558,12 +631,30 @@ Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only) setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&on, sizeof(on)); -#ifdef IPV6 - if (addr->family == AF_INET6) { - memset(&a6, 0, sizeof(a6)); - a6.sin6_family = AF_INET6; - /* FIXME: srcaddr is ignored for IPv6, because I (SGT) don't - * know how to do it. :-) */ + /* BSD IP stacks need sockaddr_in zeroed before filling in */ + memset(&a,'\0',sizeof(struct sockaddr_in)); +#ifndef NO_IPV6 +#if 0 + memset(&a6,'\0',sizeof(struct sockaddr_in6)); +#endif + hints.ai_flags = AI_NUMERICHOST; + hints.ai_family = address_family; + hints.ai_socktype = 0; + hints.ai_protocol = 0; + hints.ai_addrlen = 0; + hints.ai_addr = NULL; + hints.ai_canonname = NULL; + hints.ai_next = NULL; + sprintf(portstr, "%d", port); + if (srcaddr != NULL && getaddrinfo(srcaddr, portstr, &hints, &ai) == 0) + retcode = bind(s, ai->ai_addr, ai->ai_addrlen); + else +#if 0 + { + /* + * FIXME: Need two listening sockets, in principle, one for v4 + * and one for v6 + */ if (local_host_only) a6.sin6_addr = in6addr_loopback; else @@ -571,6 +662,7 @@ Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only) a6.sin6_port = htons(port); } else #endif +#endif { int got_addr = 0; a.sin_family = AF_INET; @@ -599,16 +691,9 @@ Socket sk_newlistener(char *srcaddr, int port, Plug plug, int local_host_only) } a.sin_port = htons((short)port); + retcode = bind(s, (struct sockaddr *) &a, sizeof(a)); } -#ifdef IPV6 - retcode = bind(s, (addr->family == AF_INET6 ? - (struct sockaddr *) &a6 : - (struct sockaddr *) &a), - (addr->family == - AF_INET6 ? sizeof(a6) : sizeof(a))); -#else - retcode = bind(s, (struct sockaddr *) &a, sizeof(a)); -#endif + if (retcode >= 0) { err = 0; } else { @@ -655,19 +740,28 @@ int sk_getxdmdata(void *sock, unsigned long *ip, int *port) if (s->fn != &tcp_fn_table) return 0; /* failure */ - /* - * If we ever implement connecting to a local X server through - * a Unix socket, we return 0xFFFFFFFF for the IP address and - * our current pid for the port. Bizarre, but such is life. - */ - addrlen = sizeof(addr); - if (getsockname(s->s, (struct sockaddr *)&addr, &addrlen) < 0 || - addr.sin_family != AF_INET) + if (getsockname(s->s, (struct sockaddr *)&addr, &addrlen) < 0) return 0; + switch(addr.sin_family) { + case AF_INET: + *ip = ntohl(addr.sin_addr.s_addr); + *port = ntohs(addr.sin_port); + break; + case AF_UNIX: + /* + * For a Unix socket, we return 0xFFFFFFFF for the IP address and + * our current pid for the port. Bizarre, but such is life. + */ + *ip = ntohl(0xFFFFFFFF); + *port = getpid(); + break; - *ip = ntohl(addr.sin_addr.s_addr); - *port = ntohs(addr.sin_port); + /* XXX IPV6 */ + + default: + return 0; + } return 1; } @@ -753,6 +847,12 @@ static int sk_tcp_write(Socket sock, const char *buf, int len) if (s->writable) try_send(s); + /* + * Update the select() status to correctly reflect whether or + * not we should be selecting for write. + */ + uxsel_tell(s); + return bufchain_size(&s->output_data); } @@ -774,6 +874,12 @@ static int sk_tcp_write_oob(Socket sock, const char *buf, int len) if (s->writable) try_send(s); + /* + * Update the select() status to correctly reflect whether or + * not we should be selecting for write. + */ + uxsel_tell(s); + return s->sending_oob; } @@ -786,7 +892,7 @@ static int net_select_result(int fd, int event) u_long atmark; /* Find the Socket structure */ - s = find234(sktree, (void *) fd, cmpforsearch); + s = find234(sktree, &fd, cmpforsearch); if (!s) return 1; /* boggle */ @@ -804,8 +910,8 @@ static int net_select_result(int fd, int event) ret = recv(s->s, buf, sizeof(buf), MSG_OOB); noise_ultralight(ret); if (ret <= 0) { - char *str = (ret == 0 ? "Internal networking trouble" : - error_string(errno)); + const char *str = (ret == 0 ? "Internal networking trouble" : + error_string(errno)); /* We're inside the Unix frontend here, so we know * that the frontend handle is unnecessary. */ logevent(NULL, str); @@ -836,14 +942,14 @@ static int net_select_result(int fd, int event) memset(&isa, 0, sizeof(struct sockaddr_in)); err = 0; - t = accept(s->s,(struct sockaddr *)&isa,&addrlen); + t = accept(s->s,(struct sockaddr *)&isa,(socklen_t *) &addrlen); if (t < 0) { break; } if (s->localhost_only && !ipv4_is_loopback(isa.sin_addr)) { close(t); /* someone let nonlocal through?! */ - } else if (plug_accepting(s->plug, (void*)t)) { + } else if (plug_accepting(s->plug, t)) { close(t); /* denied or error */ } break; @@ -970,11 +1076,11 @@ static void *sk_tcp_get_private_ptr(Socket sock) * if there's a problem. These functions extract an error message, * or return NULL if there's no problem. */ -char *sk_addr_error(SockAddr addr) +const char *sk_addr_error(SockAddr addr) { return addr->error; } -static char *sk_tcp_socket_error(Socket sock) +static const char *sk_tcp_socket_error(Socket sock) { Actual_Socket s = (Actual_Socket) sock; return s->error; @@ -1017,3 +1123,21 @@ int net_service_lookup(char *service) else return 0; } + +SockAddr platform_get_x11_unix_address(int displaynum, char **canonicalname) +{ + SockAddr ret = snew(struct SockAddr_tag); + int n; + + memset(ret, 0, sizeof *ret); + ret->family = AF_UNIX; + n = snprintf(ret->hostname, sizeof ret->hostname, + "%s%d", X11_UNIX_PATH, displaynum); + if(n < 0) + ret->error = "snprintf failed"; + else if(n >= sizeof ret->hostname) + ret->error = "X11 UNIX name too long"; + else + *canonicalname = dupstr(ret->hostname); + return ret; +}