diff options
| -rw-r--r-- | libc/inet/Makefile.in | 4 | ||||
| -rw-r--r-- | libc/inet/resolv.c | 537 |
2 files changed, 337 insertions, 204 deletions
diff --git a/libc/inet/Makefile.in b/libc/inet/Makefile.in index f905c8e35..f6ee48f9d 100644 --- a/libc/inet/Makefile.in +++ b/libc/inet/Makefile.in @@ -43,8 +43,8 @@ resolv_CSRC += encodeh.c decodeh.c encoded.c decoded.c lengthd.c encodeq.c \ ifneq ($(UCLIBC_HAS_IPV4)$(UCLIBC_HAS_IPV6),) CSRC += $(resolv_CSRC) -# unused ATM -CSRC += encodep.c decodep.c formquery.c +## # unused ATM +## CSRC += encodep.c decodep.c formquery.c endif diff --git a/libc/inet/resolv.c b/libc/inet/resolv.c index a84c6af1f..defd4d77c 100644 --- a/libc/inet/resolv.c +++ b/libc/inet/resolv.c @@ -183,6 +183,7 @@ libc_hidden_proto(fopen) libc_hidden_proto(fclose) libc_hidden_proto(random) libc_hidden_proto(getservbyport) +libc_hidden_proto(gethostname) libc_hidden_proto(uname) libc_hidden_proto(inet_addr) libc_hidden_proto(inet_aton) @@ -298,8 +299,10 @@ typedef union sockaddr46_t { __UCLIBC_MUTEX_EXTERN(__resolv_lock); /* Protected by __resolv_lock */ -extern int __nameservers attribute_hidden; -extern int __searchdomains attribute_hidden; +extern void (*__res_sync)(void) attribute_hidden; +//extern uint32_t __resolv_opts attribute_hidden; +extern unsigned __nameservers attribute_hidden; +extern unsigned __searchdomains attribute_hidden; extern sockaddr46_t *__nameserver attribute_hidden; extern char **__searchdomain attribute_hidden; /* Arbitrary */ @@ -348,6 +351,90 @@ extern void __close_nameservers(void) attribute_hidden; extern int __dn_expand(const u_char *, const u_char *, const u_char *, char *, int); +/* + * Theory of operation. + * + * gethostbyname, getaddrinfo and friends end up here, and they sometimes + * need to talk to DNS servers. In order to do this, we need to read /etc/resolv.conf + * and determine servers' addresses and the like. resolv.conf format: + * + * nameserver <IP[v6]> + * Address of DNS server. Cumulative. + * If not specified, assumed to be on localhost. + * search <domain1>[ <domain2>]... + * Append these domains to unqualified names. + * See ndots:n option. + * $LOCALDOMAIN (space-separated list) overrides this. + * domain <domain> + * Effectively same as "search" with one domain. + * If no "domain" line is present, the domain is determined + * from the local host name returned by gethostname(); + * the domain part is taken to be everything after the first dot. + * If there are no dots, there will be no "domain". + * The domain and search keywords are mutually exclusive. + * If more than one instance of these keywords is present, + * the last instance wins. + * sortlist 130.155.160.0[/255.255.240.0] 130.155.0.0 + * Allows addresses returned by gethostbyname to be sorted. + * Not supported. + * options option[ option]... + * (so far we support none) + * $RES_OPTIONS (space-separated list) is to be added to "options" + * debug sets RES_DEBUG in _res.options + * ndots:n how many dots there should be so that name will be tried + * first as an absolute name before any search list elements + * are appended to it. Default 1 + * timeout:n how long to wait for response. Default 5 + * (sun seems to have retrans:n synonym) + * attempts:n number of rounds to do before giving up and returning + * an error. Default 2 + * (sun seems to have retry:n synonym) + * rotate sets RES_ROTATE in _res.options, round robin + * selection of nameservers. Otherwise try + * the first listed server first every time + * no-check-names + * sets RES_NOCHECKNAME in _res.options, which disables + * checking of incoming host names for invalid characters + * such as underscore (_), non-ASCII, or control characters + * inet6 sets RES_USE_INET6 in _res.options. Try a AAAA query + * before an A query inside the gethostbyname(), and map + * IPv4 responses in IPv6 "tunnelled form" if no AAAA records + * are found but an A record set exists + * no_tld_query (FreeBSDism?) + * do not attempt to resolve names without dots + * + * We will read and analyze /etc/resolv.conf as needed before + * we do a DNS request. This happens in __dns_lookup. + * (TODO: also re-parse it after a timeout, it might get updated). + * + * BSD has res_init routine which is used to initialize resolver state + * which is held in global structure _res. + * Generally, programs call res_init, then fiddle with _res.XXX + * (_res.options and _res.nscount, _res.nsaddr_list[N] + * are popular targets of fiddling) and expect subsequent calls + * to gethostbyname, getaddrinfo, etc to use modified information. + * + * However, historical _res structure is quite awkward. + * Using it for storing /etc/resolv.conf info is not desirable, + * and __dns_lookup does not use it. + * + * We would like to avoid using it unless absolutely necessary. + * If user doesn't use res_init, we should arrange it so that + * _res structure doesn't even *get linked in* into user's application + * (imagine static uclibc build here). + * + * The solution is a __res_sync function pointer, which is normally NULL. + * But if res_init is called, it gets set and any subsequent gethostbyname + * et al "syncronizes" our internal structures with potentially + * modified _res.XXX stuff by calling __res_sync. + * The trick here is that if res_init is not used and not linked in, + * gethostbyname itself won't reference _res and _res won't be linked in + * either. Other possible methods like + * if (__res_sync_just_an_int_flag) + * __sync_me_with_res() + * would pull in __sync_me_with_res, which pulls in _res. Bad. + */ + #ifdef L_encodeh @@ -584,7 +671,9 @@ int attribute_hidden __length_question(const unsigned char * const message, int } #endif + #ifdef L_encodea + int attribute_hidden __encode_answer(struct resolv_answer *a, unsigned char *dest, int maxlen) { int i; @@ -659,6 +748,7 @@ int attribute_hidden __decode_answer(const unsigned char *message, int offset, #endif +#ifdef CURRENTLY_UNUSED #ifdef L_encodep int __encode_packet(struct resolv_header *h, @@ -763,6 +853,192 @@ int __form_query(int id, const char *name, int type, unsigned char *packet, return i + j; } #endif +#endif /* CURRENTLY_UNUSED */ + + +#ifdef L_opennameservers + +__UCLIBC_MUTEX_INIT(__resolv_lock, PTHREAD_MUTEX_INITIALIZER); + +/* Protected by __resolv_lock */ +void (*__res_sync)(void); +//uint32_t __resolv_opts; +unsigned __nameservers; +unsigned __searchdomains; +sockaddr46_t *__nameserver; +char **__searchdomain; + +/* Helpers. Both stop on EOL, if it's '\n', it is converted to NUL first */ +static char *skip_nospace(char *p) +{ + while (*p != '\0' && !isspace(*p)) { + if (*p == '\n') { + *p = '\0'; + break; + } + p++; + } + return p; +} +static char *skip_and_NUL_space(char *p) +{ + /* NB: '\n' is not isspace! */ + while (1) { + char c = *p; + if (c == '\0' || !isspace(c)) + break; + *p = '\0'; + if (c == '\n' || c == '#') + break; + p++; + } + return p; +} + +/* Must be called under __resolv_lock. */ +void attribute_hidden __open_nameservers(void) +{ + char szBuffer[MAXLEN_searchdomain]; + FILE *fp; + int i; + sockaddr46_t sa; + + //if (!__res_sync && last_time_was_long_ago) + // __close_nameservers(); /* force config reread */ + + if (__nameservers) + goto sync; + + fp = fopen("/etc/resolv.conf", "r"); + if (!fp) { +// TODO: why? google says nothing about this... + fp = fopen("/etc/config/resolv.conf", "r"); + } + + if (fp) { + while (fgets(szBuffer, sizeof(szBuffer), fp) != NULL) { + void *ptr; + char *keyword, *p; + + keyword = p = skip_and_NUL_space(szBuffer); + /* skip keyword */ + p = skip_nospace(p); + /* find next word */ + p = skip_and_NUL_space(p); + + if (strcmp(keyword, "nameserver") == 0) { + /* terminate IP addr */ + *skip_nospace(p) = '\0'; + memset(&sa, 0, sizeof(sa)); + if (0) /* nothing */; +#ifdef __UCLIBC_HAS_IPV6__ + else if (inet_pton(AF_INET6, p, &sa.sa6.sin6_addr) > 0) { + sa.sa6.sin6_family = AF_INET6; + sa.sa6.sin6_port = htons(NAMESERVER_PORT); + } +#endif +#ifdef __UCLIBC_HAS_IPV4__ + else if (inet_pton(AF_INET, p, &sa.sa4.sin_addr) > 0) { + sa.sa4.sin_family = AF_INET; + sa.sa4.sin_port = htons(NAMESERVER_PORT); + } +#endif + else + continue; /* garbage on this line */ + ptr = realloc(__nameserver, (__nameservers + 1) * sizeof(__nameserver[0])); + if (!ptr) + continue; + __nameserver = ptr; + __nameserver[__nameservers++] = sa; /* struct copy */ + continue; + } + if (strcmp(keyword, "domain") == 0 || strcmp(keyword, "search") == 0) { + char *p1; +//TODO: delete old domains... + next_word: + /* terminate current word */ + p1 = skip_nospace(p); + /* find next word (maybe) */ + p1 = skip_and_NUL_space(p1); + /* paranoia - done by having szBuffer[MAXLEN_searchdomain] */ + /*if (strlen(p) > MAXLEN_searchdomain)*/ + /* goto skip;*/ + /* do we have this domain already? */ + for (i = 0; i < __searchdomains; i++) + if (strcmp(p, __searchdomain[i]) == 0) + goto skip; + /* add it */ + ptr = realloc(__searchdomain, (__searchdomains + 1) * sizeof(__searchdomain[0])); + if (!ptr) + continue; + __searchdomain = ptr; + ptr = strdup(p); + if (!ptr) + continue; + DPRINTF("adding search %s\n", (char*)ptr); + __searchdomain[__searchdomains++] = (char*)ptr; + skip: + p = p1; + if (*p) + goto next_word; + continue; + } + /* if (strcmp(keyword, "sortlist") == 0)... */ + /* if (strcmp(keyword, "options") == 0)... */ + } + fclose(fp); + } + if (__nameservers == 0) { + __nameserver = malloc(sizeof(__nameserver[0])); +//TODO: error check? + memset(&__nameserver[0], 0, sizeof(__nameserver[0])); +#ifdef __UCLIBC_HAS_IPV4__ + __nameserver[0].sa4.sin_family = AF_INET; + /*__nameserver[0].sa4.sin_addr = INADDR_ANY; - done by memset */ + __nameserver[0].sa4.sin_port = htons(NAMESERVER_PORT); +#else + __nameserver[0].sa6.sin6_family = AF_INET6; + __nameserver[0].sa6.sin6_port = htons(NAMESERVER_PORT); +#endif + __nameservers++; + } + if (__searchdomains == 0) { + char buf[256]; + char *p; + i = gethostname(buf, sizeof(buf) - 1); + buf[sizeof(buf) - 1] = '\0'; + if (i == 0 && (p = strchr(buf, '.')) != NULL && p[1]) { + p = strdup(p + 1); + __searchdomain = malloc(sizeof(__searchdomain[0])); +//TODO: error check? + __searchdomain[0] = p; + __searchdomains++; + } + } + DPRINTF("nameservers = %d\n", __nameservers); + + sync: + if (__res_sync) + __res_sync(); +} +#endif + + +#ifdef L_closenameservers + +/* Must be called under __resolv_lock. */ +void attribute_hidden __close_nameservers(void) +{ + free(__nameserver); + __nameserver = NULL; + __nameservers = 0; + while (__searchdomains) + free(__searchdomain[--__searchdomains]); + free(__searchdomain); + __searchdomain = NULL; + /*__searchdomains = 0; - already is */ +} +#endif #ifdef L_dnslookup @@ -859,43 +1135,23 @@ int attribute_hidden __dns_lookup(const char *name, int type, // local_ns_num = 0; // if (_res.options & RES_ROTATE) local_ns_num = last_ns_num; - if (local_ns_num >= __nameservers) - local_ns_num = 0; } - /* __nameservers == 0 case: act as if - * we have one DNS server configured - on 127.0.0.1 */ - { - int my_nameservers = __nameservers; - if (my_nameservers == 0) - my_nameservers++; - if (local_ns_num >= my_nameservers) { - local_ns_num = 0; - retries++; - /* break if retries >= MAX_RETRIES - *after unlock*! */ - } + if (local_ns_num >= __nameservers) { + local_ns_num = 0; +//TODO: wrong method of retries++! +// Should be if (local_ns_num == starting_ns_num) retries++; + retries++; + /* break if retries >= MAX_RETRIES - *after unlock*! */ } local_id++; local_id &= 0xffff; /* write new values back while still under lock */ last_id = local_id; last_ns_num = local_ns_num; - if (__nameservers != 0) { - /* struct copy */ - /* can't just take a pointer, __nameserver[] - * is not safe to use outside of locks */ - sa = __nameserver[local_ns_num]; - } else { - /* __nameservers == 0 */ - memset(&sa, 0, sizeof(sa)); -#ifdef __UCLIBC_HAS_IPV4__ - sa.sa4.sin_family = AF_INET; - /*sa.sa4.sin_addr = INADDR_ANY; - done by memset */ - sa.sa4.sin_port = htons(NAMESERVER_PORT); -#else - sa.sa6.sin_family = AF_INET6; - sa.sa6.sin6_port = htons(NAMESERVER_PORT); -#endif - } + /* struct copy */ + /* can't just take a pointer, __nameserver[x] + * is not safe to use outside of locks */ + sa = __nameserver[local_ns_num]; __UCLIBC_MUTEX_UNLOCK(__resolv_lock); if (retries >= MAX_RETRIES) break; @@ -964,8 +1220,7 @@ int attribute_hidden __dns_lookup(const char *name, int type, goto try_next_server; } #endif -//TODO: MSG_DONTWAIT? - len = recv(fd, packet, PACKETSZ, 0); + len = recv(fd, packet, PACKETSZ, MSG_DONTWAIT); if (len < HFIXEDSZ) { /* too short! */ //TODO: why next sdomain? it's just a bogus packet from somewhere, @@ -1104,155 +1359,6 @@ int attribute_hidden __dns_lookup(const char *name, int type, } #endif -#ifdef L_opennameservers - -__UCLIBC_MUTEX_INIT(__resolv_lock, PTHREAD_MUTEX_INITIALIZER); - -/* Protected by __resolv_lock */ -int __nameservers; -int __searchdomains; -sockaddr46_t *__nameserver; -char **__searchdomain; - -/* Helpers. Both stop on EOL, if it's '\n', it is converted to NUL first */ -static char *skip_nospace(char *p) -{ - while (*p != '\0' && !isspace(*p)) { - if (*p == '\n') { - *p = '\0'; - break; - } - p++; - } - return p; -} -static char *skip_and_NUL_space(char *p) -{ - /* NB: '\n' is not isspace! */ - while (1) { - char c = *p; - if (c == '\0' || !isspace(c)) - break; - *p = '\0'; - if (c == '\n' || c == '#') - break; - p++; - } - return p; -} - -/* Must be called under __resolv_lock. */ -void attribute_hidden __open_nameservers(void) -{ - char szBuffer[MAXLEN_searchdomain]; - FILE *fp; - int i; - sockaddr46_t sa; - - if (__nameservers > 0) - return; - - fp = fopen("/etc/resolv.conf", "r"); - if (!fp) { - fp = fopen("/etc/config/resolv.conf", "r"); - if (!fp) { - DPRINTF("failed to open %s\n", "resolv.conf"); - h_errno = NO_RECOVERY; - return; - } - } - - while (fgets(szBuffer, sizeof(szBuffer), fp) != NULL) { - void *ptr; - char *keyword, *p; - - keyword = p = skip_and_NUL_space(szBuffer); - /* skip keyword */ - p = skip_nospace(p); - /* find next word */ - p = skip_and_NUL_space(p); - - if (strcmp(keyword, "nameserver") == 0) { - /* terminate IP addr */ - *skip_nospace(p) = '\0'; - memset(&sa, 0, sizeof(sa)); - if (0) /* nothing */; -#ifdef __UCLIBC_HAS_IPV6__ - else if (inet_pton(AF_INET6, p, &sa.sa6.sin6_addr) > 0) { - sa.sa6.sin6_family = AF_INET6; - sa.sa6.sin6_port = htons(NAMESERVER_PORT); - } -#endif -#ifdef __UCLIBC_HAS_IPV4__ - else if (inet_pton(AF_INET, p, &sa.sa4.sin_addr) > 0) { - sa.sa4.sin_family = AF_INET; - sa.sa4.sin_port = htons(NAMESERVER_PORT); - } -#endif - else - continue; /* garbage on this line */ - ptr = realloc(__nameserver, (__nameservers + 1) * sizeof(__nameserver[0])); - if (!ptr) - continue; - __nameserver = ptr; - __nameserver[__nameservers++] = sa; /* struct copy */ - continue; - } - if (strcmp(keyword, "domain") == 0 || strcmp(keyword, "search") == 0) { - char *p1; - next_word: - /* terminate current word */ - p1 = skip_nospace(p); - /* find next word (maybe) */ - p1 = skip_and_NUL_space(p1); - /* paranoia - done by having szBuffer[MAXLEN_searchdomain] */ - /*if (strlen(p) > MAXLEN_searchdomain)*/ - /* goto skip;*/ - /* do we have this domain already? */ - for (i = 0; i < __searchdomains; i++) - if (strcmp(p, __searchdomain[i]) == 0) - goto skip; - /* add it */ - ptr = realloc(__searchdomain, (__searchdomains + 1) * sizeof(__searchdomain[0])); - if (!ptr) - continue; - __searchdomain = ptr; - ptr = strdup(p); - if (!ptr) - continue; - DPRINTF("adding search %s\n", (char*)ptr); - __searchdomain[__searchdomains++] = (char*)ptr; - skip: - p = p1; - if (*p) - goto next_word; - continue; - } - /* if (strcmp(keyword, "sortlist") == 0)... */ - /* if (strcmp(keyword, "options") == 0)... */ - } - fclose(fp); - DPRINTF("nameservers = %d\n", __nameservers); -} -#endif - - -#ifdef L_closenameservers - -/* Must be called under __resolv_lock. */ -void attribute_hidden __close_nameservers(void) -{ - free(__nameserver); - __nameserver = NULL; - __nameservers = 0; - while (__searchdomains) - free(__searchdomain[--__searchdomains]); - free(__searchdomain); - __searchdomain = NULL; - /*__searchdomains = 0; - already is */ -} -#endif - #ifdef L_gethostbyname @@ -1298,6 +1404,38 @@ struct hostent *gethostbyname2(const char *name, int family) /* Protected by __resolv_lock */ struct __res_state _res; +#undef ARRAY_SIZE +#define ARRAY_SIZE(v) (sizeof(v) / sizeof((v)[0])) + +/* Will be called under __resolv_lock. */ +static void res_sync_func(void) +{ + struct __res_state *rp = &(_res); + + /* Track .nscount and .nsaddr_list + * (busybox's nslookup uses it). + */ + if (__nameservers > rp->nscount) + __nameservers = rp->nscount; + /* TODO: + * if (__nameservers < rp->nscount) - try to grow __nameserver[]? + */ +#ifdef __UCLIBC_HAS_IPV4__ + { + int n = __nameservers; + while (--n >= 0) { + __nameserver[n].sa.sa_family = AF_INET; + __nameserver[n].sa4 = rp->nsaddr_list[n]; /* struct copy */ + } + } +#endif + /* Extend and comment what program is known + * to use which _res.XXX member(s). + */ + // __resolv_opts = rp->options; + // ... +} + /* Our res_init never fails (always returns 0) */ int res_init(void) { @@ -1308,6 +1446,8 @@ int res_init(void) __close_nameservers(); __open_nameservers(); + __res_sync = res_sync_func; + memset(rp, 0, sizeof(*rp)); rp->options = RES_INIT; #ifdef __UCLIBC_HAS_COMPAT_RES_STATE__ @@ -1315,27 +1455,17 @@ int res_init(void) rp->retry = 4; rp->id = random(); #endif - /* man resolv.conf says: - * "On a normally configured system this file should not be necessary. - * The only name server to be queried will be on the local machine; - * the domain name is determined from the host name - * and the domain search path is constructed from the domain name" */ - rp->nscount = 1; - rp->nsaddr_list[0].sin_addr.s_addr = INADDR_ANY; - rp->nsaddr_list[0].sin_family = AF_INET; - rp->nsaddr_list[0].sin_port = htons(NAMESERVER_PORT); rp->ndots = 1; #ifdef __UCLIBC_HAS_EXTRA_COMPAT_RES_STATE__ rp->_vcsock = -1; #endif -#undef ARRAY_SIZE -#define ARRAY_SIZE(v) (sizeof(v) / sizeof((v)[0])) n = __searchdomains; if (n > ARRAY_SIZE(rp->dnsrch)) n = ARRAY_SIZE(rp->dnsrch); for (i = 0; i < n; i++) rp->dnsrch[i] = __searchdomain[i]; +#ifdef __UCLIBC_HAS_IPV4__ i = 0; n = 0; while (n < ARRAY_SIZE(rp->nsaddr_list) && i < __nameservers) { @@ -1346,13 +1476,12 @@ int res_init(void) next_i: i++; } - if (n) - rp->nscount = n; - /* else rp->nscount stays 1 */ -#undef ARRAY_SIZE + rp->nscount = n; +#endif __UCLIBC_MUTEX_UNLOCK(__resolv_lock); return 0; } +#undef ARRAY_SIZE libc_hidden_def(res_init) #ifdef __UCLIBC_HAS_BSD_RES_CLOSE__ @@ -1360,6 +1489,7 @@ void res_close(void) { __UCLIBC_MUTEX_LOCK(__resolv_lock); __close_nameservers(); + __res_sync = NULL; memset(&_res, 0, sizeof(_res)); __UCLIBC_MUTEX_UNLOCK(__resolv_lock); } @@ -1367,6 +1497,7 @@ void res_close(void) #endif /* L_res_init */ + #ifdef L_res_query int res_query(const char *dname, int class, int type, @@ -1617,15 +1748,16 @@ int res_querydomain(const char *name, const char *domain, int class, int type, return res_query(longname, class, type, answer, anslen); } libc_hidden_def(res_querydomain) - /* res_mkquery */ /* res_send */ /* dn_comp */ /* dn_expand */ #endif + #ifdef L_gethostbyaddr -struct hostent *gethostbyaddr (const void *addr, socklen_t len, int type) + +struct hostent *gethostbyaddr(const void *addr, socklen_t len, int type) { static struct hostent h; static char buf[ @@ -2023,7 +2155,7 @@ BAD_FAM: } if (!ok) { - const char *c; + const char *c = NULL; if (flags & NI_NAMEREQD) { errno = serrno; @@ -2035,7 +2167,8 @@ BAD_FAM: sin6p = (const struct sockaddr_in6 *) sa; c = inet_ntop(AF_INET6, - (const void *) &sin6p->sin6_addr, host, hostlen); + (const void *) &sin6p->sin6_addr, + host, hostlen); #if 0 /* Does scope id need to be supported? */ uint32_t scopeid; |