9408978a4
Denys Vlasenko
2018-08-01
Subject
nslookup: add support for search domains, closes 11161
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networking/nslookup.c+82 -22
| @@ -318,6 +318,8 @@ struct globals { | |
| unsigned serv_count; | |
| struct ns *server; | |
| struct query *query; | |
| + | char *search; |
| + | smalluint have_search_directive; |
| } FIX_ALIASING; | |
| #define G (*(struct globals*)bb_common_bufsiz1) | |
| #define INIT_G() do { \ | |
| @@ -667,24 +669,60 @@ static void parse_resolvconf(void) | |
| resolv = fopen("/etc/resolv.conf", "r"); | |
| if (resolv) { | |
| - | char line[128], *p; |
| + | char line[512]; /* "search" is defined to be up to 256 chars */ |
| while (fgets(line, sizeof(line), resolv)) { | |
| - | p = strtok(line, " \t\n"); |
| + | char *p, *arg; |
| - | if (!p || strcmp(p, "nameserver") != 0) |
| + | p = strtok(line, " \t\n"); |
| + | if (!p) |
| + | continue; |
| + | dbg("resolv_key:'%s'\n", p); |
| + | arg = strtok(NULL, "\n"); |
| + | dbg("resolv_arg:'%s'\n", arg); |
| + | if (!arg) |
| continue; | |
| - | p = strtok(NULL, " \t\n"); |
| + | if (strcmp(p, "domain") == 0) { |
| + | /* domain DOM */ |
| + | if (!G.have_search_directive) |
| + | goto set_search; |
| + | continue; |
| + | } |
| + | if (strcmp(p, "search") == 0) { |
| + | /* search DOM1 DOM2... */ |
| + | G.have_search_directive = 1; |
| + | set_search: |
| + | free(G.search); |
| + | G.search = xstrdup(arg); |
| + | dbg("search='%s'\n", G.search); |
| + | continue; |
| + | } |
| - | if (!p) |
| + | if (strcmp(p, "nameserver") != 0) |
| continue; | |
| - | add_ns(xstrdup(p)); |
| + | /* nameserver DNS */ |
| + | add_ns(xstrdup(arg)); |
| } | |
| fclose(resolv); | |
| } | |
| + | |
| + | if (!G.search) { |
| + | /* default search domain is domain part of hostname */ |
| + | char *h = safe_gethostname(); |
| + | char *d = strchr(h, '.'); |
| + | if (d) { |
| + | G.search = d + 1; |
| + | dbg("search='%s' (from hostname)\n", G.search); |
| + | } |
| + | /* else free(h); */ |
| + | } |
| + | |
| + | /* Cater for case of "domain ." in resolv.conf */ |
| + | if (G.search && LONE_CHAR(G.search, '.')) |
| + | G.search = NULL; |
| } | |
| static void add_query(int type, const char *dname) | |
| @@ -695,7 +733,7 @@ static void add_query(int type, const char *dname) | |
| count = G.query_count++; | |
| - | G.query = xrealloc_vector(G.query, /*2=2^1:*/ 1, count); |
| + | G.query = xrealloc_vector(G.query, /*4=2^2:*/ 2, count); |
| new_q = &G.query[count]; | |
| dbg("new query#%u type %u for '%s'\n", count, type, dname); | |
| @@ -709,6 +747,28 @@ static void add_query(int type, const char *dname) | |
| new_q->qlen = qlen; | |
| } | |
| + | static void add_query_with_search(int type, const char *dname) |
| + | { |
| + | char *s; |
| + | |
| + | if (type == T_PTR || !G.search || strchr(dname, '.')) { |
| + | add_query(type, dname); |
| + | return; |
| + | } |
| + | |
| + | s = G.search; |
| + | for (;;) { |
| + | char *fullname, *e; |
| + | |
| + | e = skip_non_whitespace(s); |
| + | fullname = xasprintf("%s.%.*s", dname, (int)(e - s), s); |
| + | add_query(type, fullname); |
| + | s = skip_whitespace(e); |
| + | if (!*s) |
| + | break; |
| + | } |
| + | } |
| + | |
| static char *make_ptr(const char *addrstr) | |
| { | |
| unsigned char addr[16]; | |
| @@ -833,6 +893,18 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv) | |
| } | |
| } | |
| + | /* Use given DNS server if present */ |
| + | if (argv[1]) { |
| + | if (argv[2]) |
| + | bb_show_usage(); |
| + | add_ns(argv[1]); |
| + | } else { |
| + | parse_resolvconf(); |
| + | /* Fall back to localhost if we could not find NS in resolv.conf */ |
| + | if (G.serv_count == 0) |
| + | add_ns("127.0.0.1"); |
| + | } |
| + | |
| if (types == 0) { | |
| /* No explicit type given, guess query type. | |
| * If we can convert the domain argument into a ptr (means that | |
| @@ -846,31 +918,19 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv) | |
| if (ptr) { | |
| add_query(T_PTR, ptr); | |
| } else { | |
| - | add_query(T_A, argv[0]); |
| + | add_query_with_search(T_A, argv[0]); |
| #if ENABLE_FEATURE_IPV6 | |
| - | add_query(T_AAAA, argv[0]); |
| + | add_query_with_search(T_AAAA, argv[0]); |
| #endif | |
| } | |
| } else { | |
| int c; | |
| for (c = 0; c < ARRAY_SIZE(qtypes); c++) { | |
| if (types & (1 << c)) | |
| - | add_query(qtypes[c].type, argv[0]); |
| + | add_query_with_search(qtypes[c].type, argv[0]); |
| } | |
| } | |
| - | /* Use given DNS server if present */ |
| - | if (argv[1]) { |
| - | if (argv[2]) |
| - | bb_show_usage(); |
| - | add_ns(argv[1]); |
| - | } else { |
| - | parse_resolvconf(); |
| - | /* Fall back to localhost if we could not find NS in resolv.conf */ |
| - | if (G.serv_count == 0) |
| - | add_ns("127.0.0.1"); |
| - | } |
| - | |
| for (rc = 0; rc < G.serv_count;) { | |
| int c; | |