nslookup: process replies immediately, do not store them

function                                             old     new   delta
nslookup_main                                       1837    2708    +871
parse_reply                                          852       -    -852
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/0 up/down: 871/-852)           Total: 19 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 110 insertions, 86 deletions

diff --git a/networking/nslookup.c b/networking/nslookup.c
index 92e07e8b1..d31801e96 100644
--- a/networking/nslookup.c
+++ b/networking/nslookup.c
@@ -264,9 +264,10 @@ struct ns {
 struct query {
         const char *name;
         unsigned qlen, rlen;
-        unsigned latency;
-        uint8_t rcode;
-        unsigned char query[512], reply[512];
+//      unsigned latency;
+//      uint8_t rcode;
+        unsigned char query[512];
+//      unsigned char reply[512];
 };
 
 static const struct {
@@ -325,9 +326,14 @@ struct globals {
         G.default_timeout = 5; \
 } while (0)
 
-static int
-parse_reply(const unsigned char *msg, size_t len)
+enum {
+        OPT_stats = (1 << 4),
+};
+
+static int parse_reply(const unsigned char *msg, size_t len)
 {
+        HEADER *header;
+
         ns_msg handle;
         ns_rr rr;
         int i, n, rdlen;
@@ -335,14 +341,18 @@ parse_reply(const unsigned char *msg, size_t len)
         char astr[INET6_ADDRSTRLEN], dname[MAXDNAME];
         const unsigned char *cp;
 
+        header = (HEADER *)msg;
+        if (!header->aa)
+                printf("Non-authoritative answer:\n");
+
         if (ns_initparse(msg, len, &handle) != 0) {
-                //fprintf(stderr, "Unable to parse reply: %s\n", strerror(errno));
+                //printf("Unable to parse reply: %s\n", strerror(errno));
                 return -1;
         }
 
         for (i = 0; i < ns_msg_count(handle, ns_s_an); i++) {
                 if (ns_parserr(&handle, ns_s_an, i, &rr) != 0) {
-                        //fprintf(stderr, "Unable to parse resource record: %s\n", strerror(errno));
+                        //printf("Unable to parse resource record: %s\n", strerror(errno));
                         return -1;
                 }
 
@@ -387,7 +397,7 @@ parse_reply(const unsigned char *msg, size_t len)
                         if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
                                         ns_rr_rdata(rr), dname, sizeof(dname)) < 0
                         ) {
-                                //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+                                //printf("Unable to uncompress domain: %s\n", strerror(errno));
                                 return -1;
                         }
                         printf(format, ns_rr_name(rr), dname);
@@ -395,14 +405,14 @@ parse_reply(const unsigned char *msg, size_t len)
 
                 case ns_t_mx:
                         if (rdlen < 2) {
-                                fprintf(stderr, "MX record too short\n");
+                                printf("MX record too short\n");
                                 return -1;
                         }
                         n = ns_get16(ns_rr_rdata(rr));
                         if (ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
                                         ns_rr_rdata(rr) + 2, dname, sizeof(dname)) < 0
                         ) {
-                                //fprintf(stderr, "Cannot uncompress MX domain: %s\n", strerror(errno));
+                                //printf("Cannot uncompress MX domain: %s\n", strerror(errno));
                                 return -1;
                         }
                         printf("%s\tmail exchanger = %d %s\n", ns_rr_name(rr), n, dname);
@@ -410,7 +420,7 @@ parse_reply(const unsigned char *msg, size_t len)
 
                 case ns_t_txt:
                         if (rdlen < 1) {
-                                //fprintf(stderr, "TXT record too short\n");
+                                //printf("TXT record too short\n");
                                 return -1;
                         }
                         n = *(unsigned char *)ns_rr_rdata(rr);
@@ -433,7 +443,7 @@ parse_reply(const unsigned char *msg, size_t len)
                         n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
                                                cp, dname, sizeof(dname));
                         if (n < 0) {
-                                //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+                                //printf("Unable to uncompress domain: %s\n", strerror(errno));
                                 return -1;
                         }
 
@@ -443,7 +453,7 @@ parse_reply(const unsigned char *msg, size_t len)
                         n = ns_name_uncompress(ns_msg_base(handle), ns_msg_end(handle),
                                                cp, dname, sizeof(dname));
                         if (n < 0) {
-                                //fprintf(stderr, "Unable to uncompress domain: %s\n", strerror(errno));
+                                //printf("Unable to uncompress domain: %s\n", strerror(errno));
                                 return -1;
                         }
 
@@ -513,11 +523,13 @@ static char *make_ptr(char resbuf[80], const char *addrstr)
  */
 static int send_queries(struct ns *ns, struct query *query, int n_queries)
 {
+        unsigned char reply[512];
+        uint8_t rcode;
         len_and_sockaddr *local_lsa;
         struct pollfd pfd;
         int servfail_retry = 0;
         int n_replies = 0;
-        int save_idx = 0;
+//      int save_idx = 0;
         unsigned retry_interval;
         unsigned timeout = G.default_timeout * 1000;
         unsigned tstart, tsent, tcur;
@@ -564,18 +576,34 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
                 if (poll(&pfd, 1, retry_interval - (tcur - tsent)) <= 0)
                         goto next;
 
-                recvlen = read(pfd.fd, query[save_idx].reply, sizeof(query[0].reply));
+                recvlen = read(pfd.fd, reply, sizeof(reply));
+                if (recvlen < 0) {
+                        bb_perror_msg("read");
+ next:
+                        tcur = monotonic_ms();
+                        continue;
+                }
 
-                /* Error/non-identifiable packet */
+                if (ns->replies++ == 0) {
+                        printf("Server:\t\t%s\n", ns->name);
+                        printf("Address:\t%s\n\n",
+                                auto_string(xmalloc_sockaddr2dotted(&ns->lsa->u.sa))
+                        );
+                        /* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
+                        /* Should we do the same? */
+                }
+
+                /* Non-identifiable packet */
                 if (recvlen < 4) {
                         dbg("read is too short:%d\n", recvlen);
                         goto next;
                 }
 
                 /* Find which query this answer goes with, if any */
-                qn = save_idx;
+//              qn = save_idx;
+                qn = 0;
                 for (;;) {
-                        if (memcmp(query[save_idx].reply, query[qn].query, 2) == 0) {
+                        if (memcmp(reply, query[qn].query, 2) == 0) {
                                 dbg("response matches query %u\n", qn);
                                 break;
                         }
@@ -590,38 +618,42 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
                         goto next;
                 }
 
-                ns->replies++;
-
-                query[qn].rcode = query[save_idx].reply[3] & 15;
-                dbg("query %u rcode:%s\n", qn, rcodes[query[qn].rcode]);
+                rcode = reply[3] & 0x0f;
+                dbg("query %u rcode:%s\n", qn, rcodes[rcode]);
 
-                /* Only accept positive or negative responses;
-                 * retry immediately on server failure, and ignore
-                 * all other codes such as refusal.
-                 */
-                switch (query[qn].rcode) {
-                case 0:
-                case 3:
-                        break;
-                case 2:
+                /* Retry immediately on SERVFAIL */
+                if (rcode == 2) {
+                        ns->failures++;
                         if (servfail_retry) {
                                 servfail_retry--;
-                                ns->failures++;
                                 write(pfd.fd, query[qn].query, query[qn].qlen);
                                 dbg("query %u resent\n", qn);
+                                goto next;
                         }
-                        /* fall through */
-                default:
- next:
-                        tcur = monotonic_ms();
-                        continue;
                 }
 
-                /* Store answer */
-                n_replies++;
+                /* Process reply */
                 query[qn].rlen = recvlen;
                 tcur = monotonic_ms();
+#if 1
+                if (option_mask32 & OPT_stats) {
+                        printf("Query #%d completed in %ums:\n", qn, tcur - tstart);
+                }
+                if (rcode != 0) {
+                        printf("** server can't find %s: %s\n",
+                                        query[qn].name, rcodes[rcode]);
+                } else {
+                        if (parse_reply(reply, recvlen) < 0)
+                                printf("*** Can't find %s: Parse error\n", query[qn].name);
+                }
+                bb_putchar('\n');
+                n_replies++;
+                if (n_replies >= n_queries)
+                        goto ret;
+#else
+//used to store replies and process them later
                 query[qn].latency = tcur - tstart;
+                n_replies++;
                 if (qn != save_idx) {
                         /* "wrong" receive buffer, move to correct one */
                         memcpy(query[qn].reply, query[save_idx].reply, recvlen);
@@ -635,6 +667,7 @@ static int send_queries(struct ns *ns, struct query *query, int n_queries)
                         if (!query[save_idx].rlen)
                                 break; /* this one is empty */
                 }
+#endif
         } /* while() */
 
  ret:
@@ -718,11 +751,9 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
         llist_t *type_strings;
         int n_queries;
         unsigned types;
-        int rc;
         int opts;
-        enum {
-                OPT_stats = (1 << 4),
-        };
+        int rc;
+        int err;
 
         INIT_G();
 
@@ -827,61 +858,54 @@ int nslookup_main(int argc UNUSED_PARAM, char **argv)
                         add_ns("127.0.0.1");
         }
 
-        for (rc = 0; rc < G.serv_count; rc++) {
-                int c = send_queries(&G.server[rc], queries, n_queries);
-                if (c > 0)
+        for (rc = 0; rc < G.serv_count;) {
+                int c;
+
+                c = send_queries(&G.server[rc], queries, n_queries);
+                if (c > 0) {
+                        /* more than zero replies received */
+                        if (opts & OPT_stats) {
+                                printf("Replies:\t%d\n", G.server[rc].replies);
+                                printf("Failures:\t%d\n\n", G.server[rc].failures);
+                        }
                         break;
+//FIXME: we "break" even though some queries may still be not answered, and other servers may know them?
+                }
                 /* c = 0: timed out waiting for replies */
                 /* c < 0: error (message already printed) */
                 rc++;
                 if (rc >= G.serv_count) {
-                        fprintf(stderr,
-                                ";; connection timed out; no servers could be reached\n\n");
+//
+// NB: bind-utils-9.11.3 behavior (all to stdout, not stderr):
+//
+// $ nslookup gmail.com 8.8.8.8
+// ;; connection timed out; no servers could be reached
+//
+// $ nslookup -s gmail.com 8.8.8.8; echo EXITCODE:$?
+//     <~10 sec>
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+//     <~10 sec>
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+//     <~10 sec>
+// ;; connection timed out; no servers could be reached
+// ;; Connection to 8.8.8.8#53(8.8.8.8) for gmail.com failed: timed out.
+//     <empty line>
+// EXITCODE:1
+// $ _
+                        printf(";; connection timed out; no servers could be reached\n\n");
                         return EXIT_FAILURE;
                 }
         }
 
-        printf("Server:\t\t%s\n", G.server[rc].name);
-        printf("Address:\t%s\n", xmalloc_sockaddr2dotted(&G.server[rc].lsa->u.sa));
-        /* In "Address", bind-utils-9.11.3 show port after a hash: "1.2.3.4#53" */
-        /* Should we do the same? */
-
-        if (opts & OPT_stats) {
-                printf("Replies:\t%d\n", G.server[rc].replies);
-                printf("Failures:\t%d\n", G.server[rc].failures);
-        }
-        printf("\n");
-
+        err = 0;
         for (rc = 0; rc < n_queries; rc++) {
-                int c;
-
-                if (opts & OPT_stats) {
-                        printf("Query #%d completed in %ums:\n", rc, queries[rc].latency);
-                }
-
-                if (queries[rc].rcode != 0) {
-                        printf("** server can't find %s: %s\n", queries[rc].name,
-                               rcodes[queries[rc].rcode]);
-                        continue;
-                }
-
-                c = 0;
-                if (queries[rc].rlen) {
-                        HEADER *header;
-
-                        header = (HEADER *)queries[rc].reply;
-                        if (!header->aa)
-                                printf("Non-authoritative answer:\n");
-                        c = parse_reply(queries[rc].reply, queries[rc].rlen);
-                }
-
-                if (c == 0)
+                if (queries[rc].rlen == 0) {
                         printf("*** Can't find %s: No answer\n", queries[rc].name);
-                else if (c < 0)
-                        printf("*** Can't find %s: Parse error\n", queries[rc].name);
-
-                bb_putchar('\n');
+                        err = 1;
+                }
         }
+        if (err)
+                bb_putchar('\n'); /* should this affect exicode too? */
 
         if (ENABLE_FEATURE_CLEAN_UP) {
                 free(ns);