Bug Summary

File:src/network/res_msend.c
Location:line 55, column 2
Description:Value stored to 'nns' is never read

Annotated Source Code

1#include <sys/socket.h>
2#include <netinet/in.h>
3#include <netdb.h>
4#include <arpa/inet.h>
5#include <stdint.h>
6#include <string.h>
7#include <poll.h>
8#include <time.h>
9#include <ctype.h>
10#include <unistd.h>
11#include <errno(*__errno_location()).h>
12#include <pthread.h>
13#include "stdio_impl.h"
14#include "syscall.h"
15#include "lookup.h"
16
17static void cleanup(void *p)
18{
19 __syscall(SYS_close, (intptr_t)p)__syscall1(6,((long) ((intptr_t)p)));
20}
21
22static unsigned long mtime()
23{
24 struct timespec ts;
25 clock_gettime(CLOCK_REALTIME0, &ts);
26 return (unsigned long)ts.tv_sec * 1000
27 + ts.tv_nsec / 1000000;
28}
29
30int __res_msend_rc(int nqueries, const unsigned char *const *queries,
31 const int *qlens, unsigned char *const *answers, int *alens, int asize,
32 const struct resolvconf *conf)
33{
34 int fd;
35 int timeout, attempts, retry_interval, servfail_retry;
36 union {
37 struct sockaddr_in sin;
38 struct sockaddr_in6 sin6;
39 } sa = {0}, ns[MAXNS3] = {{0}};
40 socklen_t sl = sizeof sa.sin;
41 int nns = 0;
42 int family = AF_INET2;
43 int rlen;
44 int next;
45 int i, j;
46 int cs;
47 struct pollfd pfd;
48 unsigned long t0, t1, t2;
49
50 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE1, &cs);
51
52 timeout = 1000*conf->timeout;
53 attempts = conf->attempts;
54
55 nns = conf->nns;
Value stored to 'nns' is never read
56 for (nns=0; nns<conf->nns; nns++) {
57 const struct address *iplit = &conf->ns[nns];
58 if (iplit->family == AF_INET2) {
59 memcpy(&ns[nns].sin.sin_addr, iplit->addr, 4);
60 ns[nns].sin.sin_port = htons(53);
61 ns[nns].sin.sin_family = AF_INET2;
62 } else {
63 sl = sizeof sa.sin6;
64 memcpy(&ns[nns].sin6.sin6_addr, iplit->addr, 16);
65 ns[nns].sin6.sin6_port = htons(53);
66 ns[nns].sin6.sin6_scope_id = iplit->scopeid;
67 ns[nns].sin6.sin6_family = family = AF_INET610;
68 }
69 }
70
71 /* Get local address and open/bind a socket */
72 sa.sin.sin_family = family;
73 fd = socket(family, SOCK_DGRAM2|SOCK_CLOEXEC02000000|SOCK_NONBLOCK04000, 0);
74
75 /* Handle case where system lacks IPv6 support */
76 if (fd < 0 && family == AF_INET610 && errno(*__errno_location()) == EAFNOSUPPORT97) {
77 fd = socket(AF_INET2, SOCK_DGRAM2|SOCK_CLOEXEC02000000|SOCK_NONBLOCK04000, 0);
78 family = AF_INET2;
79 }
80 if (fd < 0 || bind(fd, (void *)&sa, sl) < 0) return -1;
81
82 /* Past this point, there are no errors. Each individual query will
83 * yield either no reply (indicated by zero length) or an answer
84 * packet which is up to the caller to interpret. */
85
86 pthread_cleanup_push(cleanup, (void *)(intptr_t)fd)do { struct __ptcb __cb; _pthread_cleanup_push(&__cb, cleanup
, (void *)(intptr_t)fd);;
87 pthread_setcancelstate(cs, 0);
88
89 /* Convert any IPv4 addresses in a mixed environment to v4-mapped */
90 if (family == AF_INET610) {
91 setsockopt(fd, IPPROTO_IPV641, IPV6_V6ONLY26, &(int){0}, sizeof 0);
92 for (i=0; i<nns; i++) {
93 if (ns[i].sin.sin_family != AF_INET2) continue;
94 memcpy(ns[i].sin6.sin6_addr.s6_addr__in6_union.__s6_addr+12,
95 &ns[i].sin.sin_addr, 4);
96 memcpy(ns[i].sin6.sin6_addr.s6_addr__in6_union.__s6_addr,
97 "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
98 ns[i].sin6.sin6_family = AF_INET610;
99 ns[i].sin6.sin6_flowinfo = 0;
100 ns[i].sin6.sin6_scope_id = 0;
101 }
102 }
103
104 memset(alens, 0, sizeof *alens * nqueries);
105
106 pfd.fd = fd;
107 pfd.events = POLLIN0x001;
108 retry_interval = timeout / attempts;
109 next = 0;
110 t0 = t2 = mtime();
111 t1 = t2 - retry_interval;
112
113 for (; t2-t0 < timeout; t2=mtime()) {
114 if (t2-t1 >= retry_interval) {
115 /* Query all configured namservers in parallel */
116 for (i=0; i<nqueries; i++)
117 if (!alens[i])
118 for (j=0; j<nns; j++)
119 sendto(fd, queries[i],
120 qlens[i], MSG_NOSIGNAL0x4000,
121 (void *)&ns[j], sl);
122 t1 = t2;
123 servfail_retry = 2 * nqueries;
124 }
125
126 /* Wait for a response, or until time to retry */
127 if (poll(&pfd, 1, t1+retry_interval-t2) <= 0) continue;
128
129 while ((rlen = recvfrom(fd, answers[next], asize, 0,
130 (void *)&sa, (socklen_t[1]){sl})) >= 0) {
131
132 /* Ignore non-identifiable packets */
133 if (rlen < 4) continue;
134
135 /* Ignore replies from addresses we didn't send to */
136 for (j=0; j<nns && memcmp(ns+j, &sa, sl); j++);
137 if (j==nns) continue;
138
139 /* Find which query this answer goes with, if any */
140 for (i=next; i<nqueries && (
141 answers[next][0] != queries[i][0] ||
142 answers[next][1] != queries[i][1] ); i++);
143 if (i==nqueries) continue;
144 if (alens[i]) continue;
145
146 /* Only accept positive or negative responses;
147 * retry immediately on server failure, and ignore
148 * all other codes such as refusal. */
149 switch (answers[next][3] & 15) {
150 case 0:
151 case 3:
152 break;
153 case 2:
154 if (servfail_retry && servfail_retry--)
155 sendto(fd, queries[i],
156 qlens[i], MSG_NOSIGNAL0x4000,
157 (void *)&ns[j], sl);
158 default:
159 continue;
160 }
161
162 /* Store answer in the right slot, or update next
163 * available temp slot if it's already in place. */
164 alens[i] = rlen;
165 if (i == next)
166 for (; next<nqueries && alens[next]; next++);
167 else
168 memcpy(answers[i], answers[next], rlen);
169
170 if (next == nqueries) goto out;
171 }
172 }
173out:
174 pthread_cleanup_pop(1)_pthread_cleanup_pop(&__cb, (1)); } while(0);
175
176 return 0;
177}
178
179int __res_msend(int nqueries, const unsigned char *const *queries,
180 const int *qlens, unsigned char *const *answers, int *alens, int asize)
181{
182 struct resolvconf conf;
183 if (__get_resolv_conf(&conf, 0, 0) < 0) return -1;
184 return __res_msend_rc(nqueries, queries, qlens, answers, alens, asize, &conf);
185}