dnsd: fix several buglets, make smaller
This commit is contained in:
Denis Vlasenko
parent
9067f13be0
commit
d3bac03988
@ -673,7 +673,7 @@
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" -c Config filename\n" \
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" -t TTL in seconds\n" \
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" -p Listening port\n" \
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" -i Listening iface ip (default all)\n" \
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" -i Listening ip (default all)\n" \
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" -d Daemonize"
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#define dos2unix_trivial_usage \
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@ -19,13 +19,6 @@
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#include "busybox.h"
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static const char *fileconf = "/etc/dnsd.conf";
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#define LOCK_FILE "/var/run/dnsd.lock"
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// Must match getopt32 call
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#define OPT_daemon (option_mask32 & 0x10)
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#define OPT_verbose (option_mask32 & 0x20)
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//#define DEBUG 1
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#define DEBUG 0
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@ -75,9 +68,16 @@ struct dns_entry { // element of known name, ip address and reversed ip address
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char name[MAX_HOST_LEN];
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};
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static struct dns_entry *dnsentry = NULL;
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static struct dns_entry *dnsentry;
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static uint32_t ttl = DEFAULT_TTL;
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static const char *fileconf = "/etc/dnsd.conf";
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// Must match getopt32 call
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#define OPT_daemon (option_mask32 & 0x10)
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#define OPT_verbose (option_mask32 & 0x20)
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/*
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* Convert host name from C-string to dns length/string.
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*/
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@ -135,12 +135,12 @@ static int getfileentry(FILE * fp, struct dns_entry *s)
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while (*r != ' ' && *r != '\t')
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r++;
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*r++ = '\0';
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if (sscanf(r, "%u.%u.%u.%u", &a, &b, &c, &d) != 4) {
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if (sscanf(r, ".%u.%u.%u.%u"+1, &a, &b, &c, &d) != 4) {
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free(line);
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goto restart; /* skipping wrong lines */
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}
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sprintf(s->ip, "%u.%u.%u.%u", a, b, c, d);
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sprintf(s->ip, ".%u.%u.%u.%u"+1, a, b, c, d);
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sprintf(s->rip, ".%u.%u.%u.%u", d, c, b, a);
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undot((uint8_t*)s->rip);
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convname(s->name, (uint8_t*)name);
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@ -185,7 +185,7 @@ static void dnsentryinit(void)
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static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
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{
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int i;
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struct dns_entry *d=dnsentry;
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struct dns_entry *d = dnsentry;
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do {
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#if DEBUG
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@ -201,17 +201,13 @@ static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
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if (tolower(qs[i]) != d->name[i])
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break;
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if (i > (int)(d->name[0])) {
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#if DEBUG
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fprintf(stderr, " OK");
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#endif
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strcpy((char *)as, d->ip);
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#if DEBUG
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fprintf(stderr, " as:%s\n", as);
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fprintf(stderr, " OK as:%s\n", as);
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#endif
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return 0;
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return 0;
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}
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} else
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if (type == REQ_PTR) { /* search by IP-address */
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} else if (type == REQ_PTR) { /* search by IP-address */
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if (!strncmp((char*)&d->rip[1], (char*)&qs[1], strlen(d->rip)-1)) {
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strcpy((char *)as, d->name);
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return 0;
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@ -226,7 +222,6 @@ static int table_lookup(uint16_t type, uint8_t * as, uint8_t * qs)
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/*
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* Decode message and generate answer
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*/
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#define eret(s) do { fputs(s, stderr); return -1; } while (0)
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static int process_packet(uint8_t * buf)
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{
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struct dns_head *head;
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@ -241,11 +236,15 @@ static int process_packet(uint8_t * buf)
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answstr[0] = '\0';
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head = (struct dns_head *)buf;
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if (head->nquer == 0)
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eret("no queries\n");
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if (head->nquer == 0) {
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bb_error_msg("no queries");
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retunr -1;
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}
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if (head->flags & 0x8000)
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eret("ignoring response packet\n");
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if (head->flags & 0x8000) {
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bb_error_msg("ignoring response packet");
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retunr -1;
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}
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from = (void *)&head[1]; // start of query string
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next = answb = from + strlen((char *)from) + 1 + sizeof(struct dns_prop); // where to append answer block
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@ -286,8 +285,7 @@ static int process_packet(uint8_t * buf)
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}
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memcpy(answstr, &a.s_addr, 4); // save before a disappears
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outr.rlen = 4; // uint32_t IP
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}
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else
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} else
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outr.rlen = strlen((char *)answstr) + 1; // a host name
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outr.r = answstr; // 32 bit ip or a host name
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outr.flags |= 0x0400; /* authority-bit */
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@ -316,7 +314,7 @@ static int process_packet(uint8_t * buf)
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head->nauth = head->nadd = htons(0);
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head->nquer = htons(1);
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packet_len = next - (void *)buf;
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packet_len = (uint8_t *)next - buf;
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return packet_len;
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}
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@ -325,7 +323,7 @@ static int process_packet(uint8_t * buf)
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*/
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static void interrupt(int x)
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{
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unlink(LOCK_FILE);
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/* unlink("/var/run/dnsd.lock"); */
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bb_error_msg("interrupt, exiting\n");
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exit(2);
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}
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@ -333,7 +331,7 @@ static void interrupt(int x)
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int dnsd_main(int argc, char **argv);
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int dnsd_main(int argc, char **argv)
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{
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char *listen_interface = NULL;
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const char *listen_interface = "0.0.0.0";
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char *sttl, *sport;
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len_and_sockaddr *lsa;
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int udps;
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@ -346,7 +344,7 @@ int dnsd_main(int argc, char **argv)
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if (option_mask32 & 0x4) // -t
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ttl = xatou_range(sttl, 1, 0xffffffff);
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if (option_mask32 & 0x8) // -p
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port = xatou_range(sttl, 1, 0xffff);
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port = xatou_range(sport, 1, 0xffff);
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if (OPT_verbose) {
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bb_info_msg("listen_interface: %s", listen_interface);
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@ -355,7 +353,6 @@ int dnsd_main(int argc, char **argv)
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}
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if (OPT_daemon) {
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//FIXME: NOMMU will NOT set LOGMODE_SYSLOG!
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#ifdef BB_NOMMU
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if (!re_execed)
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vfork_daemon_rexec(1, 0, argv);
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@ -368,7 +365,7 @@ int dnsd_main(int argc, char **argv)
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dnsentryinit();
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signal(SIGINT, interrupt);
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signal(SIGPIPE, SIG_IGN);
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/* why? signal(SIGPIPE, SIG_IGN); */
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signal(SIGHUP, SIG_IGN);
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#ifdef SIGTSTP
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signal(SIGTSTP, SIG_IGN);
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@ -377,50 +374,31 @@ int dnsd_main(int argc, char **argv)
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signal(SIGURG, SIG_IGN);
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#endif
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lsa = xhost2sockaddr(listen_interface, port);
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lsa = xdotted2sockaddr(listen_interface, port);
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udps = xsocket(lsa->sa.sa_family, SOCK_DGRAM, 0);
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xbind(udps, &lsa->sa, lsa->len);
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// xlisten(udps, 50); - ?!! DGRAM sockets are never listened on I think?
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/* xlisten(udps, 50); - ?!! DGRAM sockets are never listened on I think? */
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bb_info_msg("Accepting UDP packets on %s",
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xmalloc_sockaddr2dotted(&lsa->sa, lsa->len));
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while (1) {
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fd_set fdset;
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int r;
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FD_ZERO(&fdset);
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FD_SET(udps, &fdset);
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// Block until a message arrives
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// FIXME: Fantastic. select'ing on just one fd??
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// Why no just block on it doing recvfrom() ?
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r = select(udps + 1, &fdset, NULL, NULL, NULL);
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if (r < 0)
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bb_perror_msg_and_die("select error");
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if (r == 0)
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bb_perror_msg_and_die("select spurious return");
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/* Can this test ever be false? - yes */
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if (FD_ISSET(udps, &fdset)) {
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socklen_t fromlen = lsa->len;
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socklen_t fromlen = lsa->len;
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// FIXME: need to get *DEST* address (to which of our addresses
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// this query was directed), and reply from the same address.
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// Or else we can exhibit usual UDP ugliness:
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// [ip1.multihomed.ip2] <= query to ip1 <= peer
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// [ip1.multihomed.ip2] => reply from ip2 => peer (confused)
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r = recvfrom(udps, buf, sizeof(buf), 0, &lsa->sa, &fromlen);
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if (OPT_verbose)
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bb_info_msg("Got UDP packet");
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if (r < 12 || r > 512) {
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bb_error_msg("invalid packet size");
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continue;
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}
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if (r <= 0)
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continue;
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r = process_packet(buf);
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if (r <= 0)
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continue;
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sendto(udps, buf, r, 0, &lsa->sa, fromlen);
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r = recvfrom(udps, buf, sizeof(buf), 0, &lsa->sa, &fromlen);
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if (OPT_verbose)
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bb_info_msg("Got UDP packet");
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if (r < 12 || r > 512) {
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bb_error_msg("invalid packet size");
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continue;
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}
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r = process_packet(buf);
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if (r <= 0)
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continue;
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sendto(udps, buf, r, 0, &lsa->sa, fromlen);
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}
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}
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