mirror of
http://thekelleys.org.uk/git/dnsmasq.git
synced 2026-10-08 07:54:32 +07:00
Matthias Andree
d578da0665
I am attaching an incremental git-am ready patch to go on top your Git HEAD, to fix all sorts of issues and make this conforming C99 with default options set, and fix another load of warnings you receive when setting the compiler to pick the nits, -pedantic-errors -std=c99 (or c11, c18, c2x). It changes many void * to uint8_t * to make the "increment by bytes" explicit. You can't do: void *foo; // ... foo += 2.
114 lines
2.9 KiB
C
114 lines
2.9 KiB
C
/* dnsmasq is Copyright (c) 2000-2024 Simon Kelley
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 dated June, 1991, or
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(at your option) version 3 dated 29 June, 2007.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "dnsmasq.h"
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#ifdef HAVE_LOOP
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static ssize_t loop_make_probe(u32 uid);
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void loop_send_probes(void)
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{
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struct server *serv;
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struct randfd_list *rfds = NULL;
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if (!option_bool(OPT_LOOP_DETECT))
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return;
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/* Loop through all upstream servers not for particular domains, and send a query to that server which is
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identifiable, via the uid. If we see that query back again, then the server is looping, and we should not use it. */
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for (serv = daemon->servers; serv; serv = serv->next)
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if (strlen(serv->domain) == 0 &&
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!(serv->flags & (SERV_FOR_NODOTS)))
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{
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ssize_t len = loop_make_probe(serv->uid);
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int fd;
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serv->flags &= ~SERV_LOOP;
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if ((fd = allocate_rfd(&rfds, serv)) == -1)
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continue;
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while (retry_send(sendto(fd, daemon->packet, len, 0,
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&serv->addr.sa, sa_len(&serv->addr))));
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}
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free_rfds(&rfds);
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}
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static ssize_t loop_make_probe(u32 uid)
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{
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struct dns_header *header = (struct dns_header *)daemon->packet;
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unsigned char *p = (unsigned char *)(header+1);
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/* packet buffer overwritten */
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daemon->srv_save = NULL;
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header->id = rand16();
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header->ancount = header->nscount = header->arcount = htons(0);
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header->qdcount = htons(1);
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header->hb3 = HB3_RD;
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header->hb4 = 0;
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SET_OPCODE(header, QUERY);
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*p++ = 8;
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sprintf((char *)p, "%.8x", uid);
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p += 8;
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*p++ = strlen(LOOP_TEST_DOMAIN);
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strcpy((char *)p, LOOP_TEST_DOMAIN); /* Add terminating zero */
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p += strlen(LOOP_TEST_DOMAIN) + 1;
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PUTSHORT(LOOP_TEST_TYPE, p);
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PUTSHORT(C_IN, p);
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return p - (unsigned char *)header;
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}
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int detect_loop(char *query, int type)
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{
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int i;
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u32 uid;
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struct server *serv;
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if (!option_bool(OPT_LOOP_DETECT))
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return 0;
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if (type != LOOP_TEST_TYPE ||
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strlen(LOOP_TEST_DOMAIN) + 9 != strlen(query) ||
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strstr(query, LOOP_TEST_DOMAIN) != query + 9)
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return 0;
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for (i = 0; i < 8; i++)
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if (!isxdigit((unsigned char)query[i]))
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return 0;
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uid = strtol(query, NULL, 16);
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for (serv = daemon->servers; serv; serv = serv->next)
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if (strlen(serv->domain) == 0 &&
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!(serv->flags & SERV_LOOP) &&
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uid == serv->uid)
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{
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serv->flags |= SERV_LOOP;
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check_servers(1); /* log new state - don't send more probes. */
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return 1;
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}
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return 0;
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}
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#endif
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