| #include <sys/socket.h> |
| #include <netinet/in.h> |
| #include <netdb.h> |
| #include <arpa/inet.h> |
| #include <stdint.h> |
| #include <string.h> |
| #include <poll.h> |
| #include <time.h> |
| #include <ctype.h> |
| #include <unistd.h> |
| #include <errno.h> |
| #include <pthread.h> |
| #include "stdio_impl.h" |
| #include "syscall.h" |
| #include "lookup.h" |
| |
| static void cleanup(void *p) |
| { |
| __syscall(SYS_close, (intptr_t)p); |
| } |
| |
| static unsigned long mtime() |
| { |
| struct timespec ts; |
| clock_gettime(CLOCK_REALTIME, &ts); |
| return (unsigned long)ts.tv_sec * 1000 |
| + ts.tv_nsec / 1000000; |
| } |
| |
| int __res_msend_rc(int nqueries, const unsigned char *const *queries, |
| const int *qlens, unsigned char *const *answers, int *alens, int asize, |
| const struct resolvconf *conf) |
| { |
| int fd; |
| int timeout, attempts, retry_interval, servfail_retry; |
| union { |
| struct sockaddr_in sin; |
| struct sockaddr_in6 sin6; |
| } sa = {0}, ns[MAXNS] = {{0}}; |
| socklen_t sl = sizeof sa.sin; |
| int nns = 0; |
| int family = AF_INET; |
| int rlen; |
| int next; |
| int i, j; |
| int cs; |
| struct pollfd pfd; |
| unsigned long t0, t1, t2; |
| |
| pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs); |
| |
| timeout = 1000*conf->timeout; |
| attempts = conf->attempts; |
| |
| for (nns=0; nns<conf->nns; nns++) { |
| const struct address *iplit = &conf->ns[nns]; |
| if (iplit->family == AF_INET) { |
| memcpy(&ns[nns].sin.sin_addr, iplit->addr, 4); |
| ns[nns].sin.sin_port = htons(53); |
| ns[nns].sin.sin_family = AF_INET; |
| } else { |
| sl = sizeof sa.sin6; |
| memcpy(&ns[nns].sin6.sin6_addr, iplit->addr, 16); |
| ns[nns].sin6.sin6_port = htons(53); |
| ns[nns].sin6.sin6_scope_id = iplit->scopeid; |
| ns[nns].sin6.sin6_family = family = AF_INET6; |
| } |
| } |
| |
| /* Get local address and open/bind a socket */ |
| sa.sin.sin_family = family; |
| fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| |
| /* Handle case where system lacks IPv6 support */ |
| if (fd < 0 && family == AF_INET6 && errno == EAFNOSUPPORT) { |
| fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| family = AF_INET; |
| } |
| if (fd < 0 || bind(fd, (void *)&sa, sl) < 0) { |
| if (fd >= 0) close(fd); |
| pthread_setcancelstate(cs, 0); |
| return -1; |
| } |
| |
| /* Past this point, there are no errors. Each individual query will |
| * yield either no reply (indicated by zero length) or an answer |
| * packet which is up to the caller to interpret. */ |
| |
| pthread_cleanup_push(cleanup, (void *)(intptr_t)fd); |
| pthread_setcancelstate(cs, 0); |
| |
| /* Convert any IPv4 addresses in a mixed environment to v4-mapped */ |
| if (family == AF_INET6) { |
| setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &(int){0}, sizeof 0); |
| for (i=0; i<nns; i++) { |
| if (ns[i].sin.sin_family != AF_INET) continue; |
| memcpy(ns[i].sin6.sin6_addr.s6_addr+12, |
| &ns[i].sin.sin_addr, 4); |
| memcpy(ns[i].sin6.sin6_addr.s6_addr, |
| "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12); |
| ns[i].sin6.sin6_family = AF_INET6; |
| ns[i].sin6.sin6_flowinfo = 0; |
| ns[i].sin6.sin6_scope_id = 0; |
| } |
| } |
| |
| memset(alens, 0, sizeof *alens * nqueries); |
| |
| pfd.fd = fd; |
| pfd.events = POLLIN; |
| retry_interval = timeout / attempts; |
| next = 0; |
| t0 = t2 = mtime(); |
| t1 = t2 - retry_interval; |
| |
| for (; t2-t0 < timeout; t2=mtime()) { |
| if (t2-t1 >= retry_interval) { |
| /* Query all configured namservers in parallel */ |
| for (i=0; i<nqueries; i++) |
| if (!alens[i]) |
| for (j=0; j<nns; j++) |
| sendto(fd, queries[i], |
| qlens[i], MSG_NOSIGNAL, |
| (void *)&ns[j], sl); |
| t1 = t2; |
| servfail_retry = 2 * nqueries; |
| } |
| |
| /* Wait for a response, or until time to retry */ |
| if (poll(&pfd, 1, t1+retry_interval-t2) <= 0) continue; |
| |
| while ((rlen = recvfrom(fd, answers[next], asize, 0, |
| (void *)&sa, (socklen_t[1]){sl})) >= 0) { |
| |
| /* Ignore non-identifiable packets */ |
| if (rlen < 4) continue; |
| |
| /* Ignore replies from addresses we didn't send to */ |
| for (j=0; j<nns && memcmp(ns+j, &sa, sl); j++); |
| if (j==nns) continue; |
| |
| /* Find which query this answer goes with, if any */ |
| for (i=next; i<nqueries && ( |
| answers[next][0] != queries[i][0] || |
| answers[next][1] != queries[i][1] ); i++); |
| if (i==nqueries) continue; |
| if (alens[i]) continue; |
| |
| /* Only accept positive or negative responses; |
| * retry immediately on server failure, and ignore |
| * all other codes such as refusal. */ |
| switch (answers[next][3] & 15) { |
| case 0: |
| case 3: |
| break; |
| case 2: |
| if (servfail_retry && servfail_retry--) |
| sendto(fd, queries[i], |
| qlens[i], MSG_NOSIGNAL, |
| (void *)&ns[j], sl); |
| default: |
| continue; |
| } |
| |
| /* Store answer in the right slot, or update next |
| * available temp slot if it's already in place. */ |
| alens[i] = rlen; |
| if (i == next) |
| for (; next<nqueries && alens[next]; next++); |
| else |
| memcpy(answers[i], answers[next], rlen); |
| |
| if (next == nqueries) goto out; |
| } |
| } |
| out: |
| pthread_cleanup_pop(1); |
| |
| return 0; |
| } |
| |
| int __res_msend(int nqueries, const unsigned char *const *queries, |
| const int *qlens, unsigned char *const *answers, int *alens, int asize) |
| { |
| struct resolvconf conf; |
| if (__get_resolv_conf(&conf, 0, 0) < 0) return -1; |
| return __res_msend_rc(nqueries, queries, qlens, answers, alens, asize, &conf); |
| } |