diff options
| -rw-r--r-- | src/network/res_init.c | 2 | ||||
| -rw-r--r-- | src/network/res_mkquery.c | 41 | ||||
| -rw-r--r-- | src/network/res_msend.c | 184 | ||||
| -rw-r--r-- | src/network/res_query.c | 28 | ||||
| -rw-r--r-- | src/network/res_querydomain.c | 14 | ||||
| -rw-r--r-- | src/network/res_send.c | 12 |
6 files changed, 263 insertions, 18 deletions
diff --git a/src/network/res_init.c b/src/network/res_init.c index cbd5b155..5dba9dfc 100644 --- a/src/network/res_init.c +++ b/src/network/res_init.c @@ -1,3 +1,5 @@ +#include <resolv.h> + int res_init() { return 0; diff --git a/src/network/res_mkquery.c b/src/network/res_mkquery.c new file mode 100644 index 00000000..f7e4e9c6 --- /dev/null +++ b/src/network/res_mkquery.c @@ -0,0 +1,41 @@ +#include <resolv.h> +#include <string.h> +#include <time.h> +#include "libc.h" + +int __res_mkquery(int op, const char *dname, int class, int type, + const unsigned char *data, int datalen, + const unsigned char *newrr, unsigned char *buf, int buflen) +{ + int id, i, j; + unsigned char q[280]; + struct timespec ts; + size_t l = strnlen(dname, 256); + + if (l-1>=254 || buflen<18+l || op>15u || class>255u || type>255u) + return -1; + + /* Construct query template - ID will be filled later */ + memset(q, 0, 18+l); + q[2] = op*8 + 1; + q[5] = 1; + memcpy((char *)q+13, dname, l); + for (i=13; q[i]; i=j+1) { + for (j=i; q[j] && q[j] != '.'; j++); + if (j-i-1u > 62u) return -1; + q[i-1] = j-i; + } + q[i+1] = type; + q[i+3] = class; + + /* Make a reasonably unpredictable id */ + clock_gettime(CLOCK_REALTIME, &ts); + id = ts.tv_nsec + ts.tv_nsec/65536UL & 0xffff; + q[0] = id/256; + q[1] = id; + + memcpy(buf, q, 18+l); + return 18+l; +} + +weak_alias(__res_mkquery, res_mkquery); diff --git a/src/network/res_msend.c b/src/network/res_msend.c new file mode 100644 index 00000000..cded5353 --- /dev/null +++ b/src/network/res_msend.c @@ -0,0 +1,184 @@ +#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" + +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(int nqueries, const unsigned char *const *queries, + const int *qlens, unsigned char *const *answers, int *alens, int asize) +{ + int fd; + FILE *f, _f; + unsigned char _buf[256]; + char line[64], *s, *z; + int timeout = 5000, attempts = 2, retry_interval; + union { + struct sockaddr_in sin; + struct sockaddr_in6 sin6; + } sa = {0}, ns[3] = {{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); + + /* Get nameservers from resolv.conf, fallback to localhost */ + f = __fopen_rb_ca("/etc/resolv.conf", &_f, _buf, sizeof _buf); + if (f) for (nns=0; nns<3 && fgets(line, sizeof line, f); ) { + if (!strncmp(line, "options", 7) && isspace(line[7])) { + unsigned long x; + char *p, *z; + p = strstr(line, "timeout:"); + if (p && isdigit(p[8])) { + p += 8; + x = strtoul(p, &z, 10); + if (z != p) timeout = x < 30 ? x*1000 : 30000; + } + p = strstr(line, "attempts:"); + if (p && isdigit(p[9])) { + p += 9; + x = strtoul(p, &z, 10); + if (z != p) attempts = x < 10 ? x : 10; + if (!attempts) attempts = 1; + } + } + if (strncmp(line, "nameserver", 10) || !isspace(line[10])) + continue; + for (s=line+11; isspace(*s); s++); + for (z=s; *z && !isspace(*z); z++); + *z=0; + + if (inet_pton(AF_INET, s, &ns[nns].sin.sin_addr)>0) { + ns[nns].sin.sin_port = htons(53); + ns[nns++].sin.sin_family = AF_INET; + } else if (inet_pton(AF_INET6, s, &ns[nns].sin6.sin6_addr)>0) { + sl = sizeof sa.sin6; + ns[nns].sin6.sin6_port = htons(53); + ns[nns++].sin6.sin6_family = family = AF_INET6; + } + } + if (f) __fclose_ca(f); + if (!nns) { + ns[0].sin.sin_family = AF_INET; + ns[0].sin.sin_port = htons(53); + ns[0].sin.sin_addr.s_addr = htonl(0x7f000001); + nns=1; + } + + /* 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) 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; + 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; + } + + /* 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 (no query id) */ + if (rlen < 2) continue; + + /* Ignore replies from addresses we didn't send to */ + for (i=0; i<nns && memcmp(ns+i, &sa, sl); i++); + if (i==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; + + /* 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; +} diff --git a/src/network/res_query.c b/src/network/res_query.c index 3847da37..2b4e4bb1 100644 --- a/src/network/res_query.c +++ b/src/network/res_query.c @@ -1,25 +1,17 @@ -#define _GNU_SOURCE #include <resolv.h> #include <netdb.h> -#include "__dns.h" #include "libc.h" -int res_query(const char *name, int class, int type, unsigned char *dest, int len) +int __res_mkquery(int, const char *, int, int, const unsigned char *, int, const unsigned char*, unsigned char *, int); +int __res_send(const unsigned char *, int, unsigned char *, int); + +int __res_query(const char *name, int class, int type, unsigned char *dest, int len) { - if (class != 1 || len < 512) - return -1; - switch(__dns_doqueries(dest, name, &type, 1)) { - case EAI_NONAME: - h_errno = HOST_NOT_FOUND; - return -1; - case EAI_AGAIN: - h_errno = TRY_AGAIN; - return -1; - case EAI_FAIL: - h_errno = NO_RECOVERY; - return -1; - } - return 512; + unsigned char q[280]; + int ql = __res_mkquery(0, name, class, type, 0, 0, 0, q, sizeof q); + if (ql < 0) return ql; + return __res_send(q, ql, dest, len); } -weak_alias(res_query, res_search); +weak_alias(__res_query, res_query); +weak_alias(__res_query, res_search); diff --git a/src/network/res_querydomain.c b/src/network/res_querydomain.c new file mode 100644 index 00000000..c746dbe6 --- /dev/null +++ b/src/network/res_querydomain.c @@ -0,0 +1,14 @@ +#include <resolv.h> +#include <string.h> + +int res_querydomain(const char *name, const char *domain, int class, int type, unsigned char *dest, int len) +{ + char tmp[256]; + size_t nl = strnlen(name, 256); + size_t dl = strnlen(domain, 256); + if (nl+dl+1 > 255) return -1; + memcpy(tmp, name, nl); + tmp[nl] = '.'; + memcpy(tmp+nl+1, domain, dl+1); + return res_query(tmp, class, type, dest, len); +} diff --git a/src/network/res_send.c b/src/network/res_send.c new file mode 100644 index 00000000..19cfe0f6 --- /dev/null +++ b/src/network/res_send.c @@ -0,0 +1,12 @@ +#include <resolv.h> +#include "libc.h" + +int __res_msend(int, const unsigned char *const *, const int *, unsigned char *const *, int *, int); + +int __res_send(const unsigned char *msg, int msglen, unsigned char *answer, int anslen) +{ + int r = __res_msend(1, &msg, &msglen, &answer, &anslen, anslen); + return r<0 ? r : anslen; +} + +weak_alias(__res_send, res_send); |