src/util.c

/* dnsmasq is Copyright (c) 2000-2009 Simon Kelley

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 dated June, 1991, or
   (at your option) version 3 dated 29 June, 2007.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/* The SURF random number generator was taken from djbdns-1.05, by
   Daniel J Bernstein, which is public domain. */

#include "dnsmasq.h"

#include <netdb.h>

#ifdef HAVE_BROKEN_RTC
#include <sys/times.h>
#endif

#ifdef LOCALEDIR
#include <idna.h>
#endif

#ifdef HAVE_ARC4RANDOM
void rand_init(void) {
    return;
}

unsigned short rand16(void) {
    return (unsigned short) (arc4random() >> 15);
}

#else

/* SURF random number generator */

typedef unsigned int uint32;

static uint32 seed[32];
static uint32 in[12];
static uint32 out[8];

void rand_init() {
    int fd = open(RANDFILE, O_RDONLY);

    if (fd == -1 || !read_write(fd, (unsigned char*) &seed, sizeof(seed), 1) ||
        !read_write(fd, (unsigned char*) &in, sizeof(in), 1))
        die(_("failed to seed the random number generator: %s"), NULL, EC_MISC);

    close(fd);
}

#define ROTATE(x, b) (((x) << (b)) | ((x) >> (32 - (b))))
#define MUSH(i, b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x, b));

static void surf(void) {
    uint32 t[12];
    uint32 x;
    uint32 sum = 0;
    int r;
    int i;
    int loop;

    for (i = 0; i < 12; ++i) t[i] = in[i] ^ seed[12 + i];
    for (i = 0; i < 8; ++i) out[i] = seed[24 + i];
    x = t[11];
    for (loop = 0; loop < 2; ++loop) {
        for (r = 0; r < 16; ++r) {
            sum += 0x9e3779b9;
            MUSH(0, 5)
            MUSH(1, 7) MUSH(2, 9) MUSH(3, 13) MUSH(4, 5) MUSH(5, 7) MUSH(6, 9) MUSH(7, 13)
                MUSH(8, 5) MUSH(9, 7) MUSH(10, 9) MUSH(11, 13)
        }
        for (i = 0; i < 8; ++i) out[i] ^= t[i + 4];
    }
}

unsigned short rand16(void) {
    static int outleft = 0;

    if (!outleft) {
        if (!++in[0])
            if (!++in[1])
                if (!++in[2]) ++in[3];
        surf();
        outleft = 8;
    }

    return (unsigned short) out[--outleft];
}

#endif

static int check_name(char* in) {
    /* remove trailing .
       also fail empty string and label > 63 chars */
    size_t dotgap = 0, l = strlen(in);
    char c;
    int nowhite = 0;

    if (l == 0 || l > MAXDNAME) return 0;

    if (in[l - 1] == '.') {
        if (l == 1) return 0;
        in[l - 1] = 0;
    }

    for (; (c = *in); in++) {
        if (c == '.')
            dotgap = 0;
        else if (++dotgap > MAXLABEL)
            return 0;
        else if (isascii(c) && iscntrl(c))
            /* iscntrl only gives expected results for ascii */
            return 0;
#ifndef LOCALEDIR
        else if (!isascii(c))
            return 0;
#endif
        else if (c != ' ')
            nowhite = 1;
    }

    if (!nowhite) return 0;

    return 1;
}

/* Hostnames have a more limited valid charset than domain names
   so check for legal char a-z A-Z 0-9 - _
   Note that this may receive a FQDN, so only check the first label
   for the tighter criteria. */
int legal_hostname(char* name) {
    char c;

    if (!check_name(name)) return 0;

    for (; (c = *name); name++)
    /* check for legal char a-z A-Z 0-9 - _ . */
    {
        if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9') ||
            c == '-' || c == '_')
            continue;

        /* end of hostname part */
        if (c == '.') return 1;

        return 0;
    }

    return 1;
}

char* canonicalise(char* in, int* nomem) {
    char* ret = NULL;
#ifdef LOCALEDIR
    int rc;
#endif

    if (nomem) *nomem = 0;

    if (!check_name(in)) return NULL;

#ifdef LOCALEDIR
    if ((rc = idna_to_ascii_lz(in, &ret, 0)) != IDNA_SUCCESS) {
        if (ret) free(ret);

        if (nomem && (rc == IDNA_MALLOC_ERROR || rc == IDNA_DLOPEN_ERROR)) {
            my_syslog(LOG_ERR, _("failed to allocate memory"));
            *nomem = 1;
        }

        return NULL;
    }
#else
    if ((ret = whine_malloc(strlen(in) + 1)))
        strcpy(ret, in);
    else if (nomem)
        *nomem = 1;
#endif

    return ret;
}

unsigned char* do_rfc1035_name(unsigned char* p, char* sval, char *limit) {
    int j;

    while (sval && *sval) {
        if (limit && p + 1 > (unsigned char*)limit)
            return p;

        unsigned char* cp = p++;
        for (j = 0; *sval && (*sval != '.'); sval++, j++) {
            if (limit && p + 1 > (unsigned char*)limit)
                return p;
            *p++ = *sval;
        }
        *cp = j;
        if (*sval) sval++;
    }
    return p;
}

/* for use during startup */
void* safe_malloc(size_t size) {
    void* ret = malloc(size);

    if (!ret) die(_("could not get memory"), NULL, EC_NOMEM);

    return ret;
}

void safe_pipe(int* fd, int read_noblock) {
    if (pipe(fd) == -1 || !fix_fd(fd[1]) || (read_noblock && !fix_fd(fd[0])))
        die(_("cannot create pipe: %s"), NULL, EC_MISC);
}

void* whine_malloc(size_t size) {
    void* ret = malloc(size);

    if (!ret) my_syslog(LOG_ERR, _("failed to allocate %d bytes"), (int) size);

    return ret;
}

int sockaddr_isequal(union mysockaddr* s1, union mysockaddr* s2) {
    if (s1->sa.sa_family == s2->sa.sa_family) {
        if (s1->sa.sa_family == AF_INET && s1->in.sin_port == s2->in.sin_port &&
            s1->in.sin_addr.s_addr == s2->in.sin_addr.s_addr)
            return 1;
#ifdef HAVE_IPV6
        if (s1->sa.sa_family == AF_INET6 && s1->in6.sin6_port == s2->in6.sin6_port &&
            IN6_ARE_ADDR_EQUAL(&s1->in6.sin6_addr, &s2->in6.sin6_addr) &&
            (!IN6_IS_ADDR_LINKLOCAL(&s1->in6.sin6_addr) ||
             (s1->in6.sin6_scope_id == s2->in6.sin6_scope_id)))
            return 1;
#endif
    }
    return 0;
}

int sa_len(union mysockaddr* addr) {
    if (addr->sa.sa_family == AF_INET6)
        return sizeof(addr->in6);
    else
        return sizeof(addr->in);
}

/* don't use strcasecmp and friends here - they may be messed up by LOCALE */
int hostname_isequal(char* a, char* b) {
    unsigned int c1, c2;

    do {
        c1 = (unsigned char) *a++;
        c2 = (unsigned char) *b++;

        if (c1 >= 'A' && c1 <= 'Z') c1 += 'a' - 'A';
        if (c2 >= 'A' && c2 <= 'Z') c2 += 'a' - 'A';

        if (c1 != c2) return 0;
    } while (c1);

    return 1;
}

time_t dnsmasq_time(void) {
#ifdef HAVE_BROKEN_RTC
    struct tms dummy;
    static long tps = 0;

    if (tps == 0) tps = sysconf(_SC_CLK_TCK);

    return (time_t)(times(&dummy) / tps);
#else
    return time(NULL);
#endif
}

int is_same_net(struct in_addr a, struct in_addr b, struct in_addr mask) {
    return (a.s_addr & mask.s_addr) == (b.s_addr & mask.s_addr);
}

int parse_addr(int family, const char* addrstr, union mysockaddr* addr) {
    struct addrinfo *res, hints = {
                              .ai_flags = AI_NUMERICHOST,
                              .ai_family = family,
                              .ai_socktype = SOCK_DGRAM,
                          };

    int ret = getaddrinfo(addrstr, NULL, &hints, &res);
    if (ret) {
        return ret;
    }

    switch (res->ai_family) {
        case AF_INET:
            addr->in = *((struct sockaddr_in*) res->ai_addr);
            break;
#ifdef HAVE_IPV6
        case AF_INET6:
            addr->in6 = *((struct sockaddr_in6*) res->ai_addr);
            break;
#endif
        default:
            errno = EAFNOSUPPORT;
            ret = -1;
            break;
    }
    freeaddrinfo(res);
    return ret;
}

/* returns port number from address */
int prettyprint_addr(const union mysockaddr* addr, char* buf) {
    int port = 0;

#ifdef HAVE_IPV6
    char portstr[strlen("65535")];
    getnameinfo((const struct sockaddr*) addr, sizeof(*addr), buf, ADDRSTRLEN, portstr,
                sizeof(portstr), NI_NUMERICHOST | NI_NUMERICSERV);
    port = atoi(portstr);
#else
    strcpy(buf, inet_ntoa(addr->in.sin_addr));
    port = ntohs(addr->in.sin_port);
#endif

    return port;
}

void prettyprint_time(char* buf, unsigned int t) {
    if (t == 0xffffffff)
        sprintf(buf, _("infinite"));
    else {
        unsigned int x, p = 0;
        if ((x = t / 86400)) p += sprintf(&buf[p], "%dd", x);
        if ((x = (t / 3600) % 24)) p += sprintf(&buf[p], "%dh", x);
        if ((x = (t / 60) % 60)) p += sprintf(&buf[p], "%dm", x);
        if ((x = t % 60)) p += sprintf(&buf[p], "%ds", x);
    }
}

/* in may equal out, when maxlen may be -1 (No max len). */
int parse_hex(char* in, unsigned char* out, int maxlen, unsigned int* wildcard_mask, int* mac_type) {
    int mask = 0, i = 0;
    char* r;

    if (mac_type) *mac_type = 0;

    while (maxlen == -1 || i < maxlen) {
        for (r = in; *r != 0 && *r != ':' && *r != '-'; r++)
            ;
        if (*r == 0) maxlen = i;

        if (r != in) {
            if (*r == '-' && i == 0 && mac_type) {
                *r = 0;
                *mac_type = strtol(in, NULL, 16);
                mac_type = NULL;
            } else {
                *r = 0;
                mask = mask << 1;
                if (strcmp(in, "*") == 0)
                    mask |= 1;
                else
                    out[i] = strtol(in, NULL, 16);
                i++;
            }
        }
        in = r + 1;
    }

    if (wildcard_mask) *wildcard_mask = mask;

    return i;
}

/* return 0 for no match, or (no matched octets) + 1 */
int memcmp_masked(unsigned char* a, unsigned char* b, int len, unsigned int mask) {
    int i, count;
    for (count = 1, i = len - 1; i >= 0; i--, mask = mask >> 1)
        if (!(mask & 1)) {
            if (a[i] == b[i])
                count++;
            else
                return 0;
        }
    return count;
}

/* _note_ may copy buffer */
int expand_buf(struct iovec* iov, size_t size) {
    void* new;

    if (size <= (size_t) iov->iov_len) return 1;

    if (!(new = whine_malloc(size))) {
        errno = ENOMEM;
        return 0;
    }

    if (iov->iov_base) {
        memcpy(new, iov->iov_base, iov->iov_len);
        free(iov->iov_base);
    }

    iov->iov_base = new;
    iov->iov_len = size;

    return 1;
}

char* print_mac(char* buff, unsigned char* mac, int len) {
    char* p = buff;
    int i;

    if (len == 0)
        sprintf(p, "<null>");
    else
        for (i = 0; i < len; i++) p += sprintf(p, "%.2x%s", mac[i], (i == len - 1) ? "" : ":");

    return buff;
}

void bump_maxfd(int fd, int* max) {
    if (fd > *max) *max = fd;
}

int retry_send(void) {
    struct timespec waiter;
    if (errno == EAGAIN) {
        waiter.tv_sec = 0;
        waiter.tv_nsec = 10000;
        nanosleep(&waiter, NULL);
        return 1;
    }

    if (errno == EINTR) return 1;

    return 0;
}

int read_write(int fd, unsigned char* packet, int size, int rw) {
    ssize_t n, done;

    for (done = 0; done < size; done += n) {
    retry:
        if (rw)
            n = read(fd, &packet[done], (size_t)(size - done));
        else
            n = write(fd, &packet[done], (size_t)(size - done));

        if (n == 0)
            return 0;
        else if (n == -1) {
            if (retry_send() || errno == ENOMEM || errno == ENOBUFS)
                goto retry;
            else
                return 0;
        }
    }
    return 1;
}