polypath: Close parent's socket in child

[secnet] / util.c

/*
 * util.c
 * - output and logging support
 * - program lifetime support
 * - IP address and subnet munging routines
 * - MPI convenience functions
 */
/*
 *  This file is
 *    Copyright (C) 1995--2001 Stephen Early <steve@greenend.org.uk>
 *
 *  It is part of secnet, which is
 *    Copyright (C) 1995--2001 Stephen Early <steve@greenend.org.uk>
 *    Copyright (C) 1998 Ross Anderson, Eli Biham, Lars Knudsen
 *  
 *  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; either version 2, or (at your option)
 *  any later version.
 *  
 *  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, write to the Free Software Foundation,
 *  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 */

#include "secnet.h"
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <assert.h>
#include <sys/wait.h>
#include <adns.h>
#include "util.h"
#include "unaligned.h"
#include "magic.h"
#include "ipaddr.h"

#define MIN_BUFFER_SIZE 64
#define DEFAULT_BUFFER_SIZE 4096
#define MAX_BUFFER_SIZE 131072

static const char *hexdigits="0123456789abcdef";

uint32_t current_phase=0;

struct phase_hook {
    hook_fn *fn;
    void *state;
    LIST_ENTRY(phase_hook) entry;
};

static LIST_HEAD(, phase_hook) hooks[NR_PHASES];

char *safe_strdup(const char *s, const char *message)
{
    char *d;
    d=strdup(s);
    if (!d) {
	fatal_perror("%s",message);
    }
    return d;
}

void *safe_malloc(size_t size, const char *message)
{
    void *r;
    if (!size)
	return 0;
    r=malloc(size);
    if (!r) {
	fatal_perror("%s",message);
    }
    return r;
}
void *safe_realloc_ary(void *p, size_t size, size_t count,
		       const char *message) {
    if (count >= INT_MAX/size) {
	fatal("array allocation overflow: %s", message);
    }
    assert(size && count);
    p = realloc(p, size*count);
    if (!p)
	fatal_perror("%s", message);
    return p;
}

void *safe_malloc_ary(size_t size, size_t count, const char *message) {
    if (!size || !count)
	return 0;
    return safe_realloc_ary(0,size,count,message);
}

/* Convert a buffer into its MP_INT representation */
void read_mpbin(MP_INT *a, uint8_t *bin, int binsize)
{
    char *buff;
    int i;

    buff=safe_malloc(binsize*2 + 1,"read_mpbin");

    for (i=0; i<binsize; i++) {
	buff[i*2]=hexdigits[(bin[i] & 0xf0) >> 4];
	buff[i*2+1]=hexdigits[(bin[i] & 0xf)];
    }
    buff[binsize*2]=0;

    mpz_set_str(a, buff, 16);
    free(buff);
}

/* Convert a MP_INT into a hex string */
char *write_mpstring(MP_INT *a)
{
    char *buff;

    buff=safe_malloc(mpz_sizeinbase(a,16)+2,"write_mpstring");
    mpz_get_str(buff, 16, a);
    return buff;
}

static uint8_t hexval(uint8_t c)
{
    switch (c) {
    case '0': return 0;
    case '1': return 1;
    case '2': return 2;
    case '3': return 3;
    case '4': return 4;
    case '5': return 5;
    case '6': return 6;
    case '7': return 7;
    case '8': return 8;
    case '9': return 9;
    case 'a': return 10;
    case 'A': return 10;
    case 'b': return 11;
    case 'B': return 11;
    case 'c': return 12;
    case 'C': return 12;
    case 'd': return 13;
    case 'D': return 13;
    case 'e': return 14;
    case 'E': return 14;
    case 'f': return 15;
    case 'F': return 15;
    }
    return -1;
}

/* Convert a MP_INT into a buffer; return length; truncate if necessary */
int32_t write_mpbin(MP_INT *a, uint8_t *buffer, int32_t buflen)
{
    char *hb;
    int i,j,l;
    
    if (buflen==0) return 0;
    hb=write_mpstring(a);
    
    l=strlen(hb);
    i=0; j=0;
    if (l&1) {
	/* The number starts with a half-byte */
	buffer[i++]=hexval(hb[j++]);
    }
    for (; hb[j] && i<buflen; i++) {
	buffer[i]=(hexval(hb[j])<<4)|hexval(hb[j+1]);
	j+=2;
    }
    free(hb);
    return i;
}

#define DEFINE_SETFDFLAG(fn,FL,FLAG)					\
void fn(int fd) {							\
    int r=fcntl(fd, F_GET##FL);						\
    if (r<0) fatal_perror("fcntl(,F_GET" #FL ") failed");		\
    r=fcntl(fd, F_SET##FL, r|FLAG);					\
    if (r<0) fatal_perror("fcntl(,F_SET" #FL ",|" #FLAG ") failed");	\
}

DEFINE_SETFDFLAG(setcloexec,FD,FD_CLOEXEC);
DEFINE_SETFDFLAG(setnonblock,FL,O_NONBLOCK);

void pipe_cloexec(int fd[2]) {
    int r=pipe(fd);
    if (r) fatal_perror("pipe");
    setcloexec(fd[0]);
    setcloexec(fd[1]);
}

static const char *phases[NR_PHASES]={
    "PHASE_INIT",
    "PHASE_GETOPTS",
    "PHASE_READCONFIG",
    "PHASE_SETUP",
    "PHASE_DAEMONIZE",
    "PHASE_GETRESOURCES",
    "PHASE_DROPPRIV",
    "PHASE_RUN",
    "PHASE_SHUTDOWN"
};

void enter_phase(uint32_t new_phase)
{
    struct phase_hook *i;

    if (!LIST_EMPTY(&hooks[new_phase]))
	Message(M_DEBUG_PHASE,"Running hooks for %s...\n", phases[new_phase]);
    current_phase=new_phase;

    LIST_FOREACH(i, &hooks[new_phase], entry)
	i->fn(i->state, new_phase);
    Message(M_DEBUG_PHASE,"Now in %s\n",phases[new_phase]);
}

void phase_hooks_init(void)
{
    int i;
    for (i=0; i<NR_PHASES; i++)
	LIST_INIT(&hooks[i]);
}

void clear_phase_hooks(uint32_t phase)
{
    struct phase_hook *h, *htmp;
    LIST_FOREACH_SAFE(h, &hooks[phase], entry, htmp)
	free(h);
    LIST_INIT(&hooks[phase]);
}

bool_t add_hook(uint32_t phase, hook_fn *fn, void *state)
{
    struct phase_hook *h;

    h=safe_malloc(sizeof(*h),"add_hook");
    h->fn=fn;
    h->state=state;
    LIST_INSERT_HEAD(&hooks[phase],h,entry);
    return True;
}

bool_t remove_hook(uint32_t phase, hook_fn *fn, void *state)
{
    fatal("remove_hook: not implemented");

    return False;
}

void vslilog(struct log_if *lf, int priority, const char *message, va_list ap)
{
    lf->vlogfn(lf->st,priority,message,ap);
}

void slilog(struct log_if *lf, int priority, const char *message, ...)
{
    va_list ap;
    
    va_start(ap,message);
    vslilog(lf,priority,message,ap);
    va_end(ap);
}

struct buffer {
    closure_t cl;
    struct buffer_if ops;
};

void buffer_assert_free(struct buffer_if *buffer, cstring_t file,
			int line)
{
    if (!buffer->free) {
	fprintf(stderr,"secnet: BUF_ASSERT_FREE, %s line %d, owned by %s",
		file,line,buffer->owner);
	assert(!"buffer_assert_free failure");
    }
}

void buffer_assert_used(struct buffer_if *buffer, cstring_t file,
			int line)
{
    if (buffer->free) {
	fprintf(stderr,"secnet: BUF_ASSERT_USED, %s line %d, last owned by %s",
		file,line,buffer->owner);
	assert(!"buffer_assert_used failure");
    }
}

void buffer_init(struct buffer_if *buffer, int32_t max_start_pad)
{
    assert(max_start_pad<=buffer->alloclen);
    buffer->start=buffer->base+max_start_pad;
    buffer->size=0;
}

void buffer_destroy(struct buffer_if *buf)
{
    BUF_ASSERT_FREE(buf);
    free(buf->base);
    buf->start=buf->base=0;
    buf->size=buf->alloclen=0;
}

void *buf_append(struct buffer_if *buf, int32_t amount) {
    void *p;
    assert(amount <= buf_remaining_space(buf));
    p=buf->start + buf->size;
    buf->size+=amount;
    return p;
}

void *buf_prepend(struct buffer_if *buf, int32_t amount) {
    assert(amount <= buf->start - buf->base);
    buf->size+=amount;
    return buf->start-=amount;
}

void *buf_unappend(struct buffer_if *buf, int32_t amount) {
    if (buf->size < amount) return 0;
    return buf->start+(buf->size-=amount);
}

void *buf_unprepend(struct buffer_if *buf, int32_t amount) {
    void *p;
    if (buf->size < amount) return 0;
    p=buf->start;
    buf->start+=amount;
    buf->size-=amount;
    return p;
}

/* Append a two-byte length and the string to the buffer. Length is in
   network byte order. */
void buf_append_string(struct buffer_if *buf, cstring_t s)
{
    size_t len;

    len=strlen(s);
    /* fixme: if string is longer than 65535, result is a corrupted packet */
    buf_append_uint16(buf,len);
    BUF_ADD_BYTES(append,buf,s,len);
}

void buffer_new(struct buffer_if *buf, int32_t len)
{
    buf->free=True;
    buf->owner=NULL;
    buf->flags=0;
    buf->loc.file=NULL;
    buf->loc.line=0;
    buf->size=0;
    buf->alloclen=len;
    buf->start=NULL;
    buf->base=safe_malloc(len,"buffer_new");
}

void buffer_readonly_view(struct buffer_if *buf, const void *data, int32_t len)
{
    buf->free=False;
    buf->owner="READONLY";
    buf->flags=0;
    buf->loc.file=NULL;
    buf->loc.line=0;
    buf->size=buf->alloclen=len;
    buf->base=buf->start=(uint8_t*)data;
}

void buffer_readonly_clone(struct buffer_if *out, const struct buffer_if *in)
{
    buffer_readonly_view(out,in->start,in->size);
}

void buffer_copy(struct buffer_if *dst, const struct buffer_if *src)
{
    if (dst->alloclen < src->alloclen) {
	dst->base=realloc(dst->base,src->alloclen);
	if (!dst->base) fatal_perror("buffer_copy");
	dst->alloclen = src->alloclen;
    }
    dst->start = dst->base + (src->start - src->base);
    dst->size = src->size;
    memcpy(dst->start, src->start, dst->size);
}

static list_t *buffer_apply(closure_t *self, struct cloc loc, dict_t *context,
			    list_t *args)
{
    struct buffer *st;
    item_t *item;
    dict_t *dict;
    bool_t lockdown=False;
    uint32_t len=DEFAULT_BUFFER_SIZE;
    
    st=safe_malloc(sizeof(*st),"buffer_apply");
    st->cl.description="buffer";
    st->cl.type=CL_BUFFER;
    st->cl.apply=NULL;
    st->cl.interface=&st->ops;

    /* First argument, if present, is buffer length */
    item=list_elem(args,0);
    if (item) {
	if (item->type!=t_number) {
	    cfgfatal(st->ops.loc,"buffer","first parameter must be a "
		     "number (buffer size)\n");
	}
	len=item->data.number;
	if (len<MIN_BUFFER_SIZE) {
	    cfgfatal(st->ops.loc,"buffer","ludicrously small buffer size\n");
	}
	if (len>MAX_BUFFER_SIZE) {
	    cfgfatal(st->ops.loc,"buffer","ludicrously large buffer size\n");
	}
    }
    /* Second argument, if present, is a dictionary */
    item=list_elem(args,1);
    if (item) {
	if (item->type!=t_dict) {
	    cfgfatal(st->ops.loc,"buffer","second parameter must be a "
		     "dictionary\n");
	}
	dict=item->data.dict;
	lockdown=dict_read_bool(dict,"lockdown",False,"buffer",st->ops.loc,
				False);
    }

    buffer_new(&st->ops,len);
    if (lockdown) {
	/* XXX mlock the buffer if possible */
    }
    
    return new_closure(&st->cl);
}

void send_nak(const struct comm_addr *dest, uint32_t our_index,
	      uint32_t their_index, uint32_t msgtype,
	      struct buffer_if *buf, const char *logwhy)
{
    buffer_init(buf,calculate_max_start_pad());
    buf_append_uint32(buf,their_index);
    buf_append_uint32(buf,our_index);
    buf_append_uint32(buf,LABEL_NAK);
    if (logwhy)
	Message(M_INFO,"%s: %08"PRIx32"<-%08"PRIx32": %08"PRIx32":"
		" %s; sending NAK\n",
		comm_addr_to_string(dest),
		our_index, their_index, msgtype, logwhy);
    dest->comm->sendmsg(dest->comm->st, buf, dest);
}

int consttime_memeq(const void *s1in, const void *s2in, size_t n)
{
    const uint8_t *s1=s1in, *s2=s2in;
    register volatile uint8_t accumulator=0;

    while (n-- > 0) {
	accumulator |= (*s1++ ^ *s2++);
    }
    accumulator |= accumulator >> 4; /* constant-time             */
    accumulator |= accumulator >> 2; /*  boolean canonicalisation */
    accumulator |= accumulator >> 1;
    accumulator &= 1;
    accumulator ^= 1;
    return accumulator;
}

void util_module(dict_t *dict)
{
    add_closure(dict,"sysbuffer",buffer_apply);
}

void update_max_start_pad(int32_t *our_module_global, int32_t our_instance)
{
    if (*our_module_global < our_instance)
	*our_module_global=our_instance;
}

int32_t	transform_max_start_pad, comm_max_start_pad;

int32_t calculate_max_start_pad(void)
{
    return
	site_max_start_pad +
	transform_max_start_pad +
	comm_max_start_pad;
}

void vslilog_part(struct log_if *lf, int priority, const char *message, va_list ap)
{
    char *buff=lf->buff;
    size_t bp;
    char *nlp;

    bp=strlen(buff);
    assert(bp < LOG_MESSAGE_BUFLEN);
    vsnprintf(buff+bp,LOG_MESSAGE_BUFLEN-bp,message,ap);
    buff[LOG_MESSAGE_BUFLEN-1] = '\n';
    buff[LOG_MESSAGE_BUFLEN] = '\0';
    /* Each line is sent separately */
    while ((nlp=strchr(buff,'\n'))) {
	*nlp=0;
	slilog(lf,priority,"%s",buff);
	memmove(buff,nlp+1,strlen(nlp+1)+1);
    }
}

extern void slilog_part(struct log_if *lf, int priority, const char *message, ...)
{
    va_list ap;
    va_start(ap,message);
    vslilog_part(lf,priority,message,ap);
    va_end(ap);
}

void string_item_to_iaddr(const item_t *item, uint16_t port, union iaddr *ia,
			  const char *desc)
{
#ifndef CONFIG_IPV6

    ia->sin.sin_family=AF_INET;
    ia->sin.sin_addr.s_addr=string_item_to_ipaddr(item,desc);

#else /* CONFIG_IPV6 => we have adns_text2addr */

    if (item->type!=t_string)
	cfgfatal(item->loc,desc,"expecting a string IP (v4 or v6) address\n");
    socklen_t salen=sizeof(*ia);
    int r=adns_text2addr(item->data.string, port,
			 adns_qf_addrlit_ipv4_quadonly,
			 &ia->sa, &salen);
    assert(r!=ENOSPC);
    if (r) cfgfatal(item->loc,desc,"invalid IP (v4 or v6) address: %s\n",
		    strerror(r));

#endif /* CONFIG_IPV6 */
}

#define IADDR_NBUFS_SHIFT 3
#define IADDR_NBUFS (1 << IADDR_NBUFS_SHIFT)

const char *iaddr_to_string(const union iaddr *ia)
{
    static int b;

    b++;
    b &= IADDR_NBUFS-1;

#ifndef CONFIG_IPV6

    static char bufs[IADDR_NBUFS][100];

    assert(ia->sa.sa_family == AF_INET);

    snprintf(bufs[b], sizeof(bufs[b]), "[%s]:%d",
	     inet_ntoa(ia->sin.sin_addr),
	     ntohs(ia->sin.sin_port));

#else /* CONFIG_IPV6 => we have adns_addr2text */

    static char bufs[IADDR_NBUFS][1+ADNS_ADDR2TEXT_BUFLEN+20];

    int port;

    char *addrbuf = bufs[b];
    *addrbuf++ = '[';
    int addrbuflen = ADNS_ADDR2TEXT_BUFLEN;

    int r = adns_addr2text(&ia->sa, 0, addrbuf, &addrbuflen, &port);
    if (r) {
	const char fmt[]= "scoped IPv6 addr, error: %.*s";
	sprintf(addrbuf, fmt,
		ADNS_ADDR2TEXT_BUFLEN - sizeof(fmt) /* underestimate */,
		strerror(r));
    }

    char *portbuf = addrbuf;
    int addrl = strlen(addrbuf);
    portbuf += addrl;

    snprintf(portbuf, sizeof(bufs[b])-addrl, "]:%d", port);

#endif /* CONFIG_IPV6 */

    return bufs[b];
}

bool_t iaddr_equal(const union iaddr *ia, const union iaddr *ib)
{
    if (ia->sa.sa_family != ib->sa.sa_family)
	return 0;
    switch (ia->sa.sa_family) {
    case AF_INET:
	return ia->sin.sin_addr.s_addr == ib->sin.sin_addr.s_addr
	    && ia->sin.sin_port        == ib->sin.sin_port;
#ifdef CONFIG_IPV6
    case AF_INET6:
	return !memcmp(&ia->sin6.sin6_addr, &ib->sin6.sin6_addr, 16)
	    && ia->sin6.sin6_scope_id  == ib->sin6.sin6_scope_id
	    && ia->sin6.sin6_port      == ib->sin6.sin6_port
	    /* we ignore the flowinfo field */;
#endif /* CONFIG_IPV6 */
    default:
	abort();
    }
}

int iaddr_socklen(const union iaddr *ia)
{
    switch (ia->sa.sa_family) {
    case AF_INET:  return sizeof(ia->sin);
#ifdef CONFIG_IPV6
    case AF_INET6: return sizeof(ia->sin6);
#endif /* CONFIG_IPV6 */
    default:       abort();
    }
}

const char *pollbadbit(int revents)
{
#define BADBIT(b) \
    if ((revents & b)) return #b
    BADBIT(POLLERR);
    BADBIT(POLLHUP);
    /* POLLNVAL is handled by the event loop - see afterpoll_fn comment */
#undef BADBIT
    return 0;
}

enum async_linebuf_result
async_linebuf_read(struct pollfd *pfd, struct buffer_if *buf,
		   const char **emsg_out)
{
    int revents=pfd->revents;

#define BAD(m) do{ *emsg_out=(m); return async_linebuf_broken; }while(0)

    const char *badbit=pollbadbit(revents);
    if (badbit) BAD(badbit);

    if (!(revents & POLLIN))
	return async_linebuf_nothing;

    /*
     * Data structure: A line which has been returned to the user is
     * stored in buf at base before start.  But we retain the usual
     * buffer meaning of size.  So:
     *
     *   | returned :    | input read,   |    unused    |
     *   |  to user : \0 |  awaiting     |     buffer   |
     *   |          :    |  processing   |      space   |
     *   |          :    |               |              |
     *   ^base           ^start          ^start+size    ^base+alloclen
     */

    BUF_ASSERT_USED(buf);

    /* firstly, eat any previous */
    if (buf->start != buf->base) {
	memmove(buf->base,buf->start,buf->size);
	buf->start=buf->base;
    }

    uint8_t *searched=buf->base;

    /*
     * During the workings here we do not use start.  We set start
     * when we return some actual data.  So we have this:
     *
     *   | searched     | read, might   |  unused      |
     *   |  for \n      |  contain \n   |   buffer     |
     *   |  none found  |  but not \0   |    space     |
     *   |              |               |              |
     *   ^base          ^searched       ^base+size     ^base+alloclen
     *  [^start]                        ^dataend
     *
     */
    for (;;) {
	uint8_t *dataend=buf->base+buf->size;
	char *newline=memchr(searched,'\n',dataend-searched);
	if (newline) {
	    *newline=0;
	    buf->start=newline+1;
	    buf->size=dataend-buf->start;
	    return async_linebuf_ok;
	}
	searched=dataend;
	ssize_t space=(buf->base+buf->alloclen)-dataend;
	if (!space) BAD("input line too long");
	ssize_t r=read(pfd->fd,searched,space);
	if (r==0) {
	    *searched=0;
	    *emsg_out=buf->size?"no newline at eof":0;
	    buf->start=searched+1;
	    buf->size=0;
	    return async_linebuf_eof;
	}
	if (r<0) {
	    if (errno==EINTR)
		continue;
	    if (iswouldblock(errno))
		return async_linebuf_nothing;
	    BAD(strerror(errno));
	}
	assert(r<=space);
	if (memchr(searched,0,r)) BAD("nul in input data");
	buf->size+=r;
    }

#undef BAD
}