github.com/afumu/libc@v0.0.6/musl/src/network/ns_parse.c (about)

     1  #define _BSD_SOURCE
     2  #include <errno.h>
     3  #include <stddef.h>
     4  #include <resolv.h>
     5  #include <arpa/nameser.h>
     6  
     7  const struct _ns_flagdata _ns_flagdata[16] = {
     8  	{ 0x8000, 15 },
     9  	{ 0x7800, 11 },
    10  	{ 0x0400, 10 },
    11  	{ 0x0200, 9 },
    12  	{ 0x0100, 8 },
    13  	{ 0x0080, 7 },
    14  	{ 0x0040, 6 },
    15  	{ 0x0020, 5 },
    16  	{ 0x0010, 4 },
    17  	{ 0x000f, 0 },
    18  	{ 0x0000, 0 },
    19  	{ 0x0000, 0 },
    20  	{ 0x0000, 0 },
    21  	{ 0x0000, 0 },
    22  	{ 0x0000, 0 },
    23  	{ 0x0000, 0 },
    24  };
    25  
    26  unsigned ns_get16(const unsigned char *cp)
    27  {
    28  	return cp[0]<<8 | cp[1];
    29  }
    30  
    31  unsigned long ns_get32(const unsigned char *cp)
    32  {
    33  	return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3];
    34  }
    35  
    36  void ns_put16(unsigned s, unsigned char *cp)
    37  {
    38  	*cp++ = s>>8;
    39  	*cp++ = s;
    40  }
    41  
    42  void ns_put32(unsigned long l, unsigned char *cp)
    43  {
    44  	*cp++ = l>>24;
    45  	*cp++ = l>>16;
    46  	*cp++ = l>>8;
    47  	*cp++ = l;
    48  }
    49  
    50  int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle)
    51  {
    52  	int i, r;
    53  
    54  	handle->_msg = msg;
    55  	handle->_eom = msg + msglen;
    56  	if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad;
    57  	NS_GET16(handle->_id, msg);
    58  	NS_GET16(handle->_flags, msg);
    59  	for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg);
    60  	for (i = 0; i < ns_s_max; i++) {
    61  		if (handle->_counts[i]) {
    62  			handle->_sections[i] = msg;
    63  			r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]);
    64  			if (r < 0) return -1;
    65  			msg += r;
    66  		} else {
    67  			handle->_sections[i] = NULL;
    68  		}
    69  	}
    70  	if (msg != handle->_eom) goto bad;
    71  	handle->_sect = ns_s_max;
    72  	handle->_rrnum = -1;
    73  	handle->_msg_ptr = NULL;
    74  	return 0;
    75  bad:
    76  	errno = EMSGSIZE;
    77  	return -1;
    78  }
    79  
    80  int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count)
    81  {
    82  	const unsigned char *p = ptr;
    83  	int r;
    84  
    85  	while (count--) {
    86  		r = dn_skipname(p, eom);
    87  		if (r < 0) goto bad;
    88  		if (r + 2 * NS_INT16SZ > eom - p) goto bad;
    89  		p += r + 2 * NS_INT16SZ;
    90  		if (section != ns_s_qd) {
    91  			if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad;
    92  			p += NS_INT32SZ;
    93  			NS_GET16(r, p);
    94  			if (r > eom - p) goto bad;
    95  			p += r;
    96  		}
    97  	}
    98  	return p - ptr;
    99  bad:
   100  	errno = EMSGSIZE;
   101  	return -1;
   102  }
   103  
   104  int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr)
   105  {
   106  	int r;
   107  
   108  	if (section < 0 || section >= ns_s_max) goto bad;
   109  	if (section != handle->_sect) {
   110  		handle->_sect = section;
   111  		handle->_rrnum = 0;
   112  		handle->_msg_ptr = handle->_sections[section];
   113  	}
   114  	if (rrnum == -1) rrnum = handle->_rrnum;
   115  	if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad;
   116  	if (rrnum < handle->_rrnum) {
   117  		handle->_rrnum = 0;
   118  		handle->_msg_ptr = handle->_sections[section];
   119  	}
   120  	if (rrnum > handle->_rrnum) {
   121  		r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum);
   122  		if (r < 0) return -1;
   123  		handle->_msg_ptr += r;
   124  		handle->_rrnum = rrnum;
   125  	}
   126  	r = ns_name_uncompress(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME);
   127  	if (r < 0) return -1;
   128  	handle->_msg_ptr += r;
   129  	if (2 * NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
   130  	NS_GET16(rr->type, handle->_msg_ptr);
   131  	NS_GET16(rr->rr_class, handle->_msg_ptr);
   132  	if (section != ns_s_qd) {
   133  		if (NS_INT32SZ + NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size;
   134  		NS_GET32(rr->ttl, handle->_msg_ptr);
   135  		NS_GET16(rr->rdlength, handle->_msg_ptr);
   136  		if (rr->rdlength > handle->_eom - handle->_msg_ptr) goto size;
   137  		rr->rdata = handle->_msg_ptr;
   138  		handle->_msg_ptr += rr->rdlength;
   139  	} else {
   140  		rr->ttl = 0;
   141  		rr->rdlength = 0;
   142  		rr->rdata = NULL;
   143  	}
   144  	handle->_rrnum++;
   145  	if (handle->_rrnum > handle->_counts[section]) {
   146  		handle->_sect = section + 1;
   147  		if (handle->_sect == ns_s_max) {
   148  			handle->_rrnum = -1;
   149  			handle->_msg_ptr = NULL;
   150  		} else {
   151  			handle->_rrnum = 0;
   152  		}
   153  	}
   154  	return 0;
   155  bad:
   156  	errno = ENODEV;
   157  	return -1;
   158  size:
   159  	errno = EMSGSIZE;
   160  	return -1;
   161  }
   162  
   163  int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom,
   164                         const unsigned char *src, char *dst, size_t dstsiz)
   165  {
   166  	int r;
   167  	r = dn_expand(msg, eom, src, dst, dstsiz);
   168  	if (r < 0) errno = EMSGSIZE;
   169  	return r;
   170  }
   171