diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/network/ns_parse.c | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/src/network/ns_parse.c b/src/network/ns_parse.c new file mode 100644 index 00000000..3ff33a87 --- /dev/null +++ b/src/network/ns_parse.c @@ -0,0 +1,171 @@ +#define _BSD_SOURCE +#include <errno.h> +#include <stddef.h> +#include <resolv.h> +#include <arpa/nameser.h> + +const struct _ns_flagdata _ns_flagdata[16] = { + { 0x8000, 15 }, + { 0x7800, 11 }, + { 0x0400, 10 }, + { 0x0200, 9 }, + { 0x0100, 8 }, + { 0x0080, 7 }, + { 0x0040, 6 }, + { 0x0020, 5 }, + { 0x0010, 4 }, + { 0x000f, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, + { 0x0000, 0 }, +}; + +unsigned ns_get16(const unsigned char *cp) +{ + return cp[0]<<8 | cp[1]; +} + +unsigned long ns_get32(const unsigned char *cp) +{ + return (unsigned)cp[0]<<24 | cp[1]<<16 | cp[2]<<8 | cp[3]; +} + +void ns_put16(unsigned s, unsigned char *cp) +{ + *cp++ = s>>8; + *cp++ = s; +} + +void ns_put32(unsigned long l, unsigned char *cp) +{ + *cp++ = l>>24; + *cp++ = l>>16; + *cp++ = l>>8; + *cp++ = l; +} + +int ns_initparse(const unsigned char *msg, int msglen, ns_msg *handle) +{ + int i, r; + + handle->_msg = msg; + handle->_eom = msg + msglen; + if (msglen < (2 + ns_s_max) * NS_INT16SZ) goto bad; + NS_GET16(handle->_id, msg); + NS_GET16(handle->_flags, msg); + for (i = 0; i < ns_s_max; i++) NS_GET16(handle->_counts[i], msg); + for (i = 0; i < ns_s_max; i++) { + if (handle->_counts[i]) { + handle->_sections[i] = msg; + r = ns_skiprr(msg, handle->_eom, i, handle->_counts[i]); + if (r < 0) return -1; + msg += r; + } else { + handle->_sections[i] = NULL; + } + } + if (msg != handle->_eom) goto bad; + handle->_sect = ns_s_max; + handle->_rrnum = -1; + handle->_msg_ptr = NULL; + return 0; +bad: + errno = EMSGSIZE; + return -1; +} + +int ns_skiprr(const unsigned char *ptr, const unsigned char *eom, ns_sect section, int count) +{ + const unsigned char *p = ptr; + int r; + + while (count--) { + r = dn_skipname(p, eom); + if (r < 0) goto bad; + if (r + 2 * NS_INT16SZ > eom - p) goto bad; + p += r + 2 * NS_INT16SZ; + if (section != ns_s_qd) { + if (NS_INT32SZ + NS_INT16SZ > eom - p) goto bad; + p += NS_INT32SZ; + NS_GET16(r, p); + if (r > eom - p) goto bad; + p += r; + } + } + return ptr - p; +bad: + errno = EMSGSIZE; + return -1; +} + +int ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) +{ + int r; + + if (section < 0 || section >= ns_s_max) goto bad; + if (section != handle->_sect) { + handle->_sect = section; + handle->_rrnum = 0; + handle->_msg_ptr = handle->_sections[section]; + } + if (rrnum == -1) rrnum = handle->_rrnum; + if (rrnum < 0 || rrnum >= handle->_counts[section]) goto bad; + if (rrnum < handle->_rrnum) { + handle->_rrnum = 0; + handle->_msg_ptr = handle->_sections[section]; + } + if (rrnum > handle->_rrnum) { + r = ns_skiprr(handle->_msg_ptr, handle->_eom, section, rrnum - handle->_rrnum); + if (r < 0) return -1; + handle->_msg_ptr += r; + handle->_rrnum = rrnum; + } + r = ns_name_uncompress(handle->_msg, handle->_eom, handle->_msg_ptr, rr->name, NS_MAXDNAME); + if (r < 0) return -1; + handle->_msg_ptr += r; + if (2 * NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size; + NS_GET16(rr->type, handle->_msg_ptr); + NS_GET16(rr->rr_class, handle->_msg_ptr); + if (section != ns_s_qd) { + if (NS_INT32SZ + NS_INT16SZ > handle->_eom - handle->_msg_ptr) goto size; + NS_GET32(rr->ttl, handle->_msg_ptr); + NS_GET16(rr->rdlength, handle->_msg_ptr); + if (rr->rdlength > handle->_eom - handle->_msg_ptr) goto size; + rr->rdata = handle->_msg_ptr; + handle->_msg_ptr += rr->rdlength; + } else { + rr->ttl = 0; + rr->rdlength = 0; + rr->rdata = NULL; + } + handle->_rrnum++; + if (handle->_rrnum > handle->_counts[section]) { + handle->_sect = section + 1; + if (handle->_sect == ns_s_max) { + handle->_rrnum = -1; + handle->_msg_ptr = NULL; + } else { + handle->_rrnum = 0; + } + } + return 0; +bad: + errno = ENODEV; + return -1; +size: + errno = EMSGSIZE; + return -1; +} + +int ns_name_uncompress(const unsigned char *msg, const unsigned char *eom, + const unsigned char *src, char *dst, size_t dstsiz) +{ + int r; + r = dn_expand(msg, eom, src, dst, dstsiz); + if (r < 0) errno = EMSGSIZE; + return r; +} + |