| 1 | /* |
| 2 | * Timestamp mechanism |
| 3 | * |
| 4 | * arguments: <max-skew> <max-age> |
| 5 | * |
| 6 | * encoding: prepend 4 bytes of UNIX time in network byte order |
| 7 | * |
| 8 | * <max-age> is maximum age in seconds we will accept a packet (or 0 |
| 9 | * for any age); <max-skew> is maximum future age in seconds we will |
| 10 | * accept a packet (or 0 for any future age). |
| 11 | * |
| 12 | */ |
| 13 | |
| 14 | #include <stdint.h> |
| 15 | #include <netinet/in.h> |
| 16 | |
| 17 | #include "forwarder.h" |
| 18 | |
| 19 | struct mechdata { |
| 20 | time_t max_skew, max_age; |
| 21 | }; |
| 22 | |
| 23 | static void mds_timestamp(struct mechdata **md_r) { |
| 24 | struct mechdata *md; |
| 25 | |
| 26 | md= xmalloc(sizeof(md)); |
| 27 | |
| 28 | md->max_skew= getarg_ulong(); |
| 29 | md->max_age= getarg_ulong(); |
| 30 | *md_r= md; |
| 31 | } |
| 32 | |
| 33 | static void mes_timestamp(struct mechdata **md_r, int *maxprefix_io, int *maxsuffix_io) { |
| 34 | mds_timestamp(md_r); |
| 35 | *maxprefix_io += 4; |
| 36 | } |
| 37 | |
| 38 | static void menc_timestamp(struct mechdata *md, struct buffer *buf) { |
| 39 | *(uint32_t*)buf_prepend(buf,4)= htonl(now()); |
| 40 | } |
| 41 | |
| 42 | static const char *mdec_timestamp(struct mechdata *md, struct buffer *buf) { |
| 43 | static char cbuf[40]; |
| 44 | |
| 45 | uint32_t *tp, timestamp, tnow; |
| 46 | long age; |
| 47 | |
| 48 | BUF_UNPREPEND(tp,buf,4); |
| 49 | timestamp= ntohl(*tp); |
| 50 | |
| 51 | tnow= now(); |
| 52 | age= timestamp - tnow; |
| 53 | if (age > 0) { |
| 54 | if (md->max_age && age > md->max_age) { |
| 55 | sprintf(cbuf,"packet too old (%lds)",age); |
| 56 | return cbuf; |
| 57 | } |
| 58 | } else if (age < 0) { |
| 59 | if (md->max_skew && age < -md->max_skew) { |
| 60 | sprintf(cbuf,"too much skew (%lds)",-age); |
| 61 | return cbuf; |
| 62 | } |
| 63 | } |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | |
| 68 | STANDARD_MECHANISMLIST("timestamp",timestamp); |