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p2mp.c
150 lines (116 loc) · 2.99 KB
/
p2mp.c
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#include "p2mp.h"
void die(const char *s, int cause)
{
if(!cause) {
fprintf(stderr, "%s\n", s);
} else {
fprintf(stderr, "%s %s\n", s, strerror(cause));
}
exit(cause);
}
void warn(const char *s, int cause)
{
if(!cause) {
fprintf(stderr, "%s\n", s);
} else {
fprintf(stderr, "%s %s\n", s, strerror(cause));
}
}
int pack_data(int seq_num, int type, int flags, unsigned char *buf, int size)
{
uint16_t csum;
if(!buf) {
return 0;
}
buf[0] = (seq_num & 0xff000000)>>24;
buf[1] = (seq_num & 0x00ff0000)>>16;
buf[2] = (seq_num & 0x0000ff00)>>8;
buf[3] = (seq_num & 0x000000ff);
buf[4] = 0; // zero it for checksum computation
buf[5] = 0; // zero it for checksum computation
buf[6] = type;
buf[7] = flags;
compute_checksum(&csum, buf, size);
//printf("computed : %x\n", csum);
buf[4] = (csum & 0xff00)>>8;
buf[5] = (csum & 0x00ff);
//printf("header\n|%02x%02x %02x %02x|\n|%02x%02x|%02x|%02x|\n",
// buf[0],buf[1],buf[2],buf[3],buf[4],buf[5],buf[6],buf[7]);
return 1;
}
int unpack_data(int *seq_num, int *type, int *flags, unsigned char *buf, int size)
{
uint16_t msg_csum=0, comp_csum=0;
if(!buf) {
return 0;
}
*seq_num = 0;
*seq_num |= buf[0]<<24;
*seq_num |= buf[1]<<16;
*seq_num |= buf[2]<<8;
*seq_num |= buf[3];
*type = buf[6];
*flags = buf[7];
msg_csum |= buf[4]<<8;
msg_csum |= buf[5];
compute_checksum(&comp_csum, buf, size);
//printf("computed : %x, from_data : %x\n", comp_csum, msg_csum);
//printf("header\n|%02x%02x %02x %02x|\n|%02x%02x|%02x|%02x|\n",
// buf[0],buf[1],buf[2],buf[3],buf[4],buf[5],buf[6],buf[7]);
if(comp_csum) {
// computed checksum should be 0. As we do another ~ in the compute_checksum function
return -1;
}
return 1;
}
void compute_checksum(uint16_t *csum, unsigned char *buf, int size)
{
int i;
int sum = 0;
for(i=0;i<size;i+=2) {
if(i+1<size) {
sum += ((buf[i]<<8)|(buf[i+1]));
} else {
sum += buf[i]<<8;
}
if(sum&0x10000) {
// overlap carry
sum = (sum & 0xffff) + 1;
}
//printf("%x\t", sum);
}
//printf("\n");
*csum = sum;
*csum = ~(*csum);
return;
}
int compute_md5(char *file_name, char *md5_sum)
{
char cmd[BUFFER_SIZE];
FILE *p = NULL;
int i, ch;
snprintf(cmd, BUFFER_SIZE, "md5sum %s 2> /dev/null", file_name);
p = popen(cmd, "r");
if(p == NULL) {
return 0;
}
for(i=0; i<MD5_LEN && isxdigit(ch = fgetc(p)); i++) {
*md5_sum++ = ch;
}
*md5_sum = '\0';
pclose(p);
return (i==MD5_LEN);
}
void compute_time_diff(struct timeval *start, struct timeval *end, struct timeval *diff)
{
if(end->tv_usec < start->tv_usec) {
diff->tv_usec = 1000000 + end->tv_usec - start->tv_usec;
diff->tv_sec = end->tv_sec-1-start->tv_sec;
} else if(end->tv_usec > start->tv_usec) {
diff->tv_usec = end->tv_usec - start->tv_usec;
diff->tv_sec = end->tv_sec-start->tv_sec;
} else {
diff->tv_usec = 0;
diff->tv_sec = end->tv_sec-start->tv_sec;
}
}