1 #include <u.h>
2 #include <libc.h>
3 #include <mp.h>
4 #include <libsec.h>
5 
6 #define STRLEN(s)	(sizeof(s)-1)
7 
8 uchar*
9 decodepem(char *s, char *type, int *len)
10 {
11 	uchar *d;
12 	char *t, *e, *tt;
13 	int n;
14 
15 	*len = 0;
16 
17 	/*
18 	 * find the correct section of the file, stripping garbage at the beginning and end.
19 	 * the data is delimited by -----BEGIN <type>-----\n and -----END <type>-----\n
20 	 */
21 	n = strlen(type);
22 	e = strchr(s, '\0');
23 	for(t = s; t != nil && t < e; ){
24 		tt = t;
25 		t = strchr(tt, '\n');
26 		if(t != nil)
27 			t++;
28 		if(strncmp(tt, "-----BEGIN ", STRLEN("-----BEGIN ")) == 0
29 		&& strncmp(&tt[STRLEN("-----BEGIN ")], type, n) == 0
30 		&& strncmp(&tt[STRLEN("-----BEGIN ")+n], "-----\n", STRLEN("-----\n")) == 0)
31 			break;
32 	}
33 	for(tt = t; tt != nil && tt < e; tt++){
34 		if(strncmp(tt, "-----END ", STRLEN("-----END ")) == 0
35 		&& strncmp(&tt[STRLEN("-----END ")], type, n) == 0
36 		&& strncmp(&tt[STRLEN("-----END ")+n], "-----\n", STRLEN("-----\n")) == 0)
37 			break;
38 		tt = strchr(tt, '\n');
39 		if(tt == nil)
40 			break;
41 	}
42 	if(tt == nil || tt == e){
43 		werrstr("incorrect .pem file format: bad header or trailer");
44 		return nil;
45 	}
46 
47 	n = ((tt - t) * 6 + 7) / 8;
48 	d = malloc(n);
49 	if(d == nil){
50 		werrstr("out of memory");
51 		return nil;
52 	}
53 	n = dec64(d, n, t, tt - t);
54 	if(n < 0){
55 		free(d);
56 		werrstr("incorrect .pem file format: bad base64 encoded data");
57 		return nil;
58 	}
59 	*len = n;
60 	return d;
61 }