a

libsec/decodepem.c

@@ -0,0 +1,59 @@
+#include <u.h>
+#include <libc.h>
+#include <mp.h>
+#include <libsec.h>
+
+#define STRLEN(s)	(sizeof(s)-1)
+
+uchar*
+decodepem(char *s, char *type, int *len)
+{
+	uchar *d;
+	char *t, *e, *tt;
+	int n;
+
+	/*
+	 * find the correct section of the file, stripping garbage at the beginning and end.
+	 * the data is delimited by -----BEGIN <type>-----\n and -----END <type>-----\n
+	 */
+	n = strlen(type);
+	e = strchr(s, '\0');
+	for(t = s; t != nil && t < e; ){
+		tt = t;
+		t = strchr(tt, '\n');
+		if(t != nil)
+			t++;
+		if(strncmp(tt, "-----BEGIN ", STRLEN("-----BEGIN ")) == 0
+		&& strncmp(&tt[STRLEN("-----BEGIN ")], type, n) == 0
+		&& strncmp(&tt[STRLEN("-----BEGIN ")+n], "-----\n", STRLEN("-----\n")) == 0)
+			break;
+	}
+	for(tt = t; tt != nil && tt < e; tt++){
+		if(strncmp(tt, "-----END ", STRLEN("-----END ")) == 0
+		&& strncmp(&tt[STRLEN("-----END ")], type, n) == 0
+		&& strncmp(&tt[STRLEN("-----END ")+n], "-----\n", STRLEN("-----\n")) == 0)
+			break;
+		tt = strchr(tt, '\n');
+		if(tt == nil)
+			break;
+	}
+	if(tt == nil || tt == e){
+		werrstr("incorrect .pem file format: bad header or trailer");
+		return nil;
+	}
+
+	n = ((tt - t) * 6 + 7) / 8;
+	d = malloc(n);
+	if(d == nil){
+		werrstr("out of memory");
+		return nil;
+	}
+	n = dec64(d, n, t, tt - t);
+	if(n < 0){
+		free(d);
+		werrstr("incorrect .pem file format: bad base64 encoded data");
+		return nil;
+	}
+	*len = n;
+	return d;
+}