tdecodepem.c - plan9port - [fork] Plan 9 from user space
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       ---
       tdecodepem.c (1828B)
       ---
            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, char **news)
           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         if(news)
           48                 *news = tt+1;
           49         n = ((tt - t) * 6 + 7) / 8;
           50         d = malloc(n);
           51         if(d == nil){
           52                 werrstr("out of memory");
           53                 return nil;
           54         }
           55         n = dec64(d, n, t, tt - t);
           56         if(n < 0){
           57                 free(d);
           58                 werrstr("incorrect .pem file format: bad base64 encoded data");
           59                 return nil;
           60         }
           61         *len = n;
           62         return d;
           63 }
           64 
           65 PEMChain*
           66 decodepemchain(char *s, char *type)
           67 {
           68         PEMChain *first = nil, *last = nil, *chp;
           69         uchar *d;
           70         char *e;
           71         int n;
           72 
           73         e = strchr(s, '\0');
           74         while (s < e) {
           75                 d = decodepem(s, type, &n, &s);
           76                 if(d == nil)
           77                         break;
           78                 chp = malloc(sizeof(PEMChain));
           79                 chp->next = nil;
           80                 chp->pem = d;
           81                 chp->pemlen = n;
           82                 if (first == nil)
           83                         first = chp;
           84                 else
           85                         last->next = chp;
           86                 last = chp;
           87         }
           88         return first;
           89 }