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pdkim.c
1774 lines (1562 loc) · 53.3 KB
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pdkim.c
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/*
* PDKIM - a RFC4871 (DKIM) implementation
*
* Copyright (C) 2009 Tom Kistner <tom@duncanthrax.net>
*
* http://duncanthrax.net/pdkim/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* $Cambridge$ */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include "pdkim.h"
#include "sha1.h"
#include "sha2.h"
#include "rsa.h"
#include "base64.h"
#define PDKIM_SIGNATURE_VERSION "1"
#define PDKIM_PUB_RECORD_VERSION "DKIM1"
#define PDKIM_MAX_HEADER_LEN 65536
#define PDKIM_MAX_HEADERS 512
#define PDKIM_MAX_BODY_LINE_LEN 16384
#define PDKIM_DNS_TXT_MAX_NAMELEN 1024
#define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
"Message-ID:To:Cc:MIME-Version:Content-Type:"\
"Content-Transfer-Encoding:Content-ID:"\
"Content-Description:Resent-Date:Resent-From:"\
"Resent-Sender:Resent-To:Resent-Cc:"\
"Resent-Message-ID:In-Reply-To:References:"\
"List-Id:List-Help:List-Unsubscribe:"\
"List-Subscribe:List-Post:List-Owner:List-Archive"
/* -------------------------------------------------------------------------- */
struct pdkim_stringlist {
char *value;
int tag;
void *next;
};
#define PDKIM_STR_ALLOC_FRAG 256
struct pdkim_str {
char *str;
unsigned int len;
unsigned int allocated;
};
/* -------------------------------------------------------------------------- */
/* A bunch of list constants */
char *pdkim_querymethods[] = {
"dns/txt",
NULL
};
char *pdkim_algos[] = {
"rsa-sha256",
"rsa-sha1",
NULL
};
char *pdkim_canons[] = {
"simple",
"relaxed",
NULL
};
char *pdkim_hashes[] = {
"sha256",
"sha1",
NULL
};
char *pdkim_keytypes[] = {
"rsa",
NULL
};
typedef struct pdkim_combined_canon_entry {
char *str;
int canon_headers;
int canon_body;
} pdkim_combined_canon_entry;
pdkim_combined_canon_entry pdkim_combined_canons[] = {
{ "simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
{ "simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED },
{ "relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
{ "relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED },
{ "simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
{ "relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
{ NULL, 0, 0 }
};
char *pdkim_verify_status_str(int status) {
switch(status) {
case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE";
case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID";
case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL";
case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS";
default: return "PDKIM_VERIFY_UNKNOWN";
}
}
char *pdkim_verify_ext_status_str(int ext_status) {
switch(ext_status) {
case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY";
case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE";
case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE";
case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE";
case PDKIM_VERIFY_INVALID_PUBKEY_PARSING: return "PDKIM_VERIFY_INVALID_PUBKEY_PARSING";
default: return "PDKIM_VERIFY_UNKNOWN";
}
}
/* -------------------------------------------------------------------------- */
/* Print debugging functions */
#ifdef PDKIM_DEBUG
void pdkim_quoteprint(FILE *stream, char *data, int len, int lf) {
int i;
unsigned char *p = (unsigned char *)data;
for (i=0;i<len;i++) {
int c = p[i];
switch (c) {
case ' ' : fprintf(stream,"{SP}"); break;
case '\t': fprintf(stream,"{TB}"); break;
case '\r': fprintf(stream,"{CR}"); break;
case '\n': fprintf(stream,"{LF}"); break;
case '{' : fprintf(stream,"{BO}"); break;
case '}' : fprintf(stream,"{BC}"); break;
default:
if ( (c < 32) || (c > 127) )
fprintf(stream,"{%02x}",c);
else
fputc(c,stream);
break;
}
}
if (lf)
fputc('\n',stream);
}
void pdkim_hexprint(FILE *stream, char *data, int len, int lf) {
int i;
unsigned char *p = (unsigned char *)data;
for (i=0;i<len;i++) {
int c = p[i];
fprintf(stream,"%02x",c);
}
if (lf)
fputc('\n',stream);
}
#endif
/* -------------------------------------------------------------------------- */
/* Simple string list implementation for convinience */
pdkim_stringlist *pdkim_append_stringlist(pdkim_stringlist *base, char *str) {
pdkim_stringlist *new_entry = malloc(sizeof(pdkim_stringlist));
if (new_entry == NULL) return NULL;
memset(new_entry,0,sizeof(pdkim_stringlist));
new_entry->value = strdup(str);
if (new_entry->value == NULL) return NULL;
if (base != NULL) {
pdkim_stringlist *last = base;
while (last->next != NULL) { last = last->next; }
last->next = new_entry;
return base;
}
else return new_entry;
}
pdkim_stringlist *pdkim_prepend_stringlist(pdkim_stringlist *base, char *str) {
pdkim_stringlist *new_entry = malloc(sizeof(pdkim_stringlist));
if (new_entry == NULL) return NULL;
memset(new_entry,0,sizeof(pdkim_stringlist));
new_entry->value = strdup(str);
if (new_entry->value == NULL) return NULL;
if (base != NULL) {
new_entry->next = base;
}
return new_entry;
}
/* -------------------------------------------------------------------------- */
/* A small "growing string" implementation to escape malloc/realloc hell */
pdkim_str *pdkim_strnew (char *cstr) {
unsigned int len = cstr?strlen(cstr):0;
pdkim_str *p = malloc(sizeof(pdkim_str));
if (p == NULL) return NULL;
memset(p,0,sizeof(pdkim_str));
p->str = malloc(len+1);
if (p->str == NULL) {
free(p);
return NULL;
}
p->allocated=(len+1);
p->len=len;
if (cstr) strcpy(p->str,cstr);
return p;
}
char *pdkim_strncat(pdkim_str *str, char *data, int len) {
if ((str->allocated - str->len) < (len+1)) {
/* Extend the buffer */
int num_frags = ((len+1)/PDKIM_STR_ALLOC_FRAG)+1;
char *n = realloc(str->str,
(str->allocated+(num_frags*PDKIM_STR_ALLOC_FRAG)));
if (n == NULL) return NULL;
str->str = n;
str->allocated += (num_frags*PDKIM_STR_ALLOC_FRAG);
}
strncpy(&(str->str[str->len]),data,len);
str->len+=len;
str->str[str->len] = '\0';
return str->str;
}
char *pdkim_strcat(pdkim_str *str, char *cstr) {
return pdkim_strncat(str, cstr, strlen(cstr));
}
char *pdkim_numcat(pdkim_str *str, unsigned long num) {
char minibuf[20];
snprintf(minibuf,20,"%lu",num);
return pdkim_strcat(str,minibuf);
}
char *pdkim_strtrim(pdkim_str *str) {
char *p = str->str;
char *q = str->str;
while ( (*p != '\0') && ((*p == '\t') || (*p == ' ')) ) p++;
while (*p != '\0') {*q = *p; q++; p++;}
*q = '\0';
while ( (q != str->str) && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) ) {
*q = '\0';
q--;
}
str->len = strlen(str->str);
return str->str;
}
char *pdkim_strclear(pdkim_str *str) {
str->str[0] = '\0';
str->len = 0;
return str->str;
}
void pdkim_strfree(pdkim_str *str) {
if (str == NULL) return;
if (str->str != NULL) free(str->str);
free(str);
}
/* -------------------------------------------------------------------------- */
void pdkim_free_pubkey(pdkim_pubkey *pub) {
if (pub) {
if (pub->version != NULL) free(pub->version);
if (pub->granularity != NULL) free(pub->granularity);
if (pub->hashes != NULL) free(pub->hashes);
if (pub->keytype != NULL) free(pub->keytype);
if (pub->srvtype != NULL) free(pub->srvtype);
if (pub->notes != NULL) free(pub->notes);
if (pub->key != NULL) free(pub->key);
free(pub);
}
}
/* -------------------------------------------------------------------------- */
void pdkim_free_sig(pdkim_signature *sig) {
if (sig) {
pdkim_signature *next = (pdkim_signature *)sig->next;
pdkim_stringlist *e = sig->headers;
while(e != NULL) {
pdkim_stringlist *c = e;
if (e->value != NULL) free(e->value);
e = e->next;
free(c);
}
if (sig->sigdata != NULL) free(sig->sigdata);
if (sig->bodyhash != NULL) free(sig->bodyhash);
if (sig->selector != NULL) free(sig->selector);
if (sig->domain != NULL) free(sig->domain);
if (sig->identity != NULL) free(sig->identity);
if (sig->headernames != NULL) free(sig->headernames);
if (sig->copiedheaders != NULL) free(sig->copiedheaders);
if (sig->rsa_privkey != NULL) free(sig->rsa_privkey);
if (sig->sign_headers != NULL) free(sig->sign_headers);
if (sig->signature_header != NULL) free(sig->signature_header);
if (sig->sha1_body != NULL) free(sig->sha1_body);
if (sig->sha2_body != NULL) free(sig->sha2_body);
if (sig->pubkey != NULL) pdkim_free_pubkey(sig->pubkey);
free(sig);
if (next != NULL) pdkim_free_sig(next);
}
}
/* -------------------------------------------------------------------------- */
DLLEXPORT void pdkim_free_ctx(pdkim_ctx *ctx) {
if (ctx) {
pdkim_stringlist *e = ctx->headers;
while(e != NULL) {
pdkim_stringlist *c = e;
if (e->value != NULL) free(e->value);
e = e->next;
free(c);
}
pdkim_free_sig(ctx->sig);
pdkim_strfree(ctx->cur_header);
free(ctx->linebuf);
free(ctx);
}
}
/* -------------------------------------------------------------------------- */
/* Matches the name of the passed raw "header" against
the passed colon-separated "list", starting at entry
"start". Returns the position of the header name in
the list. */
int header_name_match(char *header,
char *tick,
int do_tick) {
char *hname;
char *lcopy;
char *p;
char *q;
int rc = PDKIM_FAIL;
/* Get header name */
char *hcolon = strchr(header,':');
if (hcolon == NULL) return rc; /* This isn't a header */
hname = malloc((hcolon-header)+1);
if (hname == NULL) return PDKIM_ERR_OOM;
memset(hname,0,(hcolon-header)+1);
strncpy(hname,header,(hcolon-header));
/* Copy tick-off list locally, so we can punch zeroes into it */
lcopy = strdup(tick);
if (lcopy == NULL) {
free(hname);
return PDKIM_ERR_OOM;
}
p = lcopy;
q = strchr(p,':');
while (q != NULL) {
*q = '\0';
if (strcasecmp(p,hname) == 0) {
rc = PDKIM_OK;
/* Invalidate header name instance in tick-off list */
if (do_tick) tick[p-lcopy] = '_';
goto BAIL;
}
p = q+1;
q = strchr(p,':');
}
if (strcasecmp(p,hname) == 0) {
rc = PDKIM_OK;
/* Invalidate header name instance in tick-off list */
if (do_tick) tick[p-lcopy] = '_';
}
BAIL:
free(hname);
free(lcopy);
return rc;
}
/* -------------------------------------------------------------------------- */
/* Performs "relaxed" canonicalization of a header. The returned pointer needs
to be free()d. */
char *pdkim_relax_header (char *header, int crlf) {
int past_field_name = 0;
int seen_wsp = 0;
char *p = header;
char *q;
char *relaxed = malloc(strlen(header)+3);
if (relaxed == NULL) return NULL;
q = relaxed;
while (*p != '\0') {
int c = *p;
/* Ignore CR & LF */
if ( (c == '\r') || (c == '\n') ) {
p++;
continue;
}
if ( (c == '\t') || (c == ' ') ) {
c = ' '; /* Turns WSP into SP */
if (seen_wsp) {
p++;
continue;
}
else seen_wsp = 1;
}
else {
if ( (!past_field_name) && (c == ':') ) {
if (seen_wsp) q--; /* This removes WSP before the colon */
seen_wsp = 1; /* This removes WSP after the colon */
past_field_name = 1;
}
else seen_wsp = 0;
}
/* Lowercase header name */
if (!past_field_name) c = tolower(c);
*q = c;
p++;
q++;
}
if ((q>relaxed) && (*(q-1) == ' ')) q--; /* Squash eventual trailing SP */
*q = '\0';
if (crlf) strcat(relaxed,"\r\n");
return relaxed;
}
/* -------------------------------------------------------------------------- */
#define PDKIM_QP_ERROR_DECODE -1
char *pdkim_decode_qp_char(char *qp_p, int *c) {
char *initial_pos = qp_p;
/* Advance one char */
qp_p++;
/* Check for two hex digits and decode them */
if (isxdigit(*qp_p) && isxdigit(qp_p[1])) {
/* Do hex conversion */
if (isdigit(*qp_p)) {*c = *qp_p - '0';}
else {*c = toupper(*qp_p) - 'A' + 10;}
*c <<= 4;
if (isdigit(qp_p[1])) {*c |= qp_p[1] - '0';}
else {*c |= toupper(qp_p[1]) - 'A' + 10;}
return qp_p + 2;
}
/* Illegal char here */
*c = PDKIM_QP_ERROR_DECODE;
return initial_pos;
}
/* -------------------------------------------------------------------------- */
char *pdkim_decode_qp(char *str) {
int nchar = 0;
char *q;
char *p = str;
char *n = malloc(strlen(p)+1);
if (n == NULL) return NULL;
*n = '\0';
q = n;
while (*p != '\0') {
if (*p == '=') {
p = pdkim_decode_qp_char(p,&nchar);
if (nchar >= 0) {
*q = nchar;
q++;
continue;
}
}
else {
*q = *p;
q++;
}
p++;
}
*q = '\0';
return n;
}
/* -------------------------------------------------------------------------- */
char *pdkim_decode_base64(char *str, int *num_decoded) {
int dlen = 0;
char *res;
base64_decode(NULL, &dlen, (unsigned char *)str, strlen(str));
res = malloc(dlen+1);
if (res == NULL) return NULL;
if (base64_decode((unsigned char *)res,&dlen,(unsigned char *)str,strlen(str)) != 0) {
free(res);
return NULL;
}
if (num_decoded != NULL) *num_decoded = dlen;
return res;
}
/* -------------------------------------------------------------------------- */
char *pdkim_encode_base64(char *str, int num) {
int dlen = 0;
char *res;
base64_encode(NULL, &dlen, (unsigned char *)str, num);
res = malloc(dlen+1);
if (res == NULL) return NULL;
if (base64_encode((unsigned char *)res,&dlen,(unsigned char *)str,num) != 0) {
free(res);
return NULL;
}
return res;
}
/* -------------------------------------------------------------------------- */
#define PDKIM_HDR_LIMBO 0
#define PDKIM_HDR_TAG 1
#define PDKIM_HDR_VALUE 2
pdkim_signature *pdkim_parse_sig_header(pdkim_ctx *ctx, char *raw_hdr) {
pdkim_signature *sig ;
char *p,*q;
pdkim_str *cur_tag = NULL;
pdkim_str *cur_val = NULL;
int past_hname = 0;
int in_b_val = 0;
int where = PDKIM_HDR_LIMBO;
int i;
sig = malloc(sizeof(pdkim_signature));
if (sig == NULL) return NULL;
memset(sig,0,sizeof(pdkim_signature));
sig->bodylength = -1;
sig->rawsig_no_b_val = malloc(strlen(raw_hdr)+1);
if (sig->rawsig_no_b_val == NULL) {
free(sig);
return NULL;
}
p = raw_hdr;
q = sig->rawsig_no_b_val;
while (1) {
/* Ignore FWS */
if ( (*p == '\r') || (*p == '\n') )
goto NEXT_CHAR;
/* Fast-forward through header name */
if (!past_hname) {
if (*p == ':') past_hname = 1;
goto NEXT_CHAR;
}
if (where == PDKIM_HDR_LIMBO) {
/* In limbo, just wait for a tag-char to appear */
if (!((*p >= 'a') && (*p <= 'z')))
goto NEXT_CHAR;
where = PDKIM_HDR_TAG;
}
if (where == PDKIM_HDR_TAG) {
if (cur_tag == NULL)
cur_tag = pdkim_strnew(NULL);
if ((*p >= 'a') && (*p <= 'z'))
pdkim_strncat(cur_tag,p,1);
if (*p == '=') {
if (strcmp(cur_tag->str,"b") == 0) {
*q = '='; q++;
in_b_val = 1;
}
where = PDKIM_HDR_VALUE;
goto NEXT_CHAR;
}
}
if (where == PDKIM_HDR_VALUE) {
if (cur_val == NULL)
cur_val = pdkim_strnew(NULL);
if ( (*p == '\r') || (*p == '\n') || (*p == ' ') || (*p == '\t') )
goto NEXT_CHAR;
if ( (*p == ';') || (*p == '\0') ) {
if (cur_tag->len > 0) {
pdkim_strtrim(cur_val);
#ifdef PDKIM_DEBUG
if (ctx->debug_stream)
fprintf(ctx->debug_stream, "%s=%s\n", cur_tag->str, cur_val->str);
#endif
switch (cur_tag->str[0]) {
case 'b':
switch (cur_tag->str[1]) {
case 'h':
sig->bodyhash = pdkim_decode_base64(cur_val->str,&(sig->bodyhash_len));
break;
default:
sig->sigdata = pdkim_decode_base64(cur_val->str,&(sig->sigdata_len));
break;
}
break;
case 'v':
if (strcmp(cur_val->str,PDKIM_SIGNATURE_VERSION) == 0) {
/* We only support version 1, and that is currently the
only version there is. */
sig->version = 1;
}
break;
case 'a':
i = 0;
while (pdkim_algos[i] != NULL) {
if (strcmp(cur_val->str,pdkim_algos[i]) == 0 ) {
sig->algo = i;
break;
}
i++;
}
break;
case 'c':
i = 0;
while (pdkim_combined_canons[i].str != NULL) {
if (strcmp(cur_val->str,pdkim_combined_canons[i].str) == 0 ) {
sig->canon_headers = pdkim_combined_canons[i].canon_headers;
sig->canon_body = pdkim_combined_canons[i].canon_body;
break;
}
i++;
}
break;
case 'q':
i = 0;
while (pdkim_querymethods[i] != NULL) {
if (strcmp(cur_val->str,pdkim_querymethods[i]) == 0 ) {
sig->querymethod = i;
break;
}
i++;
}
break;
case 's':
sig->selector = strdup(cur_val->str);
break;
case 'd':
sig->domain = strdup(cur_val->str);
break;
case 'i':
sig->identity = pdkim_decode_qp(cur_val->str);
break;
case 't':
sig->created = strtoul(cur_val->str,NULL,10);
break;
case 'x':
sig->expires = strtoul(cur_val->str,NULL,10);
break;
case 'l':
sig->bodylength = strtol(cur_val->str,NULL,10);
break;
case 'h':
sig->headernames = strdup(cur_val->str);
break;
case 'z':
sig->copiedheaders = pdkim_decode_qp(cur_val->str);
break;
default:
#ifdef PDKIM_DEBUG
if (ctx->debug_stream)
fprintf(ctx->debug_stream, "Unknown tag encountered\n");
#endif
break;
}
}
pdkim_strclear(cur_tag);
pdkim_strclear(cur_val);
in_b_val = 0;
where = PDKIM_HDR_LIMBO;
goto NEXT_CHAR;
}
else pdkim_strncat(cur_val,p,1);
}
NEXT_CHAR:
if (*p == '\0') break;
if (!in_b_val) {
*q = *p;
q++;
}
p++;
}
/* Make sure the most important bits are there. */
if (!(sig->domain && (*(sig->domain) != '\0') &&
sig->selector && (*(sig->selector) != '\0') &&
sig->headernames && (*(sig->headernames) != '\0') &&
sig->bodyhash &&
sig->sigdata &&
sig->version)) {
pdkim_free_sig(sig);
return NULL;
}
*q = '\0';
/* Chomp raw header. The final newline must not be added to the signature. */
q--;
while( (q > sig->rawsig_no_b_val) && ((*q == '\r') || (*q == '\n')) ) {
*q = '\0'; q--;
}
#ifdef PDKIM_DEBUG
if (ctx->debug_stream) {
fprintf(ctx->debug_stream,
"PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
pdkim_quoteprint(ctx->debug_stream,
sig->rawsig_no_b_val,
strlen(sig->rawsig_no_b_val), 1);
fprintf(ctx->debug_stream,
"PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
}
#endif
sig->sha1_body = malloc(sizeof(sha1_context));
if (sig->sha1_body == NULL) {
pdkim_free_sig(sig);
return NULL;
}
sig->sha2_body = malloc(sizeof(sha2_context));
if (sig->sha2_body == NULL) {
pdkim_free_sig(sig);
return NULL;
}
sha1_starts(sig->sha1_body);
sha2_starts(sig->sha2_body,0);
return sig;
}
/* -------------------------------------------------------------------------- */
pdkim_pubkey *pdkim_parse_pubkey_record(pdkim_ctx *ctx, char *raw_record) {
pdkim_pubkey *pub ;
char *p;
pdkim_str *cur_tag = NULL;
pdkim_str *cur_val = NULL;
int where = PDKIM_HDR_LIMBO;
pub = malloc(sizeof(pdkim_pubkey));
if (pub == NULL) return NULL;
memset(pub,0,sizeof(pdkim_pubkey));
p = raw_record;
while (1) {
/* Ignore FWS */
if ( (*p == '\r') || (*p == '\n') )
goto NEXT_CHAR;
if (where == PDKIM_HDR_LIMBO) {
/* In limbo, just wait for a tag-char to appear */
if (!((*p >= 'a') && (*p <= 'z')))
goto NEXT_CHAR;
where = PDKIM_HDR_TAG;
}
if (where == PDKIM_HDR_TAG) {
if (cur_tag == NULL)
cur_tag = pdkim_strnew(NULL);
if ((*p >= 'a') && (*p <= 'z'))
pdkim_strncat(cur_tag,p,1);
if (*p == '=') {
where = PDKIM_HDR_VALUE;
goto NEXT_CHAR;
}
}
if (where == PDKIM_HDR_VALUE) {
if (cur_val == NULL)
cur_val = pdkim_strnew(NULL);
if ( (*p == '\r') || (*p == '\n') )
goto NEXT_CHAR;
if ( (*p == ';') || (*p == '\0') ) {
if (cur_tag->len > 0) {
pdkim_strtrim(cur_val);
#ifdef PDKIM_DEBUG
if (ctx->debug_stream)
fprintf(ctx->debug_stream, "%s=%s\n", cur_tag->str, cur_val->str);
#endif
switch (cur_tag->str[0]) {
case 'v':
/* This tag isn't evaluated because:
- We only support version DKIM1.
- Which is the default for this value (set below)
- Other versions are currently not specified. */
break;
case 'h':
pub->hashes = strdup(cur_val->str);
break;
case 'g':
pub->granularity = strdup(cur_val->str);
break;
case 'n':
pub->notes = pdkim_decode_qp(cur_val->str);
break;
case 'p':
pub->key = pdkim_decode_base64(cur_val->str,&(pub->key_len));
break;
case 'k':
pub->hashes = strdup(cur_val->str);
break;
case 's':
pub->srvtype = strdup(cur_val->str);
break;
case 't':
if (strchr(cur_val->str,'y') != NULL) pub->testing = 1;
if (strchr(cur_val->str,'s') != NULL) pub->no_subdomaining = 1;
break;
default:
#ifdef PDKIM_DEBUG
if (ctx->debug_stream)
fprintf(ctx->debug_stream, "Unknown tag encountered\n");
#endif
break;
}
}
pdkim_strclear(cur_tag);
pdkim_strclear(cur_val);
where = PDKIM_HDR_LIMBO;
goto NEXT_CHAR;
}
else pdkim_strncat(cur_val,p,1);
}
NEXT_CHAR:
if (*p == '\0') break;
p++;
}
/* Set fallback defaults */
if (pub->version == NULL) pub->version = strdup(PDKIM_PUB_RECORD_VERSION);
if (pub->granularity == NULL) pub->granularity = strdup("*");
if (pub->keytype == NULL) pub->keytype = strdup("rsa");
if (pub->srvtype == NULL) pub->srvtype = strdup("*");
/* p= is required */
if (pub->key == NULL) {
pdkim_free_pubkey(pub);
return NULL;
}
return pub;
}
/* -------------------------------------------------------------------------- */
int pdkim_update_bodyhash(pdkim_ctx *ctx, char *data, int len) {
pdkim_signature *sig = ctx->sig;
/* Cache relaxed version of data */
char *relaxed_data = NULL;
int relaxed_len = 0;
/* Traverse all signatures, updating their hashes. */
while (sig != NULL) {
/* Defaults to simple canon (no further treatment necessary) */
char *canon_data = data;
int canon_len = len;
if (sig->canon_body == PDKIM_CANON_RELAXED) {
/* Relax the line if not done already */
if (relaxed_data == NULL) {
int seen_wsp = 0;
char *p = data;
int q = 0;
relaxed_data = malloc(len+1);
if (relaxed_data == NULL) return PDKIM_ERR_OOM;
while (*p != '\0') {
char c = *p;
if (c == '\r') {
if ( (q > 0) && (relaxed_data[q-1] == ' ') ) q--;
}
else if ( (c == '\t') || (c == ' ') ) {
c = ' '; /* Turns WSP into SP */
if (seen_wsp) {
p++;
continue;
}
else seen_wsp = 1;
}
else seen_wsp = 0;
relaxed_data[q++] = c;
p++;
}
relaxed_data[q] = '\0';
relaxed_len = q;
}
canon_data = relaxed_data;
canon_len = relaxed_len;
}
/* Make sure we don't exceed the to-be-signed body length */
if ((sig->bodylength >= 0) &&
((sig->signed_body_bytes+(unsigned long)canon_len) > sig->bodylength))
canon_len = (sig->bodylength - sig->signed_body_bytes);
if (canon_len > 0) {
if (sig->algo == PDKIM_ALGO_RSA_SHA1)
sha1_update(sig->sha1_body,(unsigned char *)canon_data,canon_len);
else
sha2_update(sig->sha2_body,(unsigned char *)canon_data,canon_len);
sig->signed_body_bytes += canon_len;
#ifdef PDKIM_DEBUG
if (ctx->debug_stream!=NULL)
pdkim_quoteprint(ctx->debug_stream,canon_data,canon_len,0);
#endif
}
sig = sig->next;
}
if (relaxed_data != NULL) free(relaxed_data);
return PDKIM_OK;
}
/* -------------------------------------------------------------------------- */
int pdkim_finish_bodyhash(pdkim_ctx *ctx) {
pdkim_signature *sig = ctx->sig;
/* Traverse all signatures */
while (sig != NULL) {
/* Finish hashes */
unsigned char bh[32]; /* SHA-256 = 32 Bytes, SHA-1 = 20 Bytes */
if (sig->algo == PDKIM_ALGO_RSA_SHA1)
sha1_finish(sig->sha1_body,bh);
else
sha2_finish(sig->sha2_body,bh);
#ifdef PDKIM_DEBUG
if (ctx->debug_stream) {
fprintf(ctx->debug_stream, "PDKIM [%s] Body bytes hashed: %lu\n",
sig->domain, sig->signed_body_bytes);
fprintf(ctx->debug_stream, "PDKIM [%s] bh computed: ", sig->domain);
pdkim_hexprint(ctx->debug_stream, (char *)bh,
(sig->algo == PDKIM_ALGO_RSA_SHA1)?20:32,1);
}
#endif
/* SIGNING -------------------------------------------------------------- */
if (ctx->mode == PDKIM_MODE_SIGN) {
sig->bodyhash_len = (sig->algo == PDKIM_ALGO_RSA_SHA1)?20:32;
sig->bodyhash = malloc(sig->bodyhash_len);
if (sig->bodyhash == NULL) return PDKIM_ERR_OOM;
memcpy(sig->bodyhash,bh,sig->bodyhash_len);
/* If bodylength limit is set, and we have received less bytes
than the requested amount, effectively remove the limit tag. */
if (sig->signed_body_bytes < sig->bodylength) sig->bodylength = -1;
}
/* VERIFICATION --------------------------------------------------------- */
else {
/* Compare bodyhash */
if (memcmp(bh,sig->bodyhash,
(sig->algo == PDKIM_ALGO_RSA_SHA1)?20:32) == 0) {
#ifdef PDKIM_DEBUG
if (ctx->debug_stream)
fprintf(ctx->debug_stream, "PDKIM [%s] Body hash verified OK\n",
sig->domain);
#endif
}
else {
#ifdef PDKIM_DEBUG
if (ctx->debug_stream) {
fprintf(ctx->debug_stream, "PDKIM [%s] Body hash did NOT verify\n",
sig->domain);
fprintf(ctx->debug_stream, "PDKIM [%s] bh signature: ", sig->domain);
pdkim_hexprint(ctx->debug_stream, sig->bodyhash,
(sig->algo == PDKIM_ALGO_RSA_SHA1)?20:32,1);
}
#endif
sig->verify_status = PDKIM_VERIFY_FAIL;
sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
}
}