Gitweb:
http://git.exim.org/exim.git/commitdiff/05b7d6de8bb1c92587cc639eeb1be485a1b79c25
Commit: 05b7d6de8bb1c92587cc639eeb1be485a1b79c25
Parent: 3b5d5078fc82efa6405d5686610834e4a6a1bbc5
Author: Jasen Betts <jasen@???>
AuthorDate: Fri Apr 24 17:32:32 2015 +0100
Committer: Jeremy Harris <jgh146exb@???>
CommitDate: Fri Apr 24 17:32:32 2015 +0100
DKIM: Wrap signature header (more) in line with RFC 5322 and RFC 4871
---
src/src/pdkim/pdkim.c | 212 +++++++++++++++++++++++++++++++++++++++---------
1 files changed, 172 insertions(+), 40 deletions(-)
diff --git a/src/src/pdkim/pdkim.c b/src/src/pdkim/pdkim.c
index 4f0da3f..30b81c4 100644
--- a/src/src/pdkim/pdkim.c
+++ b/src/src/pdkim/pdkim.c
@@ -231,6 +231,7 @@ char *pdkim_strncat(pdkim_str *str, const char *data, int len) {
char *pdkim_strcat(pdkim_str *str, const 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);
@@ -1195,86 +1196,216 @@ DLLEXPORT int pdkim_feed (pdkim_ctx *ctx,
return PDKIM_OK;
}
+/*
+ * RFC 5322 specifies that header line length SHOULD be no more than 78
+ * lets make it so!
+ * pdkim_headcat
+ * returns char*
+ *
+ * col: this int holds and receives column number (octets since last '\n')
+ * str: partial string to append to
+ * pad: padding, split line or space after before or after eg: ";"
+ * intro: - must join to payload eg "h=", usually the tag name
+ * payload: eg base64 data - long data can be split arbitrarily.
+ *
+ * this code doesn't fold the header in some of the places that RFC4871
+ * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
+ * pairs and inside long values. it also always spaces or breaks after the
+ * "pad"
+ *
+ * no guarantees are made for output given out-of range input. like tag
+ * names loinger than 78, or bogus col. Input is assumed to be free of line breaks.
+ */
+
+static char *pdkim_headcat(int *col, pdkim_str *str, const char*pad,const char *intro, const char *payload ) {
+ size_t l;
+ if( pad)
+ {
+ l = strlen(pad);
+ if( *col + l > 78 )
+ {
+ pdkim_strcat(str, "\r\n\t");
+ *col=1;
+ }
+ pdkim_strncat(str, pad,l);
+ *col +=l;
+ }
+
+ l=(pad?1:0) + (intro?strlen(intro):0 );
+
+ if( *col + l > 78 )
+ { /*can't fit intro - start a new line to make room.*/
+ pdkim_strcat(str, "\r\n\t");
+ *col=1;
+ l= intro?strlen(intro):0;
+ }
+
+ l += payload ? strlen(payload):0 ;
+
+ while(l>77)
+ { /* this fragment will not fit on a single line */
+ if( pad )
+ {
+ pdkim_strcat(str, " ");
+ *col +=1;
+ pad=NULL; // only want this once
+ l--;
+ }
+ if( intro )
+ {
+ size_t sl=strlen(intro);
+ pdkim_strncat(str, intro,sl);
+ *col +=sl;
+ l-=sl;
+ intro=NULL; // only want this once
+ }
+ if(payload)
+ {
+ size_t sl=strlen(payload);
+ size_t chomp = *col+sl < 77 ? sl : 78-*col;
+ pdkim_strncat(str, payload,chomp);
+ *col +=chomp;
+ payload+=chomp;
+ l-=chomp-1;
+ }
+ // the while precondition tells us it didn't fit.
+ pdkim_strcat(str, "\r\n\t");
+ *col=1;
+ }
+ if( *col + l > 78 )
+ {
+ pdkim_strcat(str, "\r\n\t");
+ *col=1;
+ pad=NULL;
+ }
+
+ if( pad )
+ {
+ pdkim_strcat(str, " ");
+ *col +=1;
+ pad=NULL;
+ }
+
+ if( intro )
+ {
+ size_t sl=strlen(intro);
+ pdkim_strncat(str, intro,sl);
+ *col +=sl;
+ l-=sl;
+ intro=NULL;
+ }
+ if(payload)
+ {
+ size_t sl=strlen(payload);
+ pdkim_strncat(str, payload,sl);
+ *col +=sl;
+ }
+
+ return str->str;
+}
/* -------------------------------------------------------------------------- */
char *pdkim_create_header(pdkim_signature *sig, int final) {
char *rc = NULL;
char *base64_bh = NULL;
char *base64_b = NULL;
+ int col=0;
pdkim_str *hdr = pdkim_strnew("DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
if (hdr == NULL) return NULL;
+ pdkim_str *canon_all = pdkim_strnew(pdkim_canons[sig->canon_headers]);
+ if (canon_all == NULL) goto BAIL;
base64_bh = pdkim_encode_base64(sig->bodyhash, sig->bodyhash_len);
if (base64_bh == NULL) goto BAIL;
+ col=strlen(hdr->str);
+
/* Required and static bits */
if (
- pdkim_strcat(hdr,"; a=") &&
- pdkim_strcat(hdr,pdkim_algos[sig->algo]) &&
- pdkim_strcat(hdr,"; q=") &&
- pdkim_strcat(hdr,pdkim_querymethods[sig->querymethod]) &&
- pdkim_strcat(hdr,"; c=") &&
- pdkim_strcat(hdr,pdkim_canons[sig->canon_headers]) &&
- pdkim_strcat(hdr,"/") &&
- pdkim_strcat(hdr,pdkim_canons[sig->canon_body]) &&
- pdkim_strcat(hdr,"; d=") &&
- pdkim_strcat(hdr,sig->domain) &&
- pdkim_strcat(hdr,"; s=") &&
- pdkim_strcat(hdr,sig->selector) &&
- pdkim_strcat(hdr,";\r\n\th=") &&
- pdkim_strcat(hdr,sig->headernames) &&
- pdkim_strcat(hdr,"; bh=") &&
- pdkim_strcat(hdr,base64_bh) &&
- pdkim_strcat(hdr,";\r\n\t")
+ pdkim_headcat(&col,hdr,";","a=",pdkim_algos[sig->algo]) &&
+ pdkim_headcat(&col,hdr,";","q=",pdkim_querymethods[sig->querymethod]) &&
+ pdkim_strcat(canon_all,"/") &&
+ pdkim_strcat(canon_all,pdkim_canons[sig->canon_body]) &&
+ pdkim_headcat(&col,hdr,";","c=",canon_all->str) &&
+ pdkim_headcat(&col,hdr,";","d=",sig->domain) &&
+ pdkim_headcat(&col,hdr,";","s=",sig->selector)
) {
+ /* list of eader names can be split between items. */
+ {
+ char *n=strdup(sig->headernames);
+ char *f=n;
+ char *i="h=";
+ char *s=";";
+ if(!n) goto BAIL;
+ while (*n)
+ {
+ char *c=strchr(n,':');
+ if(c) *c='\0';
+ if(!i)
+ {
+ if (!pdkim_headcat(&col,hdr,NULL,NULL,":"))
+ {
+ free(f);
+ goto BAIL;
+ }
+ }
+ if( !pdkim_headcat(&col,hdr,s,i,n))
+ {
+ free(f);
+ goto BAIL;
+ }
+ if(c) n=c+1 ; else break;
+ s=NULL;
+ i=NULL;
+ }
+ free(f);
+ }
+ if(!pdkim_headcat(&col,hdr,";","bh=",base64_bh))
+ goto BAIL;
+
/* Optional bits */
if (sig->identity != NULL) {
- if (!( pdkim_strcat(hdr,"i=") &&
- pdkim_strcat(hdr,sig->identity) &&
- pdkim_strcat(hdr,";") ) ) {
+ if(!pdkim_headcat(&col,hdr,";","i=",sig->identity)){
goto BAIL;
}
}
+
if (sig->created > 0) {
- if (!( pdkim_strcat(hdr,"t=") &&
- pdkim_numcat(hdr,sig->created) &&
- pdkim_strcat(hdr,";") ) ) {
+ char minibuf[20];
+ snprintf(minibuf,20,"%lu",sig->created);
+ if(!pdkim_headcat(&col,hdr,";","t=",minibuf)) {
goto BAIL;
}
}
if (sig->expires > 0) {
- if (!( pdkim_strcat(hdr,"x=") &&
- pdkim_numcat(hdr,sig->expires) &&
- pdkim_strcat(hdr,";") ) ) {
+ char minibuf[20];
+ snprintf(minibuf,20,"%lu",sig->expires);
+ if(!pdkim_headcat(&col,hdr,";","x=",minibuf)) {
goto BAIL;
}
}
if (sig->bodylength >= 0) {
- if (!( pdkim_strcat(hdr,"l=") &&
- pdkim_numcat(hdr,sig->bodylength) &&
- pdkim_strcat(hdr,";") ) ) {
+ char minibuf[20];
+ snprintf(minibuf,20,"%lu",sig->bodylength);
+ if(!pdkim_headcat(&col,hdr,";","l=",minibuf)) {
goto BAIL;
}
}
- /* Extra linebreak */
- if (hdr->str[(hdr->len)-1] == ';') {
- if (!pdkim_strcat(hdr," \r\n\t")) goto BAIL;
- }
+
/* Preliminary or final version? */
if (final) {
base64_b = pdkim_encode_base64(sig->sigdata, sig->sigdata_len);
if (base64_b == NULL) goto BAIL;
- if (
- pdkim_strcat(hdr,"b=") &&
- pdkim_strcat(hdr,base64_b) &&
- pdkim_strcat(hdr,";")
- ) goto DONE;
+ if(!pdkim_headcat(&col,hdr,";","b=",base64_b)) goto BAIL;
}
else {
- if (pdkim_strcat(hdr,"b=;")) goto DONE;
+ if(!pdkim_headcat(&col,hdr,";","b=","")) goto BAIL;
}
- goto BAIL;
+ /* add trailing semicolon: I'm not sure if this is actually needed */
+ if(!pdkim_headcat(&col,hdr,NULL,";","")) goto BAIL;
+
+ goto DONE;
}
DONE:
@@ -1282,6 +1413,7 @@ char *pdkim_create_header(pdkim_signature *sig, int final) {
BAIL:
pdkim_strfree(hdr);
+ if (canon_all != NULL) pdkim_strfree(canon_all);
if (base64_bh != NULL) free(base64_bh);
if (base64_b != NULL) free(base64_b);
return rc;
