Fixes in DKIM code

* lib/dns.c (dkim_lookup): The v= tag is optional.
* src/builtin/dkim.bi (dkim_sign): Insert the created header at
the beginning.
(dkim_verify): Mark with MF_DSEXP.
* src/dkim-canonicalize.c (dkim_canonicalizer): Fix relaxed body
canonicalization: ignore whitespace at the end of the line (before
CRLF).
* src/dkim.c (dkim_str_to_canon_type): Take two arguments.  Return
the pointer to the first character after the spec in *endp.
All uses changed.
(dkim_signature_parse): Fix typo (missing else).
Fix c= tag parsing.
(dkim_sig_validate): The q= tag is optional.
Fix verification of the i= tag.
(pubkey_validate): Validate v= tag, if supplied.
Fix validation of the key type and algorithm.
* src/dkim.h (DKIM_KEYRECORD_VERSION): New constant.

4 files changed, 68 insertions, 31 deletions

diff --git a/src/builtin/dkim.bi b/src/builtin/dkim.bi
index 52ac4e3c..a85c2b51 100644
--- a/src/builtin/dkim.bi
+++ b/src/builtin/dkim.bi
@@ -198,13 +198,13 @@ STRING canon_h, STRING canon_b, STRING headers)
 	env_get_locus(env, &locus);
 	
 	if (MF_DEFINED(canon_h)) {
-		sig.canon[0] = dkim_str_to_canon_type(canon_h);
+		sig.canon[0] = dkim_str_to_canon_type(canon_h, NULL);
 		if (sig.canon[0] == DKIM_CANON_ERR)
 			MF_THROW(mfe_failure,
 				 _("bad canonicalization type: %s"), canon_h);
 	}
 	if (MF_DEFINED(canon_b)) {
-		sig.canon[1] = dkim_str_to_canon_type(canon_b);
+		sig.canon[1] = dkim_str_to_canon_type(canon_b, NULL);
 		if (sig.canon[1] == DKIM_CANON_ERR)
 			MF_THROW(mfe_failure,
 				 _("bad canonicalization type: %s"), canon_b);
@@ -260,12 +260,13 @@ STRING canon_h, STRING canon_b, STRING headers)
 	while (mu_isblank(*p))
 		p++;
 
-	trace("%s%s:%u: %s \"%s: %s\"",
+	trace("%s%s:%u: %s %d \"%s: %s\"",
 	      mailfromd_msgid(env_get_context(env)),
 	      locus.beg.mu_file, locus.beg.mu_line,
-	      msgmod_opcode_str(header_add),
+	      msgmod_opcode_str(header_insert),
+	      1,
 	      sighdr, p);
-	env_msgmod_append(env, header_add, sighdr, p, 1);
+	env_msgmod_append(env, header_insert, sighdr, p, 1);
 	free(sighdr);
 }
 END
@@ -273,6 +274,7 @@ END
 MF_VAR(dkim_explanation_code, NUMBER);
 MF_VAR(dkim_explanation, STRING);
 
+MF_DSEXP
 MF_DEFUN(dkim_verify, NUMBER, NUMBER nmsg)
 {
 	mu_message_t msg = bi_message_from_descr(env, nmsg);
diff --git a/src/dkim-canonicalize.c b/src/dkim-canonicalize.c
index 42e01413..ff221b7d 100644
--- a/src/dkim-canonicalize.c
+++ b/src/dkim-canonicalize.c
@@ -128,7 +128,13 @@ dkim_canonicalizer(void *xd,
 			} else if (*iptr == ':') {
 				*optr++ = *iptr++;
 				encoder->state = HR_COLON;
-			} else if (mu_isheadr(*iptr)) {
+			} else if (mu_isheadr(*iptr) ||
+				   /* 
+				    * Work around the bug in mailutils 3.9:
+				    * the MU_CTYPE_HEADR class did not include
+				    * underscore.
+				    */
+				   *iptr == '_') {
 				*optr++ = mu_tolower(*iptr++);
 			} else {
 				iobuf->errcode = MU_ERR_USER0;
@@ -237,14 +243,14 @@ dkim_canonicalizer(void *xd,
 			break;
 
 		case BR_WS:
-			if (!mu_isblank(*iptr)) {
+			if (*iptr == '\n') {
+				iptr++;				
+				encoder->nlcount++;		  
+				encoder->state = BR_NL;
+			} else if (!mu_isblank(*iptr)) {
 				*optr++ = ' ';
 				encoder->state = BR_INIT;
 			} else {
-				if (*iptr == '\n') {
-					encoder->nlcount++;		  
-					encoder->state = BR_NL;
-				}
 				iptr++;
 			}
 			break;
diff --git a/src/dkim.c b/src/dkim.c
index bc3c3da8..18ad159b 100644
--- a/src/dkim.c
+++ b/src/dkim.c
@@ -458,14 +458,26 @@ dkim_rsa_sha256_sign(struct rsa_private_key *priv, struct sha256_ctx *ctx,
  */
 static char const *dkim_canon_string[] = { "simple", "relaxed", NULL };
 
+/*
+ * Convert STR to a DKIM_CANON_* constant (return DKIM_CANON_ERR on error).
+ * If ENDP is NULL, STR must be one of the strings from dkim_canon_string.
+ * Otherwise, STR may be followed by '\0' or '/'.  The pointer to that
+ * character will be returned in the memory location pointed to by ENDP.
+ */
 int
-dkim_str_to_canon_type(char const *str)
+dkim_str_to_canon_type(char const *str, char **endp)
 {
 	int i;
-
-	for (i = 0; dkim_canon_string[i]; i++)
-		if (strcmp(str, dkim_canon_string[i]) == 0)
-			return i;
+	size_t len = strcspn(str, "/");
+	if (endp || str[len] == 0) {
+		for (i = 0; dkim_canon_string[i]; i++)
+			if (len == strlen(dkim_canon_string[i]) &&
+			    memcmp(str, dkim_canon_string[i], len) == 0) {
+				if (endp)
+					*endp = (char*)(str + len);
+				return i;
+			}
+	}
 	return DKIM_CANON_ERR;
 }
 
@@ -595,24 +607,28 @@ dkim_signature_parse(char *str, struct dkim_signature *ret_sig)
 		*p++ = 0;
 		if (strcmp(k, "a") == 0) {
 			sig.a = (char*) mu_strdup(p);
-		} if (strcmp(k, "b") == 0) {
+		} else if (strcmp(k, "b") == 0) {
 			sig.b = (uint8_t*) mu_strdup(p);
 		} else if (strcmp(k, "bh") == 0) {
 			sig.bh = (uint8_t*) mu_strdup(p);
 		} else if (strcmp(k, "q") == 0) {
 			sig.q = mu_strdup(p);
 		} else if (strcmp(k, "c") == 0) {
-			char *s = strchr(p, '/');
-			if (!s) {
+			char *s;
+			
+			if ((sig.canon[0] = dkim_str_to_canon_type(p, &s))
+			    == DKIM_CANON_ERR) {
 				rc = -1;
 				goto end;
 			}
-			*s++ = 0;
-			if ((sig.canon[0] = dkim_str_to_canon_type(p)) == DKIM_CANON_ERR ||
-			    (sig.canon[1] = dkim_str_to_canon_type(s)) == DKIM_CANON_ERR) {
+
+			if (*s == 0)
+				sig.canon[1] = sig.canon[0];
+			else if (*s != '/' ||
+				 (sig.canon[1] = dkim_str_to_canon_type(s + 1, NULL)) == DKIM_CANON_ERR) {
 				rc = -1;
 				goto end;
-			}
+			} 
 		} else if (strcmp(k, "d") == 0) {
 			sig.d = mu_strdup(p);
 		} else if (strcmp(k, "s") == 0) {
@@ -1159,7 +1175,7 @@ int dkim_result_trans[] = {
 };
 
 static int
-dkim_sig_validate(struct dkim_signature const *sig)
+dkim_sig_validate(struct dkim_signature *sig)
 {
 	if (!sig->a
 	    || !sig->b
@@ -1167,18 +1183,19 @@ dkim_sig_validate(struct dkim_signature const *sig)
 	    || !sig->d
 	    || !sig->h
 	    || !sig->s
-	    || !sig->q
 	    || !sig->v) {
 		return DKIM_EXPL_SIG_MISS;
 	}
-
+	    
 	if (strcmp(sig->v, DKIM_VERSION))
 		return DKIM_EXPL_BAD_VERSION;
 
 	if (strcmp(sig->a, DKIM_ALGORITHM))
 		return DKIM_EXPL_BAD_ALGORITHM;
 	
-	if (strcmp(sig->q, DKIM_QUERY_METHOD))
+        if (!sig->q)
+		sig->q = mu_strdup(DKIM_QUERY_METHOD);
+	else if (strcmp(sig->q, DKIM_QUERY_METHOD))
 		return DKIM_EXPL_BAD_QUERY;
 	
 	if (sig->i) {
@@ -1191,7 +1208,7 @@ dkim_sig_validate(struct dkim_signature const *sig)
 		dlen = strlen(sig->d);
 		if (!(dlen <= ilen &&
 		      mu_c_strcasecmp(sig->d, p + ilen - dlen) == 0 &&
-		      sig->d[ilen - dlen - 1] == '.'))
+		      (p[ilen - dlen - 1] == '.' || p[ilen - dlen - 1] == '@')))
 			return DKIM_EXPL_DOMAIN_MISMATCH;
 	}
 	
@@ -1261,14 +1278,25 @@ static int
 pubkey_validate(mu_assoc_t a, struct dkim_signature const *sig)
 {
 	char *s;
+	size_t n;
+	
+	if ((s = mu_assoc_get(a, "v")) != NULL &&
+	    strcmp(s, DKIM_KEYRECORD_VERSION))
+		return DKIM_EXPL_KEY_SYNTAX;
+
 	if ((s = mu_assoc_get(a, "p")) == NULL) 
 		return DKIM_EXPL_KEY_SYNTAX;
 	
 	if (s[0] == 0)
 		return DKIM_EXPL_KEY_REVOKED;
-		
+
+	n = strcspn(sig->a, "-");
+	if ((s = mu_assoc_get(a, "k")) != NULL &&
+	    !(n == strlen(s) && memcmp(s, sig->a, n) == 0))
+		return DKIM_EXPL_BAD_ALGORITHM;
+
 	if ((s = mu_assoc_get(a, "h")) != NULL &&
-	    !dkim_header_list_match(s, sig->a))
+	    !dkim_header_list_match(s, sig->a + n + 1))
 		return DKIM_EXPL_BAD_ALGORITHM;
 	return DKIM_EXPL_OK;
 }
diff --git a/src/dkim.h b/src/dkim.h
index aaa83a93..7b52d11f 100644
--- a/src/dkim.h
+++ b/src/dkim.h
@@ -27,6 +27,7 @@ enum {
 };
 
 #define DKIM_VERSION "1"
+#define DKIM_KEYRECORD_VERSION "DKIM1"
 #define DKIM_SIGNATURE_HEADER "DKIM-Signature"
 #define DKIM_QUERY_METHOD "dns/txt"
 #define DKIM_ALGORITHM "rsa-sha256"
@@ -52,7 +53,7 @@ struct dkim_signature {
 };
 
 /* Convert canonicalization type to a DKIM_CANON_ constant. */
-int dkim_str_to_canon_type(char const *str);
+int dkim_str_to_canon_type(char const *str, char **endp);
 
 /*
  * Create canonicalizer filter for STREAM.  Use canonicalization types