Tidy up a number of uglies in the code, remove some magic consts, make++

This code:

 * Adds NULL guard checks.
 * Detects mlen overflow in encrypt.
 * Allows you to specify CSTD=c89, CSTD=c99, CSTD=c11 for the library.
 * Supports E4_OUTPUT_DIR for building code anywhere.

include/e4/e4.h

@@ -32,6 +32,9 @@ extern "C" {
 #define E4_RESULT_OK 0
 /* A control message was handled. Applications may discard the resulting buffer */
 #define E4_RESULT_OK_CONTROL -1
+
+/* Internal error: for exception conditions that indicate the code has a bug */
+#define E4_ERROR_INTERNAL -100
 /* Invalid authentication tag indicates corrupted ciphertext  */
 #define E4_ERROR_INVALID_TAG -101
 /* Message received outside of error window for clock.  */
@@ -48,15 +51,18 @@ extern "C" {
 #define E4_ERROR_INVALID_COMMAND -107
 /* E4 Persistence layer reported an error.  */
 #define E4_ERROR_PERSISTENCE_ERROR -108
-
 /* Unable to find public key for device;e4 */
 #define E4_ERROR_DEVICEPK_MISSING -109
 /* Signature verification failed */
 #define E4_ERROR_PK_SIGVERIF_FAILED -110
-
+/* Overflow detected */
+#define E4_ERROR_PARAMETER_OVERFLOW -111
+/* Invalid parameters, e.g. NULL pointers */
+#define E4_ERROR_PARAMETER_INVALID -112
 
 /* Size of the timestamp field */
 #define E4_TS_LEN 8
+#define E4_TIMESTAMP_LEN 8
 /* Size of the ID, truncated sha3(alias) */
 #define E4_ID_LEN 16
 
@@ -70,7 +76,7 @@ extern "C" {
 #define E4_CTRLTOPIC_LEN (2 * E4_ID_LEN) + 3
 
 #define E4_TAG_LEN 16
-#define E4_TIMESTAMP_LEN 8
+
 #define E4_MSGHDR_LEN (E4_TAG_LEN + E4_TIMESTAMP_LEN)
 
 /* Public key support */
@@ -152,7 +158,8 @@ int e4c_unprotect_message(uint8_t *message,
                           const uint8_t *ciphertext,
                           size_t ciphertext_len,
                           const char *topic_name,
-                          e4storage *storage);
+                          e4storage *storage
+                          );
 
 
 /* the e4storage type pre-defined above implements these API calls */
@@ -168,10 +175,13 @@ int e4c_set_topic_key(e4storage *store, const uint8_t *topic_hash, const uint8_t
 int e4c_remove_topic(e4storage *store, const uint8_t *topic_hash);
 int e4c_reset_topics(e4storage *store);
 
+#ifdef E4_MODE_SYMKEY
 int e4c_set_idkey(e4storage *store, const uint8_t *key);
+#endif
 #ifdef E4_MODE_PUBKEY 
 /* pubkey storage apis */
 int e4c_set_idpubkey(e4storage *store, const uint8_t *pubkey);
+int e4c_set_idseckey(e4storage *store, const uint8_t *key);
 int e4c_getdeviceindex(e4storage *store, const uint8_t* id);
 int e4c_getdevicekey(uint8_t* key, e4storage *store, const int index);
 int e4c_set_device_key(e4storage *store, const uint8_t *id, const uint8_t *key);

include/e4/stdint.h

@@ -23,6 +23,7 @@ extern "C" {
 #endif
 
 #if __STDC_VERSION__ >= 199901L
+   #include <stddef.h>
    #include <stdint.h>
 #else
    #include "e4/pstdint.h"

mk/conf.mk

@@ -1,4 +1,25 @@
 
 VERSION=1.0.0
 
+CC       ?= clang
+AR       ?= ar
+LD       ?= clang
+ARFLAGS  = rcs
+CFLAGS	 = -Wall -Werror -fPIC -std=$(CSTD) $(E4_CFLAGS)
+LDFLAGS	 = -L. $(E4_LDFLAGS)
+
+O = o
+
+TESTCFLAGS = -Wall -Werror -g -std=c11 $(E4_CFLAGS)
+TESTLDFLAGS= $(E4_LDFLAGS)
+
+GITCOMMIT=$(shell git rev-list -1 HEAD)
+NOW=$(shell date "+%Y%m%d%H%M")
+
+INCDIR  = include
+SRCDIR  = src
+DOCDIR  = doc
+
+LIBNAME = libe4
+
 

mk/pubkey/conf.mk

@@ -1,34 +1,19 @@
 
-CC       ?= clang
-AR       ?= ar
-LD       ?= clang
-ARFLAGS  = rcs
-CFLAGS	 = -Wall -Werror -fPIC -std=c89 $(E4_CFLAGS)
-LDFLAGS	 = -L. $(E4_CFLAGS)
-LDSOFLAGS = -shared -fPIC -Wl,-soname,libe4p.so.1
-INCLUDES = -Iinclude/ -Ibuild/pubkey/include/
+E4_OUTPUT_DIR ?= build/pubkey
 
-# BUILD environment
-GITCOMMIT=$(shell git rev-list -1 HEAD)
-NOW=$(shell date "+%Y%m%d%H%M")
+LDSOFLAGS = -shared -fPIC -Wl,-soname,libe4p.so.1
+INCLUDES = -Iinclude/ -I$(E4_OUTPUT_DIR)/include/
 
 # OBJ paths match their src folder equivalents
-INCDIR  = include
 OBJDIR  = tmp/pubkey/build
 TESTOBJDIR = tmp/pubkey/test
-SRCDIR  = src
-DOCDIR  = doc
-BUILDDIR = build/pubkey
-LIBDIR  = build/pubkey/lib
-OUTINCDIR = build/pubkey/include
-LIBNAME = libe4
-LIB	= $(LIBDIR)/$(LIBNAME).a
-LIBSO	= $(LIBDIR)/$(LIBNAME)p.so.$(VERSION)
+
+BUILDDIR = $(E4_OUTPUT_DIR)
+LIBDIR  = $(BUILDDIR)/lib
+OUTINCDIR = $(BUILDDIR)/include
 DISTDIR	= dist/pubkey/
-TESTDIR = build/pubkey/test
+TESTDIR = $(BUILDDIR)/test
 
-O = o
+LIB	= $(LIBDIR)/$(LIBNAME).a
+LIBSO	= $(LIBDIR)/$(LIBNAME)p.so.$(VERSION)
 
-# test specific parts:
-TESTCFLAGS = -Wall -Werror -g -std=c11 -Wno-unused-variable $(E4_CFLAGS)
-TESTLDFLAGS = $(LDFLAGS)

mk/pubkey/rules.mk

@@ -9,9 +9,9 @@ pub_so: setup pub_header $(OBJS)
         cp -rfv $(INCDIR)/* $(OUTINCDIR)/; \
 	$(CC) $(LDSOFLAGS) $(OBJS) -o $(LIBSO)
 
-.PHONY pub_header: build/pubkey/include/e4config/e4_config.h
+.PHONY pub_header: $(BUILDDIR)/include/e4config/e4_config.h
 
-build/pubkey/include/e4config/e4_config.h:
+$(BUILDDIR)/include/e4config/e4_config.h:
 	echo '#define E4_MODE_PUBKEY 1' > $@
 ifeq ("$(STORE)", "mem")
 	echo "#define E4_STORE_MEM 1" >> $@

mk/symkey/conf.mk

@@ -1,33 +1,20 @@
 
-CC       ?= clang
-AR       ?= ar
-ARFLAGS  = rcs
-CFLAGS	 = -Wall -fPIC -Werror -std=c89 $(E4_CFLAGS) 
-LDFLAGS	 = -L. $(E4_CFLAGS)
-LDSOFLAGS = -shared -fPIC -Wl,-soname,libe4s.so.1
-INCLUDES = -Iinclude/ -Ibuild/symkey/include/
+E4_OUTPUT_DIR ?= build/symkey
 
-# BUILD environment
-GITCOMMIT=$(shell git rev-list -1 HEAD)
-NOW=$(shell date "+%Y%m%d%H%M")
+LDSOFLAGS = -shared -fPIC -Wl,-soname,libe4s.so.1
+INCLUDES = -Iinclude/ -I$(E4_OUTPUT_DIR)/include/
 
 # OBJ paths match their src folder equivalents
-INCDIR  = include
 OBJDIR  = tmp/symkey/build
 TESTOBJDIR = tmp/symkey/test
-SRCDIR  = src
-DOCDIR  = doc
-BUILDDIR = build/symkey
-LIBDIR  = build/symkey/lib
-OUTINCDIR = build/symkey/include
-LIBNAME = libe4
-LIB	= $(LIBDIR)/$(LIBNAME).a
-LIBSO	= $(LIBDIR)/$(LIBNAME).so.$(VERSION)
+
+BUILDDIR = $(E4_OUTPUT_DIR)
+LIBDIR  = $(BUILDDIR)/lib
+OUTINCDIR = $(BUILDDIR)/include
 DISTDIR	= dist/symkey/
-TESTDIR = build/symkey/test
+TESTDIR = $(BUILDDIR)/test
+
+LIB	= $(LIBDIR)/$(LIBNAME).a
+LIBSO	= $(LIBDIR)/$(LIBNAME)s.so.$(VERSION)
 
-O = o
 
-# test specific parts:
-TESTCFLAGS = -Wall -Werror -g -std=c11 $(E4_CFLAGS)
-TESTLDFLAGS =

mk/symkey/rules.mk

@@ -9,9 +9,9 @@ sym_so: setup sym_header $(OBJS)
         cp -rfv $(INCDIR)/* $(OUTINCDIR)/; \
 	$(CC) $(LDSOFLAGS) $(OBJS) -o $(LIBSO)
 
-.PHONY sym_header: build/symkey/include/e4config/e4_config.h
+.PHONY sym_header: $(BUILDDIR)/include/e4config/e4_config.h
 
-build/symkey/include/e4config/e4_config.h:
+$(BUILDDIR)/include/e4config/e4_config.h:
 	echo '#define E4_MODE_SYMKEY 1' > $@
 ifeq ("$(STORE)", "mem")
 	echo "#define E4_STORE_MEM 1" >> $@

mk/unix.mk

@@ -4,6 +4,8 @@ include mk/conf.mk
 
 CONF ?= symkey
 STORE ?= file
+CSTD ?= -std=c89
+
 include mk/$(CONF)/conf.mk
 include mk/$(CONF)/objects.mk
 include mk/$(CONF)/tests.mk

src/e4c_pk_store_file.c

@@ -266,7 +266,7 @@ int e4c_set_id(e4storage *store, const uint8_t *id)
 exit:
     return r;
 }
-int e4c_set_idkey(e4storage *store, const uint8_t *key)
+int e4c_set_idseckey(e4storage *store, const uint8_t *key)
 {
     memmove(store->privkey, key, sizeof store->privkey);
     e4c_sync(store);

src/e4c_pk_store_mem.c

@@ -73,7 +73,7 @@ int e4c_set_id(e4storage *store, const uint8_t *id)
     return r;
 }
 
-int e4c_set_idkey(e4storage *store, const uint8_t *key)
+int e4c_set_idseckey(e4storage *store, const uint8_t *key)
 {
     memmove(store->privkey, key, sizeof store->privkey);
     e4c_sync(store);

src/e4pkcclient.c

@@ -50,17 +50,30 @@ int e4c_protect_message(uint8_t *cptr,
                         e4storage *storage)
 {
     int i = 0;
-    size_t clen2 = 0;
+    size_t clen_siv = 0;
     uint8_t key[E4_KEY_LEN];
     uint64_t time_now = 0;
     uint8_t* signaturep = NULL;
     size_t signeddatalen=0;
 
     /* pubkey messages are: Timestamp (8) | id (16) | IV (16) | Ciphertext (n) | sig (64) */
-
     if (mlen + E4_PK_TOPICMSGHDR_LEN + E4_PK_EDDSA_SIG_LEN > cmax) /* actually: not enough space */
         return E4_ERROR_CIPHERTEXT_TOO_SHORT;
-    *clen = mlen + E4_MSGHDR_LEN;
+
+    if (mlen + E4_PK_TOPICMSGHDR_LEN + E4_PK_EDDSA_SIG_LEN < mlen) /* overflow */
+        return E4_ERROR_PARAMETER_OVERFLOW;
+
+    if (cptr == NULL    ||
+        mptr == NULL    ||
+        topic == NULL   ||
+        clen == NULL    ||
+        storage == NULL)
+    {
+        return E4_ERROR_PARAMETER_INVALID;
+    }
+
+    *clen = mlen + E4_PK_TOPICMSGHDR_LEN;
+
 
     /* get the key */
     i = e4c_getindex(storage, topic);
@@ -86,17 +99,15 @@ int e4c_protect_message(uint8_t *cptr,
         time_now >>= 8;
     }
 
-    /* set our ID in the output buffer
-     * if Avi is reading this code, hope you are enjoying this memcpy.
-     */
-    memcpy(cptr + E4_TS_LEN, storage->id, E4_ID_LEN);
+    /* set our ID in the output buffer */
+    memcpy(cptr + E4_TIMESTAMP_LEN, storage->id, E4_ID_LEN);
 
     /* encrypt */
-    clen2 = 0;
-    aes256_encrypt_siv(cptr + E4_TS_LEN + E4_ID_LEN, &clen2, cptr, 8, mptr, mlen, key);
+    clen_siv = 0;
+    aes256_encrypt_siv(cptr + E4_TIMESTAMP_LEN + E4_ID_LEN, &clen_siv, cptr, 8, mptr, mlen, key);
 
     /* sign the result */
-    signeddatalen = E4_TS_LEN + E4_ID_LEN + E4_TAG_LEN + mlen;
+    signeddatalen = E4_TIMESTAMP_LEN + E4_ID_LEN + E4_TAG_LEN + mlen;
     signaturep = &cptr[0] + signeddatalen;
 
     /*
@@ -112,6 +123,13 @@ int e4c_protect_message(uint8_t *cptr,
                  storage->pubkey,
                  storage->privkey);
 
+    /* pubkey messages are: Timestamp (8) | id (16) | IV (16) | Ciphertext (n) | sig (64) */
+    /* safety check. clen_siv = msglen+E4_TAG_LEN. Therefore adding E4_PK_EDDSA_SIG_LEN + E4_TIMESTAMP_LEN + E4_ID_LEN should 
+     * equal clen */
+    if ( *clen != clen_siv + E4_PK_EDDSA_SIG_LEN + E4_TIMESTAMP_LEN + E4_ID_LEN ) {
+        return E4_ERROR_INTERNAL;
+    }
+
     return E4_RESULT_OK;
 }
 
@@ -138,6 +156,15 @@ int e4c_unprotect_message(uint8_t *mptr,
 
     secs1970 = (uint64_t)time(NULL); / this system has a RTC */
 #endif
+
+    if (cptr == NULL ||
+        mptr == NULL ||
+        topic == NULL ||
+        storage == NULL)
+    {
+        return E4_ERROR_PARAMETER_INVALID;
+    }
+
 
     /* There are two possible message formats:
 
@@ -175,8 +202,8 @@ int e4c_unprotect_message(uint8_t *mptr,
 
         /* set things up for symmetric decryption: */
         /* From the C2:        Timestamp (8) | IV (16) | Ciphertext (n) */
-        assocdatalen = E4_TS_LEN;
-        sivpayloadlen = clen - E4_TS_LEN;
+        assocdatalen = E4_TIMESTAMP_LEN;
+        sivpayloadlen = clen - E4_TIMESTAMP_LEN;
     }
     else
     {
@@ -234,8 +261,8 @@ int e4c_unprotect_message(uint8_t *mptr,
 
         /* set things up for symmetric decryption: */
         /* From other clients: Timestamp (8) | id (16) | IV (16) | Ciphertext (n) | sig (64) */
-        assocdatalen = E4_ID_LEN + E4_TS_LEN;
-        sivpayloadlen = clen - (E4_TS_LEN + E4_ID_LEN + E4_PK_EDDSA_SIG_LEN);
+        assocdatalen = E4_ID_LEN + E4_TIMESTAMP_LEN;
+        sivpayloadlen = clen - (E4_TIMESTAMP_LEN + E4_ID_LEN + E4_PK_EDDSA_SIG_LEN);
     }
 
     /* Retrieve timestamp encoded as little endian */
@@ -320,8 +347,8 @@ int e4c_unprotect_message(uint8_t *mptr,
         return r == 0 ? E4_RESULT_OK_CONTROL : r;
 
     case 0x02: /* SetIdKey(key) */
-        if (*mlen != (1 + E4_KEY_LEN)) return E4_ERROR_INVALID_COMMAND;
-        r = e4c_set_idkey(storage, mptr + 1);
+        if (*mlen != (1 + E4_PK_EDDSA_PRIVKEY_LEN)) return E4_ERROR_INVALID_COMMAND;
+        r = e4c_set_idseckey(storage, mptr + 1);
         return r == 0 ? E4_RESULT_OK_CONTROL : r;
 
     case 0x03: /* SetTopicKey(topic, key) */