c-libp2p/secio/exchange.c

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#include <stdlib.h>
#include <string.h>
#include "libp2p/secio/exchange.h"
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#include "libp2p/crypto/ephemeral.h"
#include "protobuf.h"
// epubkey signature
enum WireType secio_exchange_message_fields[] = { WIRETYPE_LENGTH_DELIMITED, WIRETYPE_LENGTH_DELIMITED };
struct Exchange* libp2p_secio_exchange_new() {
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struct Exchange* out = (struct Exchange*)malloc(sizeof(struct Exchange));
if (out != NULL) {
out->epubkey = NULL;
out->epubkey_size = 0;
out->signature = NULL;
out->signature_size = 0;
}
return out;
}
void libp2p_secio_exchange_free( struct Exchange* in) {
if (in != NULL) {
if (in->epubkey != NULL)
free(in->epubkey);
if (in->signature != NULL)
free(in->signature);
free(in);
}
}
/**
* retrieves the approximate size of an encoded version of the passed in struct
* @param in the struct to look at
* @reutrns the size of buffer needed
*/
size_t libp2p_secio_exchange_protobuf_encode_size(struct Exchange* in) {
size_t retVal = 0;
retVal += 11 + in->epubkey_size;
retVal += 11 + in->signature_size;
return retVal;
}
/**
* Encode the struct Exchange in protobuf format
* @param in the struct to be encoded
* @param buffer where to put the results
* @param max_buffer_length the max to write
* @param bytes_written how many bytes were written to the buffer
* @returns true(1) on success, otherwise false(0)
*/
int libp2p_secio_exchange_protobuf_encode(struct Exchange* in, unsigned char* buffer, size_t max_buffer_length, size_t* bytes_written) {
*bytes_written = 0;
size_t bytes_used;
// epubkey
if (!protobuf_encode_length_delimited(1, secio_exchange_message_fields[0], (char*)in->epubkey, in->epubkey_size, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_used))
return 0;
*bytes_written += bytes_used;
// signature
if (!protobuf_encode_length_delimited(2, secio_exchange_message_fields[1], (char*)in->signature, in->signature_size, &buffer[*bytes_written], max_buffer_length - *bytes_written, &bytes_used))
return 0;
*bytes_written += bytes_used;
return 1;
}
/**
* Turns a protobuf array into an Exchange struct
* @param buffer the protobuf array
* @param buffer_length the length of the buffer
* @param out a pointer to the new struct Exchange NOTE: this method allocates memory
* @returns true(1) on success, otherwise false(0)
*/
int libp2p_secio_exchange_protobuf_decode(unsigned char* buffer, size_t buffer_length, struct Exchange** out) {
size_t pos = 0;
int retVal = 0;
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if ( (*out = libp2p_secio_exchange_new()) == NULL)
goto exit;
while(pos < buffer_length) {
size_t bytes_read = 0;
int field_no;
enum WireType field_type;
if (protobuf_decode_field_and_type(&buffer[pos], buffer_length, &field_no, &field_type, &bytes_read) == 0) {
goto exit;
}
pos += bytes_read;
switch(field_no) {
case (1): // epubkey
if (protobuf_decode_length_delimited(&buffer[pos], buffer_length - pos, (char**)&((*out)->epubkey), &((*out)->epubkey_size), &bytes_read) == 0)
goto exit;
pos += bytes_read;
break;
case (2): // signature
if (protobuf_decode_length_delimited(&buffer[pos], buffer_length - pos, (char**)&((*out)->signature), &((*out)->signature_size), &bytes_read) == 0)
goto exit;
pos += bytes_read;
break;
}
}
retVal = 1;
exit:
if (retVal == 0) {
libp2p_secio_exchange_free(*out);
}
return retVal;
}
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/***
* Forward declaration
*/
int libp2p_secio_sign(struct PrivateKey* priv, const char* bytes_to_send, size_t bytes_size, uint8_t** signature, size_t* signature_size);
/***
* Build an exchange object based on passed in values
* @param local_session the SessionContext
* @param private_key the local RsaPrivateKey
* @param bytes_to_be_signed the bytes that should be signed
* @param bytes_size the length of bytes_to_be_signed
* @returns an Exchange object or NULL
*/
struct Exchange* libp2p_secio_exchange_build(struct SessionContext* local_session, struct RsaPrivateKey* private_key, const char* bytes_to_be_signed, size_t bytes_size) {
struct Exchange* exchange_out = libp2p_secio_exchange_new();
if (exchange_out != NULL) {
// don't send the first byte (to stay compatible with GO version)
exchange_out->epubkey = (unsigned char*)malloc(local_session->ephemeral_private_key->public_key->bytes_size - 1);
if (exchange_out->epubkey == NULL) {
libp2p_secio_exchange_free(exchange_out);
return NULL;
}
memcpy(exchange_out->epubkey, &local_session->ephemeral_private_key->public_key->bytes[1], local_session->ephemeral_private_key->public_key->bytes_size - 1);
exchange_out->epubkey_size = local_session->ephemeral_private_key->public_key->bytes_size - 1;
struct PrivateKey* priv = libp2p_crypto_private_key_new();
priv->type = KEYTYPE_RSA;
priv->data = (unsigned char*)private_key->der;
priv->data_size = private_key->der_length;
libp2p_secio_sign(priv, bytes_to_be_signed, bytes_size, &exchange_out->signature, &exchange_out->signature_size);
free(priv);
}
return exchange_out;
}