我正在对 wireshark 源代码进行一些更改。在某个特定点,我打印出一个名为 SSLDecoder
的结构,如下所示
FILE *f;
f=fopen("file.txt","a+");
size_decoder=sizeof(SslDecoder);
for(i=0; i < size_decoder; i++){
fprintf(f,"%02x",*(ssl_session->client_new+i));
}
fprintf(f,"\n");
ssl_session
属于 struct SslDecryptSession
类型,定义为
typedef struct _SslDecryptSession {
guchar _master_secret[SSL_MASTER_SECRET_LENGTH];
guchar _session_id[256];
guchar _client_random[32];
guchar _server_random[32];
StringInfo session_id;
StringInfo session_ticket;
StringInfo server_random;
StringInfo client_random;
StringInfo master_secret;
StringInfo handshake_data;
/* the data store for this StringInfo must be allocated explicitly with a capture lifetime scope */
StringInfo pre_master_secret;
guchar _server_data_for_iv[24];
StringInfo server_data_for_iv;
guchar _client_data_for_iv[24];
StringInfo client_data_for_iv;
gint state;
SslCipherSuite cipher_suite;
SslDecoder *server;
SslDecoder *client;
SslDecoder *server_new;
SslDecoder *client_new;
gcry_sexp_t private_key;
StringInfo psk;
guint16 version_netorder;
StringInfo app_data_segment;
SslSession session;
} SslDecryptSession;
SslDecoder
是类型
typedef struct _SslDecoder {
SslCipherSuite* cipher_suite;
gint compression;
guchar _mac_key_or_write_iv[48];
StringInfo mac_key; /* for block and stream ciphers */
StringInfo write_iv; /* for AEAD ciphers (at least GCM, CCM) */
SSL_CIPHER_CTX evp;
SslDecompress *decomp;
guint32 seq;
guint16 epoch;
SslFlow *flow;
} SslDecoder;
但是,打印到文件的输出是不规则的。 样本输出在 pastebin 上
有人可以告诉我我做错了什么吗?
我后来在文件中使用这个输出来填充另一个像这样的解码器(现在,由于文件打印不规则,我面临段错误)
SslDecoder *temp_decoder;
c = malloc(sizeof(SslDecoder));
for (i=0; i<sizeof(SslDecoder); i++){
fscanf(f,"%02x",&c[i]);
}
memcpy(temp_decoder,c, sizeof(SslDecoder));
最佳答案
当你执行指针运算时,指针偏移指向类型大小的倍数;它不会将指针偏移指定的字节数。请记住,如果您有 T* p
,则 *(p + i)
等同于 p[i]
。
在您的代码中,您可以:
size_decoder=sizeof(SslDecoder);
for(i=0; i < size_decoder; i++){
fprintf(f,"%02x",*(ssl_session->client_new+i));
}
*(ssl_session->client_new+i)
在每次迭代时将 client_new
指针偏移 i * sizeof (SslDecoder)
字节。
您打算在每次迭代时仅将指针前进一个字节,因此您必须对指向 char
的指针执行指针运算:
size_decoder=sizeof(SslDecoder);
const unsigned char* p = (unsigned char*) ssl_session->client_new;
for(i=0; i < size_decoder; i++){
fprintf(f,"%02x", p[i]);
}
在回读文件时,您同样需要做类似的事情。我还应该指出,在您的阅读代码中:
SslDecoder *temp_decoder;
c = malloc(sizeof(SslDecoder));
for (i=0; i<sizeof(SslDecoder); i++){
fscanf(f,"%02x",&c[i]);
}
memcpy(temp_decoder,c, sizeof(SslDecoder));
memcpy
调用不正确;您还没有为 temp_decoder
分配任何内存。您根本不需要使用 memcpy
:
SslDecoder *temp_decoder = malloc(sizeof *temp_decoder);
unsigned char* p = (unsigned char*) temp_decoder;
for (i=0; i<sizeof(SslDecoder); i++){
int temp; // "%x" corresponds to an int type
fscanf(f, "%02x", &temp);
p[i] = (unsigned char) temp;
}
关于c - 在 C 中打印结构,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39927607/