我正在使用 civetweb 和openssl-1.1.0h。我需要创建一个可与多个客户端一起使用的网络。服务器和客户端之间的通信应该使用预共享密钥进行加密。
据我了解，在建立连接时，分别从服务器端和客户端调用回调 psk_server_cb 和 psk_client_cb。这些是更新服务器和客户端预共享密钥的要点。
假设我有需要知道哪个预共享密钥用于哪个客户端连接的信息，我怎么知道，在回调psk_server_cb（服务器端）期间，我打开了哪个客户端的连接（为了知道我需要哪个 psk在此回调期间更新）？
将不胜感激任何帮助，
齐皮
附加信息：
psk_server_cb 原型：
静态 unsigned int psk_server_cb（SSL *ssl，const char *identity，unsigned char *psk，unsigned int max_psk_len）
SSL结构：
struct ssl_st
{
/*
* protocol version (one of SSL2_VERSION, SSL3_VERSION, TLS1_VERSION,
* DTLS1_VERSION)
*/
int version;
/* SSLv3 */
const SSL_METHOD *method;
/*
* There are 2 BIO's even though they are normally both the same. This
* is so data can be read and written to different handlers
*/
/* used by SSL_read */
BIO *rbio;
/* used by SSL_write */
BIO *wbio;
/* used during session-id reuse to concatenate messages */
BIO *bbio;
/*
* This holds a variable that indicates what we were doing when a 0 or -1
* is returned. This is needed for non-blocking IO so we know what
* request needs re-doing when in SSL_accept or SSL_connect
*/
int rwstate;
int (*handshake_func) (SSL *);
/*
* Imagine that here's a boolean member "init" that is switched as soon
* as SSL_set_{accept/connect}_state is called for the first time, so
* that "state" and "handshake_func" are properly initialized. But as
* handshake_func is == 0 until then, we use this test instead of an
* "init" member.
*/
/* are we the server side? */
int server;
/*
* Generate a new session or reuse an old one.
* NB: For servers, the 'new' session may actually be a previously
* cached session or even the previous session unless
* SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION is set
*/
int new_session;
/* don't send shutdown packets */
int quiet_shutdown;
/* we have shut things down, 0x01 sent, 0x02 for received */
int shutdown;
/* where we are */
OSSL_STATEM statem;
BUF_MEM *init_buf; /* buffer used during init */
void *init_msg; /* pointer to handshake message body, set by
* ssl3_get_message() */
int init_num; /* amount read/written */
int init_off; /* amount read/written */
struct ssl3_state_st *s3; /* SSLv3 variables */
struct dtls1_state_st *d1; /* DTLSv1 variables */
/* callback that allows applications to peek at protocol messages */
void (*msg_callback) (int write_p, int version, int content_type,
const void *buf, size_t len, SSL *ssl, void *arg);
void *msg_callback_arg;
int hit; /* reusing a previous session */
X509_VERIFY_PARAM *param;
/* Per connection DANE state */
SSL_DANE dane;
/* crypto */
STACK_OF(SSL_CIPHER) *cipher_list;
STACK_OF(SSL_CIPHER) *cipher_list_by_id;
/*
* These are the ones being used, the ones in SSL_SESSION are the ones to
* be 'copied' into these ones
*/
uint32_t mac_flags;
EVP_CIPHER_CTX *enc_read_ctx; /* cryptographic state */
EVP_MD_CTX *read_hash; /* used for mac generation */
COMP_CTX *compress; /* compression */
COMP_CTX *expand; /* uncompress */
EVP_CIPHER_CTX *enc_write_ctx; /* cryptographic state */
EVP_MD_CTX *write_hash; /* used for mac generation */
/* session info */
/* client cert? */
/* This is used to hold the server certificate used */
struct cert_st /* CERT */ *cert;
/*
* the session_id_context is used to ensure sessions are only reused in
* the appropriate context
*/
unsigned int sid_ctx_length;
unsigned char sid_ctx[SSL_MAX_SID_CTX_LENGTH];
/* This can also be in the session once a session is established */
SSL_SESSION *session;
/* Default generate session ID callback. */
GEN_SESSION_CB generate_session_id;
/* Used in SSL3 */
/*
* 0 don't care about verify failure.
* 1 fail if verify fails
*/
uint32_t verify_mode;
/* fail if callback returns 0 */
int (*verify_callback) (int ok, X509_STORE_CTX *ctx);
/* optional informational callback */
void (*info_callback) (const SSL *ssl, int type, int val);
/* error bytes to be written */
int error;
/* actual code */
int error_code;
# ifndef OPENSSL_NO_PSK
unsigned int (*psk_client_callback) (SSL *ssl, const char *hint,
char *identity,
unsigned int max_identity_len,
unsigned char *psk,
unsigned int max_psk_len);
unsigned int (*psk_server_callback) (SSL *ssl, const char *identity,
unsigned char *psk,
unsigned int max_psk_len);
# endif
SSL_CTX *ctx;
/* Verified chain of peer */
STACK_OF(X509) *verified_chain;
long verify_result;
/* extra application data */
CRYPTO_EX_DATA ex_data;
/* for server side, keep the list of CA_dn we can use */
STACK_OF(X509_NAME) *client_CA;
int references;
/* protocol behaviour */
uint32_t options;
/* API behaviour */
uint32_t mode;
int min_proto_version;
int max_proto_version;
long max_cert_list;
int first_packet;
/* what was passed, used for SSLv3/TLS rollback check */
int client_version;
/*
* If we're using more than one pipeline how should we divide the data
* up between the pipes?
*/
unsigned int split_send_fragment;
/*
* Maximum amount of data to send in one fragment. actual record size can
* be more than this due to padding and MAC overheads.
*/
unsigned int max_send_fragment;
/* Up to how many pipelines should we use? If 0 then 1 is assumed */
unsigned int max_pipelines;
/* TLS extension debug callback */
void (*tlsext_debug_cb) (SSL *s, int client_server, int type,
const unsigned char *data, int len, void *arg);
void *tlsext_debug_arg;
char *tlsext_hostname;
/*-
* no further mod of servername
* 0 : call the servername extension callback.
* 1 : prepare 2, allow last ack just after in server callback.
* 2 : don't call servername callback, no ack in server hello
*/
int servername_done;
/* certificate status request info */
/* Status type or -1 if no status type */
int tlsext_status_type;
# ifndef OPENSSL_NO_CT
/*
* Validates that the SCTs (Signed Certificate Timestamps) are sufficient.
* If they are not, the connection should be aborted.
*/
ssl_ct_validation_cb ct_validation_callback;
/* User-supplied argument tha tis passed to the ct_validation_callback */
void *ct_validation_callback_arg;
/*
* Consolidated stack of SCTs from all sources.
* Lazily populated by CT_get_peer_scts(SSL*)
*/
STACK_OF(SCT) *scts;
/* Raw extension data, if seen */
unsigned char *tlsext_scts;
/* Length of raw extension data, if seen */
uint16_t tlsext_scts_len;
/* Have we attempted to find/parse SCTs yet? */
int scts_parsed;
# endif
/* Expect OCSP CertificateStatus message */
int tlsext_status_expected;
/* OCSP status request only */
STACK_OF(OCSP_RESPID) *tlsext_ocsp_ids;
X509_EXTENSIONS *tlsext_ocsp_exts;
/* OCSP response received or to be sent */
unsigned char *tlsext_ocsp_resp;
int tlsext_ocsp_resplen;
/* RFC4507 session ticket expected to be received or sent */
int tlsext_ticket_expected;
# ifndef OPENSSL_NO_EC
size_t tlsext_ecpointformatlist_length;
/* our list */
unsigned char *tlsext_ecpointformatlist;
size_t tlsext_ellipticcurvelist_length;
/* our list */
unsigned char *tlsext_ellipticcurvelist;
# endif /* OPENSSL_NO_EC */
/* TLS Session Ticket extension override */
TLS_SESSION_TICKET_EXT *tlsext_session_ticket;
/* TLS Session Ticket extension callback */
tls_session_ticket_ext_cb_fn tls_session_ticket_ext_cb;
void *tls_session_ticket_ext_cb_arg;
/* TLS pre-shared secret session resumption */
tls_session_secret_cb_fn tls_session_secret_cb;
void *tls_session_secret_cb_arg;
SSL_CTX *session_ctx; /* initial ctx, used to store sessions */
# ifndef OPENSSL_NO_NEXTPROTONEG
/*
* Next protocol negotiation. For the client, this is the protocol that
* we sent in NextProtocol and is set when handling ServerHello
* extensions. For a server, this is the client's selected_protocol from
* NextProtocol and is set when handling the NextProtocol message, before
* the Finished message.
*/
unsigned char *next_proto_negotiated;
unsigned char next_proto_negotiated_len;
# endif
/* What we'll do */
STACK_OF(SRTP_PROTECTION_PROFILE) *srtp_profiles;
/* What's been chosen */
SRTP_PROTECTION_PROFILE *srtp_profile;
/*-
* Is use of the Heartbeat extension negotiated?
* 0: disabled
* 1: enabled
* 2: enabled, but not allowed to send Requests
*/
unsigned int tlsext_heartbeat;
/* Indicates if a HeartbeatRequest is in flight */
unsigned int tlsext_hb_pending;
/* HeartbeatRequest sequence number */
unsigned int tlsext_hb_seq;
/*
* For a client, this contains the list of supported protocols in wire
* format.
*/
unsigned char *alpn_client_proto_list;
unsigned alpn_client_proto_list_len;
/* Set to one if we have negotiated ETM */
int tlsext_use_etm;
/*-
* 1 if we are renegotiating.
* 2 if we are a server and are inside a handshake
* (i.e. not just sending a HelloRequest)
*/
int renegotiate;
# ifndef OPENSSL_NO_SRP
/* ctx for SRP authentication */
SRP_CTX srp_ctx;
# endif
/*
* Callback for disabling session caching and ticket support on a session
* basis, depending on the chosen cipher.
*/
int (*not_resumable_session_cb) (SSL *ssl, int is_forward_secure);
RECORD_LAYER rlayer;
/* Default password callback. */
pem_password_cb *default_passwd_callback;
/* Default password callback user data. */
void *default_passwd_callback_userdata;
/* Async Job info */
ASYNC_JOB *job;
ASYNC_WAIT_CTX *waitctx;
CRYPTO_RWLOCK *lock;
};