C TLS 通讯

1. TLS 通讯server sample: server.c

 

#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <resolv.h>
#include "openssl/ssl.h"
#include "openssl/err.h"

int OpenListener(int port){   
    int sd;
    struct sockaddr_in addr;
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;
    if (bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 ){
        perror("can't bind port");
        abort();
    }
    if ( listen(sd, 10) != 0 ){
        perror("Can't configure listening port");
        abort();
    }
    return sd;
}
SSL_CTX* InitServerCTX(void){   
    const SSL_METHOD *method;
    SSL_CTX *ctx;
    OpenSSL_add_all_algorithms();  /* load & register all cryptos, etc. */
    SSL_load_error_strings();   /* load all error messages */
    method = TLSv1_2_server_method();  /* create new server-method instance */
    ctx = SSL_CTX_new(method);   /* create new context from method */
    if ( ctx == NULL ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}
void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile){
    if (SSL_CTX_load_verify_locations(ctx, CertFile, KeyFile) != 1)
        ERR_print_errors_fp(stderr);

    SSL_CTX_set_default_passwd_cb_userdata(ctx, "xxxxx");

    if (SSL_CTX_set_default_verify_paths(ctx) != 1)
        ERR_print_errors_fp(stderr);

    /* set the local certificate from CertFile */
    if ( SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0 ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* set the private key from KeyFile (may be the same as CertFile) */
    if ( SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0 ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* verify private key */
    if ( !SSL_CTX_check_private_key(ctx) ){
        fprintf(stderr, "Private key does not match the public certificate\n");
        abort();
    }

    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);
    SSL_CTX_set_verify_depth(ctx, 4);
}
void ShowCerts(SSL* ssl){   
    X509 *cert;
    char *line;
    cert = SSL_get_peer_certificate(ssl); /* Get certificates (if available) */
    if ( cert != NULL ){
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);
        X509_free(cert);
    }else{
        printf("No certificates.\n");
    }
}
void Servlet(SSL* ssl){ /* Serve the connection -- threadable */   
    char buf[1024] = {0};
    int sd, bytes;
    const char* ServerResponse="receive and return content";
    const char *cpValidMessage = "helloword";							 
    if ( SSL_accept(ssl) == -1 ){     /* do SSL-protocol accept */
        ERR_print_errors_fp(stderr);
    }else{
        ShowCerts(ssl);        /* get any certificates */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get request */
        buf[bytes] = '\0';
        printf("Client msg: \"%s\"\n", buf);

        const char *cpRequestMessage = "this is content from client: \"%s\" and send to client";
        char acClientRequest[1024] ={0};							 
        sprintf(acClientRequest, cpRequestMessage, buf);

        if ( bytes > 0 ){
            //if(strcmp(cpValidMessage,buf) == 0){
            //    SSL_write(ssl, ServerResponse, strlen(ServerResponse)); /* send reply */
            //}else{
                SSL_write(ssl, acClientRequest, strlen(acClientRequest)); /* send reply */
            //}
        }else{
            ERR_print_errors_fp(stderr);
        }
    }
    sd = SSL_get_fd(ssl);       /* get socket connection */
    SSL_free(ssl);         /* release SSL state */
    close(sd);          /* close connection */
}
int main(int count, char *Argc[]){   
    SSL_CTX *ctx;
    int server;
    char *portnum;
    if ( count != 2 ){
        printf("Usage: %s <portnum>\n", Argc[0]);
        exit(0);
    }
    // Initialize the SSL library
    SSL_library_init();
    portnum = Argc[1];
    ctx = InitServerCTX();        /* initialize SSL */
    LoadCertificates(ctx, "cert.pem", "key.pem"); /* load certs */
    server = OpenListener(atoi(portnum));    /* create server socket */
    while (1){   
        struct sockaddr_in addr;
        socklen_t len = sizeof(addr);
        SSL *ssl;
        int client = accept(server, (struct sockaddr*)&addr, &len);  /* accept connection as usual */
        printf("Connection: %s:%d\n",inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
        ssl = SSL_new(ctx);              /* get new SSL state with context */
        SSL_set_fd(ssl, client);      /* set connection socket to SSL state */
        Servlet(ssl);         /* service connection */
    }
    close(server);          /* close server socket */
    SSL_CTX_free(ctx);         /* release context */
}

 编译命令: gcc -Wall -o server  server.c -L/usr/lib -lssl -lcrypto 

 

 

2. TLS 通讯client sample: client.c

 

#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/err.h>
#define FAIL    -1
int OpenConnection(const char *hostname, int port){   
    int sd;
    struct hostent *host;
    struct sockaddr_in addr;
    if ( (host = gethostbyname(hostname)) == NULL ){
        perror(hostname);
        abort();
    }
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = *(long*)(host->h_addr);
    if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 ){
        close(sd);
        perror(hostname);
        abort();
    }
    return sd;
}
SSL_CTX* InitCTX(void){   
    const SSL_METHOD *method;
    SSL_CTX *ctx;
    OpenSSL_add_all_algorithms();  /* Load cryptos, et.al. */
    SSL_load_error_strings();   /* Bring in and register error messages */
    method = TLSv1_2_client_method();  /* Create new client-method instance */
    ctx = SSL_CTX_new(method);   /* Create new context */
    if ( ctx == NULL ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}
void ShowCerts(SSL* ssl){   
    X509 *cert;
    char *line;
    cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
    if ( cert != NULL ){
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);       /* free the malloc'ed string */
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);       /* free the malloc'ed string */
        X509_free(cert);     /* free the malloc'ed certificate copy */
    }else{
        printf("Info: No client certificates configured.\n");
    }
}
void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile){
    /* set the local certificate from CertFile */
    if ( SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0 ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* set the private key from KeyFile (may be the same as CertFile) */
    if ( SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0 ){
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* verify private key */
    if ( !SSL_CTX_check_private_key(ctx) ){
        fprintf(stderr, "Private key does not match the public certificate\n");
        abort();
    }
}
int main(int count, char *strings[]){   
    SSL_CTX *ctx;
    int server;
    SSL *ssl;
    char buf[5000];
    char acClientRequest[5000] ={0};
    int bytes;
    char *hostname, *portnum;
    if ( count != 3 ){
        printf("usage: %s <hostname> <portnum>\n", strings[0]);
        exit(0);
    }
    SSL_library_init();
    hostname=strings[1];
    portnum=strings[2];
    ctx = InitCTX();
    printf("start load mycert1.pem file!\n"); //server request client send certificates file, otherwise can not receive msg
    LoadCertificates(ctx, "cert.pem", "key.pem"); /* load certs */
    server = OpenConnection(hostname, atoi(portnum));
    ssl = SSL_new(ctx);      /* create new SSL connection state */
    SSL_set_fd(ssl, server);    /* attach the socket descriptor */
    if ( SSL_connect(ssl) == FAIL ){   /* perform the connection */
        ERR_print_errors_fp(stderr);
    }else{  
        char acUsername[16] ={0};
        const char *quit = "exit";
        //char acPassword[16] ={0};
        //const char *cpRequestMessage = "<Body><UserName>%s<UserName><Password>%s<Password><\Body>";	
        while(1){
            const char *cpRequestMessage = "%s";							 
            printf("please enter the transport content : ");
            scanf("%s",acUsername);
            sprintf(acClientRequest, cpRequestMessage, acUsername);
            const char *a123 = acUsername;
            int index = strncmp(a123, quit,strlen(quit));
            printf("strncmp = %d\n",index);
            if( index == 0){
                break;
            }
            printf("\n\nConnected with %s encryption\n", SSL_get_cipher(ssl));
            ShowCerts(ssl);        /* get any certs */
            SSL_write(ssl,acClientRequest, strlen(acClientRequest));   /* encrypt & send message */
            bytes = SSL_read(ssl, buf, sizeof(buf)); /* get reply & decrypt */
            buf[bytes] = 0;
            printf("Received: \"%s\"\n", buf);
            memset(buf,0,sizeof(buf));
        }
        SSL_free(ssl);        /* release connection state */
    }
    close(server);         /* close socket */
    SSL_CTX_free(ctx);        /* release context */
    return 0;
}

 编译命令: gcc -Wall -o client  client.c -L/usr/lib -lssl -lcrypto

 

 

3. 生成私钥文件和生成自签署证书:

openssl genrsa -des3 -out key.pem 2048 //使用密码

openssl genrsa -out key.pem 2048

 

 

openssl req -new -x509 -key key.pem -days 3665 -out cert.pem

-new 为生成新的证书，会要求用户填写相关的信息

-x509 通常用于自签署证书，生成测试证书或用于CA自签署 

-key私钥位置  

-days申请的天数（默认30天） 

 

-out生成位置

 

参考链接:

https://wiki.openssl.org/index.php/Simple_TLS_Server

https://stackoverflow.com/questions/11705815/client-and-server-communication-using-ssl-c-c-ssl-protocol-dont-works