diff --git a/.vscode/settings.json b/.vscode/settings.json
index 728bda3..28c5256 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,3 +1,8 @@
 {
-    "C_Cpp.default.defines": ["_GNU_SOURCE"]
+    "C_Cpp.default.defines": [
+        "_GNU_SOURCE"
+    ],
+    "files.associations": {
+        "socket_wrapper.h": "c"
+    }
 }
\ No newline at end of file
diff --git a/Makefile b/Makefile
index 76853c6..767b38f 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 CC = gcc
 CFLAGS = -lm -Wall -O2
 
-Bin = server client
+Bin = server client p-server p-client
 
 all:
 	make $(Bin)
@@ -11,8 +11,12 @@ socket_wrapper.o: socket_wrapper.c socket_wrapper.h
 
 client: socket_wrapper.o client.c
 	$(CC) -o client client.c socket_wrapper.o $(CFLAGS)
-server:
+server:  socket_wrapper.o server.c
 	$(CC) -o server server.c socket_wrapper.o $(CFLAGS)
+p-server: socket_wrapper.o p-server.c
+	$(CC) -o p-server p-server.c socket_wrapper.o $(CFLAGS)
+p-client: socket_wrapper.o p-client.c
+	$(CC) -o p-client p-client.c socket_wrapper.o $(CFLAGS)
 
 .PHONY: clean
 clean:
diff --git a/client.c b/client.c
index 5601ebd..38c9fbf 100644
--- a/client.c
+++ b/client.c
@@ -140,10 +140,10 @@ int main(int argc, const char *argv[]){
         perror("sock create fail");
         return 1;
     }
-    err = getsockaddrbyname(AF_INET,SOCK_STREAM,0,server_name,&addr);
+    err = getsockaddrbyname(AF_INET,SOCK_STREAM,0,server_name,((struct sockaddr *)&addr));
     if (err != 0){
         int check;
-        fprintf(stderr,"netdb fail: %s\n",gai_error(err));
+        fprintf(stderr,"netdb fail: %s\n",gai_strerror(err));
         //assume that sernmae is *.*.*.* and try to parse addr
         check = inet_pton(AF_INET,server_name,&addr.sin_addr);
         assert(check != -1);
diff --git a/p-client.c b/p-client.c
new file mode 100644
index 0000000..f010eeb
--- /dev/null
+++ b/p-client.c
@@ -0,0 +1,169 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <sys/stat.h>
+
+#include <assert.h>
+#include <fcntl.h>
+#include "socket_wrapper.h"
+
+#ifdef USE_SENDFILE
+#include <sys/sendfile.h>
+const size_t SEND_FILE_CHUNK_SIZE = 0x100000; /*1MB*/
+#endif
+
+/*========
+ *Operation
+ *========*/
+
+int sendReadOp(int sock,const char * filename){
+    struct ReadOp op;
+    op.file_url_size = strlen(filename);
+    op.padding0 = 0;
+    if(send(sock,&op,sizeof(op),0)<0){
+        perror("readop send fail");
+        return -1;
+    }
+    if(send(sock,filename,op.file_url_size,0)<0){
+        perror("readop filename send fail");
+        return -1;
+    }
+    return 0;
+}
+
+int recvFile(int sock, const char * filename,size_t file_size){
+    int fd;
+    size_t count = 0;
+    int i;
+    int cur_progress = 1;
+    int return_value = 0;
+    int buf_sz = getBufferSizeFrom(sock);
+    uint8_t * buf = malloc(buf_sz*sizeof(*buf));
+    if (buf == NULL){
+        return -1;
+    }
+    fd = open(filename,O_WRONLY|O_CREAT|O_TRUNC,S_IRWXU|S_IRWXG|S_IROTH);
+    if (fd < 0)
+    {
+        perror("file open fail");
+        return -1;
+    }
+    
+    while (file_size - count > 0)
+    {
+        int readed = buf_sz < file_size - count ? buf_sz : file_size - count;
+        if((i = recv_until_byte(sock,buf,readed,TIMEOUT)) < 0){
+            if(i == -2) 
+                fprintf(stderr,"recv file failed : timeout connetion lost\n");
+            else perror("recv file failed");
+            return_value = -1;
+            goto END;
+        }
+        if(write(fd,buf,readed)<0){
+            perror("file write failed");
+            return_value = -1;
+            goto END;
+        }
+        if( ((double)count / (double)file_size) * 100.0 > ((double)cur_progress) ){
+            printf("\rprogress : %d%% current bytes: %ld bytes",cur_progress,count);
+            cur_progress = (int)((((double)count / (double)file_size)) * 100.0 + 1.0);
+            fflush(stdout);
+        }
+        count += readed;
+    }
+    printf("\rprogress : 100.00%% current bytes: %ld bytes\n",count);
+END:
+    free(buf);
+    return return_value;
+}
+
+int recvData(int sock,const char * filename){
+    struct TransferResult res;
+    int i=0;
+    if((i=recv_until_byte(sock,&res,sizeof(res),TIMEOUT)) < 0){
+        if (i == -2) fprintf(stderr,"timeout");
+        else perror("recv fail");
+        return -1;
+    }
+    static char error_meesage_buf[80] = "";
+    switch(res.res){
+        case RES_ERR:
+            fprintf(stderr,"Server Fail: %s", strerror(res.err_number));
+            return -1;
+        case RES_USR_ERR:
+            assert(res.error_msg_size < 80);/*todo : fix*/
+            if((i=recv_until_byte(sock,error_meesage_buf,res.error_msg_size,TIMEOUT)) < 0){
+                if (i == -2) fprintf(stderr,"timeout");
+                else perror("recv fail");
+                return -1;
+            }
+            fprintf(stderr,"Error Message From Server: %s",error_meesage_buf);
+            return -1;
+        case RES_OK:
+            return recvFile(sock,filename,res.file_size);
+            break;
+        default:
+            fprintf(stderr,"unknown value!");
+            return -1;
+    }
+
+    return 0;
+}
+
+int main(int argc, const char *argv[]){
+    struct sockaddr_in addr;
+    const char * filename;
+    const char * server_name;
+    in_port_t server_port = SERVER_PORT;
+    int sock, err;
+    if (argc != 4){
+        fprintf(stderr,"invaild arguments number.");
+        return 1;
+    }
+    server_name = argv[1];
+    server_port = atoi(argv[2]);
+    filename = argv[3];
+    if (server_port == 0)
+    {
+        fprintf(stderr,"port invalid");
+        return 1;
+    }
+    sock = socket(AF_INET,SOCK_STREAM,0);
+    if(sock < 0){
+        perror("sock create fail");
+        return 1;
+    }
+    err = getsockaddrbyname(AF_INET,SOCK_STREAM,0,server_name,(struct sockaddr *)&addr);
+    if (err != 0){
+        int check;
+        fprintf(stderr,"netdb fail: %s\n",gai_strerror(err));
+        //assume that sernmae is *.*.*.* and try to parse addr
+        check = inet_pton(AF_INET,server_name,&addr.sin_addr);
+        assert(check != -1);
+        if (check == 0){
+            fprintf(stderr,"parsing fail : invaild format\n");
+            close(sock);
+            return 1;
+        }
+    }
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(server_port);
+    if(connect(sock,(struct sockaddr *)&addr,sizeof(addr)) < 0){
+        perror("connect failed");
+        return 1;
+    }
+    if(sendReadOp(sock,filename) == 0){
+        int ret = recvData(sock,filename);
+        close(sock);
+        return ret;
+    }
+    close(sock);
+    return 0;
+}
\ No newline at end of file
diff --git a/p-server.c b/p-server.c
new file mode 100644
index 0000000..44c2547
--- /dev/null
+++ b/p-server.c
@@ -0,0 +1,224 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <signal.h>
+#include <assert.h>
+#include <fcntl.h>
+#include "socket_wrapper.h"
+
+/*========
+ *Operation
+ *========*/
+
+/**
+ * send user error message
+ * 80 character limit
+ * thread safe
+*/
+int send_fail(int sock,const char * msg){
+    struct TransferResult res;
+    res.res = RES_USR_ERR;
+    res.file_size = 0;
+    res.err_number = 0;
+    res.error_msg_size = strlen(msg);
+    //os will be combining if tcp_autocorking emabled.
+    if(send(sock,&res,sizeof(res),0) < 0){
+        perror("error msg send");
+        return -1;
+    }
+    if (send(sock,msg,res.error_msg_size,0) < 0){
+        perror("error msg send");
+        return -1;
+    }
+    return 0;
+}
+/**
+ * send errno to client
+ * thread safe
+ */
+int send_errno(int sock){
+    struct TransferResult r;
+    r.res = RES_ERR;
+    r.err_number = errno;
+    r.file_size = 0;
+    r.error_msg_size = 0;
+    if(send(sock,&r,sizeof(r),0)){
+        perror("errno send");
+        return -1;
+    }
+    return 0;
+}
+/**
+ * return fd, if success. otherwise, return -1.
+ * thread safe
+*/
+int read_request(int sock,uint8_t * buf,size_t bufsize){
+    struct ReadOp p;
+    int fd;
+    ssize_t n = recv_until_byte(sock,&p,sizeof(p),TIMEOUT);
+    if (n < 0){
+        if (n == -2) fprintf(stderr,"timeout!");
+        else perror("receive fail"); 
+        return -1;
+    }
+    if(bufsize <= ((size_t)p.file_url_size) + sizeof(p) + 1){
+        send_fail(sock,"buffer overflow");
+        return -1;
+    }
+    else if(p.file_url_size + 1 > MAX_PATH_SIZE){
+        send_fail(sock,"max path fail");
+        return -1;
+    }
+    else if(p.file_url_size == 0){
+        send_fail(sock,"filename zero fail");
+        return -1;
+    }
+    n = recv_until_byte(sock,buf,p.file_url_size,TIMEOUT);
+    buf[p.file_url_size] = '\0';    //truncate
+    fprintf(stdout,"str size: %d, request %s\n",p.file_url_size,buf);
+    if(strchr((char *)buf,'/') != NULL){
+        send_fail(sock,"Illegal character /");
+        return -1;
+    }
+    fd = open((char *)buf,O_RDONLY);
+    if(fd < 0){
+        send_errno(sock);
+        close(fd);
+        return -1;
+    }
+    return fd;
+}
+/**
+ * send response to client
+ * thread safe
+*/
+int send_response(int sock,int fd, uint8_t * buf, size_t bufsize){
+    struct TransferResult r;
+    struct stat st;
+    off_t offset = 0;
+    ssize_t readed = 0;
+    r.res = RES_OK;
+    r.err_number = 0;
+    r.error_msg_size = 0;
+    if(fstat(fd,&st) < 0){
+        return send_errno(sock);
+    }
+    if(S_ISDIR(st.st_mode)){
+        return send_fail(sock,"is a directory");
+    }
+    r.file_size = st.st_size;
+    if(send(sock,&r,sizeof(r),0)<0){
+        perror("send fail");
+        return -1;
+    }
+#ifdef USE_SENDFILE
+    while (r.file_size != offset)
+    {
+        size_t count = SEND_FILE_CHUNK_SIZE < (r.file_size - offset) ? SEND_FILE_CHUNK_SIZE : (r.file_size - offset);
+        if((readed = sendfile(sock,fd,&offset,count)) < 0){
+            perror("send file fail");
+            return -1;
+        }
+    }
+#else
+    while (offset < r.file_size)
+    {
+        readed = bufsize < (r.file_size - offset) ? bufsize : r.file_size - offset;
+        if(read(fd,buf,readed)<0){
+            perror("send response read fail");
+            return -1;
+        }
+        if(send(sock,buf,readed,0)<0){
+            perror("send response send fail");
+            return -1;
+        }
+        offset += readed;
+    }
+    
+#endif
+    return 0;
+}
+static int sock;
+void safe_exit(){
+    close(sock);
+}
+int main(int argc, const char *argv[]){
+    uint8_t * buf;
+    struct sockaddr_in addr;
+    struct sockaddr_in client_addr;
+    socklen_t client_addr_len = sizeof(client_addr);
+    int csock;
+    int bufsize;
+    int i;
+    sock = socket(AF_INET,SOCK_STREAM,0);
+    atexit(safe_exit);
+    if(sock < 0){
+        perror("sock create fail");
+        return 1;
+    }
+    else {
+        int option = 1;
+        if(setsockopt(sock,SOL_SOCKET,SO_REUSEADDR,&option,sizeof(option)) < 0){
+            perror("setsockopt");
+        }
+    }
+    bufsize = getBufferSizeFrom(sock);
+    buf = malloc(bufsize * sizeof(*buf));
+    if (buf == NULL){
+        fprintf(stderr,"lack of memory");
+        return 1;
+    }
+    
+    addr.sin_addr.s_addr = htonl(INADDR_ANY); /*0.0.0.0 모든 네트워크 인터페이스에 묶임.*/
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons(SERVER_PORT);
+
+    if(bind(sock, (struct sockaddr *)&addr,sizeof(addr)) < 0){
+        perror("bind failed");
+        return 1;
+    } else {
+        char ip_buf[INET_ADDRSTRLEN];
+        const char * msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
+        assert(msg != NULL);
+        fprintf(stderr,"server bind on %s:%d\n",msg ,SERVER_PORT);
+    }
+    if(listen(sock,1) < 0){
+        perror("listen failed");
+        return 1;
+    }
+
+    for (i = 0; i < 3; i++)
+    {
+        int fd, pid;
+        char ip_buf[INET_ADDRSTRLEN];
+        const char * msg;
+        if((csock = accept(sock, (struct sockaddr *)&client_addr,&client_addr_len)) < 0){
+            free(buf);
+            perror("accept error");
+            return 1;
+        }
+        msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
+        fprintf(stderr,"Connected on : %s:%d\n",msg == NULL ? "(null)" : msg , ntohs(addr.sin_port));
+        pid = fork();
+        if(pid == 0){
+            if((fd = read_request(csock,buf,bufsize)) > 0){
+                send_response(csock,fd,buf,bufsize);
+                close(fd);
+            }
+            if(close(csock) < 0)
+                perror("csock close error");
+            free(buf);
+            return 0;
+        }
+    }
+    free(buf);
+    return 0;
+}
\ No newline at end of file
diff --git a/server.c b/server.c
index 21b990e..c654071 100644
--- a/server.c
+++ b/server.c
@@ -185,7 +185,7 @@ int main(int argc, const char *argv[]){
         return 1;
     } else {
         char ip_buf[INET_ADDRSTRLEN];
-        char * msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
+        const char * msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
         assert(msg != NULL);
         fprintf(stderr,"server bind on %s:%d\n",msg ,SERVER_PORT);
     }
@@ -199,7 +199,7 @@ int main(int argc, const char *argv[]){
     {
         int fd;
         char ip_buf[INET_ADDRSTRLEN];
-        char * msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
+        const char * msg = inet_ntop(AF_INET,&addr.sin_addr,ip_buf,sizeof(ip_buf));
         fprintf(stderr,"Connected on : %s:%d\n",msg == NULL ? "(null)" : msg , ntohs(addr.sin_port));
         if((fd = read_request(csock,buf,bufsize)) > 0){
             send_response(csock,fd,buf,bufsize);
diff --git a/socket_wrapper.c b/socket_wrapper.c
index 4e8ef57..5153bcf 100644
--- a/socket_wrapper.c
+++ b/socket_wrapper.c
@@ -67,8 +67,6 @@ int getsockaddrbyname(int domain,int type, int protocol, const char * hostname_s
     struct addrinfo hints;
     struct addrinfo * result, *entry;
     int ret, i;
-    char hostname[_SC_HOST_NAME_MAX];
-    strncpy(hostname,hostname_str,sizeof(hostname));
     memset(&hints,0,sizeof(hints));
     hints.ai_family = domain;
     hints.ai_socktype = type;
@@ -76,9 +74,9 @@ int getsockaddrbyname(int domain,int type, int protocol, const char * hostname_s
     hints.ai_protocol = protocol;
 
     //try 5 times
-    for (size_t i = 0; i < 5; i++)
+    for (i = 0; i < 5; i++)
     {
-        ret = getaddrinfo(hostname,NULL,&hints,&result);
+        ret = getaddrinfo(hostname_str,NULL,&hints,&result);
         if(ret == EAI_AGAIN) continue;
         else if (ret != 0) return ret;
         break;