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1 /* |
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2 * Copyright (c) 1995 Danny Gasparovski |
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3 * |
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4 * Please read the file COPYRIGHT for the |
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5 * terms and conditions of the copyright. |
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6 */ |
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7 |
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8 /* |
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9 * mbuf's in SLiRP are much simpler than the real mbufs in |
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10 * FreeBSD. They are fixed size, determined by the MTU, |
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11 * so that one whole packet can fit. Mbuf's cannot be |
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12 * chained together. If there's more data than the mbuf |
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13 * could hold, an external malloced buffer is pointed to |
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14 * by m_ext (and the data pointers) and M_EXT is set in |
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15 * the flags |
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16 */ |
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17 |
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18 #include <slirp.h> |
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19 |
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20 int mbuf_alloced = 0; |
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21 struct mbuf m_freelist, m_usedlist; |
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22 #define MBUF_THRESH 30 |
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23 int mbuf_max = 0; |
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24 |
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25 /* |
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26 * Find a nice value for msize |
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27 * XXX if_maxlinkhdr already in mtu |
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28 */ |
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29 #define SLIRP_MSIZE (IF_MTU + IF_MAXLINKHDR + sizeof(struct m_hdr ) + 6) |
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30 |
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31 void |
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32 m_init() |
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33 { |
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34 m_freelist.m_next = m_freelist.m_prev = &m_freelist; |
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35 m_usedlist.m_next = m_usedlist.m_prev = &m_usedlist; |
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36 } |
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37 |
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38 /* |
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39 * Get an mbuf from the free list, if there are none |
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40 * malloc one |
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41 * |
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42 * Because fragmentation can occur if we alloc new mbufs and |
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43 * free old mbufs, we mark all mbufs above mbuf_thresh as M_DOFREE, |
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44 * which tells m_free to actually free() it |
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45 */ |
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46 struct mbuf * |
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47 m_get() |
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48 { |
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49 register struct mbuf *m; |
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50 int flags = 0; |
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51 |
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52 DEBUG_CALL("m_get"); |
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53 |
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54 if (m_freelist.m_next == &m_freelist) { |
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55 m = (struct mbuf *)malloc(SLIRP_MSIZE); |
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56 if (m == NULL) goto end_error; |
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57 mbuf_alloced++; |
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58 if (mbuf_alloced > MBUF_THRESH) |
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59 flags = M_DOFREE; |
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60 if (mbuf_alloced > mbuf_max) |
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61 mbuf_max = mbuf_alloced; |
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62 } else { |
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63 m = m_freelist.m_next; |
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64 remque(m); |
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65 } |
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66 |
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67 /* Insert it in the used list */ |
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68 insque(m,&m_usedlist); |
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69 m->m_flags = (flags | M_USEDLIST); |
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70 |
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71 /* Initialise it */ |
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72 m->m_size = SLIRP_MSIZE - sizeof(struct m_hdr); |
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73 m->m_data = m->m_dat; |
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74 m->m_len = 0; |
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75 m->m_nextpkt = 0; |
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76 m->m_prevpkt = 0; |
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77 end_error: |
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78 DEBUG_ARG("m = %lx", (long )m); |
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79 return m; |
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80 } |
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81 |
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82 void |
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83 m_free(m) |
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84 struct mbuf *m; |
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85 { |
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86 |
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87 DEBUG_CALL("m_free"); |
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88 DEBUG_ARG("m = %lx", (long )m); |
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89 |
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90 if(m) { |
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91 /* Remove from m_usedlist */ |
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92 if (m->m_flags & M_USEDLIST) |
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93 remque(m); |
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94 |
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95 /* If it's M_EXT, free() it */ |
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96 if (m->m_flags & M_EXT) |
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97 free(m->m_ext); |
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98 |
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99 /* |
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100 * Either free() it or put it on the free list |
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101 */ |
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102 if (m->m_flags & M_DOFREE) { |
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103 free(m); |
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104 mbuf_alloced--; |
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105 } else if ((m->m_flags & M_FREELIST) == 0) { |
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106 insque(m,&m_freelist); |
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107 m->m_flags = M_FREELIST; /* Clobber other flags */ |
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108 } |
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109 } /* if(m) */ |
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110 } |
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111 |
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112 /* |
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113 * Copy data from one mbuf to the end of |
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114 * the other.. if result is too big for one mbuf, malloc() |
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115 * an M_EXT data segment |
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116 */ |
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117 void |
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118 m_cat(m, n) |
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119 register struct mbuf *m, *n; |
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120 { |
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121 /* |
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122 * If there's no room, realloc |
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123 */ |
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124 if (M_FREEROOM(m) < n->m_len) |
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125 m_inc(m,m->m_size+MINCSIZE); |
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126 |
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127 memcpy(m->m_data+m->m_len, n->m_data, n->m_len); |
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128 m->m_len += n->m_len; |
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129 |
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130 m_free(n); |
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131 } |
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132 |
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133 |
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134 /* make m size bytes large */ |
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135 void |
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136 m_inc(m, size) |
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137 struct mbuf *m; |
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138 int size; |
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139 { |
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140 int datasize; |
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141 |
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142 /* some compiles throw up on gotos. This one we can fake. */ |
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143 if(m->m_size>size) return; |
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144 |
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145 if (m->m_flags & M_EXT) { |
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146 datasize = m->m_data - m->m_ext; |
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147 m->m_ext = (char *)realloc(m->m_ext,size); |
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148 /* if (m->m_ext == NULL) |
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149 * return (struct mbuf *)NULL; |
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150 */ |
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151 m->m_data = m->m_ext + datasize; |
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152 } else { |
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153 char *dat; |
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154 datasize = m->m_data - m->m_dat; |
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155 dat = (char *)malloc(size); |
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156 /* if (dat == NULL) |
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157 * return (struct mbuf *)NULL; |
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158 */ |
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159 memcpy(dat, m->m_dat, m->m_size); |
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160 |
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161 m->m_ext = dat; |
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162 m->m_data = m->m_ext + datasize; |
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163 m->m_flags |= M_EXT; |
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164 } |
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165 |
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166 m->m_size = size; |
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167 |
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168 } |
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169 |
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170 |
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171 |
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172 void |
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173 m_adj(m, len) |
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174 struct mbuf *m; |
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175 int len; |
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176 { |
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177 if (m == NULL) |
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178 return; |
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179 if (len >= 0) { |
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180 /* Trim from head */ |
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181 m->m_data += len; |
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182 m->m_len -= len; |
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183 } else { |
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184 /* Trim from tail */ |
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185 len = -len; |
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186 m->m_len -= len; |
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187 } |
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188 } |
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189 |
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190 |
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191 /* |
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192 * Copy len bytes from m, starting off bytes into n |
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193 */ |
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194 int |
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195 m_copy(n, m, off, len) |
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196 struct mbuf *n, *m; |
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197 int off, len; |
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198 { |
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199 if (len > M_FREEROOM(n)) |
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200 return -1; |
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201 |
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202 memcpy((n->m_data + n->m_len), (m->m_data + off), len); |
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203 n->m_len += len; |
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204 return 0; |
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205 } |
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206 |
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207 |
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208 /* |
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209 * Given a pointer into an mbuf, return the mbuf |
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210 * XXX This is a kludge, I should eliminate the need for it |
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211 * Fortunately, it's not used often |
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212 */ |
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213 struct mbuf * |
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214 dtom(dat) |
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215 void *dat; |
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216 { |
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217 struct mbuf *m; |
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218 |
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219 DEBUG_CALL("dtom"); |
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220 DEBUG_ARG("dat = %lx", (long )dat); |
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221 |
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222 /* bug corrected for M_EXT buffers */ |
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223 for (m = m_usedlist.m_next; m != &m_usedlist; m = m->m_next) { |
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224 if (m->m_flags & M_EXT) { |
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225 if( (char *)dat>=m->m_ext && (char *)dat<(m->m_ext + m->m_size) ) |
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226 return m; |
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227 } else { |
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228 if( (char *)dat >= m->m_dat && (char *)dat<(m->m_dat + m->m_size) ) |
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229 return m; |
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230 } |
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231 } |
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232 |
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233 DEBUG_ERROR((dfd, "dtom failed")); |
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234 |
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235 return (struct mbuf *)0; |
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236 } |